[dev.inline] merge with master at 894d24d617

Change-Id: I845eec08108c69228ebcba921f8a807a376d3fae

VERSION

@@ -1,2 +0,0 @@
-go1.21.12
-time 2024-06-27T20:11:12Z

api/go1.21.txt

@@ -60,9 +60,7 @@ pkg crypto/tls, method (*QUICConn) Close() error #44886
 pkg crypto/tls, method (*QUICConn) ConnectionState() ConnectionState #44886
 pkg crypto/tls, method (*QUICConn) HandleData(QUICEncryptionLevel, []uint8) error #44886
 pkg crypto/tls, method (*QUICConn) NextEvent() QUICEvent #44886
-pkg crypto/tls, method (*QUICConn) SendSessionTicket(QUICSessionTicketOptions) error #60107
-pkg crypto/tls, type QUICSessionTicketOptions struct #60107
-pkg crypto/tls, type QUICSessionTicketOptions struct, EarlyData bool #60107
+pkg crypto/tls, method (*QUICConn) SendSessionTicket(bool) error #60107
 pkg crypto/tls, method (*QUICConn) SetTransportParameters([]uint8) #44886
 pkg crypto/tls, method (*QUICConn) Start(context.Context) error #44886
 pkg crypto/tls, method (QUICEncryptionLevel) String() string #44886
@@ -221,18 +219,18 @@ pkg log/slog, func Any(string, interface{}) Attr #56345
 pkg log/slog, func AnyValue(interface{}) Value #56345
 pkg log/slog, func Bool(string, bool) Attr #56345
 pkg log/slog, func BoolValue(bool) Value #56345
-pkg log/slog, func DebugContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, func DebugCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, func Debug(string, ...interface{}) #56345
 pkg log/slog, func Default() *Logger #56345
 pkg log/slog, func Duration(string, time.Duration) Attr #56345
 pkg log/slog, func DurationValue(time.Duration) Value #56345
-pkg log/slog, func ErrorContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, func ErrorCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, func Error(string, ...interface{}) #56345
 pkg log/slog, func Float64(string, float64) Attr #56345
 pkg log/slog, func Float64Value(float64) Value #56345
 pkg log/slog, func Group(string, ...interface{}) Attr #59204
 pkg log/slog, func GroupValue(...Attr) Value #56345
-pkg log/slog, func InfoContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, func InfoCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, func Info(string, ...interface{}) #56345
 pkg log/slog, func Int64(string, int64) Attr #56345
 pkg log/slog, func Int64Value(int64) Value #56345
@@ -252,7 +250,7 @@ pkg log/slog, func Time(string, time.Time) Attr #56345
 pkg log/slog, func TimeValue(time.Time) Value #56345
 pkg log/slog, func Uint64(string, uint64) Attr #56345
 pkg log/slog, func Uint64Value(uint64) Value #56345
-pkg log/slog, func WarnContext(context.Context, string, ...interface{})  #61200
+pkg log/slog, func WarnCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, func Warn(string, ...interface{}) #56345
 pkg log/slog, func With(...interface{}) *Logger #56345
 pkg log/slog, method (Attr) Equal(Attr) bool #56345
@@ -273,17 +271,17 @@ pkg log/slog, method (*LevelVar) MarshalText() ([]uint8, error) #56345
 pkg log/slog, method (*LevelVar) Set(Level) #56345
 pkg log/slog, method (*LevelVar) String() string #56345
 pkg log/slog, method (*LevelVar) UnmarshalText([]uint8) error #56345
-pkg log/slog, method (*Logger) DebugContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, method (*Logger) DebugCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Debug(string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Enabled(context.Context, Level) bool #56345
-pkg log/slog, method (*Logger) ErrorContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, method (*Logger) ErrorCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Error(string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Handler() Handler #56345
-pkg log/slog, method (*Logger) InfoContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, method (*Logger) InfoCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Info(string, ...interface{}) #56345
 pkg log/slog, method (*Logger) LogAttrs(context.Context, Level, string, ...Attr) #56345
 pkg log/slog, method (*Logger) Log(context.Context, Level, string, ...interface{}) #56345
-pkg log/slog, method (*Logger) WarnContext(context.Context, string, ...interface{}) #61200
+pkg log/slog, method (*Logger) WarnCtx(context.Context, string, ...interface{}) #56345
 pkg log/slog, method (*Logger) Warn(string, ...interface{}) #56345
 pkg log/slog, method (*Logger) WithGroup(string) *Logger #56345
 pkg log/slog, method (*Logger) With(...interface{}) *Logger #56345
@@ -346,6 +344,8 @@ pkg maps, func Copy[$0 interface{ ~map[$2]$3 }, $1 interface{ ~map[$2]$3 }, $2 c
 pkg maps, func DeleteFunc[$0 interface{ ~map[$1]$2 }, $1 comparable, $2 interface{}]($0, func($1, $2) bool) #57436
 pkg maps, func Equal[$0 interface{ ~map[$2]$3 }, $1 interface{ ~map[$2]$3 }, $2 comparable, $3 comparable]($0, $1) bool #57436
 pkg maps, func EqualFunc[$0 interface{ ~map[$2]$3 }, $1 interface{ ~map[$2]$4 }, $2 comparable, $3 interface{}, $4 interface{}]($0, $1, func($3, $4) bool) bool #57436
+pkg maps, func Keys[$0 interface{ ~map[$1]$2 }, $1 comparable, $2 interface{}]($0) []$1 #57436
+pkg maps, func Values[$0 interface{ ~map[$1]$2 }, $1 comparable, $2 interface{}]($0) []$2 #57436
 pkg math/big, method (*Int) Float64() (float64, Accuracy) #56984
 pkg net/http, method (*ProtocolError) Is(error) bool #41198
 pkg net/http, method (*ResponseController) EnableFullDuplex() error #57786

codereview.cfg

@@ -1,2 +1,2 @@
-branch: release-branch.go1.21
+branch: dev.inline
 parent-branch: master

doc/go_spec.html

@@ -1,6 +1,6 @@
 <!--{
 	"Title": "The Go Programming Language Specification",
-	"Subtitle": "Version of Aug 2, 2023",
+	"Subtitle": "Version of June 14, 2023",
 	"Path": "/ref/spec"
 }-->
 
@@ -2511,7 +2511,7 @@ type (
 
 <p>
 A type definition creates a new, distinct type with the same
-<a href="#Underlying_types">underlying type</a> and operations as the given type
+<a href="#Types">underlying type</a> and operations as the given type
 and binds an identifier, the <i>type name</i>, to it.
 </p>
 
@@ -4343,7 +4343,7 @@ type parameter list    type arguments    after substitution
 When using a generic function, type arguments may be provided explicitly,
 or they may be partially or completely <a href="#Type_inference">inferred</a>
 from the context in which the function is used.
-Provided that they can be inferred, type argument lists may be omitted entirely if the function is:
+Provided that they can be inferred, type arguments may be omitted entirely if the function is:
 </p>
 
 <ul>
@@ -4351,7 +4351,7 @@ Provided that they can be inferred, type argument lists may be omitted entirely
 	<a href="#Calls">called</a> with ordinary arguments,
 </li>
 <li>
-	<a href="#Assignment_statements">assigned</a> to a variable with a known type
+	<a href="#Assignment_statements">assigned</a> to a variable with an explicitly declared type,
 </li>
 <li>
 	<a href="#Calls">passed as an argument</a> to another function, or
@@ -4371,7 +4371,7 @@ must be inferrable from the context in which the function is used.
 // sum returns the sum (concatenation, for strings) of its arguments.
 func sum[T ~int | ~float64 | ~string](x... T) T { … }
 
-x := sum                       // illegal: the type of x is unknown
+x := sum                       // illegal: sum must have a type argument (x is a variable without a declared type)
 intSum := sum[int]             // intSum has type func(x... int) int
 a := intSum(2, 3)              // a has value 5 of type int
 b := sum[float64](2.0, 3)      // b has value 5.0 of type float64
@@ -4406,323 +4406,402 @@ For a generic type, all type arguments must always be provided explicitly.
 <h3 id="Type_inference">Type inference</h3>
 
 <p>
-A use of a generic function may omit some or all type arguments if they can be
-<i>inferred</i> from the context within which the function is used, including
-the constraints of the function's type parameters.
-Type inference succeeds if it can infer the missing type arguments
-and <a href="#Instantiations">instantiation</a> succeeds with the
-inferred type arguments.
-Otherwise, type inference fails and the program is invalid.
+<em>NOTE: This section is not yet up-to-date for Go 1.21.</em>
 </p>
 
 <p>
-Type inference uses the type relationships between pairs of types for inference:
-For instance, a function argument must be <a href="#Assignability">assignable</a>
-to its respective function parameter; this establishes a relationship between the
-type of the argument and the type of the parameter.
-If either of these two types contains type parameters, type inference looks for the
-type arguments to substitute the type parameters with such that the assignability
-relationship is satisfied.
-Similarly, type inference uses the fact that a type argument must
-<a href="#Satisfying_a_type_constraint">satisfy</a> the constraint of its respective
-type parameter.
+Missing function type arguments may be <i>inferred</i> by a series of steps, described below.
+Each step attempts to use known information to infer additional type arguments.
+Type inference stops as soon as all type arguments are known.
+After type inference is complete, it is still necessary to substitute all type arguments
+for type parameters and verify that each type argument
+<a href="#Implementing_an_interface">implements</a> the relevant constraint;
+it is possible for an inferred type argument to fail to implement a constraint, in which
+case instantiation fails.
 </p>
 
 <p>
-Each such pair of matched types corresponds to a <i>type equation</i> containing
-one or multiple type parameters, from one or possibly multiple generic functions.
-Inferring the missing type arguments means solving the resulting set of type
-equations for the respective type parameters.
-</p>
-
-<p>
-For example, given
-</p>
-
-<pre>
-// dedup returns a copy of the argument slice with any duplicate entries removed.
-func dedup[S ~[]E, E comparable](S) S { … }
-
-type Slice []int
-var s Slice
-s = dedup(s)   // same as s = dedup[Slice, int](s)
-</pre>
-
-<p>
-the variable <code>s</code> of type <code>Slice</code> must be assignable to
-the function parameter type <code>S</code> for the program to be valid.
-To reduce complexity, type inference ignores the directionality of assignments,
-so the type relationship between <code>Slice</code> and <code>S</code> can be
-expressed via the (symmetric) type equation <code>Slice ≡<sub>A</sub> S</code>
-(or <code>S ≡<sub>A</sub> Slice</code> for that matter),
-where the <code><sub>A</sub></code> in <code>≡<sub>A</sub></code>
-indicates that the LHS and RHS types must match per assignability rules
-(see the section on <a href="#Type_unification">type unification</a> for
-details).
-Similarly, the type parameter <code>S</code> must satisfy its constraint
-<code>~[]E</code>. This can be expressed as <code>S ≡<sub>C</sub> ~[]E</code>
-where <code>X ≡<sub>C</sub> Y</code> stands for
-"<code>X</code> satisfies constraint <code>Y</code>".
-These observations lead to a set of two equations
-</p>
-
-<pre>
-	Slice ≡<sub>A</sub> S      (1)
-	S     ≡<sub>C</sub> ~[]E   (2)
-</pre>
-
-<p>
-which now can be solved for the type parameters <code>S</code> and <code>E</code>.
-From (1) a compiler can infer that the type argument for <code>S</code> is <code>Slice</code>.
-Similarly, because the underlying type of <code>Slice</code> is <code>[]int</code>
-and <code>[]int</code> must match <code>[]E</code> of the constraint,
-a compiler can infer that <code>E</code> must be <code>int</code>.
-Thus, for these two equations, type inference infers
-</p>
-
-<pre>
-	S ➞ Slice
-	E ➞ int
-</pre>
-
-<p>
-Given a set of type equations, the type parameters to solve for are
-the type parameters of the functions that need to be instantiated
-and for which no explicit type arguments is provided.
-These type parameters are called <i>bound</i> type parameters.
-For instance, in the <code>dedup</code> example above, the type parameters
-<code>P</code> and <code>E</code> are bound to <code>dedup</code>.
-An argument to a generic function call may be a generic function itself.
-The type parameters of that function are included in the set of bound
-type parameters.
-The types of function arguments may contain type parameters from other
-functions (such as a generic function enclosing a function call).
-Those type parameters may also appear in type equations but they are
-not bound in that context.
-Type equations are always solved for the bound type parameters only.
-</p>
-
-<p>
-Type inference supports calls of generic functions and assignments
-of generic functions to (explicitly function-typed) variables.
-This includes passing generic functions as arguments to other
-(possibly also generic) functions, and returning generic functions
-as results.
-Type inference operates on a set of equations specific to each of
-these cases.
-The equations are as follows (type argument lists are omitted for clarity):
+Type inference is based on
 </p>
 
 <ul>
 <li>
-	<p>
-	For a function call <code>f(a<sub>0</sub>, a<sub>1</sub>, …)</code> where
-	<code>f</code> or a function argument <code>a<sub>i</sub></code> is
-	a generic function:
-	<br>
-	Each pair <code>(a<sub>i</sub>, p<sub>i</sub>)</code> of corresponding
-	function arguments and parameters where <code>a<sub>i</sub></code> is not an
-	<a href="#Constants">untyped constant</a> yields an equation
-	<code>typeof(p<sub>i</sub>) ≡<sub>A</sub> typeof(a<sub>i</sub>)</code>.
-	<br>
-	If <code>a<sub>i</sub></code> is an untyped constant <code>c<sub>j</sub></code>,
-	and <code>typeof(p<sub>i</sub>)</code> is a bound type parameter <code>P<sub>k</sub></code>,
-	the pair <code>(c<sub>j</sub>, P<sub>k</sub>)</code> is collected separately from
-	the type equations.
-	</p>
+	a <a href="#Type_parameter_declarations">type parameter list</a>
 </li>
 <li>
-	<p>
-	For an assignment <code>v = f</code> of a generic function <code>f</code> to a
-	(non-generic) variable <code>v</code> of function type:
-	<br>
-	<code>typeof(v) ≡<sub>A</sub> typeof(f)</code>.
-	</p>
+	a substitution map <i>M</i> initialized with the known type arguments, if any
 </li>
 <li>
-	<p>
-	For a return statement <code>return …, f, … </code> where <code>f</code> is a
-	generic function returned as a result to a (non-generic) result variable
-	<code>r</code> of function type:
-	<br>
-	<code>typeof(r) ≡<sub>A</sub> typeof(f)</code>.
-	</p>
+	a (possibly empty) list of ordinary function arguments (in case of a function call only)
 </li>
 </ul>
 
 <p>
-Additionally, each type parameter <code>P<sub>k</sub></code> and corresponding type constraint
-<code>C<sub>k</sub></code> yields the type equation
-<code>P<sub>k</sub> ≡<sub>C</sub> C<sub>k</sub></code>.
-</p>
-
-<p>
-Type inference gives precedence to type information obtained from typed operands
-before considering untyped constants.
-Therefore, inference proceeds in two phases:
+and then proceeds with the following steps:
 </p>
 
 <ol>
 <li>
-	<p>
-	The type equations are solved for the bound
-	type parameters using <a href="#Type_unification">type unification</a>.
-	If unification fails, type inference fails.
-	</p>
+	apply <a href="#Function_argument_type_inference"><i>function argument type inference</i></a>
+	to all <i>typed</i> ordinary function arguments
 </li>
 <li>
-	<p>
-	For each bound type parameter <code>P<sub>k</sub></code> for which no type argument
-	has been inferred yet and for which one or more pairs
-	<code>(c<sub>j</sub>, P<sub>k</sub>)</code> with that same type parameter
-	were collected, determine the <a href="#Constant_expressions">constant kind</a>
-	of the constants <code>c<sub>j</sub></code> in all those pairs the same way as for
-	<a href="#Constant_expressions">constant expressions</a>.
-	The type argument for <code>P<sub>k</sub></code> is the
-	<a href="#Constants">default type</a> for the determined constant kind.
-	If a constant kind cannot be determined due to conflicting constant kinds,
-	type inference fails.
-	</p>
+	apply <a href="#Constraint_type_inference"><i>constraint type inference</i></a>
+</li>
+<li>
+	apply function argument type inference to all <i>untyped</i> ordinary function arguments
+	using the default type for each of the untyped function arguments
+</li>
+<li>
+	apply constraint type inference
 </li>
 </ol>
 
 <p>
-If not all type arguments have been found after these two phases, type inference fails.
+If there are no ordinary or untyped function arguments, the respective steps are skipped.
+Constraint type inference is skipped if the previous step didn't infer any new type arguments,
+but it is run at least once if there are missing type arguments.
 </p>
 
 <p>
-If the two phases are successful, type inference determined a type argument for each
-bound type parameter:
-</p>
-
-<pre>
-	P<sub>k</sub> ➞ A<sub>k</sub>
-</pre>
-
-<p>
-A type argument <code>A<sub>k</sub></code> may be a composite type,
-containing other bound type parameters <code>P<sub>k</sub></code> as element types
-(or even be just another bound type parameter).
-In a process of repeated simplification, the bound type parameters in each type
-argument are substituted with the respective type arguments for those type
-parameters until each type argument is free of bound type parameters.
-</p>
-
-<p>
-If type arguments contain cyclic references to themselves
-through bound type parameters, simplification and thus type
-inference fails.
-Otherwise, type inference succeeds.
+The substitution map <i>M</i> is carried through all steps, and each step may add entries to <i>M</i>.
+The process stops as soon as <i>M</i> has a type argument for each type parameter or if an inference step fails.
+If an inference step fails, or if <i>M</i> is still missing type arguments after the last step, type inference fails.
 </p>
 
 <h4 id="Type_unification">Type unification</h4>
 
 <p>
-Type inference solves type equations through <i>type unification</i>.
-Type unification recursively compares the LHS and RHS types of an
-equation, where either or both types may be or contain bound type parameters,
-and looks for type arguments for those type parameters such that the LHS
-and RHS match (become identical or assignment-compatible, depending on
-context).
-To that effect, type inference maintains a map of bound type parameters
-to inferred type arguments; this map is consulted and updated during type unification.
-Initially, the bound type parameters are known but the map is empty.
-During type unification, if a new type argument <code>A</code> is inferred,
-the respective mapping <code>P ➞ A</code> from type parameter to argument
-is added to the map.
-Conversely, when comparing types, a known type argument
-(a type argument for which a map entry already exists)
-takes the place of its corresponding type parameter.
-As type inference progresses, the map is populated more and more
-until all equations have been considered, or until unification fails.
-Type inference succeeds if no unification step fails and the map has
-an entry for each type parameter.
+Type inference is based on <i>type unification</i>. A single unification step
+applies to a <a href="#Type_inference">substitution map</a> and two types, either
+or both of which may be or contain type parameters. The substitution map tracks
+the known (explicitly provided or already inferred) type arguments: the map
+contains an entry <code>P</code> &RightArrow; <code>A</code> for each type
+parameter <code>P</code> and corresponding known type argument <code>A</code>.
+During unification, known type arguments take the place of their corresponding type
+parameters when comparing types. Unification is the process of finding substitution
+map entries that make the two types equivalent.
 </p>
 
-</pre>
-For example, given the type equation with the bound type parameter
-<code>P</code>
+<p>
+For unification, two types that don't contain any type parameters from the current type
+parameter list are <i>equivalent</i>
+if they are identical, or if they are channel types that are identical ignoring channel
+direction, or if their underlying types are equivalent.
+</p>
+
+<p>
+Unification works by comparing the structure of pairs of types: their structure
+disregarding type parameters must be identical, and types other than type parameters
+must be equivalent.
+A type parameter in one type may match any complete subtype in the other type;
+each successful match causes an entry to be added to the substitution map.
+If the structure differs, or types other than type parameters are not equivalent,
+unification fails.
+</p>
+
+<!--
+TODO(gri) Somewhere we need to describe the process of adding an entry to the
+          substitution map: if the entry is already present, the type argument
+	  values are themselves unified.
+-->
+
+<p>
+For example, if <code>T1</code> and <code>T2</code> are type parameters,
+<code>[]map[int]bool</code> can be unified with any of the following:
 </p>
 
 <pre>
-	[10]struct{ elem P, list []P } ≡<sub>A</sub> [10]struct{ elem string; list []string }
+[]map[int]bool   // types are identical
+T1               // adds T1 &RightArrow; []map[int]bool to substitution map
+[]T1             // adds T1 &RightArrow; map[int]bool to substitution map
+[]map[T1]T2      // adds T1 &RightArrow; int and T2 &RightArrow; bool to substitution map
 </pre>
 
 <p>
-type inference starts with an empty map.
-Unification first compares the top-level structure of the LHS and RHS
-types.
-Both are arrays of the same length; they unify if the element types unify.
-Both element types are structs; they unify if they have
-the same number of fields with the same names and if the
-field types unify.
-The type argument for <code>P</code> is not known yet (there is no map entry),
-so unifying <code>P</code> with <code>string</code> adds
-the mapping <code>P ➞ string</code> to the map.
-Unifying the types of the <code>list</code> field requires
-unifying <code>[]P</code> and <code>[]string</code> and
-thus <code>P</code> and <code>string</code>.
-Since the type argument for <code>P</code> is known at this point
-(there is a map entry for <code>P</code>), its type argument
-<code>string</code> takes the place of <code>P</code>.
-And since <code>string</code> is identical to <code>string</code>,
-this unification step succeeds as well.
-Unification of the LHS and RHS of the equation is now finished.
-Type inference succeeds because there is only one type equation,
-no unification step failed, and the map is fully populated.
+On the other hand, <code>[]map[int]bool</code> cannot be unified with any of
+</p>
+
+<pre>
+int              // int is not a slice
+struct{}         // a struct is not a slice
+[]struct{}       // a struct is not a map
+[]map[T1]string  // map element types don't match
+</pre>
+
+<p>
+As an exception to this general rule, because a <a href="#Type_definitions">defined type</a>
+<code>D</code> and a type literal <code>L</code> are never equivalent,
+unification compares the underlying type of <code>D</code> with <code>L</code> instead.
+For example, given the defined type
+</p>
+
+<pre>
+type Vector []float64
+</pre>
+
+<p>
+and the type literal <code>[]E</code>, unification compares <code>[]float64</code> with
+<code>[]E</code> and adds an entry <code>E</code> &RightArrow; <code>float64</code> to
+the substitution map.
+</p>
+
+<h4 id="Function_argument_type_inference">Function argument type inference</h4>
+
+<!-- In this section and the section on constraint type inference we start with examples
+rather than have the examples follow the rules as is customary elsewhere in spec.
+Hopefully this helps building an intuition and makes the rules easier to follow. -->
+
+<p>
+Function argument type inference infers type arguments from function arguments:
+if a function parameter is declared with a type <code>T</code> that uses
+type parameters,
+<a href="#Type_unification">unifying</a> the type of the corresponding
+function argument with <code>T</code> may infer type arguments for the type
+parameters used by <code>T</code>.
 </p>
 
 <p>
-Unification uses a combination of <i>exact</i> and <i>loose</i>
-unification depending on whether two types have to be
-<a href="#Type_identity">identical</a>,
-<a href="#Assignability">assignment-compatible</a>, or
-only structurally equal.
-The respective <a href="#Type_unification_rules">type unification rules</a>
-are spelled out in detail in the <a href="#Appendix">Appendix</a>.
+For instance, given the generic function
+</p>
+
+<pre>
+func scale[Number ~int64|~float64|~complex128](v []Number, s Number) []Number
+</pre>
+
+<p>
+and the call
+</p>
+
+<pre>
+var vector []float64
+scaledVector := scale(vector, 42)
+</pre>
+
+<p>
+the type argument for <code>Number</code> can be inferred from the function argument
+<code>vector</code> by unifying the type of <code>vector</code> with the corresponding
+parameter type: <code>[]float64</code> and <code>[]Number</code>
+match in structure and <code>float64</code> matches with <code>Number</code>.
+This adds the entry <code>Number</code> &RightArrow; <code>float64</code> to the
+<a href="#Type_unification">substitution map</a>.
+Untyped arguments, such as the second function argument <code>42</code> here, are ignored
+in the first round of function argument type inference and only considered if there are
+unresolved type parameters left.
 </p>
 
 <p>
-For an equation of the form <code>X ≡<sub>A</sub> Y</code>,
-where <code>X</code> and <code>Y</code> are types involved
-in an assignment (including parameter passing and return statements),
-the top-level type structures may unify loosely but element types
-must unify exactly, matching the rules for assignments.
+Inference happens in two separate phases; each phase operates on a specific list of
+(parameter, argument) pairs:
 </p>
 
-<p>
-For an equation of the form <code>P ≡<sub>C</sub> C</code>,
-where <code>P</code> is a type parameter and <code>C</code>
-its corresponding constraint, the unification rules are bit
-more complicated:
-</p>
-
-<ul>
+<ol>
 <li>
-	If <code>C</code> has a <a href="#Core_types">core type</a>
-	<code>core(C)</code>
-	and <code>P</code> has a known type argument <code>A</code>,
-	<code>core(C)</code> and <code>A</code> must unify loosely.
-	If <code>P</code> does not have a known type argument
-	and <code>C</code> contains exactly one type term <code>T</code>
-	that is not an underlying (tilde) type, unification adds the
-	mapping <code>P ➞ T</code> to the map.
+	The list <i>Lt</i> contains all (parameter, argument) pairs where the parameter
+	type uses type parameters and where the function argument is <i>typed</i>.
 </li>
 <li>
-	If <code>C</code> does not have a core type
-	and <code>P</code> has a known type argument <code>A</code>,
-	<code>A</code> must have all methods of <code>C</code>, if any,
-	and corresponding method types must unify exactly.
+	The list <i>Lu</i> contains all remaining pairs where the parameter type is a single
+	type parameter. In this list, the respective function arguments are untyped.
 </li>
-</ul>
+</ol>
 
 <p>
-When solving type equations from type constraints,
-solving one equation may infer additional type arguments,
-which in turn may enable solving other equations that depend
-on those type arguments.
-Type inference repeats type unification as long as new type
-arguments are inferred.
+Any other (parameter, argument) pair is ignored.
+</p>
+
+<p>
+By construction, the arguments of the pairs in <i>Lu</i> are <i>untyped</i> constants
+(or the untyped boolean result of a comparison). And because <a href="#Constants">default types</a>
+of untyped values are always predeclared non-composite types, they can never match against
+a composite type, so it is sufficient to only consider parameter types that are single type
+parameters.
+</p>
+
+<p>
+Each list is processed in a separate phase:
+</p>
+
+<ol>
+<li>
+	In the first phase, the parameter and argument types of each pair in <i>Lt</i>
+	are unified. If unification succeeds for a pair, it may yield new entries that
+	are added to the substitution map <i>M</i>. If unification fails, type inference
+	fails.
+</li>
+<li>
+	The second phase considers the entries of list <i>Lu</i>. Type parameters for
+	which the type argument has already been determined are ignored in this phase.
+	For each remaining pair, the parameter type (which is a single type parameter) and
+	the <a href="#Constants">default type</a> of the corresponding untyped argument is
+	unified. If unification fails, type inference fails.
+</li>
+</ol>
+
+<p>
+While unification is successful, processing of each list continues until all list elements
+are considered, even if all type arguments are inferred before the last list element has
+been processed.
+</p>
+
+<p>
+Example:
+</p>
+
+<pre>
+func min[T ~int|~float64](x, y T) T
+
+var x int
+min(x, 2.0)    // T is int, inferred from typed argument x; 2.0 is assignable to int
+min(1.0, 2.0)  // T is float64, inferred from default type for 1.0 and matches default type for 2.0
+min(1.0, 2)    // illegal: default type float64 (for 1.0) doesn't match default type int (for 2)
+</pre>
+
+<p>
+In the example <code>min(1.0, 2)</code>, processing the function argument <code>1.0</code>
+yields the substitution map entry <code>T</code> &RightArrow; <code>float64</code>. Because
+processing continues until all untyped arguments are considered, an error is reported. This
+ensures that type inference does not depend on the order of the untyped arguments.
+</p>
+
+<h4 id="Constraint_type_inference">Constraint type inference</h4>
+
+<p>
+Constraint type inference infers type arguments by considering type constraints.
+If a type parameter <code>P</code> has a constraint with a
+<a href="#Core_types">core type</a> <code>C</code>,
+<a href="#Type_unification">unifying</a> <code>P</code> with <code>C</code>
+may infer additional type arguments, either the type argument for <code>P</code>,
+or if that is already known, possibly the type arguments for type parameters
+used in <code>C</code>.
+</p>
+
+<p>
+For instance, consider the type parameter list with type parameters <code>List</code> and
+<code>Elem</code>:
+</p>
+
+<pre>
+[List ~[]Elem, Elem any]
+</pre>
+
+<p>
+Constraint type inference can deduce the type of <code>Elem</code> from the type argument
+for <code>List</code> because <code>Elem</code> is a type parameter in the core type
+<code>[]Elem</code> of <code>List</code>.
+If the type argument is <code>Bytes</code>:
+</p>
+
+<pre>
+type Bytes []byte
+</pre>
+
+<p>
+unifying the underlying type of <code>Bytes</code> with the core type means
+unifying <code>[]byte</code> with <code>[]Elem</code>. That unification succeeds and yields
+the <a href="#Type_unification">substitution map</a> entry
+<code>Elem</code> &RightArrow; <code>byte</code>.
+Thus, in this example, constraint type inference can infer the second type argument from the
+first one.
+</p>
+
+<p>
+Using the core type of a constraint may lose some information: In the (unlikely) case that
+the constraint's type set contains a single <a href="#Type_definitions">defined type</a>
+<code>N</code>, the corresponding core type is <code>N</code>'s underlying type rather than
+<code>N</code> itself. In this case, constraint type inference may succeed but instantiation
+will fail because the inferred type is not in the type set of the constraint.
+Thus, constraint type inference uses the <i>adjusted core type</i> of
+a constraint: if the type set contains a single type, use that type; otherwise use the
+constraint's core type.
+</p>
+
+<p>
+Generally, constraint type inference proceeds in two phases: Starting with a given
+substitution map <i>M</i>
+</p>
+
+<ol>
+<li>
+For all type parameters with an adjusted core type, unify the type parameter with that
+type. If any unification fails, constraint type inference fails.
+</li>
+
+<li>
+At this point, some entries in <i>M</i> may map type parameters to other
+type parameters or to types containing type parameters. For each entry
+<code>P</code> &RightArrow; <code>A</code> in <i>M</i> where <code>A</code> is or
+contains type parameters <code>Q</code> for which there exist entries
+<code>Q</code> &RightArrow; <code>B</code> in <i>M</i>, substitute those
+<code>Q</code> with the respective <code>B</code> in <code>A</code>.
+Stop when no further substitution is possible.
+</li>
+</ol>
+
+<p>
+The result of constraint type inference is the final substitution map <i>M</i> from type
+parameters <code>P</code> to type arguments <code>A</code> where no type parameter <code>P</code>
+appears in any of the <code>A</code>.
+</p>
+
+<p>
+For instance, given the type parameter list
+</p>
+
+<pre>
+[A any, B []C, C *A]
+</pre>
+
+<p>
+and the single provided type argument <code>int</code> for type parameter <code>A</code>,
+the initial substitution map <i>M</i> contains the entry <code>A</code> &RightArrow; <code>int</code>.
+</p>
+
+<p>
+In the first phase, the type parameters <code>B</code> and <code>C</code> are unified
+with the core type of their respective constraints. This adds the entries
+<code>B</code> &RightArrow; <code>[]C</code> and <code>C</code> &RightArrow; <code>*A</code>
+to <i>M</i>.
+
+<p>
+At this point there are two entries in <i>M</i> where the right-hand side
+is or contains type parameters for which there exists other entries in <i>M</i>:
+<code>[]C</code> and <code>*A</code>.
+In the second phase, these type parameters are replaced with their respective
+types. It doesn't matter in which order this happens. Starting with the state
+of <i>M</i> after the first phase:
+</p>
+
+<p>
+<code>A</code> &RightArrow; <code>int</code>,
+<code>B</code> &RightArrow; <code>[]C</code>,
+<code>C</code> &RightArrow; <code>*A</code>
+</p>
+
+<p>
+Replace <code>A</code> on the right-hand side of &RightArrow; with <code>int</code>:
+</p>
+
+<p>
+<code>A</code> &RightArrow; <code>int</code>,
+<code>B</code> &RightArrow; <code>[]C</code>,
+<code>C</code> &RightArrow; <code>*int</code>
+</p>
+
+<p>
+Replace <code>C</code> on the right-hand side of &RightArrow; with <code>*int</code>:
+</p>
+
+<p>
+<code>A</code> &RightArrow; <code>int</code>,
+<code>B</code> &RightArrow; <code>[]*int</code>,
+<code>C</code> &RightArrow; <code>*int</code>
+</p>
+
+<p>
+At this point no further substitution is possible and the map is full.
+Therefore, <code>M</code> represents the final map of type parameters
+to type arguments for the given type parameter list.
 </p>
 
 <h3 id="Operators">Operators</h3>
@@ -5400,7 +5479,7 @@ in any of these cases:
 	ignoring struct tags (see below),
 	<code>x</code>'s type and <code>T</code> are not
 	<a href="#Type_parameter_declarations">type parameters</a> but have
-	<a href="#Type_identity">identical</a> <a href="#Underlying_types">underlying types</a>.
+	<a href="#Type_identity">identical</a> <a href="#Types">underlying types</a>.
 	</li>
 	<li>
 	ignoring struct tags (see below),
@@ -7245,8 +7324,7 @@ clear(t)    type parameter    see below
 </pre>
 
 <p>
-If the type of the argument to <code>clear</code> is a
-<a href="#Type_parameter_declarations">type parameter</a>,
+If the argument type is a <a href="#Type_parameter_declarations">type parameter</a>,
 all types in its type set must be maps or slices, and <code>clear</code>
 performs the operation corresponding to the actual type argument.
 </p>
@@ -8212,7 +8290,7 @@ of if the general conversion rules take care of this.
 <p>
 A <code>Pointer</code> is a <a href="#Pointer_types">pointer type</a> but a <code>Pointer</code>
 value may not be <a href="#Address_operators">dereferenced</a>.
-Any pointer or value of <a href="#Underlying_types">underlying type</a> <code>uintptr</code> can be
+Any pointer or value of <a href="#Types">underlying type</a> <code>uintptr</code> can be
 <a href="#Conversions">converted</a> to a type of underlying type <code>Pointer</code> and vice versa.
 The effect of converting between <code>Pointer</code> and <code>uintptr</code> is implementation-defined.
 </p>
@@ -8360,145 +8438,3 @@ The following minimal alignment properties are guaranteed:
 <p>
 A struct or array type has size zero if it contains no fields (or elements, respectively) that have a size greater than zero. Two distinct zero-size variables may have the same address in memory.
 </p>
-
-<h2 id="Appendix">Appendix</h2>
-
-<h3 id="Type_unification_rules">Type unification rules</h3>
-
-<p>
-The type unification rules describe if and how two types unify.
-The precise details are relevant for Go implementations,
-affect the specifics of error messages (such as whether
-a compiler reports a type inference or other error),
-and may explain why type inference fails in unusual code situations.
-But by and large these rules can be ignored when writing Go code:
-type inference is designed to mostly "work as expected",
-and the unification rules are fine-tuned accordingly.
-</p>
-
-<p>
-Type unification is controlled by a <i>matching mode</i>, which may
-be <i>exact</i> or <i>loose</i>.
-As unification recursively descends a composite type structure,
-the matching mode used for elements of the type, the <i>element matching mode</i>,
-remains the same as the matching mode except when two types are unified for
-<a href="#Assignability">assignability</a> (<code>≡<sub>A</sub></code>):
-in this case, the matching mode is <i>loose</i> at the top level but
-then changes to <i>exact</i> for element types, reflecting the fact
-that types don't have to be identical to be assignable.
-</p>
-
-<p>
-Two types that are not bound type parameters unify exactly if any of
-following conditions is true:
-</p>
-
-<ul>
-<li>
-	Both types are <a href="#Type_identity">identical</a>.
-</li>
-<li>
-	Both types have identical structure and their element types
-	unify exactly.
-</li>
-<li>
-	Exactly one type is an <a href="#Type_inference">unbound</a>
-	type parameter with a <a href="#Core_types">core type</a>,
-	and that core type unifies with the other type per the
-	unification rules for <code>≡<sub>A</sub></code>
-	(loose unification at the top level and exact unification
-	for element types).
-</li>
-</ul>
-
-<p>
-If both types are bound type parameters, they unify per the given
-matching modes if:
-</p>
-
-<ul>
-<li>
-	Both type parameters are identical.
-</li>
-<li>
-	At most one of the type parameters has a known type argument.
-	In this case, the type parameters are <i>joined</i>:
-	they both stand for the same type argument.
-	If neither type parameter has a known type argument yet,
-	a future type argument inferred for one the type parameters
-	is simultaneously inferred for both of them.
-</li>
-<li>
-	Both type parameters have a known type argument
-	and the type arguments unify per the given matching modes.
-</li>
-</ul>
-
-<p>
-A single bound type parameter <code>P</code> and another type <code>T</code> unify
-per the given matching modes if:
-</p>
-
-<ul>
-<li>
-	<code>P</code> doesn't have a known type argument.
-	In this case, <code>T</code> is inferred as the type argument for <code>P</code>.
-</li>
-<li>
-	<code>P</code> does have a known type argument <code>A</code>,
-	<code>A</code> and <code>T</code> unify per the given matching modes,
-	and one of the following conditions is true:
-	<ul>
-	<li>
-		Both <code>A</code> and <code>T</code> are interface types:
-		In this case, if both <code>A</code> and <code>T</code> are
-		also <a href="#Type_definitions">defined</a> types,
-		they must be <a href="#Type_identity">identical</a>.
-		Otherwise, if neither of them is a defined type, they must
-		have the same number of methods
-		(unification of <code>A</code> and <code>T</code> already
-		established that the methods match).
-	</li>
-	<li>
-		Neither <code>A</code> nor <code>T</code> are interface types:
-		In this case, if <code>T</code> is a defined type, <code>T</code>
-		replaces <code>A</code> as the inferred type argument for <code>P</code>.
-	</li>
-	</ul>
-</li>
-</ul>
-
-<p>
-Finally, two types that are not bound type parameters unify loosely
-(and per the element matching mode) if:
-</p>
-
-<ul>
-<li>
-	Both types unify exactly.
-</li>
-<li>
-	One type is a <a href="#Type_definitions">defined type</a>,
-	the other type is a type literal, but not an interface,
-	and their underlying types unify per the element matching mode.
-</li>
-<li>
-	Both types are interfaces (but not type parameters) with
-	identical <a href="#Interface_types">type terms</a>,
-	both or neither embed the predeclared type
-	<a href="#Predeclared_identifiers">comparable</a>,
-	corresponding method types unify per the element matching mode,
-	and the method set of one of the interfaces is a subset of
-	the method set of the other interface.
-</li>
-<li>
-	Only one type is an interface (but not a type parameter),
-	corresponding methods of the two types unify per the element matching mode,
-	and the method set of the interface is a subset of
-	the method set of the other type.
-</li>
-<li>
-	Both types have the same structure and their element types
-	unify per the element matching mode.
-</li>
-</ul>

doc/godebug.md

@@ -126,27 +126,6 @@ for example,
 see the [runtime documentation](/pkg/runtime#hdr-Environment_Variables)
 and the [go command documentation](/cmd/go#hdr-Build_and_test_caching).
 
-### Go 1.22
-
-Go 1.22 adds a configurable limit to control the maximum acceptable RSA key size
-that can be used in TLS handshakes, controlled by the [`tlsmaxrsasize`setting](/pkg/crypto/tls#Conn.Handshake).
-The default is tlsmaxrsasize=8192, limiting RSA to 8192-bit keys. To avoid
-denial of service attacks, this setting and default was backported to Go
-1.19.13, Go 1.20.8, and Go 1.21.1.
-
-Go 1.22 changed how the runtime interacts with transparent huge pages on Linux.
-In particular, a common default Linux kernel configuration can result in
-significant memory overheads, and Go 1.22 no longer works around this default.
-To work around this issue without adjusting kernel settings, transparent huge
-pages can be disabled for Go memory with the
-[`disablethp` setting](/pkg/runtime#hdr-Environment_Variable).
-This behavior was backported to Go 1.21.1, but the setting is only available
-starting with Go 1.21.6.
-This setting may be removed in a future release, and users impacted by this issue
-should adjust their Linux configuration according to the recommendations in the
-[GC guide](/doc/gc-guide#Linux_transparent_huge_pages), or switch to a Linux
-distribution that disables transparent huge pages altogether.
-
 ### Go 1.21
 
 Go 1.21 made it a run-time error to call `panic` with a nil interface value,
@@ -163,10 +142,6 @@ forms, controlled by the
 respectively.
 This behavior was backported to Go 1.19.8+ and Go 1.20.3+.
 
-Go 1.21 adds the support of Multipath TCP but it is only used if the application
-explicitly asked for it. This behavior can be controlled by the
-[`multipathtcp` setting](/pkg/net#Dialer.SetMultipathTCP).
-
 There is no plan to remove any of these settings.
 
 ### Go 1.20
@@ -201,13 +176,6 @@ Go 1.19 made it an error for path lookups to resolve to binaries in the current
 controlled by the [`execerrdot` setting](/pkg/os/exec#hdr-Executables_in_the_current_directory).
 There is no plan to remove this setting.
 
-Go 1.19 started sending EDNS0 additional headers on DNS requests.
-This can reportedly break the DNS server provided on some routers,
-such as CenturyLink Zyxel C3000Z.
-This can be changed by the [`netedns0` setting](/pkg/net#hdr-Name_Resolution).
-This setting is available in Go 1.21.12, Go 1.22.5, Go 1.23, and later.
-There is no plan to remove this setting.
-
 ### Go 1.18
 
 Go 1.18 removed support for SHA1 in most X.509 certificates,

misc/wasm/go_wasip1_wasm_exec

@@ -10,12 +10,12 @@ case "$GOWASIRUNTIME" in
 	"wasmer")
 		exec wasmer run --dir=/ --env PWD="$PWD" --env PATH="$PATH" ${GOWASIRUNTIMEARGS:-} "$1" -- "${@:2}"
 		;;
-	"wazero")
-		exec wazero run -mount /:/ -env-inherit -cachedir "${TMPDIR:-/tmp}"/wazero ${GOWASIRUNTIMEARGS:-} "$1" "${@:2}"
-		;;
-	"wasmtime" | "")
+	"wasmtime")
 		exec wasmtime run --dir=/ --env PWD="$PWD" --env PATH="$PATH" --max-wasm-stack 1048576 ${GOWASIRUNTIMEARGS:-} "$1" -- "${@:2}"
 		;;
+	"wazero" | "")
+		exec wazero run -mount /:/ -env-inherit -cachedir "${TMPDIR:-/tmp}"/wazero ${GOWASIRUNTIMEARGS:-} "$1" "${@:2}"
+		;;
 	*)
 		echo "Unknown Go WASI runtime specified: $GOWASIRUNTIME"
 		exit 1

src/README.vendor

@@ -38,7 +38,7 @@ The vendor directory may be updated with 'go mod vendor'.
 A typical sequence might be:
 
     cd src
-    go get golang.org/x/net@master
+    go get golang.org/x/net@latest
     go mod tidy
     go mod vendor
 

src/archive/zip/reader.go

@@ -699,13 +699,9 @@ func findSignatureInBlock(b []byte) int {
 		if b[i] == 'P' && b[i+1] == 'K' && b[i+2] == 0x05 && b[i+3] == 0x06 {
 			// n is length of comment
 			n := int(b[i+directoryEndLen-2]) | int(b[i+directoryEndLen-1])<<8
-			if n+directoryEndLen+i > len(b) {
-				// Truncated comment.
-				// Some parsers (such as Info-ZIP) ignore the truncated comment
-				// rather than treating it as a hard error.
-				return -1
+			if n+directoryEndLen+i <= len(b) {
+				return i
 			}
-			return i
 		}
 	}
 	return -1

src/archive/zip/reader_test.go

@@ -570,14 +570,6 @@ var tests = []ZipTest{
 			},
 		},
 	},
-	// Issue 66869: Don't skip over an EOCDR with a truncated comment.
-	// The test file sneakily hides a second EOCDR before the first one;
-	// previously we would extract one file ("file") from this archive,
-	// while most other tools would reject the file or extract a different one ("FILE").
-	{
-		Name:  "comment-truncated.zip",
-		Error: ErrFormat,
-	},
 }
 
 func TestReader(t *testing.T) {

src/bytes/compare_test.go

@@ -7,6 +7,7 @@ package bytes_test
 import (
 	. "bytes"
 	"fmt"
+	"internal/testenv"
 	"testing"
 )
 
@@ -72,7 +73,7 @@ func TestCompareBytes(t *testing.T) {
 	}
 	lengths = append(lengths, 256, 512, 1024, 1333, 4095, 4096, 4097)
 
-	if !testing.Short() {
+	if !testing.Short() || testenv.Builder() != "" {
 		lengths = append(lengths, 65535, 65536, 65537, 99999)
 	}
 

src/cmd/api/api.go

@@ -2,10 +2,9 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// This package computes the exported API of a set of Go packages.
+// Package api computes the exported API of a set of Go packages.
 // It is only a test, not a command, nor a usefully importable package.
-
-package main
+package api
 
 import (
 	"bufio"

src/cmd/api/api_test.go

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-package main
+package api
 
 import (
 	"flag"

src/cmd/api/boring_test.go

@@ -4,7 +4,7 @@
 
 //go:build boringcrypto
 
-package main
+package api
 
 import (
 	"fmt"

src/cmd/asm/internal/asm/testdata/riscv64.s

@@ -183,28 +183,28 @@ start:
 	// 8.2: Load-Reserved/Store-Conditional
 	LRW	(X5), X6				// 2fa30214
 	LRD	(X5), X6				// 2fb30214
-	SCW	X5, (X6), X7				// af23531a
-	SCD	X5, (X6), X7				// af33531a
+	SCW	X5, (X6), X7				// af23531c
+	SCD	X5, (X6), X7				// af33531c
 
 	// 8.3: Atomic Memory Operations
-	AMOSWAPW	X5, (X6), X7			// af23530e
-	AMOSWAPD	X5, (X6), X7			// af33530e
-	AMOADDW		X5, (X6), X7			// af235306
-	AMOADDD		X5, (X6), X7			// af335306
-	AMOANDW		X5, (X6), X7			// af235366
-	AMOANDD		X5, (X6), X7			// af335366
-	AMOORW		X5, (X6), X7			// af235346
-	AMOORD		X5, (X6), X7			// af335346
-	AMOXORW		X5, (X6), X7			// af235326
-	AMOXORD		X5, (X6), X7			// af335326
-	AMOMAXW		X5, (X6), X7			// af2353a6
-	AMOMAXD		X5, (X6), X7			// af3353a6
-	AMOMAXUW	X5, (X6), X7			// af2353e6
-	AMOMAXUD	X5, (X6), X7			// af3353e6
-	AMOMINW		X5, (X6), X7			// af235386
-	AMOMIND		X5, (X6), X7			// af335386
-	AMOMINUW	X5, (X6), X7			// af2353c6
-	AMOMINUD	X5, (X6), X7			// af3353c6
+	AMOSWAPW	X5, (X6), X7			// af23530c
+	AMOSWAPD	X5, (X6), X7			// af33530c
+	AMOADDW		X5, (X6), X7			// af235304
+	AMOADDD		X5, (X6), X7			// af335304
+	AMOANDW		X5, (X6), X7			// af235364
+	AMOANDD		X5, (X6), X7			// af335364
+	AMOORW		X5, (X6), X7			// af235344
+	AMOORD		X5, (X6), X7			// af335344
+	AMOXORW		X5, (X6), X7			// af235324
+	AMOXORD		X5, (X6), X7			// af335324
+	AMOMAXW		X5, (X6), X7			// af2353a4
+	AMOMAXD		X5, (X6), X7			// af3353a4
+	AMOMAXUW	X5, (X6), X7			// af2353e4
+	AMOMAXUD	X5, (X6), X7			// af3353e4
+	AMOMINW		X5, (X6), X7			// af235384
+	AMOMIND		X5, (X6), X7			// af335384
+	AMOMINUW	X5, (X6), X7			// af2353c4
+	AMOMINUD	X5, (X6), X7			// af3353c4
 
 	// 10.1: Base Counters and Timers
 	RDCYCLE		X5				// f32200c0

src/cmd/cgo/internal/swig/swig_test.go

@@ -44,18 +44,11 @@ func run(t *testing.T, dir string, lto bool, args ...string) {
 	cmd := exec.Command("go", runArgs...)
 	cmd.Dir = dir
 	if lto {
-		// On the builders we're using the default /usr/bin/ld, but
-		// that has problems when asking for LTO in particular. Force
-		// use of lld, which ships with our clang installation.
-		extraLDFlags := ""
-		if strings.Contains(testenv.Builder(), "clang") {
-			extraLDFlags += " -fuse-ld=lld"
-		}
 		const cflags = "-flto -Wno-lto-type-mismatch -Wno-unknown-warning-option"
 		cmd.Env = append(cmd.Environ(),
 			"CGO_CFLAGS="+cflags,
 			"CGO_CXXFLAGS="+cflags,
-			"CGO_LDFLAGS="+cflags+extraLDFlags)
+			"CGO_LDFLAGS="+cflags)
 	}
 	out, err := cmd.CombinedOutput()
 	if string(out) != "OK\n" {

src/cmd/cgo/internal/test/issue8756.go

@@ -1,7 +1,7 @@
 package cgotest
 
 /*
-#cgo !darwin LDFLAGS: -lm
+#cgo LDFLAGS: -lm
 #include <math.h>
 */
 import "C"

src/cmd/cgo/internal/test/issue8756/issue8756.go

@@ -1,7 +1,7 @@
 package issue8756
 
 /*
-#cgo !darwin LDFLAGS: -lm
+#cgo LDFLAGS: -lm
 #include <math.h>
 */
 import "C"

src/cmd/cgo/internal/test/test.go

@@ -23,7 +23,7 @@ package cgotest
 #include <unistd.h>
 #include <sys/stat.h>
 #include <errno.h>
-#cgo !darwin LDFLAGS: -lm
+#cgo LDFLAGS: -lm
 
 #ifndef WIN32
 #include <pthread.h>

src/cmd/cgo/internal/testcarchive/carchive_test.go

@@ -1365,35 +1365,3 @@ func TestDeepStack(t *testing.T) {
 		t.Error(err)
 	}
 }
-
-func TestSharedObject(t *testing.T) {
-	// Test that we can put a Go c-archive into a C shared object.
-	globalSkip(t)
-	testenv.MustHaveGoBuild(t)
-	testenv.MustHaveCGO(t)
-	testenv.MustHaveBuildMode(t, "c-archive")
-
-	t.Parallel()
-
-	if !testWork {
-		defer func() {
-			os.Remove("libgo_s.a")
-			os.Remove("libgo_s.h")
-			os.Remove("libgo_s.so")
-		}()
-	}
-
-	cmd := exec.Command("go", "build", "-buildmode=c-archive", "-o", "libgo_s.a", "./libgo")
-	out, err := cmd.CombinedOutput()
-	t.Logf("%v\n%s", cmd.Args, out)
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	ccArgs := append(cc, "-shared", "-o", "libgo_s.so", "libgo_s.a")
-	out, err = exec.Command(ccArgs[0], ccArgs[1:]...).CombinedOutput()
-	t.Logf("%v\n%s", ccArgs, out)
-	if err != nil {
-		t.Fatal(err)
-	}
-}

src/cmd/cgo/internal/testerrors/errors_test.go

@@ -111,7 +111,6 @@ func TestReportsTypeErrors(t *testing.T) {
 	for _, file := range []string{
 		"err1.go",
 		"err2.go",
-		"err5.go",
 		"issue11097a.go",
 		"issue11097b.go",
 		"issue18452.go",

src/cmd/cgo/internal/testerrors/testdata/err5.go

@@ -1,10 +0,0 @@
-// Copyright 2023 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-package main
-
-//line /tmp/_cgo_.go:1
-//go:cgo_dynamic_linker "/elf/interp" // ERROR HERE: only allowed in cgo-generated code
-
-func main() {}

src/cmd/cgo/internal/testplugin/plugin_test.go

@@ -389,18 +389,9 @@ func TestForkExec(t *testing.T) {
 	}
 }
 
-func TestSymbolNameMangle(t *testing.T) {
+func TestGeneric(t *testing.T) {
 	// Issue 58800: generic function name may contain weird characters
 	// that confuse the external linker.
-	// Issue 62098: the name mangling code doesn't handle some string
-	// symbols correctly.
 	globalSkip(t)
-	goCmd(t, "build", "-buildmode=plugin", "-o", "mangle.so", "./mangle/plugin.go")
-}
-
-func TestIssue62430(t *testing.T) {
-	globalSkip(t)
-	goCmd(t, "build", "-buildmode=plugin", "-o", "issue62430.so", "./issue62430/plugin.go")
-	goCmd(t, "build", "-o", "issue62430.exe", "./issue62430/main.go")
-	run(t, "./issue62430.exe")
+	goCmd(t, "build", "-buildmode=plugin", "-o", "generic.so", "./generic/plugin.go")
 }

src/cmd/cgo/internal/testplugin/testdata/generic/plugin.go

@@ -2,37 +2,21 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// Test cases for symbol name mangling.
-
-package main
-
-import (
-	"fmt"
-	"strings"
-)
-
-// Issue 58800:
 // Instantiated function name may contain weird characters
 // that confuse the external linker, so it needs to be
 // mangled.
-type S struct {
-	X int `parser:"|@@)"`
-}
+
+package main
 
 //go:noinline
 func F[T any]() {}
 
+type S struct {
+	X int `parser:"|@@)"`
+}
+
 func P() {
 	F[S]()
 }
 
-// Issue 62098: the name mangling code doesn't handle some string
-// symbols correctly.
-func G(id string) error {
-	if strings.ContainsAny(id, "&$@;/:+,?\\{^}%`]\">[~<#|") {
-		return fmt.Errorf("invalid")
-	}
-	return nil
-}
-
 func main() {}

src/cmd/cgo/internal/testplugin/testdata/issue62430/main.go

@@ -1,35 +0,0 @@
-// Copyright 2023 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-// Issue 62430: a program that uses plugins may appear
-// to have no references to an initialized global map variable defined
-// in some stdlib package (ex: unicode), however there
-// may be references to that map var from a plugin that
-// gets loaded.
-
-package main
-
-import (
-	"fmt"
-	"plugin"
-	"unicode"
-)
-
-func main() {
-	p, err := plugin.Open("issue62430.so")
-	if err != nil {
-		panic(err)
-	}
-	s, err := p.Lookup("F")
-	if err != nil {
-		panic(err)
-	}
-
-	f := s.(func(string) *unicode.RangeTable)
-	if f("C") == nil {
-		panic("unicode.Categories not properly initialized")
-	} else {
-		fmt.Println("unicode.Categories properly initialized")
-	}
-}

src/cmd/cgo/internal/testplugin/testdata/issue62430/plugin.go

@@ -1,11 +0,0 @@
-package main
-
-import (
-	"unicode"
-)
-
-func F(s string) *unicode.RangeTable {
-	return unicode.Categories[s]
-}
-
-func main() {}

src/cmd/cgo/internal/testsanitizers/cc_test.go

@@ -16,10 +16,8 @@ import (
 	"encoding/json"
 	"errors"
 	"fmt"
-	"internal/testenv"
 	"os"
 	"os/exec"
-	"os/user"
 	"path/filepath"
 	"regexp"
 	"strconv"
@@ -268,28 +266,12 @@ func compilerSupportsLocation() bool {
 	case "gcc":
 		return compiler.major >= 10
 	case "clang":
-		// TODO(65606): The clang toolchain on the LUCI builders is not built against
-		// zlib, the ASAN runtime can't actually symbolize its own stack trace. Once
-		// this is resolved, one way or another, switch this back to 'true'. We still
-		// have coverage from the 'gcc' case above.
-		if inLUCIBuild() {
-			return false
-		}
 		return true
 	default:
 		return false
 	}
 }
 
-// inLUCIBuild returns true if we're currently executing in a LUCI build.
-func inLUCIBuild() bool {
-	u, err := user.Current()
-	if err != nil {
-		return false
-	}
-	return testenv.Builder() != "" && u.Username == "swarming"
-}
-
 // compilerRequiredTsanVersion reports whether the compiler is the version required by Tsan.
 // Only restrictions for ppc64le are known; otherwise return true.
 func compilerRequiredTsanVersion(goos, goarch string) bool {

src/cmd/cgo/internal/testsanitizers/libfuzzer_test.go

@@ -12,11 +12,6 @@ import (
 )
 
 func TestLibFuzzer(t *testing.T) {
-	// Skip tests in short mode.
-	if testing.Short() {
-		t.Skip("libfuzzer tests can take upwards of minutes to run; skipping in short mode")
-	}
-
 	goos, err := goEnv("GOOS")
 	if err != nil {
 		t.Fatal(err)

src/cmd/compile/internal/compare/compare.go

@@ -148,7 +148,7 @@ func calculateCostForType(t *types.Type) int64 {
 		return EqStructCost(t)
 	case types.TSLICE:
 		// Slices are not comparable.
-		base.Fatalf("calculateCostForType: unexpected slice type")
+		base.Fatalf("eqStructFieldCost: unexpected slice type")
 	case types.TARRAY:
 		elemCost := calculateCostForType(t.Elem())
 		cost = t.NumElem() * elemCost
@@ -374,11 +374,6 @@ func eqmem(p ir.Node, q ir.Node, field *types.Sym, size int64) ir.Node {
 }
 
 func eqmemfunc(size int64, t *types.Type) (fn *ir.Name, needsize bool) {
-	if !base.Ctxt.Arch.CanMergeLoads && t.Alignment() < int64(base.Ctxt.Arch.Alignment) && t.Alignment() < t.Size() {
-		// We can't use larger comparisons if the value might not be aligned
-		// enough for the larger comparison. See issues 46283 and 67160.
-		size = 0
-	}
 	switch size {
 	default:
 		fn = typecheck.LookupRuntime("memequal")

src/cmd/compile/internal/escape/call.go

@@ -186,7 +186,7 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 		argument(e.discardHole(), &call.X)
 		argument(e.discardHole(), &call.Y)
 
-	case ir.ODELETE, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
+	case ir.ODELETE, ir.OMAX, ir.OMIN, ir.OPRINT, ir.OPRINTN, ir.ORECOVER:
 		call := call.(*ir.CallExpr)
 		fixRecoverCall(call)
 		for i := range call.Args {
@@ -194,14 +194,6 @@ func (e *escape) callCommon(ks []hole, call ir.Node, init *ir.Nodes, wrapper *ir
 		}
 		argumentRType(&call.RType)
 
-	case ir.OMIN, ir.OMAX:
-		call := call.(*ir.CallExpr)
-		fixRecoverCall(call)
-		for i := range call.Args {
-			argument(ks[0], &call.Args[i])
-		}
-		argumentRType(&call.RType)
-
 	case ir.OLEN, ir.OCAP, ir.OREAL, ir.OIMAG, ir.OCLOSE, ir.OCLEAR:
 		call := call.(*ir.UnaryExpr)
 		argument(e.discardHole(), &call.X)

src/cmd/compile/internal/noder/noder.go

@@ -333,14 +333,8 @@ func (p *noder) pragma(pos syntax.Pos, blankLine bool, text string, old syntax.P
 // contain cgo directives, and for security reasons
 // (primarily misuse of linker flags), other files are not.
 // See golang.org/issue/23672.
-// Note that cmd/go ignores files whose names start with underscore,
-// so the only _cgo_ files we will see from cmd/go are generated by cgo.
-// It's easy to bypass this check by calling the compiler directly;
-// we only protect against uses by cmd/go.
 func isCgoGeneratedFile(pos syntax.Pos) bool {
-	// We need the absolute file, independent of //line directives,
-	// so we call pos.Base().Pos().
-	return strings.HasPrefix(filepath.Base(trimFilename(pos.Base().Pos().Base())), "_cgo_")
+	return strings.HasPrefix(filepath.Base(trimFilename(pos.Base())), "_cgo_")
 }
 
 // safeArg reports whether arg is a "safe" command-line argument,

src/cmd/compile/internal/ssa/_gen/ARM64.rules

@@ -1552,27 +1552,33 @@
 (GreaterEqualU (FlagConstant [fc])) => (MOVDconst [b2i(fc.uge())])
 
 // absorb InvertFlags into boolean values
-(Equal            (InvertFlags x)) => (Equal x)
-(NotEqual         (InvertFlags x)) => (NotEqual x)
-(LessThan         (InvertFlags x)) => (GreaterThan x)
-(LessThanU        (InvertFlags x)) => (GreaterThanU x)
-(GreaterThan      (InvertFlags x)) => (LessThan x)
-(GreaterThanU     (InvertFlags x)) => (LessThanU x)
-(LessEqual        (InvertFlags x)) => (GreaterEqual x)
-(LessEqualU       (InvertFlags x)) => (GreaterEqualU x)
-(GreaterEqual     (InvertFlags x)) => (LessEqual x)
-(GreaterEqualU    (InvertFlags x)) => (LessEqualU x)
-(LessThanF        (InvertFlags x)) => (GreaterThanF x)
-(LessEqualF       (InvertFlags x)) => (GreaterEqualF x)
-(GreaterThanF     (InvertFlags x)) => (LessThanF x)
-(GreaterEqualF    (InvertFlags x)) => (LessEqualF x)
-(LessThanNoov     (InvertFlags x)) => (BIC (GreaterEqualNoov <typ.Bool> x) (Equal <typ.Bool> x))
-(GreaterEqualNoov (InvertFlags x)) => (OR (LessThanNoov <typ.Bool> x) (Equal <typ.Bool> x))
+(Equal         (InvertFlags x)) => (Equal x)
+(NotEqual      (InvertFlags x)) => (NotEqual x)
+(LessThan      (InvertFlags x)) => (GreaterThan x)
+(LessThanU     (InvertFlags x)) => (GreaterThanU x)
+(GreaterThan   (InvertFlags x)) => (LessThan x)
+(GreaterThanU  (InvertFlags x)) => (LessThanU x)
+(LessEqual     (InvertFlags x)) => (GreaterEqual x)
+(LessEqualU    (InvertFlags x)) => (GreaterEqualU x)
+(GreaterEqual  (InvertFlags x)) => (LessEqual x)
+(GreaterEqualU (InvertFlags x)) => (LessEqualU x)
+(LessThanF     (InvertFlags x)) => (GreaterThanF x)
+(LessEqualF    (InvertFlags x)) => (GreaterEqualF x)
+(GreaterThanF  (InvertFlags x)) => (LessThanF x)
+(GreaterEqualF (InvertFlags x)) => (LessEqualF x)
 
 // Boolean-generating instructions (NOTE: NOT all boolean Values) always
 // zero upper bit of the register; no need to zero-extend
 (MOVBUreg x:((Equal|NotEqual|LessThan|LessThanU|LessThanF|LessEqual|LessEqualU|LessEqualF|GreaterThan|GreaterThanU|GreaterThanF|GreaterEqual|GreaterEqualU|GreaterEqualF) _)) => (MOVDreg x)
 
+// omit unsign extension
+(MOVWUreg x) && zeroUpper32Bits(x, 3) => x
+
+// omit sign extension
+(MOVWreg <t> (ANDconst x [c])) && uint64(c) & uint64(0xffffffff80000000) == 0 => (ANDconst <t> x [c])
+(MOVHreg <t> (ANDconst x [c])) && uint64(c) & uint64(0xffffffffffff8000) == 0 => (ANDconst <t> x [c])
+(MOVBreg <t> (ANDconst x [c])) && uint64(c) & uint64(0xffffffffffffff80) == 0 => (ANDconst <t> x [c])
+
 // absorb flag constants into conditional instructions
 (CSEL  [cc] x _ flag) && ccARM64Eval(cc, flag) > 0 => x
 (CSEL  [cc] _ y flag) && ccARM64Eval(cc, flag) < 0 => y

src/cmd/compile/internal/ssa/_gen/ARM64Ops.go

@@ -13,6 +13,7 @@ import "strings"
 //  - *const instructions may use a constant larger than the instruction can encode.
 //    In this case the assembler expands to multiple instructions and uses tmp
 //    register (R27).
+//  - All 32-bit Ops will zero the upper 32 bits of the destination register.
 
 // Suffixes encode the bit width of various instructions.
 // D (double word) = 64 bit

src/cmd/compile/internal/ssa/_gen/PPC64.rules

@@ -588,16 +588,16 @@
 
 // small and of zero-extend => either zero-extend or small and
 (Select0 (ANDCCconst [c] y:(MOVBZreg _))) && c&0xFF == 0xFF => y
-(Select0 (ANDCCconst [0xFF] (MOVBreg x))) => (MOVBZreg x)
+(Select0 (ANDCCconst [0xFF] y:(MOVBreg _))) => y
 (Select0 (ANDCCconst [c] y:(MOVHZreg _)))  && c&0xFFFF == 0xFFFF => y
-(Select0 (ANDCCconst [0xFFFF] (MOVHreg x))) => (MOVHZreg x)
+(Select0 (ANDCCconst [0xFFFF] y:(MOVHreg _))) => y
 
 (AND (MOVDconst [c]) y:(MOVWZreg _))  && c&0xFFFFFFFF == 0xFFFFFFFF => y
 (AND (MOVDconst [0xFFFFFFFF]) y:(MOVWreg x)) => (MOVWZreg x)
 // normal case
-(Select0 (ANDCCconst [c] (MOVBZreg x))) => (Select0 (ANDCCconst [c&0xFF] x))
-(Select0 (ANDCCconst [c] (MOVHZreg x))) => (Select0 (ANDCCconst [c&0xFFFF] x))
-(Select0 (ANDCCconst [c] (MOVWZreg x))) => (Select0 (ANDCCconst [c&0xFFFFFFFF] x))
+(Select0 (ANDCCconst [c] (MOV(B|BZ)reg x))) => (Select0 (ANDCCconst [c&0xFF] x))
+(Select0 (ANDCCconst [c] (MOV(H|HZ)reg x))) => (Select0 (ANDCCconst [c&0xFFFF] x))
+(Select0 (ANDCCconst [c] (MOV(W|WZ)reg x))) => (Select0 (ANDCCconst [c&0xFFFFFFFF] x))
 
 // Eliminate unnecessary sign/zero extend following right shift
 (MOV(B|H|W)Zreg (SRWconst [c] (MOVBZreg x))) => (SRWconst [c] (MOVBZreg x))

src/cmd/compile/internal/ssa/_gen/generic.rules

@@ -981,7 +981,7 @@
     (ConstNil <typ.Uintptr>)
     (ConstNil <typ.BytePtr>))
 
-(NilCheck ptr:(GetG mem) mem) => ptr
+(NilCheck (GetG mem) mem) => mem
 
 (If (Not cond) yes no) => (If cond no yes)
 (If (ConstBool [c]) yes no) && c => (First yes no)
@@ -2055,19 +2055,19 @@
 	&& isSameCall(call.Aux, "runtime.newobject")
 	=> mem
 
-(NilCheck ptr:(SelectN [0] call:(StaticLECall _ _)) _)
+(NilCheck (SelectN [0] call:(StaticLECall _ _)) _)
 	&& isSameCall(call.Aux, "runtime.newobject")
 	&& warnRule(fe.Debug_checknil(), v, "removed nil check")
-	=> ptr
+	=> (Invalid)
 
-(NilCheck ptr:(OffPtr (SelectN [0] call:(StaticLECall _ _))) _)
+(NilCheck (OffPtr (SelectN [0] call:(StaticLECall _ _))) _)
 	&& isSameCall(call.Aux, "runtime.newobject")
 	&& warnRule(fe.Debug_checknil(), v, "removed nil check")
-	=> ptr
+	=> (Invalid)
 
 // Addresses of globals are always non-nil.
-(NilCheck          ptr:(Addr {_} (SB))    _) => ptr
-(NilCheck ptr:(Convert (Addr {_} (SB)) _) _) => ptr
+(NilCheck          (Addr {_} (SB))    _) => (Invalid)
+(NilCheck (Convert (Addr {_} (SB)) _) _) => (Invalid)
 
 // for late-expanded calls, recognize memequal applied to a single constant byte
 // Support is limited by 1, 2, 4, 8 byte sizes

src/cmd/compile/internal/ssa/_gen/genericOps.go

@@ -471,7 +471,7 @@ var genericOps = []opData{
 	{name: "IsNonNil", argLength: 1, typ: "Bool"},        // arg0 != nil
 	{name: "IsInBounds", argLength: 2, typ: "Bool"},      // 0 <= arg0 < arg1. arg1 is guaranteed >= 0.
 	{name: "IsSliceInBounds", argLength: 2, typ: "Bool"}, // 0 <= arg0 <= arg1. arg1 is guaranteed >= 0.
-	{name: "NilCheck", argLength: 2, nilCheck: true},     // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns the ptr unmodified.
+	{name: "NilCheck", argLength: 2, typ: "Void"},        // arg0=ptr, arg1=mem. Panics if arg0 is nil. Returns void.
 
 	// Pseudo-ops
 	{name: "GetG", argLength: 1, zeroWidth: true}, // runtime.getg() (read g pointer). arg0=mem

src/cmd/compile/internal/ssa/check.go

@@ -317,28 +317,7 @@ func checkFunc(f *Func) {
 				if !v.Aux.(*ir.Name).Type().HasPointers() {
 					f.Fatalf("vardef must have pointer type %s", v.Aux.(*ir.Name).Type().String())
 				}
-			case OpNilCheck:
-				// nil checks have pointer type before scheduling, and
-				// void type after scheduling.
-				if f.scheduled {
-					if v.Uses != 0 {
-						f.Fatalf("nilcheck must have 0 uses %s", v.Uses)
-					}
-					if !v.Type.IsVoid() {
-						f.Fatalf("nilcheck must have void type %s", v.Type.String())
-					}
-				} else {
-					if !v.Type.IsPtrShaped() && !v.Type.IsUintptr() {
-						f.Fatalf("nilcheck must have pointer type %s", v.Type.String())
-					}
-				}
-				if !v.Args[0].Type.IsPtrShaped() && !v.Args[0].Type.IsUintptr() {
-					f.Fatalf("nilcheck must have argument of pointer type %s", v.Args[0].Type.String())
-				}
-				if !v.Args[1].Type.IsMemory() {
-					f.Fatalf("bad arg 1 type to %s: want mem, have %s",
-						v.Op, v.Args[1].Type.String())
-				}
+
 			}
 
 			// TODO: check for cycles in values

src/cmd/compile/internal/ssa/deadcode.go

@@ -110,15 +110,16 @@ func liveValues(f *Func, reachable []bool) (live []bool, liveOrderStmts []*Value
 			}
 		}
 		for _, v := range b.Values {
-			if (opcodeTable[v.Op].call || opcodeTable[v.Op].hasSideEffects || opcodeTable[v.Op].nilCheck) && !live[v.ID] {
+			if (opcodeTable[v.Op].call || opcodeTable[v.Op].hasSideEffects) && !live[v.ID] {
 				live[v.ID] = true
 				q = append(q, v)
 				if v.Pos.IsStmt() != src.PosNotStmt {
 					liveOrderStmts = append(liveOrderStmts, v)
 				}
 			}
-			if v.Op == OpInlMark {
-				if !liveInlIdx[int(v.AuxInt)] {
+			if v.Type.IsVoid() && !live[v.ID] {
+				// The only Void ops are nil checks and inline marks.  We must keep these.
+				if v.Op == OpInlMark && !liveInlIdx[int(v.AuxInt)] {
 					// We don't need marks for bodies that
 					// have been completely optimized away.
 					// TODO: save marks only for bodies which

src/cmd/compile/internal/ssa/deadstore.go

@@ -73,9 +73,9 @@ func dse(f *Func) {
 		}
 
 		// Walk backwards looking for dead stores. Keep track of shadowed addresses.
-		// A "shadowed address" is a pointer, offset, and size describing a memory region that
-		// is known to be written. We keep track of shadowed addresses in the shadowed map,
-		// mapping the ID of the address to a shadowRange where future writes will happen.
+		// A "shadowed address" is a pointer and a size describing a memory region that
+		// is known to be written. We keep track of shadowed addresses in the shadowed
+		// map, mapping the ID of the address to the size of the shadowed region.
 		// Since we're walking backwards, writes to a shadowed region are useless,
 		// as they will be immediately overwritten.
 		shadowed.clear()
@@ -88,20 +88,13 @@ func dse(f *Func) {
 			shadowed.clear()
 		}
 		if v.Op == OpStore || v.Op == OpZero {
-			ptr := v.Args[0]
-			var off int64
-			for ptr.Op == OpOffPtr { // Walk to base pointer
-				off += ptr.AuxInt
-				ptr = ptr.Args[0]
-			}
 			var sz int64
 			if v.Op == OpStore {
 				sz = v.Aux.(*types.Type).Size()
 			} else { // OpZero
 				sz = v.AuxInt
 			}
-			sr := shadowRange(shadowed.get(ptr.ID))
-			if sr.contains(off, off+sz) {
+			if shadowedSize := int64(shadowed.get(v.Args[0].ID)); shadowedSize != -1 && shadowedSize >= sz {
 				// Modify the store/zero into a copy of the memory state,
 				// effectively eliding the store operation.
 				if v.Op == OpStore {
@@ -115,8 +108,10 @@ func dse(f *Func) {
 				v.AuxInt = 0
 				v.Op = OpCopy
 			} else {
-				// Extend shadowed region.
-				shadowed.set(ptr.ID, int32(sr.merge(off, off+sz)))
+				if sz > 0x7fffffff { // work around sparseMap's int32 value type
+					sz = 0x7fffffff
+				}
+				shadowed.set(v.Args[0].ID, int32(sz))
 			}
 		}
 		// walk to previous store
@@ -136,49 +131,6 @@ func dse(f *Func) {
 	}
 }
 
-// A shadowRange encodes a set of byte offsets [lo():hi()] from
-// a given pointer that will be written to later in the block.
-// A zero shadowRange encodes an empty shadowed range (and so
-// does a -1 shadowRange, which is what sparsemap.get returns
-// on a failed lookup).
-type shadowRange int32
-
-func (sr shadowRange) lo() int64 {
-	return int64(sr & 0xffff)
-}
-func (sr shadowRange) hi() int64 {
-	return int64((sr >> 16) & 0xffff)
-}
-
-// contains reports whether [lo:hi] is completely within sr.
-func (sr shadowRange) contains(lo, hi int64) bool {
-	return lo >= sr.lo() && hi <= sr.hi()
-}
-
-// merge returns the union of sr and [lo:hi].
-// merge is allowed to return something smaller than the union.
-func (sr shadowRange) merge(lo, hi int64) shadowRange {
-	if lo < 0 || hi > 0xffff {
-		// Ignore offsets that are too large or small.
-		return sr
-	}
-	if sr.lo() == sr.hi() {
-		// Old range is empty - use new one.
-		return shadowRange(lo + hi<<16)
-	}
-	if hi < sr.lo() || lo > sr.hi() {
-		// The two regions don't overlap or abut, so we would
-		// have to keep track of multiple disjoint ranges.
-		// Because we can only keep one, keep the larger one.
-		if sr.hi()-sr.lo() >= hi-lo {
-			return sr
-		}
-		return shadowRange(lo + hi<<16)
-	}
-	// Regions overlap or abut - compute the union.
-	return shadowRange(min(lo, sr.lo()) + max(hi, sr.hi())<<16)
-}
-
 // elimDeadAutosGeneric deletes autos that are never accessed. To achieve this
 // we track the operations that the address of each auto reaches and if it only
 // reaches stores then we delete all the stores. The other operations will then
@@ -249,7 +201,7 @@ func elimDeadAutosGeneric(f *Func) {
 		}
 
 		if v.Uses == 0 && v.Op != OpNilCheck && !v.Op.IsCall() && !v.Op.HasSideEffects() || len(args) == 0 {
-			// We need to keep nil checks even if they have no use.
+			// Nil check has no use, but we need to keep it.
 			// Also keep calls and values that have side effects.
 			return
 		}

src/cmd/compile/internal/ssa/expand_calls.go

@@ -855,7 +855,7 @@ func storeOneArg(x *expandState, pos src.XPos, b *Block, locs []*LocalSlot, suff
 // storeOneLoad creates a decomposed (one step) load that is then stored.
 func storeOneLoad(x *expandState, pos src.XPos, b *Block, source, mem *Value, t *types.Type, offArg, offStore int64, loadRegOffset Abi1RO, storeRc registerCursor) *Value {
 	from := x.offsetFrom(source.Block, source.Args[0], offArg, types.NewPtr(t))
-	w := b.NewValue2(source.Pos, OpLoad, t, from, mem)
+	w := source.Block.NewValue2(source.Pos, OpLoad, t, from, mem)
 	return x.storeArgOrLoad(pos, b, w, mem, t, offStore, loadRegOffset, storeRc)
 }
 
@@ -962,7 +962,7 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 		eltRO := x.regWidth(elt)
 		source.Type = t
 		for i := int64(0); i < t.NumElem(); i++ {
-			sel := b.NewValue1I(pos, OpArraySelect, elt, i, source)
+			sel := source.Block.NewValue1I(pos, OpArraySelect, elt, i, source)
 			mem = x.storeArgOrLoad(pos, b, sel, mem, elt, storeOffset+i*elt.Size(), loadRegOffset, storeRc.at(t, 0))
 			loadRegOffset += eltRO
 			pos = pos.WithNotStmt()
@@ -997,7 +997,7 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 		source.Type = t
 		for i := 0; i < t.NumFields(); i++ {
 			fld := t.Field(i)
-			sel := b.NewValue1I(pos, OpStructSelect, fld.Type, int64(i), source)
+			sel := source.Block.NewValue1I(pos, OpStructSelect, fld.Type, int64(i), source)
 			mem = x.storeArgOrLoad(pos, b, sel, mem, fld.Type, storeOffset+fld.Offset, loadRegOffset, storeRc.next(fld.Type))
 			loadRegOffset += x.regWidth(fld.Type)
 			pos = pos.WithNotStmt()
@@ -1009,48 +1009,48 @@ func (x *expandState) storeArgOrLoad(pos src.XPos, b *Block, source, mem *Value,
 			break
 		}
 		tHi, tLo := x.intPairTypes(t.Kind())
-		sel := b.NewValue1(pos, OpInt64Hi, tHi, source)
+		sel := source.Block.NewValue1(pos, OpInt64Hi, tHi, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, tHi, storeOffset+x.hiOffset, loadRegOffset+x.hiRo, storeRc.plus(x.hiRo))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpInt64Lo, tLo, source)
+		sel = source.Block.NewValue1(pos, OpInt64Lo, tLo, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, tLo, storeOffset+x.lowOffset, loadRegOffset+x.loRo, storeRc.plus(x.hiRo))
 
 	case types.TINTER:
-		sel := b.NewValue1(pos, OpITab, x.typs.BytePtr, source)
+		sel := source.Block.NewValue1(pos, OpITab, x.typs.BytePtr, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpIData, x.typs.BytePtr, source)
+		sel = source.Block.NewValue1(pos, OpIData, x.typs.BytePtr, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset+x.ptrSize, loadRegOffset+RO_iface_data, storeRc)
 
 	case types.TSTRING:
-		sel := b.NewValue1(pos, OpStringPtr, x.typs.BytePtr, source)
+		sel := source.Block.NewValue1(pos, OpStringPtr, x.typs.BytePtr, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.BytePtr, storeOffset, loadRegOffset, storeRc.next(x.typs.BytePtr))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpStringLen, x.typs.Int, source)
+		sel = source.Block.NewValue1(pos, OpStringLen, x.typs.Int, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+x.ptrSize, loadRegOffset+RO_string_len, storeRc)
 
 	case types.TSLICE:
 		et := types.NewPtr(t.Elem())
-		sel := b.NewValue1(pos, OpSlicePtr, et, source)
+		sel := source.Block.NewValue1(pos, OpSlicePtr, et, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, et, storeOffset, loadRegOffset, storeRc.next(et))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpSliceLen, x.typs.Int, source)
+		sel = source.Block.NewValue1(pos, OpSliceLen, x.typs.Int, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+x.ptrSize, loadRegOffset+RO_slice_len, storeRc.next(x.typs.Int))
-		sel = b.NewValue1(pos, OpSliceCap, x.typs.Int, source)
+		sel = source.Block.NewValue1(pos, OpSliceCap, x.typs.Int, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Int, storeOffset+2*x.ptrSize, loadRegOffset+RO_slice_cap, storeRc)
 
 	case types.TCOMPLEX64:
-		sel := b.NewValue1(pos, OpComplexReal, x.typs.Float32, source)
+		sel := source.Block.NewValue1(pos, OpComplexReal, x.typs.Float32, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float32, storeOffset, loadRegOffset, storeRc.next(x.typs.Float32))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpComplexImag, x.typs.Float32, source)
+		sel = source.Block.NewValue1(pos, OpComplexImag, x.typs.Float32, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float32, storeOffset+4, loadRegOffset+RO_complex_imag, storeRc)
 
 	case types.TCOMPLEX128:
-		sel := b.NewValue1(pos, OpComplexReal, x.typs.Float64, source)
+		sel := source.Block.NewValue1(pos, OpComplexReal, x.typs.Float64, source)
 		mem = x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float64, storeOffset, loadRegOffset, storeRc.next(x.typs.Float64))
 		pos = pos.WithNotStmt()
-		sel = b.NewValue1(pos, OpComplexImag, x.typs.Float64, source)
+		sel = source.Block.NewValue1(pos, OpComplexImag, x.typs.Float64, source)
 		return x.storeArgOrLoad(pos, b, sel, mem, x.typs.Float64, storeOffset+8, loadRegOffset+RO_complex_imag, storeRc)
 	}
 
@@ -1113,9 +1113,6 @@ func (x *expandState) rewriteArgs(v *Value, firstArg int) {
 					}
 				}
 			}
-			if x.debug > 1 {
-				x.Printf("...storeArg %s, %v, %d\n", a.LongString(), aType, aOffset)
-			}
 			// "Dereference" of addressed (probably not-SSA-eligible) value becomes Move
 			// TODO(register args) this will be more complicated with registers in the picture.
 			mem = x.rewriteDereference(v.Block, sp, a, mem, aOffset, aux.SizeOfArg(auxI), aType, v.Pos)

src/cmd/compile/internal/ssa/fuse.go

@@ -169,7 +169,7 @@ func fuseBlockIf(b *Block) bool {
 // There may be false positives.
 func isEmpty(b *Block) bool {
 	for _, v := range b.Values {
-		if v.Uses > 0 || v.Op.IsCall() || v.Op.HasSideEffects() || v.Type.IsVoid() || opcodeTable[v.Op].nilCheck {
+		if v.Uses > 0 || v.Op.IsCall() || v.Op.HasSideEffects() || v.Type.IsVoid() {
 			return false
 		}
 	}

src/cmd/compile/internal/ssa/fuse_test.go

@@ -254,7 +254,7 @@ func TestFuseSideEffects(t *testing.T) {
 			Valu("p", OpArg, c.config.Types.IntPtr, 0, nil),
 			If("c1", "z0", "exit")),
 		Bloc("z0",
-			Valu("nilcheck", OpNilCheck, c.config.Types.IntPtr, 0, nil, "p", "mem"),
+			Valu("nilcheck", OpNilCheck, types.TypeVoid, 0, nil, "p", "mem"),
 			Goto("exit")),
 		Bloc("exit",
 			Exit("mem"),

src/cmd/compile/internal/ssa/loopbce.go

@@ -127,13 +127,6 @@ func findIndVar(f *Func) []indVar {
 			less = false
 		}
 
-		if ind.Block != b {
-			// TODO: Could be extended to include disjointed loop headers.
-			// I don't think this is causing missed optimizations in real world code often.
-			// See https://go.dev/issue/63955
-			continue
-		}
-
 		// Expect the increment to be a nonzero constant.
 		if !inc.isGenericIntConst() {
 			continue

src/cmd/compile/internal/ssa/memcombine.go

@@ -41,7 +41,6 @@ func memcombineLoads(f *Func) {
 		}
 	}
 	for _, b := range f.Blocks {
-		order = order[:0]
 		for _, v := range b.Values {
 			if v.Op != OpOr16 && v.Op != OpOr32 && v.Op != OpOr64 {
 				continue
@@ -313,8 +312,8 @@ func combineLoads(root *Value, n int64) bool {
 	if isLittleEndian && shift0 != 0 {
 		v = leftShift(loadBlock, pos, v, shift0)
 	}
-	if isBigEndian && shift0-(n-1)*size*8 != 0 {
-		v = leftShift(loadBlock, pos, v, shift0-(n-1)*size*8)
+	if isBigEndian && shift0-(n-1)*8 != 0 {
+		v = leftShift(loadBlock, pos, v, shift0-(n-1)*8)
 	}
 
 	// Install with (Copy v).
@@ -588,14 +587,14 @@ func combineStores(root *Value, n int64) bool {
 	isLittleEndian := true
 	shift0 := shift(a[0].store, shiftBase)
 	for i := int64(1); i < n; i++ {
-		if shift(a[i].store, shiftBase) != shift0+i*size*8 {
+		if shift(a[i].store, shiftBase) != shift0+i*8 {
 			isLittleEndian = false
 			break
 		}
 	}
 	isBigEndian := true
 	for i := int64(1); i < n; i++ {
-		if shift(a[i].store, shiftBase) != shift0-i*size*8 {
+		if shift(a[i].store, shiftBase) != shift0-i*8 {
 			isBigEndian = false
 			break
 		}
@@ -618,8 +617,8 @@ func combineStores(root *Value, n int64) bool {
 	if isLittleEndian && shift0 != 0 {
 		sv = rightShift(root.Block, root.Pos, sv, shift0)
 	}
-	if isBigEndian && shift0-(n-1)*size*8 != 0 {
-		sv = rightShift(root.Block, root.Pos, sv, shift0-(n-1)*size*8)
+	if isBigEndian && shift0-(n-1)*8 != 0 {
+		sv = rightShift(root.Block, root.Pos, sv, shift0-(n-1)*8)
 	}
 	if sv.Type.Size() > size*n {
 		sv = truncate(root.Block, root.Pos, sv, sv.Type.Size(), size*n)

src/cmd/compile/internal/ssa/nilcheck.go

@@ -38,14 +38,11 @@ func nilcheckelim(f *Func) {
 	work := make([]bp, 0, 256)
 	work = append(work, bp{block: f.Entry})
 
-	// map from value ID to known non-nil version of that value ID
-	// (in the current dominator path being walked). This slice is updated by
+	// map from value ID to bool indicating if value is known to be non-nil
+	// in the current dominator path being walked. This slice is updated by
 	// walkStates to maintain the known non-nil values.
-	// If there is extrinsic information about non-nil-ness, this map
-	// points a value to itself. If a value is known non-nil because we
-	// already did a nil check on it, it points to the nil check operation.
-	nonNilValues := f.Cache.allocValueSlice(f.NumValues())
-	defer f.Cache.freeValueSlice(nonNilValues)
+	nonNilValues := f.Cache.allocBoolSlice(f.NumValues())
+	defer f.Cache.freeBoolSlice(nonNilValues)
 
 	// make an initial pass identifying any non-nil values
 	for _, b := range f.Blocks {
@@ -57,7 +54,7 @@ func nilcheckelim(f *Func) {
 			// We assume that SlicePtr is non-nil because we do a bounds check
 			// before the slice access (and all cap>0 slices have a non-nil ptr). See #30366.
 			if v.Op == OpAddr || v.Op == OpLocalAddr || v.Op == OpAddPtr || v.Op == OpOffPtr || v.Op == OpAdd32 || v.Op == OpAdd64 || v.Op == OpSub32 || v.Op == OpSub64 || v.Op == OpSlicePtr {
-				nonNilValues[v.ID] = v
+				nonNilValues[v.ID] = true
 			}
 		}
 	}
@@ -71,16 +68,16 @@ func nilcheckelim(f *Func) {
 				if v.Op == OpPhi {
 					argsNonNil := true
 					for _, a := range v.Args {
-						if nonNilValues[a.ID] == nil {
+						if !nonNilValues[a.ID] {
 							argsNonNil = false
 							break
 						}
 					}
 					if argsNonNil {
-						if nonNilValues[v.ID] == nil {
+						if !nonNilValues[v.ID] {
 							changed = true
 						}
-						nonNilValues[v.ID] = v
+						nonNilValues[v.ID] = true
 					}
 				}
 			}
@@ -106,8 +103,8 @@ func nilcheckelim(f *Func) {
 			if len(b.Preds) == 1 {
 				p := b.Preds[0].b
 				if p.Kind == BlockIf && p.Controls[0].Op == OpIsNonNil && p.Succs[0].b == b {
-					if ptr := p.Controls[0].Args[0]; nonNilValues[ptr.ID] == nil {
-						nonNilValues[ptr.ID] = ptr
+					if ptr := p.Controls[0].Args[0]; !nonNilValues[ptr.ID] {
+						nonNilValues[ptr.ID] = true
 						work = append(work, bp{op: ClearPtr, ptr: ptr})
 					}
 				}
@@ -120,11 +117,14 @@ func nilcheckelim(f *Func) {
 			pendingLines.clear()
 
 			// Next, process values in the block.
+			i := 0
 			for _, v := range b.Values {
+				b.Values[i] = v
+				i++
 				switch v.Op {
 				case OpIsNonNil:
 					ptr := v.Args[0]
-					if nonNilValues[ptr.ID] != nil {
+					if nonNilValues[ptr.ID] {
 						if v.Pos.IsStmt() == src.PosIsStmt { // Boolean true is a terrible statement boundary.
 							pendingLines.add(v.Pos)
 							v.Pos = v.Pos.WithNotStmt()
@@ -135,7 +135,7 @@ func nilcheckelim(f *Func) {
 					}
 				case OpNilCheck:
 					ptr := v.Args[0]
-					if nilCheck := nonNilValues[ptr.ID]; nilCheck != nil {
+					if nonNilValues[ptr.ID] {
 						// This is a redundant implicit nil check.
 						// Logging in the style of the former compiler -- and omit line 1,
 						// which is usually in generated code.
@@ -145,13 +145,14 @@ func nilcheckelim(f *Func) {
 						if v.Pos.IsStmt() == src.PosIsStmt { // About to lose a statement boundary
 							pendingLines.add(v.Pos)
 						}
-						v.Op = OpCopy
-						v.SetArgs1(nilCheck)
+						v.reset(OpUnknown)
+						f.freeValue(v)
+						i--
 						continue
 					}
 					// Record the fact that we know ptr is non nil, and remember to
 					// undo that information when this dominator subtree is done.
-					nonNilValues[ptr.ID] = v
+					nonNilValues[ptr.ID] = true
 					work = append(work, bp{op: ClearPtr, ptr: ptr})
 					fallthrough // a non-eliminated nil check might be a good place for a statement boundary.
 				default:
@@ -162,7 +163,7 @@ func nilcheckelim(f *Func) {
 				}
 			}
 			// This reduces the lost statement count in "go" by 5 (out of 500 total).
-			for j := range b.Values { // is this an ordering problem?
+			for j := 0; j < i; j++ { // is this an ordering problem?
 				v := b.Values[j]
 				if v.Pos.IsStmt() != src.PosNotStmt && !isPoorStatementOp(v.Op) && pendingLines.contains(v.Pos) {
 					v.Pos = v.Pos.WithIsStmt()
@@ -173,6 +174,7 @@ func nilcheckelim(f *Func) {
 				b.Pos = b.Pos.WithIsStmt()
 				pendingLines.remove(b.Pos)
 			}
+			b.truncateValues(i)
 
 			// Add all dominated blocks to the work list.
 			for w := sdom[node.block.ID].child; w != nil; w = sdom[w.ID].sibling {
@@ -180,7 +182,7 @@ func nilcheckelim(f *Func) {
 			}
 
 		case ClearPtr:
-			nonNilValues[node.ptr.ID] = nil
+			nonNilValues[node.ptr.ID] = false
 			continue
 		}
 	}

src/cmd/compile/internal/ssa/opGen.go

@@ -39373,10 +39373,9 @@ var opcodeTable = [...]opInfo{
 		generic: true,
 	},
 	{
-		name:     "NilCheck",
-		argLen:   2,
-		nilCheck: true,
-		generic:  true,
+		name:    "NilCheck",
+		argLen:  2,
+		generic: true,
 	},
 	{
 		name:      "GetG",

src/cmd/compile/internal/ssa/rewrite.go

@@ -859,9 +859,6 @@ func disjoint(p1 *Value, n1 int64, p2 *Value, n2 int64) bool {
 			offset += base.AuxInt
 			base = base.Args[0]
 		}
-		if opcodeTable[base.Op].nilCheck {
-			base = base.Args[0]
-		}
 		return base, offset
 	}
 	p1, off1 := baseAndOffset(p1)
@@ -1186,12 +1183,6 @@ func min(x, y int64) int64 {
 	}
 	return y
 }
-func max(x, y int64) int64 {
-	if x > y {
-		return x
-	}
-	return y
-}
 
 func isConstZero(v *Value) bool {
 	switch v.Op {
@@ -1290,6 +1281,10 @@ func zeroUpper32Bits(x *Value, depth int) bool {
 		OpAMD64SHRL, OpAMD64SHRLconst, OpAMD64SARL, OpAMD64SARLconst,
 		OpAMD64SHLL, OpAMD64SHLLconst:
 		return true
+	case OpARM64REV16W, OpARM64REVW, OpARM64RBITW, OpARM64CLZW, OpARM64EXTRWconst,
+		OpARM64MULW, OpARM64MNEGW, OpARM64UDIVW, OpARM64DIVW, OpARM64UMODW,
+		OpARM64MADDW, OpARM64MSUBW, OpARM64RORW, OpARM64RORWconst:
+		return true
 	case OpArg:
 		return x.Type.Size() == 4
 	case OpPhi, OpSelect0, OpSelect1:

src/cmd/compile/internal/ssa/rewriteARM64.go

@@ -154,8 +154,6 @@ func rewriteValueARM64(v *Value) bool {
 		return rewriteValueARM64_OpARM64GreaterEqual(v)
 	case OpARM64GreaterEqualF:
 		return rewriteValueARM64_OpARM64GreaterEqualF(v)
-	case OpARM64GreaterEqualNoov:
-		return rewriteValueARM64_OpARM64GreaterEqualNoov(v)
 	case OpARM64GreaterEqualU:
 		return rewriteValueARM64_OpARM64GreaterEqualU(v)
 	case OpARM64GreaterThan:
@@ -176,8 +174,6 @@ func rewriteValueARM64(v *Value) bool {
 		return rewriteValueARM64_OpARM64LessThan(v)
 	case OpARM64LessThanF:
 		return rewriteValueARM64_OpARM64LessThanF(v)
-	case OpARM64LessThanNoov:
-		return rewriteValueARM64_OpARM64LessThanNoov(v)
 	case OpARM64LessThanU:
 		return rewriteValueARM64_OpARM64LessThanU(v)
 	case OpARM64MADD:
@@ -5957,27 +5953,6 @@ func rewriteValueARM64_OpARM64GreaterEqualF(v *Value) bool {
 	}
 	return false
 }
-func rewriteValueARM64_OpARM64GreaterEqualNoov(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	typ := &b.Func.Config.Types
-	// match: (GreaterEqualNoov (InvertFlags x))
-	// result: (OR (LessThanNoov <typ.Bool> x) (Equal <typ.Bool> x))
-	for {
-		if v_0.Op != OpARM64InvertFlags {
-			break
-		}
-		x := v_0.Args[0]
-		v.reset(OpARM64OR)
-		v0 := b.NewValue0(v.Pos, OpARM64LessThanNoov, typ.Bool)
-		v0.AddArg(x)
-		v1 := b.NewValue0(v.Pos, OpARM64Equal, typ.Bool)
-		v1.AddArg(x)
-		v.AddArg2(v0, v1)
-		return true
-	}
-	return false
-}
 func rewriteValueARM64_OpARM64GreaterEqualU(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (GreaterEqualU (FlagConstant [fc]))
@@ -6692,27 +6667,6 @@ func rewriteValueARM64_OpARM64LessThanF(v *Value) bool {
 	}
 	return false
 }
-func rewriteValueARM64_OpARM64LessThanNoov(v *Value) bool {
-	v_0 := v.Args[0]
-	b := v.Block
-	typ := &b.Func.Config.Types
-	// match: (LessThanNoov (InvertFlags x))
-	// result: (BIC (GreaterEqualNoov <typ.Bool> x) (Equal <typ.Bool> x))
-	for {
-		if v_0.Op != OpARM64InvertFlags {
-			break
-		}
-		x := v_0.Args[0]
-		v.reset(OpARM64BIC)
-		v0 := b.NewValue0(v.Pos, OpARM64GreaterEqualNoov, typ.Bool)
-		v0.AddArg(x)
-		v1 := b.NewValue0(v.Pos, OpARM64Equal, typ.Bool)
-		v1.AddArg(x)
-		v.AddArg2(v0, v1)
-		return true
-	}
-	return false
-}
 func rewriteValueARM64_OpARM64LessThanU(v *Value) bool {
 	v_0 := v.Args[0]
 	// match: (LessThanU (FlagConstant [fc]))
@@ -8714,6 +8668,25 @@ func rewriteValueARM64_OpARM64MOVBreg(v *Value) bool {
 		v.AuxInt = int64ToAuxInt(int64(int8(c)))
 		return true
 	}
+	// match: (MOVBreg <t> (ANDconst x [c]))
+	// cond: uint64(c) & uint64(0xffffffffffffff80) == 0
+	// result: (ANDconst <t> x [c])
+	for {
+		t := v.Type
+		if v_0.Op != OpARM64ANDconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
+		x := v_0.Args[0]
+		if !(uint64(c)&uint64(0xffffffffffffff80) == 0) {
+			break
+		}
+		v.reset(OpARM64ANDconst)
+		v.Type = t
+		v.AuxInt = int64ToAuxInt(c)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVBreg (SLLconst [lc] x))
 	// cond: lc < 8
 	// result: (SBFIZ [armBFAuxInt(lc, 8-lc)] x)
@@ -10792,6 +10765,25 @@ func rewriteValueARM64_OpARM64MOVHreg(v *Value) bool {
 		v.AuxInt = int64ToAuxInt(int64(int16(c)))
 		return true
 	}
+	// match: (MOVHreg <t> (ANDconst x [c]))
+	// cond: uint64(c) & uint64(0xffffffffffff8000) == 0
+	// result: (ANDconst <t> x [c])
+	for {
+		t := v.Type
+		if v_0.Op != OpARM64ANDconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
+		x := v_0.Args[0]
+		if !(uint64(c)&uint64(0xffffffffffff8000) == 0) {
+			break
+		}
+		v.reset(OpARM64ANDconst)
+		v.Type = t
+		v.AuxInt = int64ToAuxInt(c)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVHreg (SLLconst [lc] x))
 	// cond: lc < 16
 	// result: (SBFIZ [armBFAuxInt(lc, 16-lc)] x)
@@ -11951,6 +11943,17 @@ func rewriteValueARM64_OpARM64MOVWUreg(v *Value) bool {
 		v.AuxInt = int64ToAuxInt(int64(uint32(c)))
 		return true
 	}
+	// match: (MOVWUreg x)
+	// cond: zeroUpper32Bits(x, 3)
+	// result: x
+	for {
+		x := v_0
+		if !(zeroUpper32Bits(x, 3)) {
+			break
+		}
+		v.copyOf(x)
+		return true
+	}
 	// match: (MOVWUreg (SLLconst [lc] x))
 	// cond: lc >= 32
 	// result: (MOVDconst [0])
@@ -12455,6 +12458,25 @@ func rewriteValueARM64_OpARM64MOVWreg(v *Value) bool {
 		v.AuxInt = int64ToAuxInt(int64(int32(c)))
 		return true
 	}
+	// match: (MOVWreg <t> (ANDconst x [c]))
+	// cond: uint64(c) & uint64(0xffffffff80000000) == 0
+	// result: (ANDconst <t> x [c])
+	for {
+		t := v.Type
+		if v_0.Op != OpARM64ANDconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
+		x := v_0.Args[0]
+		if !(uint64(c)&uint64(0xffffffff80000000) == 0) {
+			break
+		}
+		v.reset(OpARM64ANDconst)
+		v.Type = t
+		v.AuxInt = int64ToAuxInt(c)
+		v.AddArg(x)
+		return true
+	}
 	// match: (MOVWreg (SLLconst [lc] x))
 	// cond: lc < 32
 	// result: (SBFIZ [armBFAuxInt(lc, 32-lc)] x)

src/cmd/compile/internal/ssa/rewritePPC64.go

@@ -14410,19 +14410,17 @@ func rewriteValuePPC64_OpSelect0(v *Value) bool {
 		v.copyOf(y)
 		return true
 	}
-	// match: (Select0 (ANDCCconst [0xFF] (MOVBreg x)))
-	// result: (MOVBZreg x)
+	// match: (Select0 (ANDCCconst [0xFF] y:(MOVBreg _)))
+	// result: y
 	for {
 		if v_0.Op != OpPPC64ANDCCconst || auxIntToInt64(v_0.AuxInt) != 0xFF {
 			break
 		}
-		v_0_0 := v_0.Args[0]
-		if v_0_0.Op != OpPPC64MOVBreg {
+		y := v_0.Args[0]
+		if y.Op != OpPPC64MOVBreg {
 			break
 		}
-		x := v_0_0.Args[0]
-		v.reset(OpPPC64MOVBZreg)
-		v.AddArg(x)
+		v.copyOf(y)
 		return true
 	}
 	// match: (Select0 (ANDCCconst [c] y:(MOVHZreg _)))
@@ -14440,19 +14438,36 @@ func rewriteValuePPC64_OpSelect0(v *Value) bool {
 		v.copyOf(y)
 		return true
 	}
-	// match: (Select0 (ANDCCconst [0xFFFF] (MOVHreg x)))
-	// result: (MOVHZreg x)
+	// match: (Select0 (ANDCCconst [0xFFFF] y:(MOVHreg _)))
+	// result: y
 	for {
 		if v_0.Op != OpPPC64ANDCCconst || auxIntToInt64(v_0.AuxInt) != 0xFFFF {
 			break
 		}
+		y := v_0.Args[0]
+		if y.Op != OpPPC64MOVHreg {
+			break
+		}
+		v.copyOf(y)
+		return true
+	}
+	// match: (Select0 (ANDCCconst [c] (MOVBreg x)))
+	// result: (Select0 (ANDCCconst [c&0xFF] x))
+	for {
+		if v_0.Op != OpPPC64ANDCCconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
 		v_0_0 := v_0.Args[0]
-		if v_0_0.Op != OpPPC64MOVHreg {
+		if v_0_0.Op != OpPPC64MOVBreg {
 			break
 		}
 		x := v_0_0.Args[0]
-		v.reset(OpPPC64MOVHZreg)
-		v.AddArg(x)
+		v.reset(OpSelect0)
+		v0 := b.NewValue0(v.Pos, OpPPC64ANDCCconst, types.NewTuple(typ.Int, types.TypeFlags))
+		v0.AuxInt = int64ToAuxInt(c & 0xFF)
+		v0.AddArg(x)
+		v.AddArg(v0)
 		return true
 	}
 	// match: (Select0 (ANDCCconst [c] (MOVBZreg x)))
@@ -14474,6 +14489,25 @@ func rewriteValuePPC64_OpSelect0(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	// match: (Select0 (ANDCCconst [c] (MOVHreg x)))
+	// result: (Select0 (ANDCCconst [c&0xFFFF] x))
+	for {
+		if v_0.Op != OpPPC64ANDCCconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpPPC64MOVHreg {
+			break
+		}
+		x := v_0_0.Args[0]
+		v.reset(OpSelect0)
+		v0 := b.NewValue0(v.Pos, OpPPC64ANDCCconst, types.NewTuple(typ.Int, types.TypeFlags))
+		v0.AuxInt = int64ToAuxInt(c & 0xFFFF)
+		v0.AddArg(x)
+		v.AddArg(v0)
+		return true
+	}
 	// match: (Select0 (ANDCCconst [c] (MOVHZreg x)))
 	// result: (Select0 (ANDCCconst [c&0xFFFF] x))
 	for {
@@ -14493,6 +14527,25 @@ func rewriteValuePPC64_OpSelect0(v *Value) bool {
 		v.AddArg(v0)
 		return true
 	}
+	// match: (Select0 (ANDCCconst [c] (MOVWreg x)))
+	// result: (Select0 (ANDCCconst [c&0xFFFFFFFF] x))
+	for {
+		if v_0.Op != OpPPC64ANDCCconst {
+			break
+		}
+		c := auxIntToInt64(v_0.AuxInt)
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpPPC64MOVWreg {
+			break
+		}
+		x := v_0_0.Args[0]
+		v.reset(OpSelect0)
+		v0 := b.NewValue0(v.Pos, OpPPC64ANDCCconst, types.NewTuple(typ.Int, types.TypeFlags))
+		v0.AuxInt = int64ToAuxInt(c & 0xFFFFFFFF)
+		v0.AddArg(x)
+		v.AddArg(v0)
+		return true
+	}
 	// match: (Select0 (ANDCCconst [c] (MOVWZreg x)))
 	// result: (Select0 (ANDCCconst [c&0xFFFFFFFF] x))
 	for {

src/cmd/compile/internal/ssa/rewritegeneric.go

@@ -18967,84 +18967,79 @@ func rewriteValuegeneric_OpNilCheck(v *Value) bool {
 	v_0 := v.Args[0]
 	b := v.Block
 	fe := b.Func.fe
-	// match: (NilCheck ptr:(GetG mem) mem)
-	// result: ptr
+	// match: (NilCheck (GetG mem) mem)
+	// result: mem
 	for {
-		ptr := v_0
-		if ptr.Op != OpGetG {
+		if v_0.Op != OpGetG {
 			break
 		}
-		mem := ptr.Args[0]
+		mem := v_0.Args[0]
 		if mem != v_1 {
 			break
 		}
-		v.copyOf(ptr)
+		v.copyOf(mem)
 		return true
 	}
-	// match: (NilCheck ptr:(SelectN [0] call:(StaticLECall _ _)) _)
+	// match: (NilCheck (SelectN [0] call:(StaticLECall _ _)) _)
 	// cond: isSameCall(call.Aux, "runtime.newobject") && warnRule(fe.Debug_checknil(), v, "removed nil check")
-	// result: ptr
+	// result: (Invalid)
 	for {
-		ptr := v_0
-		if ptr.Op != OpSelectN || auxIntToInt64(ptr.AuxInt) != 0 {
+		if v_0.Op != OpSelectN || auxIntToInt64(v_0.AuxInt) != 0 {
 			break
 		}
-		call := ptr.Args[0]
+		call := v_0.Args[0]
 		if call.Op != OpStaticLECall || len(call.Args) != 2 || !(isSameCall(call.Aux, "runtime.newobject") && warnRule(fe.Debug_checknil(), v, "removed nil check")) {
 			break
 		}
-		v.copyOf(ptr)
+		v.reset(OpInvalid)
 		return true
 	}
-	// match: (NilCheck ptr:(OffPtr (SelectN [0] call:(StaticLECall _ _))) _)
+	// match: (NilCheck (OffPtr (SelectN [0] call:(StaticLECall _ _))) _)
 	// cond: isSameCall(call.Aux, "runtime.newobject") && warnRule(fe.Debug_checknil(), v, "removed nil check")
-	// result: ptr
+	// result: (Invalid)
 	for {
-		ptr := v_0
-		if ptr.Op != OpOffPtr {
+		if v_0.Op != OpOffPtr {
 			break
 		}
-		ptr_0 := ptr.Args[0]
-		if ptr_0.Op != OpSelectN || auxIntToInt64(ptr_0.AuxInt) != 0 {
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSelectN || auxIntToInt64(v_0_0.AuxInt) != 0 {
 			break
 		}
-		call := ptr_0.Args[0]
+		call := v_0_0.Args[0]
 		if call.Op != OpStaticLECall || len(call.Args) != 2 || !(isSameCall(call.Aux, "runtime.newobject") && warnRule(fe.Debug_checknil(), v, "removed nil check")) {
 			break
 		}
-		v.copyOf(ptr)
+		v.reset(OpInvalid)
 		return true
 	}
-	// match: (NilCheck ptr:(Addr {_} (SB)) _)
-	// result: ptr
+	// match: (NilCheck (Addr {_} (SB)) _)
+	// result: (Invalid)
 	for {
-		ptr := v_0
-		if ptr.Op != OpAddr {
+		if v_0.Op != OpAddr {
 			break
 		}
-		ptr_0 := ptr.Args[0]
-		if ptr_0.Op != OpSB {
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpSB {
 			break
 		}
-		v.copyOf(ptr)
+		v.reset(OpInvalid)
 		return true
 	}
-	// match: (NilCheck ptr:(Convert (Addr {_} (SB)) _) _)
-	// result: ptr
+	// match: (NilCheck (Convert (Addr {_} (SB)) _) _)
+	// result: (Invalid)
 	for {
-		ptr := v_0
-		if ptr.Op != OpConvert {
+		if v_0.Op != OpConvert {
 			break
 		}
-		ptr_0 := ptr.Args[0]
-		if ptr_0.Op != OpAddr {
+		v_0_0 := v_0.Args[0]
+		if v_0_0.Op != OpAddr {
 			break
 		}
-		ptr_0_0 := ptr_0.Args[0]
-		if ptr_0_0.Op != OpSB {
+		v_0_0_0 := v_0_0.Args[0]
+		if v_0_0_0.Op != OpSB {
 			break
 		}
-		v.copyOf(ptr)
+		v.reset(OpInvalid)
 		return true
 	}
 	return false

src/cmd/compile/internal/ssa/schedule.go

@@ -312,21 +312,14 @@ func schedule(f *Func) {
 	}
 
 	// Remove SPanchored now that we've scheduled.
-	// Also unlink nil checks now that ordering is assured
-	// between the nil check and the uses of the nil-checked pointer.
 	for _, b := range f.Blocks {
 		for _, v := range b.Values {
 			for i, a := range v.Args {
-				if a.Op == OpSPanchored || opcodeTable[a.Op].nilCheck {
+				if a.Op == OpSPanchored {
 					v.SetArg(i, a.Args[0])
 				}
 			}
 		}
-		for i, c := range b.ControlValues() {
-			if c.Op == OpSPanchored || opcodeTable[c.Op].nilCheck {
-				b.ReplaceControl(i, c.Args[0])
-			}
-		}
 	}
 	for _, b := range f.Blocks {
 		i := 0
@@ -339,15 +332,6 @@ func schedule(f *Func) {
 				v.resetArgs()
 				f.freeValue(v)
 			} else {
-				if opcodeTable[v.Op].nilCheck {
-					if v.Uses != 0 {
-						base.Fatalf("nilcheck still has %d uses", v.Uses)
-					}
-					// We can't delete the nil check, but we mark
-					// it as having void type so regalloc won't
-					// try to allocate a register for it.
-					v.Type = types.TypeVoid
-				}
 				b.Values[i] = v
 				i++
 			}

src/cmd/compile/internal/ssa/value.go

@@ -552,11 +552,7 @@ func (v *Value) LackingPos() bool {
 // if its use count drops to 0.
 func (v *Value) removeable() bool {
 	if v.Type.IsVoid() {
-		// Void ops (inline marks), must stay.
-		return false
-	}
-	if opcodeTable[v.Op].nilCheck {
-		// Nil pointer checks must stay.
+		// Void ops, like nil pointer checks, must stay.
 		return false
 	}
 	if v.Type.IsMemory() {

src/cmd/compile/internal/ssa/writebarrier.go

@@ -53,10 +53,7 @@ func mightContainHeapPointer(ptr *Value, size int64, mem *Value, zeroes map[ID]Z
 	}
 
 	ptrSize := ptr.Block.Func.Config.PtrSize
-	if off%ptrSize != 0 {
-		return true // see issue 61187
-	}
-	if size%ptrSize != 0 {
+	if off%ptrSize != 0 || size%ptrSize != 0 {
 		ptr.Fatalf("unaligned pointer write")
 	}
 	if off < 0 || off+size > 64*ptrSize {
@@ -133,7 +130,7 @@ func needWBdst(ptr, mem *Value, zeroes map[ID]ZeroRegion) bool {
 	}
 	ptrSize := ptr.Block.Func.Config.PtrSize
 	if off%ptrSize != 0 {
-		return true // see issue 61187
+		ptr.Fatalf("unaligned pointer write")
 	}
 	if off < 0 || off >= 64*ptrSize {
 		// write goes off end of tracked offsets

src/cmd/compile/internal/ssagen/ssa.go

@@ -1991,8 +1991,7 @@ func (s *state) stmt(n ir.Node) {
 	case ir.OCHECKNIL:
 		n := n.(*ir.UnaryExpr)
 		p := s.expr(n.X)
-		_ = s.nilCheck(p)
-		// TODO: check that throwing away the nilcheck result is ok.
+		s.nilCheck(p)
 
 	case ir.OINLMARK:
 		n := n.(*ir.InlineMarkStmt)
@@ -5622,20 +5621,18 @@ func (s *state) exprPtr(n ir.Node, bounded bool, lineno src.XPos) *ssa.Value {
 		}
 		return p
 	}
-	p = s.nilCheck(p)
+	s.nilCheck(p)
 	return p
 }
 
 // nilCheck generates nil pointer checking code.
 // Used only for automatically inserted nil checks,
 // not for user code like 'x != nil'.
-// Returns a "definitely not nil" copy of x to ensure proper ordering
-// of the uses of the post-nilcheck pointer.
-func (s *state) nilCheck(ptr *ssa.Value) *ssa.Value {
+func (s *state) nilCheck(ptr *ssa.Value) {
 	if base.Debug.DisableNil != 0 || s.curfn.NilCheckDisabled() {
-		return ptr
+		return
 	}
-	return s.newValue2(ssa.OpNilCheck, ptr.Type, ptr, s.mem())
+	s.newValue2(ssa.OpNilCheck, types.TypeVoid, ptr, s.mem())
 }
 
 // boundsCheck generates bounds checking code. Checks if 0 <= idx <[=] len, branches to exit if not.
@@ -5987,8 +5984,8 @@ func (s *state) slice(v, i, j, k *ssa.Value, bounded bool) (p, l, c *ssa.Value)
 		if !t.Elem().IsArray() {
 			s.Fatalf("bad ptr to array in slice %v\n", t)
 		}
-		nv := s.nilCheck(v)
-		ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), nv)
+		s.nilCheck(v)
+		ptr = s.newValue1(ssa.OpCopy, types.NewPtr(t.Elem().Elem()), v)
 		len = s.constInt(types.Types[types.TINT], t.Elem().NumElem())
 		cap = len
 	default:
@@ -7086,21 +7083,8 @@ func genssa(f *ssa.Func, pp *objw.Progs) {
 		// for an empty block this will be used for its control
 		// instruction. We won't use the actual liveness map on a
 		// control instruction. Just mark it something that is
-		// preemptible, unless this function is "all unsafe", or
-		// the empty block is in a write barrier.
-		unsafe := liveness.IsUnsafe(f)
-		if b.Kind == ssa.BlockPlain {
-			// Empty blocks that are part of write barriers need
-			// to have their control instructions marked unsafe.
-			c := b.Succs[0].Block()
-			for _, v := range c.Values {
-				if v.Op == ssa.OpWBend {
-					unsafe = true
-					break
-				}
-			}
-		}
-		s.pp.NextLive = objw.LivenessIndex{StackMapIndex: -1, IsUnsafePoint: unsafe}
+		// preemptible, unless this function is "all unsafe".
+		s.pp.NextLive = objw.LivenessIndex{StackMapIndex: -1, IsUnsafePoint: liveness.IsUnsafe(f)}
 
 		if idx, ok := argLiveBlockMap[b.ID]; ok && idx != argLiveIdx {
 			argLiveIdx = idx

src/cmd/compile/internal/test/memcombine_test.go

@@ -71,129 +71,3 @@ func readUint32be(b []byte) uint64 {
 //go:noinline
 func nop() {
 }
-
-type T32 struct {
-	a, b uint32
-}
-
-//go:noinline
-func (t *T32) bigEndianLoad() uint64 {
-	return uint64(t.a)<<32 | uint64(t.b)
-}
-
-//go:noinline
-func (t *T32) littleEndianLoad() uint64 {
-	return uint64(t.a) | (uint64(t.b) << 32)
-}
-
-//go:noinline
-func (t *T32) bigEndianStore(x uint64) {
-	t.a = uint32(x >> 32)
-	t.b = uint32(x)
-}
-
-//go:noinline
-func (t *T32) littleEndianStore(x uint64) {
-	t.a = uint32(x)
-	t.b = uint32(x >> 32)
-}
-
-type T16 struct {
-	a, b uint16
-}
-
-//go:noinline
-func (t *T16) bigEndianLoad() uint32 {
-	return uint32(t.a)<<16 | uint32(t.b)
-}
-
-//go:noinline
-func (t *T16) littleEndianLoad() uint32 {
-	return uint32(t.a) | (uint32(t.b) << 16)
-}
-
-//go:noinline
-func (t *T16) bigEndianStore(x uint32) {
-	t.a = uint16(x >> 16)
-	t.b = uint16(x)
-}
-
-//go:noinline
-func (t *T16) littleEndianStore(x uint32) {
-	t.a = uint16(x)
-	t.b = uint16(x >> 16)
-}
-
-type T8 struct {
-	a, b uint8
-}
-
-//go:noinline
-func (t *T8) bigEndianLoad() uint16 {
-	return uint16(t.a)<<8 | uint16(t.b)
-}
-
-//go:noinline
-func (t *T8) littleEndianLoad() uint16 {
-	return uint16(t.a) | (uint16(t.b) << 8)
-}
-
-//go:noinline
-func (t *T8) bigEndianStore(x uint16) {
-	t.a = uint8(x >> 8)
-	t.b = uint8(x)
-}
-
-//go:noinline
-func (t *T8) littleEndianStore(x uint16) {
-	t.a = uint8(x)
-	t.b = uint8(x >> 8)
-}
-
-func TestIssue64468(t *testing.T) {
-	t32 := T32{1, 2}
-	if got, want := t32.bigEndianLoad(), uint64(1<<32+2); got != want {
-		t.Errorf("T32.bigEndianLoad got %x want %x\n", got, want)
-	}
-	if got, want := t32.littleEndianLoad(), uint64(1+2<<32); got != want {
-		t.Errorf("T32.littleEndianLoad got %x want %x\n", got, want)
-	}
-	t16 := T16{1, 2}
-	if got, want := t16.bigEndianLoad(), uint32(1<<16+2); got != want {
-		t.Errorf("T16.bigEndianLoad got %x want %x\n", got, want)
-	}
-	if got, want := t16.littleEndianLoad(), uint32(1+2<<16); got != want {
-		t.Errorf("T16.littleEndianLoad got %x want %x\n", got, want)
-	}
-	t8 := T8{1, 2}
-	if got, want := t8.bigEndianLoad(), uint16(1<<8+2); got != want {
-		t.Errorf("T8.bigEndianLoad got %x want %x\n", got, want)
-	}
-	if got, want := t8.littleEndianLoad(), uint16(1+2<<8); got != want {
-		t.Errorf("T8.littleEndianLoad got %x want %x\n", got, want)
-	}
-	t32.bigEndianStore(1<<32 + 2)
-	if got, want := t32, (T32{1, 2}); got != want {
-		t.Errorf("T32.bigEndianStore got %x want %x\n", got, want)
-	}
-	t32.littleEndianStore(1<<32 + 2)
-	if got, want := t32, (T32{2, 1}); got != want {
-		t.Errorf("T32.littleEndianStore got %x want %x\n", got, want)
-	}
-	t16.bigEndianStore(1<<16 + 2)
-	if got, want := t16, (T16{1, 2}); got != want {
-		t.Errorf("T16.bigEndianStore got %x want %x\n", got, want)
-	}
-	t16.littleEndianStore(1<<16 + 2)
-	if got, want := t16, (T16{2, 1}); got != want {
-		t.Errorf("T16.littleEndianStore got %x want %x\n", got, want)
-	}
-	t8.bigEndianStore(1<<8 + 2)
-	if got, want := t8, (T8{1, 2}); got != want {
-		t.Errorf("T8.bigEndianStore got %x want %x\n", got, want)
-	}
-	t8.littleEndianStore(1<<8 + 2)
-	if got, want := t8, (T8{2, 1}); got != want {
-		t.Errorf("T8.littleEndianStore got %x want %x\n", got, want)
-	}
-}

src/cmd/compile/internal/typecheck/func.go

@@ -94,24 +94,40 @@ func ClosureType(clo *ir.ClosureExpr) *types.Type {
 	// and has one float64 argument and no results,
 	// the generated code looks like:
 	//
-	//	clos = &struct{F uintptr; X0 *int; X1 *string}{func.1, &i, &s}
+	//	clos = &struct{.F uintptr; i *int; s *string}{func.1, &i, &s}
 	//
 	// The use of the struct provides type information to the garbage
-	// collector so that it can walk the closure. We could use (in this
-	// case) [3]unsafe.Pointer instead, but that would leave the gc in
-	// the dark. The information appears in the binary in the form of
-	// type descriptors; the struct is unnamed and uses exported field
-	// names so that closures in multiple packages with the same struct
-	// type can share the descriptor.
+	// collector so that it can walk the closure. We could use (in this case)
+	// [3]unsafe.Pointer instead, but that would leave the gc in the dark.
+	// The information appears in the binary in the form of type descriptors;
+	// the struct is unnamed so that closures in multiple packages with the
+	// same struct type can share the descriptor.
 
-	fields := make([]*types.Field, 1+len(clo.Func.ClosureVars))
-	fields[0] = types.NewField(base.AutogeneratedPos, types.LocalPkg.Lookup("F"), types.Types[types.TUINTPTR])
-	for i, v := range clo.Func.ClosureVars {
+	// Make sure the .F field is in the same package as the rest of the
+	// fields. This deals with closures in instantiated functions, which are
+	// compiled as if from the source package of the generic function.
+	var pkg *types.Pkg
+	if len(clo.Func.ClosureVars) == 0 {
+		pkg = types.LocalPkg
+	} else {
+		for _, v := range clo.Func.ClosureVars {
+			if pkg == nil {
+				pkg = v.Sym().Pkg
+			} else if pkg != v.Sym().Pkg {
+				base.Fatalf("Closure variables from multiple packages: %+v", clo)
+			}
+		}
+	}
+
+	fields := []*types.Field{
+		types.NewField(base.Pos, pkg.Lookup(".F"), types.Types[types.TUINTPTR]),
+	}
+	for _, v := range clo.Func.ClosureVars {
 		typ := v.Type()
 		if !v.Byval() {
 			typ = types.NewPtr(typ)
 		}
-		fields[1+i] = types.NewField(base.AutogeneratedPos, types.LocalPkg.LookupNum("X", i), typ)
+		fields = append(fields, types.NewField(base.Pos, v.Sym(), typ))
 	}
 	typ := types.NewStruct(fields)
 	typ.SetNoalg(true)

src/cmd/compile/internal/types/fmt.go

@@ -642,6 +642,9 @@ func fldconv(b *bytes.Buffer, f *Field, verb rune, mode fmtMode, visited map[*Ty
 				name = fmt.Sprint(f.Nname)
 			} else if verb == 'L' {
 				name = s.Name
+				if name == ".F" {
+					name = "F" // Hack for toolstash -cmp.
+				}
 				if !IsExported(name) && mode != fmtTypeIDName {
 					name = sconv(s, 0, mode) // qualify non-exported names (used on structs, not on funarg)
 				}

src/cmd/compile/internal/types2/api.go

@@ -110,11 +110,11 @@ type Config struct {
 	// type checker will initialize this field with a newly created context.
 	Context *Context
 
-	// GoVersion describes the accepted Go language version. The string must
-	// start with a prefix of the form "go%d.%d" (e.g. "go1.20", "go1.21rc1", or
-	// "go1.21.0") or it must be empty; an empty string disables Go language
-	// version checks. If the format is invalid, invoking the type checker will
-	// result in an error.
+	// GoVersion describes the accepted Go language version. The string
+	// must follow the format "go%d.%d" (e.g. "go1.12") or ist must be
+	// empty; an empty string disables Go language version checks.
+	// If the format is invalid, invoking the type checker will cause a
+	// panic.
 	GoVersion string
 
 	// If IgnoreFuncBodies is set, function bodies are not

src/cmd/compile/internal/types2/api_test.go

@@ -2070,29 +2070,6 @@ func TestIdenticalUnions(t *testing.T) {
 	}
 }
 
-func TestIssue61737(t *testing.T) {
-	// This test verifies that it is possible to construct invalid interfaces
-	// containing duplicate methods using the go/types API.
-	//
-	// It must be possible for importers to construct such invalid interfaces.
-	// Previously, this panicked.
-
-	sig1 := NewSignatureType(nil, nil, nil, NewTuple(NewParam(nopos, nil, "", Typ[Int])), nil, false)
-	sig2 := NewSignatureType(nil, nil, nil, NewTuple(NewParam(nopos, nil, "", Typ[String])), nil, false)
-
-	methods := []*Func{
-		NewFunc(nopos, nil, "M", sig1),
-		NewFunc(nopos, nil, "M", sig2),
-	}
-
-	embeddedMethods := []*Func{
-		NewFunc(nopos, nil, "M", sig2),
-	}
-	embedded := NewInterfaceType(embeddedMethods, nil)
-	iface := NewInterfaceType(methods, []Type{embedded})
-	iface.NumMethods() // unlike go/types, there is no Complete() method, so we complete implicitly
-}
-
 func TestIssue15305(t *testing.T) {
 	const src = "package p; func f() int16; var _ = f(undef)"
 	f := mustParse(src)

src/cmd/compile/internal/types2/builtins.go

@@ -576,11 +576,6 @@ func (check *Checker) builtin(x *operand, call *syntax.CallExpr, id builtinId) (
 		// If nargs == 1, make sure x.mode is either a value or a constant.
 		if x.mode != constant_ {
 			x.mode = value
-			// A value must not be untyped.
-			check.assignment(x, &emptyInterface, "argument to "+bin.name)
-			if x.mode == invalid {
-				return
-			}
 		}
 
 		// Use the final type computed above for all arguments.

src/cmd/compile/internal/types2/call.go

@@ -569,14 +569,6 @@ func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []T
 		for i, arg := range args {
 			// generic arguments cannot have a defined (*Named) type - no need for underlying type below
 			if asig, _ := arg.typ.(*Signature); asig != nil && asig.TypeParams().Len() > 0 {
-				// The argument type is a generic function signature. This type is
-				// pointer-identical with (it's copied from) the type of the generic
-				// function argument and thus the function object.
-				// Before we change the type (type parameter renaming, below), make
-				// a clone of it as otherwise we implicitly modify the object's type
-				// (go.dev/issues/63260).
-				clone := *asig
-				asig = &clone
 				// Rename type parameters for cases like f(g, g); this gives each
 				// generic function argument a unique type identity (go.dev/issues/59956).
 				// TODO(gri) Consider only doing this if a function argument appears
@@ -618,17 +610,20 @@ func (check *Checker) arguments(call *syntax.CallExpr, sig *Signature, targs []T
 			return // error already reported
 		}
 
-		// update result signature: instantiate if needed
+		// compute result signature: instantiate if needed
+		rsig = sig
 		if n > 0 {
 			rsig = check.instantiateSignature(call.Pos(), call.Fun, sig, targs[:n], xlist)
-			// If the callee's parameter list was adjusted we need to update (instantiate)
-			// it separately. Otherwise we can simply use the result signature's parameter
-			// list.
-			if adjusted {
-				sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(tparams[:n], targs[:n]), nil, check.context()).(*Tuple)
-			} else {
-				sigParams = rsig.params
-			}
+		}
+
+		// Optimization: Only if the callee's parameter list was adjusted do we need to
+		// compute it from the adjusted list; otherwise we can simply use the result
+		// signature's parameter list. We only need the n type parameters and arguments
+		// of the callee.
+		if n > 0 && adjusted {
+			sigParams = check.subst(call.Pos(), sigParams, makeSubstMap(tparams[:n], targs[:n]), nil, check.context()).(*Tuple)
+		} else {
+			sigParams = rsig.params
 		}
 
 		// compute argument signatures: instantiate if needed

src/cmd/compile/internal/types2/const.go

@@ -73,6 +73,7 @@ func representableConst(x constant.Value, check *Checker, typ *Basic, rounded *c
 
 	sizeof := func(T Type) int64 {
 		s := conf.sizeof(T)
+		assert(s == 4 || s == 8)
 		return s
 	}
 

src/cmd/compile/internal/types2/infer.go

@@ -96,7 +96,7 @@ func (check *Checker) infer(pos syntax.Pos, tparams []*TypeParam, targs []Type,
 	// Unify parameter and argument types for generic parameters with typed arguments
 	// and collect the indices of generic parameters with untyped arguments.
 	// Terminology: generic parameter = function parameter with a type-parameterized type
-	u := newUnifier(tparams, targs, check.allowVersion(check.pkg, pos, go1_21))
+	u := newUnifier(tparams, targs)
 
 	errorf := func(kind string, tpar, targ Type, arg *operand) {
 		// provide a better error message if we can

src/cmd/compile/internal/types2/issues_test.go

@@ -900,84 +900,3 @@ func _cgoCheckResult(interface{})
 		*boolFieldAddr(cfg, "go115UsesCgo") = true
 	})
 }
-
-func TestIssue61931(t *testing.T) {
-	const src = `
-package p
-
-func A(func(any), ...any) {}
-func B[T any](T)          {}
-
-func _() {
-	A(B, nil // syntax error: missing ',' before newline in argument list
-}
-`
-	f, err := syntax.Parse(syntax.NewFileBase(pkgName(src)), strings.NewReader(src), func(error) {}, nil, 0)
-	if err == nil {
-		t.Fatal("expected syntax error")
-	}
-
-	var conf Config
-	conf.Check(f.PkgName.Value, []*syntax.File{f}, nil) // must not panic
-}
-
-func TestIssue63260(t *testing.T) {
-	const src = `
-package p
-
-func _() {
-        use(f[*string])
-}
-
-func use(func()) {}
-
-func f[I *T, T any]() {
-        var v T
-        _ = v
-}`
-
-	info := Info{
-		Defs: make(map[*syntax.Name]Object),
-	}
-	pkg := mustTypecheck(src, nil, &info)
-
-	// get type parameter T in signature of f
-	T := pkg.Scope().Lookup("f").Type().(*Signature).TypeParams().At(1)
-	if T.Obj().Name() != "T" {
-		t.Fatalf("got type parameter %s, want T", T)
-	}
-
-	// get type of variable v in body of f
-	var v Object
-	for name, obj := range info.Defs {
-		if name.Value == "v" {
-			v = obj
-			break
-		}
-	}
-	if v == nil {
-		t.Fatal("variable v not found")
-	}
-
-	// type of v and T must be pointer-identical
-	if v.Type() != T {
-		t.Fatalf("types of v and T are not pointer-identical: %p != %p", v.Type().(*TypeParam), T)
-	}
-}
-
-func TestIssue64759(t *testing.T) {
-	const src = `
-//go:build go1.18
-package p
-
-func f[S ~[]E, E any](S) {}
-
-func _() {
-	f([]string{})
-}
-`
-	// Per the go:build directive, the source must typecheck
-	// even though the (module) Go version is set to go1.17.
-	conf := Config{GoVersion: "go1.17"}
-	mustTypecheck(src, &conf, nil)
-}

src/cmd/compile/internal/types2/subst.go

@@ -169,7 +169,6 @@ func (subst *subster) typ(typ Type) Type {
 		if mcopied || ecopied {
 			iface := subst.check.newInterface()
 			iface.embeddeds = embeddeds
-			iface.embedPos = t.embedPos
 			iface.implicit = t.implicit
 			iface.complete = t.complete
 			// If we've changed the interface type, we may need to replace its

src/cmd/compile/internal/types2/typeset.go

@@ -6,6 +6,7 @@ package types2
 
 import (
 	"cmd/compile/internal/syntax"
+	"fmt"
 	. "internal/types/errors"
 	"sort"
 	"strings"
@@ -211,6 +212,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 	// we can get rid of the mpos map below and simply use the cloned method's
 	// position.
 
+	var todo []*Func
 	var seen objset
 	var allMethods []*Func
 	mpos := make(map[*Func]syntax.Pos) // method specification or method embedding position, for good error messages
@@ -220,30 +222,36 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			allMethods = append(allMethods, m)
 			mpos[m] = pos
 		case explicit:
-			if check != nil {
-				var err error_
-				err.code = DuplicateDecl
-				err.errorf(pos, "duplicate method %s", m.name)
-				err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-				check.report(&err)
+			if check == nil {
+				panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
 			}
+			// check != nil
+			var err error_
+			err.code = DuplicateDecl
+			err.errorf(pos, "duplicate method %s", m.name)
+			err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+			check.report(&err)
 		default:
 			// We have a duplicate method name in an embedded (not explicitly declared) method.
 			// Check method signatures after all types are computed (go.dev/issue/33656).
 			// If we're pre-go1.14 (overlapping embeddings are not permitted), report that
 			// error here as well (even though we could do it eagerly) because it's the same
 			// error message.
-			if check != nil {
-				check.later(func() {
-					if !check.allowVersion(m.pkg, pos, go1_14) || !Identical(m.typ, other.Type()) {
-						var err error_
-						err.code = DuplicateDecl
-						err.errorf(pos, "duplicate method %s", m.name)
-						err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
-						check.report(&err)
-					}
-				}).describef(pos, "duplicate method check for %s", m.name)
+			if check == nil {
+				// check method signatures after all locally embedded interfaces are computed
+				todo = append(todo, m, other.(*Func))
+				break
 			}
+			// check != nil
+			check.later(func() {
+				if !check.allowVersion(m.pkg, pos, go1_14) || !Identical(m.typ, other.Type()) {
+					var err error_
+					err.code = DuplicateDecl
+					err.errorf(pos, "duplicate method %s", m.name)
+					err.errorf(mpos[other.(*Func)], "other declaration of %s", m.name)
+					check.report(&err)
+				}
+			}).describef(pos, "duplicate method check for %s", m.name)
 		}
 	}
 
@@ -255,8 +263,9 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 	allTerms := allTermlist
 	allComparable := false
 	for i, typ := range ityp.embeddeds {
-		// The embedding position is nil for imported interfaces.
-		// We don't need to do version checks in those cases.
+		// The embedding position is nil for imported interfaces
+		// and also for interface copies after substitution (but
+		// in that case we don't need to report errors again).
 		var pos syntax.Pos // embedding position
 		if ityp.embedPos != nil {
 			pos = (*ityp.embedPos)[i]
@@ -269,7 +278,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			assert(!isTypeParam(typ))
 			tset := computeInterfaceTypeSet(check, pos, u)
 			// If typ is local, an error was already reported where typ is specified/defined.
-			if pos.IsKnown() && check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
+			if check != nil && check.isImportedConstraint(typ) && !check.verifyVersionf(pos, go1_18, "embedding constraint interface %s", typ) {
 				continue
 			}
 			comparable = tset.comparable
@@ -278,7 +287,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			}
 			terms = tset.terms
 		case *Union:
-			if pos.IsKnown() && check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
+			if check != nil && !check.verifyVersionf(pos, go1_18, "embedding interface element %s", u) {
 				continue
 			}
 			tset := computeUnionTypeSet(check, unionSets, pos, u)
@@ -292,7 +301,7 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 			if u == Typ[Invalid] {
 				continue
 			}
-			if pos.IsKnown() && check != nil && !check.verifyVersionf(pos, go1_18, "embedding non-interface type %s", typ) {
+			if check != nil && !check.verifyVersionf(pos, go1_18, "embedding non-interface type %s", typ) {
 				continue
 			}
 			terms = termlist{{false, typ}}
@@ -303,6 +312,16 @@ func computeInterfaceTypeSet(check *Checker, pos syntax.Pos, ityp *Interface) *_
 		// separately. Here we only need to intersect the term lists and comparable bits.
 		allTerms, allComparable = intersectTermLists(allTerms, allComparable, terms, comparable)
 	}
+	ityp.embedPos = nil // not needed anymore (errors have been reported)
+
+	// process todo's (this only happens if check == nil)
+	for i := 0; i < len(todo); i += 2 {
+		m := todo[i]
+		other := todo[i+1]
+		if !Identical(m.typ, other.typ) {
+			panic(fmt.Sprintf("%s: duplicate method %s", m.pos, m.name))
+		}
+	}
 
 	ityp.tset.comparable = allComparable
 	if len(allMethods) != 0 {

src/cmd/compile/internal/types2/unify.go

@@ -53,6 +53,11 @@ const (
 	// the core types, if any, of non-local (unbound) type parameters.
 	enableCoreTypeUnification = true
 
+	// If enableInterfaceInference is set, type inference uses
+	// shared methods for improved type inference involving
+	// interfaces.
+	enableInterfaceInference = true
+
 	// If traceInference is set, unification will print a trace of its operation.
 	// Interpretation of trace:
 	//   x ≡ y    attempt to unify types x and y
@@ -76,16 +81,15 @@ type unifier struct {
 	// that inferring the type for a given type parameter P will
 	// automatically infer the same type for all other parameters
 	// unified (joined) with P.
-	handles                  map[*TypeParam]*Type
-	depth                    int  // recursion depth during unification
-	enableInterfaceInference bool // use shared methods for better inference
+	handles map[*TypeParam]*Type
+	depth   int // recursion depth during unification
 }
 
 // newUnifier returns a new unifier initialized with the given type parameter
 // and corresponding type argument lists. The type argument list may be shorter
 // than the type parameter list, and it may contain nil types. Matching type
 // parameters and arguments must have the same index.
-func newUnifier(tparams []*TypeParam, targs []Type, enableInterfaceInference bool) *unifier {
+func newUnifier(tparams []*TypeParam, targs []Type) *unifier {
 	assert(len(tparams) >= len(targs))
 	handles := make(map[*TypeParam]*Type, len(tparams))
 	// Allocate all handles up-front: in a correct program, all type parameters
@@ -99,7 +103,7 @@ func newUnifier(tparams []*TypeParam, targs []Type, enableInterfaceInference boo
 		}
 		handles[x] = &t
 	}
-	return &unifier{handles, 0, enableInterfaceInference}
+	return &unifier{handles, 0}
 }
 
 // unifyMode controls the behavior of the unifier.
@@ -335,7 +339,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 	// we will fail at function instantiation or argument assignment time.
 	//
 	// If we have at least one defined type, there is one in y.
-	if ny, _ := y.(*Named); mode&exact == 0 && ny != nil && isTypeLit(x) && !(u.enableInterfaceInference && IsInterface(x)) {
+	if ny, _ := y.(*Named); mode&exact == 0 && ny != nil && isTypeLit(x) && !(enableInterfaceInference && IsInterface(x)) {
 		if traceInference {
 			u.tracef("%s ≡ under %s", x, ny)
 		}
@@ -401,40 +405,18 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 					// Therefore, we must fail unification (go.dev/issue/60933).
 					return false
 				}
-				// If we have inexact unification and one of x or y is a defined type, select the
-				// defined type. This ensures that in a series of types, all matching against the
-				// same type parameter, we infer a defined type if there is one, independent of
-				// order. Type inference or assignment may fail, which is ok.
-				// Selecting a defined type, if any, ensures that we don't lose the type name;
-				// and since we have inexact unification, a value of equally named or matching
-				// undefined type remains assignable (go.dev/issue/43056).
+				// If y is a defined type, make sure we record that type
+				// for type parameter x, which may have until now only
+				// recorded an underlying type (go.dev/issue/43056).
+				// Either both types are interfaces, or neither type is.
+				// If both are interfaces, they have the same methods.
 				//
-				// Similarly, if we have inexact unification and there are no defined types but
-				// channel types, select a directed channel, if any. This ensures that in a series
-				// of unnamed types, all matching against the same type parameter, we infer the
-				// directed channel if there is one, independent of order.
-				// Selecting a directional channel, if any, ensures that a value of another
-				// inexactly unifying channel type remains assignable (go.dev/issue/62157).
-				//
-				// If we have multiple defined channel types, they are either identical or we
-				// have assignment conflicts, so we can ignore directionality in this case.
-				//
-				// If we have defined and literal channel types, a defined type wins to avoid
-				// order dependencies.
-				if mode&exact == 0 {
-					switch {
-					case xn:
-						// x is a defined type: nothing to do.
-					case yn:
-						// x is not a defined type and y is a defined type: select y.
-						u.set(px, y)
-					default:
-						// Neither x nor y are defined types.
-						if yc, _ := under(y).(*Chan); yc != nil && yc.dir != SendRecv {
-							// y is a directed channel type: select y.
-							u.set(px, y)
-						}
-					}
+				// Note: Changing the recorded type for a type parameter to
+				// a defined type is only ok when unification is inexact.
+				// But in exact unification, if we have a match, x and y must
+				// be identical, so changing the recorded type for x is a no-op.
+				if yn {
+					u.set(px, y)
 				}
 				return true
 			}
@@ -455,12 +437,12 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 		emode |= exact
 	}
 
-	// If u.EnableInterfaceInference is set and we don't require exact unification,
+	// If EnableInterfaceInference is set and we don't require exact unification,
 	// if both types are interfaces, one interface must have a subset of the
 	// methods of the other and corresponding method signatures must unify.
 	// If only one type is an interface, all its methods must be present in the
 	// other type and corresponding method signatures must unify.
-	if u.enableInterfaceInference && mode&exact == 0 {
+	if enableInterfaceInference && mode&exact == 0 {
 		// One or both interfaces may be defined types.
 		// Look under the name, but not under type parameters (go.dev/issue/60564).
 		xi := asInterface(x)
@@ -523,7 +505,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 			}
 			// All xmethods must exist in ymethods and corresponding signatures must unify.
 			for _, xm := range xmethods {
-				if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
+				if ym := ymap[xm.Id()]; ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
 					return false
 				}
 			}
@@ -544,7 +526,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 			xmethods := xi.typeSet().methods
 			for _, xm := range xmethods {
 				obj, _, _ := LookupFieldOrMethod(y, false, xm.pkg, xm.name)
-				if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, exact, p) {
+				if ym, _ := obj.(*Func); ym == nil || !u.nify(xm.typ, ym.typ, emode, p) {
 					return false
 				}
 			}
@@ -650,7 +632,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 		}
 
 	case *Interface:
-		assert(!u.enableInterfaceInference || mode&exact != 0) // handled before this switch
+		assert(!enableInterfaceInference || mode&exact != 0) // handled before this switch
 
 		// Two interface types unify if they have the same set of methods with
 		// the same names, and corresponding function types unify.
@@ -703,7 +685,7 @@ func (u *unifier) nify(x, y Type, mode unifyMode, p *ifacePair) (result bool) {
 				}
 				for i, f := range a {
 					g := b[i]
-					if f.Id() != g.Id() || !u.nify(f.typ, g.typ, exact, q) {
+					if f.Id() != g.Id() || !u.nify(f.typ, g.typ, emode, q) {
 						return false
 					}
 				}

src/cmd/compile/internal/walk/builtin.go

@@ -135,11 +135,7 @@ func walkClear(n *ir.UnaryExpr) ir.Node {
 	typ := n.X.Type()
 	switch {
 	case typ.IsSlice():
-		if n := arrayClear(n.X.Pos(), n.X, nil); n != nil {
-			return n
-		}
-		// If n == nil, we are clearing an array which takes zero memory, do nothing.
-		return ir.NewBlockStmt(n.Pos(), nil)
+		return arrayClear(n.X.Pos(), n.X, nil)
 	case typ.IsMap():
 		return mapClear(n.X, reflectdata.TypePtrAt(n.X.Pos(), n.X.Type()))
 	}
@@ -255,10 +251,7 @@ func walkLenCap(n *ir.UnaryExpr, init *ir.Nodes) ir.Node {
 		return mkcall("countrunes", n.Type(), init, typecheck.Conv(n.X.(*ir.ConvExpr).X, types.Types[types.TSTRING]))
 	}
 	if isByteCount(n) {
-		conv := n.X.(*ir.ConvExpr)
-		walkStmtList(conv.Init())
-		init.Append(ir.TakeInit(conv)...)
-		_, len := backingArrayPtrLen(cheapExpr(conv.X, init))
+		_, len := backingArrayPtrLen(cheapExpr(n.X.(*ir.ConvExpr).X, init))
 		return len
 	}
 

src/cmd/compile/internal/walk/walk.go

@@ -278,10 +278,8 @@ func backingArrayPtrLen(n ir.Node) (ptr, length ir.Node) {
 	} else {
 		ptr.SetType(n.Type().Elem().PtrTo())
 	}
-	ptr.SetTypecheck(1)
 	length = ir.NewUnaryExpr(base.Pos, ir.OLEN, n)
 	length.SetType(types.Types[types.TINT])
-	length.SetTypecheck(1)
 	return ptr, length
 }
 

src/cmd/covdata/doc.go

@@ -3,78 +3,82 @@
 // license that can be found in the LICENSE file.
 
 /*
-Covdata is a program for manipulating and generating reports
-from 2nd-generation coverage testing output files, those produced
-from running applications or integration tests. E.g.
-
-	$ mkdir ./profiledir
-	$ go build -cover -o myapp.exe .
-	$ GOCOVERDIR=./profiledir ./myapp.exe <arguments>
-	$ ls ./profiledir
-	covcounters.cce1b350af34b6d0fb59cc1725f0ee27.821598.1663006712821344241
-	covmeta.cce1b350af34b6d0fb59cc1725f0ee27
-	$
-
-Run covdata via "go tool covdata <mode>", where 'mode' is a subcommand
-selecting a specific reporting, merging, or data manipulation operation.
-Descriptions on the various modes (run "go tool cover <mode> -help" for
-specifics on usage of a given mode:
-
-1. Report percent of statements covered in each profiled package
-
-	$ go tool covdata percent -i=profiledir
-	cov-example/p	coverage: 41.1% of statements
-	main	coverage: 87.5% of statements
-	$
-
-2. Report import paths of packages profiled
-
-	$ go tool covdata pkglist -i=profiledir
-	cov-example/p
-	main
-	$
-
-3. Report percent statements covered by function:
-
-	$ go tool covdata func -i=profiledir
-	cov-example/p/p.go:12:		emptyFn			0.0%
-	cov-example/p/p.go:32:		Small			100.0%
-	cov-example/p/p.go:47:		Medium			90.9%
-	...
-	$
-
-4. Convert coverage data to legacy textual format:
-
-	$ go tool covdata textfmt -i=profiledir -o=cov.txt
-	$ head cov.txt
-	mode: set
-	cov-example/p/p.go:12.22,13.2 0 0
-	cov-example/p/p.go:15.31,16.2 1 0
-	cov-example/p/p.go:16.3,18.3 0 0
-	cov-example/p/p.go:19.3,21.3 0 0
-	...
-	$ go tool cover -html=cov.txt
-	$
-
-5. Merge profiles together:
-
-	$ go tool covdata merge -i=indir1,indir2 -o=outdir -modpaths=github.com/go-delve/delve
-	$
-
-6. Subtract one profile from another
-
-	$ go tool covdata subtract -i=indir1,indir2 -o=outdir
-	$
-
-7. Intersect profiles
-
-	$ go tool covdata intersect -i=indir1,indir2 -o=outdir
-	$
-
-8. Dump a profile for debugging purposes.
-
-	$ go tool covdata debugdump -i=indir
-	<human readable output>
-	$
+//
+// Covdata is a program for manipulating and generating reports
+// from 2nd-generation coverage testing output files, those produced
+// from running applications or integration tests. E.g.
+//
+//		$ mkdir ./profiledir
+//		$ go build -cover -o myapp.exe .
+//		$ GOCOVERDIR=./profiledir ./myapp.exe <arguments>
+//		$ ls ./profiledir
+//		covcounters.cce1b350af34b6d0fb59cc1725f0ee27.821598.1663006712821344241
+//		covmeta.cce1b350af34b6d0fb59cc1725f0ee27
+//		$
+//
+// Run covdata via "go tool covdata <mode>", where 'mode' is a subcommand
+// selecting a specific reporting, merging, or data manipulation operation.
+// Descriptions on the various modes (run "go tool cover <mode> -help" for
+// specifics on usage of a given mode:
+//
+// 1. Report percent of statements covered in each profiled package
+//
+//		$ go tool covdata percent -i=profiledir
+//		cov-example/p	coverage: 41.1% of statements
+//		main	coverage: 87.5% of statements
+//      $
+//
+//
+// 2. Report import paths of packages profiled
+//
+//		$ go tool covdata pkglist -i=profiledir
+//		cov-example/p
+//		main
+//      $
+//
+// 3. Report percent statements covered by function:
+//
+//		$ go tool covdata func -i=profiledir
+//		cov-example/p/p.go:12:		emptyFn			0.0%
+//		cov-example/p/p.go:32:		Small			100.0%
+//		cov-example/p/p.go:47:		Medium			90.9%
+//      ...
+//      $
+//
+// 4. Convert coverage data to legacy textual format:
+//
+//		$ go tool covdata textfmt -i=profiledir -o=cov.txt
+//      $ head cov.txt
+//      mode: set
+//      cov-example/p/p.go:12.22,13.2 0 0
+//      cov-example/p/p.go:15.31,16.2 1 0
+//      cov-example/p/p.go:16.3,18.3 0 0
+//      cov-example/p/p.go:19.3,21.3 0 0
+//      ...
+//      $ go tool cover -html=cov.txt
+//      $
+//
+// 5. Merge profiles together:
+//
+//		$ go tool covdata merge -i=indir1,indir2 -o=outdir -modpaths=github.com/go-delve/delve
+//      $
+//
+// 6. Subtract one profile from another
+//
+//		$ go tool covdata subtract -i=indir1,indir2 -o=outdir
+//      $
+//
+// 7. Intersect profiles
+//
+//		$ go tool covdata intersect -i=indir1,indir2 -o=outdir
+//      $
+//
+// 8. Dump a profile for debugging purposes.
+//
+//		$ go tool covdata debugdump -i=indir
+//      <human readable output>
+//      $
+//
 */
+
 package main

src/cmd/dist/test.go

@@ -91,29 +91,6 @@ type work struct {
 	end   chan bool
 }
 
-// printSkip prints a skip message for all of work.
-func (w *work) printSkip(t *tester, msg string) {
-	if t.json {
-		type event struct {
-			Time    time.Time
-			Action  string
-			Package string
-			Output  string `json:",omitempty"`
-		}
-		enc := json.NewEncoder(&w.out)
-		ev := event{Time: time.Now(), Package: w.dt.name, Action: "start"}
-		enc.Encode(ev)
-		ev.Action = "output"
-		ev.Output = msg
-		enc.Encode(ev)
-		ev.Action = "skip"
-		ev.Output = ""
-		enc.Encode(ev)
-		return
-	}
-	fmt.Fprintln(&w.out, msg)
-}
-
 // A distTest is a test run by dist test.
 // Each test has a unique name and belongs to a group (heading)
 type distTest struct {
@@ -428,9 +405,6 @@ func (opts *goTest) buildArgs(t *tester) (build, run, pkgs, testFlags []string,
 	if opts.timeout != 0 {
 		d := opts.timeout * time.Duration(t.timeoutScale)
 		run = append(run, "-timeout="+d.String())
-	} else if t.timeoutScale != 1 {
-		const goTestDefaultTimeout = 10 * time.Minute // Default value of go test -timeout flag.
-		run = append(run, "-timeout="+(goTestDefaultTimeout*time.Duration(t.timeoutScale)).String())
 	}
 	if opts.short || t.short {
 		run = append(run, "-short")
@@ -1261,7 +1235,7 @@ func (t *tester) runPending(nextTest *distTest) {
 		go func(w *work) {
 			if !<-w.start {
 				timelog("skip", w.dt.name)
-				w.printSkip(t, "skipped due to earlier error")
+				w.out.WriteString("skipped due to earlier error\n")
 			} else {
 				timelog("start", w.dt.name)
 				w.err = w.cmd.Run()
@@ -1272,7 +1246,7 @@ func (t *tester) runPending(nextTest *distTest) {
 					if isUnsupportedVMASize(w) {
 						timelog("skip", w.dt.name)
 						w.out.Reset()
-						w.printSkip(t, "skipped due to unsupported VMA")
+						w.out.WriteString("skipped due to unsupported VMA\n")
 						w.err = nil
 					}
 				}

src/cmd/distpack/archive.go

@@ -44,7 +44,7 @@ type fileInfo struct {
 func (i fileInfo) Name() string       { return path.Base(i.f.Name) }
 func (i fileInfo) ModTime() time.Time { return i.f.Time }
 func (i fileInfo) Mode() fs.FileMode  { return i.f.Mode }
-func (i fileInfo) IsDir() bool        { return i.f.Mode&fs.ModeDir != 0 }
+func (i fileInfo) IsDir() bool        { return false }
 func (i fileInfo) Size() int64        { return i.f.Size }
 func (i fileInfo) Sys() any           { return nil }
 

src/cmd/distpack/pack.go

@@ -329,47 +329,8 @@ func writeTgz(name string, a *Archive) {
 
 	zw := check(gzip.NewWriterLevel(out, gzip.BestCompression))
 	tw := tar.NewWriter(zw)
-
-	// Find the mode and mtime to use for directory entries,
-	// based on the mode and mtime of the first file we see.
-	// We know that modes and mtimes are uniform across the archive.
-	var dirMode fs.FileMode
-	var mtime time.Time
-	for _, f := range a.Files {
-		dirMode = fs.ModeDir | f.Mode | (f.Mode&0444)>>2 // copy r bits down to x bits
-		mtime = f.Time
-		break
-	}
-
-	// mkdirAll ensures that the tar file contains directory
-	// entries for dir and all its parents. Some programs reading
-	// these tar files expect that. See go.dev/issue/61862.
-	haveDir := map[string]bool{".": true}
-	var mkdirAll func(string)
-	mkdirAll = func(dir string) {
-		if dir == "/" {
-			panic("mkdirAll /")
-		}
-		if haveDir[dir] {
-			return
-		}
-		haveDir[dir] = true
-		mkdirAll(path.Dir(dir))
-		df := &File{
-			Name: dir + "/",
-			Time: mtime,
-			Mode: dirMode,
-		}
-		h := check(tar.FileInfoHeader(df.Info(), ""))
-		h.Name = dir + "/"
-		if err := tw.WriteHeader(h); err != nil {
-			panic(err)
-		}
-	}
-
 	for _, f = range a.Files {
 		h := check(tar.FileInfoHeader(f.Info(), ""))
-		mkdirAll(path.Dir(f.Name))
 		h.Name = f.Name
 		if err := tw.WriteHeader(h); err != nil {
 			panic(err)

src/cmd/go.mod

@@ -4,12 +4,12 @@ go 1.21
 
 require (
 	github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26
-	golang.org/x/arch v0.4.0
-	golang.org/x/mod v0.12.0
-	golang.org/x/sync v0.3.0
-	golang.org/x/sys v0.10.0
-	golang.org/x/term v0.10.0
-	golang.org/x/tools v0.11.1-0.20230712164437-1ca21856af7b
+	golang.org/x/arch v0.3.0
+	golang.org/x/mod v0.10.1-0.20230606122920-62c7e578f1a7
+	golang.org/x/sync v0.2.1-0.20230601203510-93782cc822b6
+	golang.org/x/sys v0.9.0
+	golang.org/x/term v0.9.0
+	golang.org/x/tools v0.9.4-0.20230613194514-c6c983054920
 )
 
 require github.com/ianlancetaylor/demangle v0.0.0-20220319035150-800ac71e25c2 // indirect

src/cmd/go.sum

@@ -2,15 +2,15 @@ github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26 h1:Xim43kblpZXfIBQsbu
 github.com/google/pprof v0.0.0-20221118152302-e6195bd50e26/go.mod h1:dDKJzRmX4S37WGHujM7tX//fmj1uioxKzKxz3lo4HJo=
 github.com/ianlancetaylor/demangle v0.0.0-20220319035150-800ac71e25c2 h1:rcanfLhLDA8nozr/K289V1zcntHr3V+SHlXwzz1ZI2g=
 github.com/ianlancetaylor/demangle v0.0.0-20220319035150-800ac71e25c2/go.mod h1:aYm2/VgdVmcIU8iMfdMvDMsRAQjcfZSKFby6HOFvi/w=
-golang.org/x/arch v0.4.0 h1:A8WCeEWhLwPBKNbFi5Wv5UTCBx5zzubnXDlMOFAzFMc=
-golang.org/x/arch v0.4.0/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
-golang.org/x/mod v0.12.0 h1:rmsUpXtvNzj340zd98LZ4KntptpfRHwpFOHG188oHXc=
-golang.org/x/mod v0.12.0/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
-golang.org/x/sync v0.3.0 h1:ftCYgMx6zT/asHUrPw8BLLscYtGznsLAnjq5RH9P66E=
-golang.org/x/sync v0.3.0/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
-golang.org/x/sys v0.10.0 h1:SqMFp9UcQJZa+pmYuAKjd9xq1f0j5rLcDIk0mj4qAsA=
-golang.org/x/sys v0.10.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
-golang.org/x/term v0.10.0 h1:3R7pNqamzBraeqj/Tj8qt1aQ2HpmlC+Cx/qL/7hn4/c=
-golang.org/x/term v0.10.0/go.mod h1:lpqdcUyK/oCiQxvxVrppt5ggO2KCZ5QblwqPnfZ6d5o=
-golang.org/x/tools v0.11.1-0.20230712164437-1ca21856af7b h1:KIZCni6lCdxd4gxHx49Zp9mhckTFRbI/ZPDbR3jKu90=
-golang.org/x/tools v0.11.1-0.20230712164437-1ca21856af7b/go.mod h1:anzJrxPjNtfgiYQYirP2CPGzGLxrH2u2QBhn6Bf3qY8=
+golang.org/x/arch v0.3.0 h1:02VY4/ZcO/gBOH6PUaoiptASxtXU10jazRCP865E97k=
+golang.org/x/arch v0.3.0/go.mod h1:5om86z9Hs0C8fWVUuoMHwpExlXzs5Tkyp9hOrfG7pp8=
+golang.org/x/mod v0.10.1-0.20230606122920-62c7e578f1a7 h1:OSEstGpBW1+G0wiXI0bBgOnI8nRJQKX3GCNxF75VR1s=
+golang.org/x/mod v0.10.1-0.20230606122920-62c7e578f1a7/go.mod h1:iBbtSCu2XBx23ZKBPSOrRkjjQPZFPuis4dIYUhu/chs=
+golang.org/x/sync v0.2.1-0.20230601203510-93782cc822b6 h1:kiysxTbHE5FVnrNyc9BC/yeJi3DTUBHIJtNbC9uvXk4=
+golang.org/x/sync v0.2.1-0.20230601203510-93782cc822b6/go.mod h1:FU7BRWz2tNW+3quACPkgCx/L+uEAv1htQ0V83Z9Rj+Y=
+golang.org/x/sys v0.9.0 h1:KS/R3tvhPqvJvwcKfnBHJwwthS11LRhmM5D59eEXa0s=
+golang.org/x/sys v0.9.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/term v0.9.0 h1:GRRCnKYhdQrD8kfRAdQ6Zcw1P0OcELxGLKJvtjVMZ28=
+golang.org/x/term v0.9.0/go.mod h1:M6DEAAIenWoTxdKrOltXcmDY3rSplQUkrvaDU5FcQyo=
+golang.org/x/tools v0.9.4-0.20230613194514-c6c983054920 h1:FJIPEU9owLOeJgghpx63YhobtkWkORJ3O5ZnbFr8Bzs=
+golang.org/x/tools v0.9.4-0.20230613194514-c6c983054920/go.mod h1:owI94Op576fPu3cIGQeHs3joujW/2Oc6MtlxbF5dfNc=

src/cmd/go/internal/cfg/cfg.go

@@ -490,43 +490,25 @@ func findGOROOT(env string) string {
 		// depend on the executable's location.
 		return def
 	}
-
-	// canonical returns a directory path that represents
-	// the same directory as dir,
-	// preferring the spelling in def if the two are the same.
-	canonical := func(dir string) string {
-		if isSameDir(def, dir) {
-			return def
-		}
-		return dir
-	}
-
 	exe, err := os.Executable()
 	if err == nil {
 		exe, err = filepath.Abs(exe)
 		if err == nil {
-			// cmd/go may be installed in GOROOT/bin or GOROOT/bin/GOOS_GOARCH,
-			// depending on whether it was cross-compiled with a different
-			// GOHOSTOS (see https://go.dev/issue/62119). Try both.
 			if dir := filepath.Join(exe, "../.."); isGOROOT(dir) {
-				return canonical(dir)
+				// If def (runtime.GOROOT()) and dir are the same
+				// directory, prefer the spelling used in def.
+				if isSameDir(def, dir) {
+					return def
+				}
+				return dir
 			}
-			if dir := filepath.Join(exe, "../../.."); isGOROOT(dir) {
-				return canonical(dir)
-			}
-
-			// Depending on what was passed on the command line, it is possible
-			// that os.Executable is a symlink (like /usr/local/bin/go) referring
-			// to a binary installed in a real GOROOT elsewhere
-			// (like /usr/lib/go/bin/go).
-			// Try to find that GOROOT by resolving the symlinks.
 			exe, err = filepath.EvalSymlinks(exe)
 			if err == nil {
 				if dir := filepath.Join(exe, "../.."); isGOROOT(dir) {
-					return canonical(dir)
-				}
-				if dir := filepath.Join(exe, "../../.."); isGOROOT(dir) {
-					return canonical(dir)
+					if isSameDir(def, dir) {
+						return def
+					}
+					return dir
 				}
 			}
 		}

src/cmd/go/internal/generate/generate.go

@@ -181,8 +181,6 @@ func init() {
 }
 
 func runGenerate(ctx context.Context, cmd *base.Command, args []string) {
-	modload.InitWorkfile()
-
 	if generateRunFlag != "" {
 		var err error
 		generateRunRE, err = regexp.Compile(generateRunFlag)

src/cmd/go/internal/gover/gover.go

@@ -179,9 +179,6 @@ func parse(x string) version {
 	// Parse prerelease.
 	i := 0
 	for i < len(x) && (x[i] < '0' || '9' < x[i]) {
-		if x[i] < 'a' || 'z' < x[i] {
-			return version{}
-		}
 		i++
 	}
 	if i == 0 {

src/cmd/go/internal/gover/gover_test.go

@@ -95,25 +95,6 @@ var prevTests = []testCase1[string, string]{
 	{"1.40000000000000000", "1.39999999999999999"},
 }
 
-func TestIsValid(t *testing.T) { test1(t, isValidTests, "IsValid", IsValid) }
-
-var isValidTests = []testCase1[string, bool]{
-	{"1.2rc3", true},
-	{"1.2.3", true},
-	{"1.999testmod", true},
-	{"1.600+auto", false},
-	{"1.22", true},
-	{"1.21.0", true},
-	{"1.21rc2", true},
-	{"1.21", true},
-	{"1.20.0", true},
-	{"1.20", true},
-	{"1.19", true},
-	{"1.3", true},
-	{"1.2", true},
-	{"1", true},
-}
-
 type testCase1[In, Out any] struct {
 	in  In
 	out Out

src/cmd/go/internal/gover/toolchain.go

@@ -15,20 +15,13 @@ import (
 // FromToolchain returns the Go version for the named toolchain,
 // derived from the name itself (not by running the toolchain).
 // A toolchain is named "goVERSION".
-// A suffix after the VERSION introduced by a -, space, or tab is removed.
+// A suffix after the VERSION introduced by a +, -, space, or tab is removed.
 // Examples:
 //
 //	FromToolchain("go1.2.3") == "1.2.3"
 //	FromToolchain("go1.2.3-bigcorp") == "1.2.3"
 //	FromToolchain("invalid") == ""
 func FromToolchain(name string) string {
-	if strings.ContainsAny(name, "\\/") {
-		// The suffix must not include a path separator, since that would cause
-		// exec.LookPath to resolve it from a relative directory instead of from
-		// $PATH.
-		return ""
-	}
-
 	var v string
 	if strings.HasPrefix(name, "go") {
 		v = name[2:]

src/cmd/go/internal/list/list.go

@@ -959,10 +959,7 @@ func collectDepsErrors(p *load.Package) {
 			if len(stkj) != 0 {
 				return true
 			}
-
 			return p.DepsErrors[i].Err.Error() < p.DepsErrors[j].Err.Error()
-		} else if len(stkj) == 0 {
-			return false
 		}
 		pathi, pathj := stki[len(stki)-1], stkj[len(stkj)-1]
 		return pathi < pathj

src/cmd/go/internal/load/test.go

@@ -473,7 +473,6 @@ func recompileForTest(pmain, preal, ptest, pxtest *Package) *PackageError {
 			p.Target = ""
 			p.Internal.BuildInfo = nil
 			p.Internal.ForceLibrary = true
-			p.Internal.PGOProfile = preal.Internal.PGOProfile
 		}
 
 		// Update p.Internal.Imports to use test copies.
@@ -497,11 +496,6 @@ func recompileForTest(pmain, preal, ptest, pxtest *Package) *PackageError {
 		if p.Name == "main" && p != pmain && p != ptest {
 			split()
 		}
-		// Split and attach PGO information to test dependencies if preal
-		// is built with PGO.
-		if preal.Internal.PGOProfile != "" && p.Internal.PGOProfile == "" {
-			split()
-		}
 	}
 
 	// Do search to find cycle.

src/cmd/go/internal/modcmd/download.go

@@ -10,7 +10,6 @@ import (
 	"errors"
 	"os"
 	"runtime"
-	"sync"
 
 	"cmd/go/internal/base"
 	"cmd/go/internal/cfg"
@@ -18,7 +17,6 @@ import (
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/modfetch/codehost"
 	"cmd/go/internal/modload"
-	"cmd/go/internal/toolchain"
 
 	"golang.org/x/mod/module"
 )
@@ -155,10 +153,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 				// 'go mod graph', and similar commands.
 				_, err := modload.LoadModGraph(ctx, "")
 				if err != nil {
-					// TODO(#64008): call base.Fatalf instead of toolchain.SwitchOrFatal
-					// here, since we can only reach this point with an outdated toolchain
-					// if the go.mod file is inconsistent.
-					toolchain.SwitchOrFatal(ctx, err)
+					base.Fatal(err)
 				}
 
 				for _, m := range modFile.Require {
@@ -199,26 +194,8 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 	// from the resulting TooNewError), all before we try the actual full download
 	// of each module.
 	//
-	// For now, we go ahead and try all the downloads and collect the errors, and
-	// if any download failed due to a TooNewError, we switch toolchains and try
-	// again. Any downloads that already succeeded will still be in cache.
-	// That won't give optimal concurrency (we'll do two batches of concurrent
-	// downloads instead of all in one batch), and it might add a little overhead
-	// to look up the downloads from the first batch in the module cache when
-	// we see them again in the second batch. On the other hand, it's way simpler
-	// to implement, and not really any more expensive if the user is requesting
-	// no explicit arguments (their go.mod file should already list an appropriate
-	// toolchain version) or only one module (as is used by the Go Module Proxy).
-
-	if infosErr != nil {
-		var sw toolchain.Switcher
-		sw.Error(infosErr)
-		if sw.NeedSwitch() {
-			sw.Switch(ctx)
-		}
-		// Otherwise, wait to report infosErr after we have downloaded
-		// when we can.
-	}
+	// For now, we just let it fail: the user can explicitly set GOTOOLCHAIN
+	// and retry if they want to.
 
 	if !haveExplicitArgs && modload.WorkFilePath() == "" {
 		// 'go mod download' is sometimes run without arguments to pre-populate the
@@ -228,7 +205,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 		// (golang.org/issue/45332). We do still fix inconsistencies in go.mod
 		// though.
 		//
-		// TODO(#64008): In the future, report an error if go.mod or go.sum need to
+		// TODO(#45551): In the future, report an error if go.mod or go.sum need to
 		// be updated after loading the build list. This may require setting
 		// the mode to "mod" or "readonly" depending on haveExplicitArgs.
 		if err := modload.WriteGoMod(ctx, modload.WriteOpts{}); err != nil {
@@ -236,7 +213,6 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 		}
 	}
 
-	var downloadErrs sync.Map
 	for _, info := range infos {
 		if info.Replace != nil {
 			info = info.Replace
@@ -263,11 +239,7 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 		}
 		sem <- token{}
 		go func() {
-			err := DownloadModule(ctx, m)
-			if err != nil {
-				downloadErrs.Store(m, err)
-				m.Error = err.Error()
-			}
+			DownloadModule(ctx, m)
 			<-sem
 		}()
 	}
@@ -277,39 +249,6 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 		sem <- token{}
 	}
 
-	// If there were explicit arguments
-	// (like 'go mod download golang.org/x/tools@latest'),
-	// check whether we need to upgrade the toolchain in order to download them.
-	//
-	// (If invoked without arguments, we expect the module graph to already
-	// be tidy and the go.mod file to declare a 'go' version that satisfies
-	// transitive requirements. If that invariant holds, then we should have
-	// already upgraded when we loaded the module graph, and should not need
-	// an additional check here. See https://go.dev/issue/45551.)
-	//
-	// We also allow upgrades if in a workspace because in workspace mode
-	// with no arguments we download the module pattern "all",
-	// which may include dependencies that are normally pruned out
-	// of the individual modules in the workspace.
-	if haveExplicitArgs || modload.WorkFilePath() != "" {
-		var sw toolchain.Switcher
-		// Add errors to the Switcher in deterministic order so that they will be
-		// logged deterministically.
-		for _, m := range mods {
-			if erri, ok := downloadErrs.Load(m); ok {
-				sw.Error(erri.(error))
-			}
-		}
-		// Only call sw.Switch if it will actually switch.
-		// Otherwise, we may want to write the errors as JSON
-		// (instead of using base.Error as sw.Switch would),
-		// and we may also have other errors to report from the
-		// initial infos returned by ListModules.
-		if sw.NeedSwitch() {
-			sw.Switch(ctx)
-		}
-	}
-
 	if *downloadJSON {
 		for _, m := range mods {
 			b, err := json.MarshalIndent(m, "", "\t")
@@ -363,27 +302,34 @@ func runDownload(ctx context.Context, cmd *base.Command, args []string) {
 
 // DownloadModule runs 'go mod download' for m.Path@m.Version,
 // leaving the results (including any error) in m itself.
-func DownloadModule(ctx context.Context, m *ModuleJSON) error {
+func DownloadModule(ctx context.Context, m *ModuleJSON) {
 	var err error
 	_, file, err := modfetch.InfoFile(ctx, m.Path, m.Version)
 	if err != nil {
-		return err
+		m.Error = err.Error()
+		return
 	}
 	m.Info = file
 	m.GoMod, err = modfetch.GoModFile(ctx, m.Path, m.Version)
 	if err != nil {
-		return err
+		m.Error = err.Error()
+		return
 	}
 	m.GoModSum, err = modfetch.GoModSum(ctx, m.Path, m.Version)
 	if err != nil {
-		return err
+		m.Error = err.Error()
+		return
 	}
 	mod := module.Version{Path: m.Path, Version: m.Version}
 	m.Zip, err = modfetch.DownloadZip(ctx, mod)
 	if err != nil {
-		return err
+		m.Error = err.Error()
+		return
 	}
 	m.Sum = modfetch.Sum(ctx, mod)
 	m.Dir, err = modfetch.Download(ctx, mod)
-	return err
+	if err != nil {
+		m.Error = err.Error()
+		return
+	}
 }

src/cmd/go/internal/modcmd/verify.go

@@ -61,7 +61,7 @@ func runVerify(ctx context.Context, cmd *base.Command, args []string) {
 	if err != nil {
 		base.Fatal(err)
 	}
-	mods := mg.BuildList()
+	mods := mg.BuildList()[modload.MainModules.Len():]
 	// Use a slice of result channels, so that the output is deterministic.
 	errsChans := make([]<-chan []error, len(mods))
 
@@ -94,9 +94,6 @@ func verifyMod(ctx context.Context, mod module.Version) []error {
 		// "go" and "toolchain" have no disk footprint; nothing to verify.
 		return nil
 	}
-	if modload.MainModules.Contains(mod.Path) {
-		return nil
-	}
 	var errs []error
 	zip, zipErr := modfetch.CachePath(ctx, mod, "zip")
 	if zipErr == nil {

src/cmd/go/internal/modfetch/codehost/git.go

@@ -18,7 +18,6 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
-	"slices"
 	"sort"
 	"strconv"
 	"strings"
@@ -155,7 +154,7 @@ type gitRepo struct {
 	refsErr error
 
 	localTagsOnce sync.Once
-	localTags     sync.Map // map[string]bool
+	localTags     map[string]bool
 }
 
 const (
@@ -167,6 +166,7 @@ const (
 
 // loadLocalTags loads tag references from the local git cache
 // into the map r.localTags.
+// Should only be called as r.localTagsOnce.Do(r.loadLocalTags).
 func (r *gitRepo) loadLocalTags(ctx context.Context) {
 	// The git protocol sends all known refs and ls-remote filters them on the client side,
 	// so we might as well record both heads and tags in one shot.
@@ -176,9 +176,10 @@ func (r *gitRepo) loadLocalTags(ctx context.Context) {
 		return
 	}
 
+	r.localTags = make(map[string]bool)
 	for _, line := range strings.Split(string(out), "\n") {
 		if line != "" {
-			r.localTags.Store(line, true)
+			r.localTags[line] = true
 		}
 	}
 }
@@ -429,7 +430,7 @@ func (r *gitRepo) stat(ctx context.Context, rev string) (info *RevInfo, err erro
 	// Maybe rev is a tag we already have locally.
 	// (Note that we're excluding branches, which can be stale.)
 	r.localTagsOnce.Do(func() { r.loadLocalTags(ctx) })
-	if _, ok := r.localTags.Load(rev); ok {
+	if r.localTags[rev] {
 		return r.statLocal(ctx, rev, "refs/tags/"+rev)
 	}
 
@@ -505,18 +506,11 @@ func (r *gitRepo) stat(ctx context.Context, rev string) (info *RevInfo, err erro
 	// Either way, try a local stat before falling back to network I/O.
 	if !didStatLocal {
 		if info, err := r.statLocal(ctx, rev, hash); err == nil {
-			tag, fromTag := strings.CutPrefix(ref, "refs/tags/")
-			if fromTag && !slices.Contains(info.Tags, tag) {
-				// The local repo includes the commit hash we want, but it is missing
-				// the corresponding tag. Add that tag and try again.
-				_, err := Run(ctx, r.dir, "git", "tag", tag, hash)
-				if err != nil {
-					return nil, err
-				}
-				r.localTags.Store(tag, true)
-				return r.statLocal(ctx, rev, ref)
+			if after, found := strings.CutPrefix(ref, "refs/tags/"); found {
+				// Make sure tag exists, so it will be in localTags next time the go command is run.
+				Run(ctx, r.dir, "git", "tag", after, hash)
 			}
-			return info, err
+			return info, nil
 		}
 	}
 

src/cmd/go/internal/modfetch/toolchain.go

@@ -60,15 +60,6 @@ func (r *toolchainRepo) Versions(ctx context.Context, prefix string) (*Versions,
 		}
 	}
 
-	// Always include our own version.
-	// This means that the development branch of Go 1.21 (say) will allow 'go get go@1.21'
-	// even though there are no Go 1.21 releases yet.
-	// Once there is a release, 1.21 will be treated as a query matching the latest available release.
-	// Before then, 1.21 will be treated as a query that resolves to this entry we are adding (1.21).
-	if v := gover.Local(); !have[v] {
-		list = append(list, goPrefix+v)
-	}
-
 	if r.path == "go" {
 		sort.Slice(list, func(i, j int) bool {
 			return gover.Compare(list[i], list[j]) < 0
@@ -83,38 +74,21 @@ func (r *toolchainRepo) Versions(ctx context.Context, prefix string) (*Versions,
 }
 
 func (r *toolchainRepo) Stat(ctx context.Context, rev string) (*RevInfo, error) {
+	// If we're asking about "go" (not "toolchain"), pretend to have
+	// all earlier Go versions available without network access:
+	// we will provide those ourselves, at least in GOTOOLCHAIN=auto mode.
+	if r.path == "go" && gover.Compare(rev, gover.Local()) <= 0 {
+		return &RevInfo{Version: rev}, nil
+	}
+
 	// Convert rev to DL version and stat that to make sure it exists.
-	// In theory the go@ versions should be like 1.21.0
-	// and the toolchain@ versions should be like go1.21.0
-	// but people will type the wrong one, and so we accept
-	// both and silently correct it to the standard form.
 	prefix := ""
 	v := rev
 	v = strings.TrimPrefix(v, "go")
 	if r.path == "toolchain" {
 		prefix = "go"
 	}
-
-	if !gover.IsValid(v) {
-		return nil, fmt.Errorf("invalid %s version %s", r.path, rev)
-	}
-
-	// If we're asking about "go" (not "toolchain"), pretend to have
-	// all earlier Go versions available without network access:
-	// we will provide those ourselves, at least in GOTOOLCHAIN=auto mode.
-	if r.path == "go" && gover.Compare(v, gover.Local()) <= 0 {
-		return &RevInfo{Version: prefix + v}, nil
-	}
-
-	// Similarly, if we're asking about *exactly* the current toolchain,
-	// we don't need to access the network to know that it exists.
-	if r.path == "toolchain" && v == gover.Local() {
-		return &RevInfo{Version: prefix + v}, nil
-	}
-
 	if gover.IsLang(v) {
-		// We can only use a language (development) version if the current toolchain
-		// implements that version, and the two checks above have ruled that out.
 		return nil, fmt.Errorf("go language version %s is not a toolchain version", rev)
 	}
 

src/cmd/go/internal/modget/query.go

@@ -239,13 +239,10 @@ func (q *query) matchesPath(path string) bool {
 // canMatchInModule reports whether the given module path can potentially
 // contain q.pattern.
 func (q *query) canMatchInModule(mPath string) bool {
-	if gover.IsToolchain(mPath) {
-		return false
-	}
 	if q.canMatchWildcardInModule != nil {
 		return q.canMatchWildcardInModule(mPath)
 	}
-	return str.HasPathPrefix(q.pattern, mPath)
+	return str.HasPathPrefix(q.pattern, mPath) && !gover.IsToolchain(mPath)
 }
 
 // pathOnce invokes f to generate the pathSet for the given path,

src/cmd/go/internal/modload/list.go

@@ -110,13 +110,7 @@ func ListModules(ctx context.Context, args []string, mode ListMode, reuseFile st
 
 	if err == nil {
 		requirements = rs
-		// TODO(#61605): The extra ListU clause fixes a problem with Go 1.21rc3
-		// where "go mod tidy" and "go list -m -u all" fight over whether the go.sum
-		// should be considered up-to-date. The fix for now is to always treat the
-		// go.sum as up-to-date during list -m -u. Probably the right fix is more targeted,
-		// but in general list -u is looking up other checksums in the checksum database
-		// that won't be necessary later, so it makes sense not to write the go.sum back out.
-		if !ExplicitWriteGoMod && mode&ListU == 0 {
+		if !ExplicitWriteGoMod {
 			err = commitRequirements(ctx, WriteOpts{})
 		}
 	}

src/cmd/go/internal/modload/modfile.go

@@ -190,7 +190,7 @@ func CheckRetractions(ctx context.Context, m module.Version) (err error) {
 		return err
 	}
 	summary, err := rawGoModSummary(rm)
-	if err != nil && !errors.Is(err, gover.ErrTooNew) {
+	if err != nil {
 		return err
 	}
 
@@ -298,7 +298,7 @@ func CheckDeprecation(ctx context.Context, m module.Version) (deprecation string
 		return "", err
 	}
 	summary, err := rawGoModSummary(latest)
-	if err != nil && !errors.Is(err, gover.ErrTooNew) {
+	if err != nil {
 		return "", err
 	}
 	return summary.deprecated, nil
@@ -637,8 +637,6 @@ func goModSummary(m module.Version) (*modFileSummary, error) {
 // its dependencies.
 //
 // rawGoModSummary cannot be used on the main module outside of workspace mode.
-// The modFileSummary can still be used for retractions and deprecations
-// even if a TooNewError is returned.
 func rawGoModSummary(m module.Version) (*modFileSummary, error) {
 	if gover.IsToolchain(m.Path) {
 		if m.Path == "go" && gover.Compare(m.Version, gover.GoStrictVersion) >= 0 {
@@ -693,7 +691,12 @@ func rawGoModSummary(m module.Version) (*modFileSummary, error) {
 				summary.require = append(summary.require, req.Mod)
 			}
 		}
-
+		if summary.goVersion != "" && gover.Compare(summary.goVersion, gover.GoStrictVersion) >= 0 {
+			if gover.Compare(summary.goVersion, gover.Local()) > 0 {
+				return nil, &gover.TooNewError{What: "module " + m.String(), GoVersion: summary.goVersion}
+			}
+			summary.require = append(summary.require, module.Version{Path: "go", Version: summary.goVersion})
+		}
 		if len(f.Retract) > 0 {
 			summary.retract = make([]retraction, 0, len(f.Retract))
 			for _, ret := range f.Retract {
@@ -704,16 +707,6 @@ func rawGoModSummary(m module.Version) (*modFileSummary, error) {
 			}
 		}
 
-		// This block must be kept at the end of the function because the summary may
-		// be used for reading retractions or deprecations even if a TooNewError is
-		// returned.
-		if summary.goVersion != "" && gover.Compare(summary.goVersion, gover.GoStrictVersion) >= 0 {
-			summary.require = append(summary.require, module.Version{Path: "go", Version: summary.goVersion})
-			if gover.Compare(summary.goVersion, gover.Local()) > 0 {
-				return summary, &gover.TooNewError{What: "module " + m.String(), GoVersion: summary.goVersion}
-			}
-		}
-
 		return summary, nil
 	})
 }

src/cmd/go/internal/modload/query.go

@@ -473,11 +473,7 @@ func newQueryMatcher(path string, query, current string, allowed AllowedFunc) (*
 // AllowedFunc of qm.
 func (qm *queryMatcher) allowsVersion(ctx context.Context, v string) bool {
 	if qm.prefix != "" && !strings.HasPrefix(v, qm.prefix) {
-		if gover.IsToolchain(qm.path) && strings.TrimSuffix(qm.prefix, ".") == v {
-			// Allow 1.21 to match "1.21." prefix.
-		} else {
-			return false
-		}
+		return false
 	}
 	if qm.filter != nil && !qm.filter(v) {
 		return false

src/cmd/go/internal/test/test.go

@@ -1363,87 +1363,65 @@ func (r *runTestActor) Act(b *work.Builder, ctx context.Context, a *work.Action)
 	ctx, cancel := context.WithTimeout(ctx, testKillTimeout)
 	defer cancel()
 
-	// Now we're ready to actually run the command.
-	//
-	// If the -o flag is set, or if at some point we change cmd/go to start
-	// copying test executables into the build cache, we may run into spurious
-	// ETXTBSY errors on Unix platforms (see https://go.dev/issue/22315).
-	//
-	// Since we know what causes those, and we know that they should resolve
-	// quickly (the ETXTBSY error will resolve as soon as the subprocess
-	// holding the descriptor open reaches its 'exec' call), we retry them
-	// in a loop.
+	cmd := exec.CommandContext(ctx, args[0], args[1:]...)
+	cmd.Dir = a.Package.Dir
+
+	env := slices.Clip(cfg.OrigEnv)
+	env = base.AppendPATH(env)
+	env = base.AppendPWD(env, cmd.Dir)
+	cmd.Env = env
+	if addToEnv != "" {
+		cmd.Env = append(cmd.Env, addToEnv)
+	}
+
+	cmd.Stdout = stdout
+	cmd.Stderr = stdout
+
+	// If there are any local SWIG dependencies, we want to load
+	// the shared library from the build directory.
+	if a.Package.UsesSwig() {
+		env := cmd.Env
+		found := false
+		prefix := "LD_LIBRARY_PATH="
+		for i, v := range env {
+			if strings.HasPrefix(v, prefix) {
+				env[i] = v + ":."
+				found = true
+				break
+			}
+		}
+		if !found {
+			env = append(env, "LD_LIBRARY_PATH=.")
+		}
+		cmd.Env = env
+	}
 
 	var (
-		cmd            *exec.Cmd
-		t0             time.Time
 		cancelKilled   = false
 		cancelSignaled = false
 	)
-	for {
-		cmd = exec.CommandContext(ctx, args[0], args[1:]...)
-		cmd.Dir = a.Package.Dir
-
-		env := slices.Clip(cfg.OrigEnv)
-		env = base.AppendPATH(env)
-		env = base.AppendPWD(env, cmd.Dir)
-		cmd.Env = env
-		if addToEnv != "" {
-			cmd.Env = append(cmd.Env, addToEnv)
-		}
-
-		cmd.Stdout = stdout
-		cmd.Stderr = stdout
-
-		// If there are any local SWIG dependencies, we want to load
-		// the shared library from the build directory.
-		if a.Package.UsesSwig() {
-			env := cmd.Env
-			found := false
-			prefix := "LD_LIBRARY_PATH="
-			for i, v := range env {
-				if strings.HasPrefix(v, prefix) {
-					env[i] = v + ":."
-					found = true
-					break
-				}
-			}
-			if !found {
-				env = append(env, "LD_LIBRARY_PATH=.")
-			}
-			cmd.Env = env
-		}
-
-		cmd.Cancel = func() error {
-			if base.SignalTrace == nil {
-				err := cmd.Process.Kill()
-				if err == nil {
-					cancelKilled = true
-				}
-				return err
-			}
-
-			// Send a quit signal in the hope that the program will print
-			// a stack trace and exit.
-			err := cmd.Process.Signal(base.SignalTrace)
+	cmd.Cancel = func() error {
+		if base.SignalTrace == nil {
+			err := cmd.Process.Kill()
 			if err == nil {
-				cancelSignaled = true
+				cancelKilled = true
 			}
 			return err
 		}
-		cmd.WaitDelay = testWaitDelay
 
-		base.StartSigHandlers()
-		t0 = time.Now()
-		err = cmd.Run()
-
-		if !isETXTBSY(err) {
-			// We didn't hit the race in #22315, so there is no reason to retry the
-			// command.
-			break
+		// Send a quit signal in the hope that the program will print
+		// a stack trace and exit.
+		err := cmd.Process.Signal(base.SignalTrace)
+		if err == nil {
+			cancelSignaled = true
 		}
+		return err
 	}
+	cmd.WaitDelay = testWaitDelay
 
+	base.StartSigHandlers()
+	t0 := time.Now()
+	err = cmd.Run()
 	out := buf.Bytes()
 	a.TestOutput = &buf
 	t := fmt.Sprintf("%.3fs", time.Since(t0).Seconds())

src/cmd/go/internal/test/test_nonunix.go

@@ -1,12 +0,0 @@
-// Copyright 2023 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build !unix
-
-package test
-
-func isETXTBSY(err error) bool {
-	// syscall.ETXTBSY is only meaningful on Unix platforms.
-	return false
-}

src/cmd/go/internal/test/test_unix.go

@@ -1,16 +0,0 @@
-// Copyright 2023 The Go Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style
-// license that can be found in the LICENSE file.
-
-//go:build unix
-
-package test
-
-import (
-	"errors"
-	"syscall"
-)
-
-func isETXTBSY(err error) bool {
-	return errors.Is(err, syscall.ETXTBSY)
-}

src/cmd/go/internal/test/testflag.go

@@ -61,7 +61,7 @@ func init() {
 	cf.String("run", "", "")
 	cf.Bool("short", false, "")
 	cf.String("skip", "", "")
-	cf.DurationVar(&testTimeout, "timeout", 10*time.Minute, "") // known to cmd/dist
+	cf.DurationVar(&testTimeout, "timeout", 10*time.Minute, "")
 	cf.String("fuzztime", "", "")
 	cf.String("fuzzminimizetime", "", "")
 	cf.StringVar(&testTrace, "trace", "", "")

src/cmd/go/internal/toolchain/select.go

@@ -8,7 +8,6 @@ package toolchain
 import (
 	"context"
 	"errors"
-	"flag"
 	"fmt"
 	"go/build"
 	"io/fs"
@@ -26,7 +25,6 @@ import (
 	"cmd/go/internal/modfetch"
 	"cmd/go/internal/modload"
 	"cmd/go/internal/run"
-	"cmd/go/internal/work"
 
 	"golang.org/x/mod/module"
 )
@@ -133,7 +131,7 @@ func Select() {
 	} else {
 		min, suffix, plus := strings.Cut(gotoolchain, "+") // go1.2.3+auto
 		if min != "local" {
-			v := gover.FromToolchain(min)
+			v := gover.FromToolchain(gotoolchain)
 			if v == "" {
 				if plus {
 					base.Fatalf("invalid GOTOOLCHAIN %q: invalid minimum toolchain %q", gotoolchain, min)
@@ -183,13 +181,6 @@ func Select() {
 			}
 			if gover.Compare(goVers, minVers) > 0 {
 				gotoolchain = "go" + goVers
-				// Starting with Go 1.21, the first released version has a .0 patch version suffix.
-				// Don't try to download a language version (sans patch component), such as go1.22.
-				// Instead, use the first toolchain of that language version, such as 1.22.0.
-				// See golang.org/issue/62278.
-				if gover.IsLang(goVers) && gover.Compare(goVers, "1.21") >= 0 {
-					gotoolchain += ".0"
-				}
 				gover.Startup.AutoGoVersion = goVers
 				gover.Startup.AutoToolchain = "" // in case we are overriding it for being too old
 			}
@@ -318,10 +309,6 @@ func Exec(gotoolchain string) {
 	dir, err := modfetch.Download(context.Background(), m)
 	if err != nil {
 		if errors.Is(err, fs.ErrNotExist) {
-			toolVers := gover.FromToolchain(gotoolchain)
-			if gover.IsLang(toolVers) && gover.Compare(toolVers, "1.21") >= 0 {
-				base.Fatalf("invalid toolchain: %s is a language version but not a toolchain version (%s.x)", gotoolchain, gotoolchain)
-			}
 			base.Fatalf("download %s for %s/%s: toolchain not available", gotoolchain, runtime.GOOS, runtime.GOARCH)
 		}
 		base.Fatalf("download %s: %v", gotoolchain, err)
@@ -498,132 +485,74 @@ func goInstallVersion() bool {
 	// Note: We assume there are no flags between 'go' and 'install' or 'run'.
 	// During testing there are some debugging flags that are accepted
 	// in that position, but in production go binaries there are not.
-	if len(os.Args) < 3 {
+	if len(os.Args) < 3 || (os.Args[1] != "install" && os.Args[1] != "run") {
 		return false
 	}
 
-	var cmdFlags *flag.FlagSet
+	// Check for pkg@version.
+	var arg string
 	switch os.Args[1] {
 	default:
-		// Command doesn't support a pkg@version as the main module.
 		return false
 	case "install":
-		cmdFlags = &work.CmdInstall.Flag
+		// We would like to let 'go install -newflag pkg@version' work even
+		// across a toolchain switch. To make that work, assume the pkg@version
+		// is the last argument and skip the flag parsing.
+		arg = os.Args[len(os.Args)-1]
 	case "run":
-		cmdFlags = &run.CmdRun.Flag
-	}
-
-	// The modcachrw flag is unique, in that it affects how we fetch the
-	// requested module to even figure out what toolchain it needs.
-	// We need to actually set it before we check the toolchain version.
-	// (See https://go.dev/issue/64282.)
-	modcacherwFlag := cmdFlags.Lookup("modcacherw")
-	if modcacherwFlag == nil {
-		base.Fatalf("internal error: modcacherw flag not registered for command")
-	}
-	modcacherwVal, ok := modcacherwFlag.Value.(interface {
-		IsBoolFlag() bool
-		flag.Value
-	})
-	if !ok || !modcacherwVal.IsBoolFlag() {
-		base.Fatalf("internal error: modcacherw is not a boolean flag")
-	}
-
-	// Make a best effort to parse the command's args to find the pkg@version
-	// argument and the -modcacherw flag.
-	var (
-		pkgArg         string
-		modcacherwSeen bool
-	)
-	for args := os.Args[2:]; len(args) > 0; {
-		a := args[0]
-		args = args[1:]
-		if a == "--" {
-			if len(args) == 0 {
+		// For run, the pkg@version can be anywhere on the command line,
+		// because it is preceded by run flags and followed by arguments to the
+		// program being run. To handle that precisely, we have to interpret the
+		// flags a little bit, to know whether each flag takes an optional argument.
+		// We can still allow unknown flags as long as they have an explicit =value.
+		args := os.Args[2:]
+		for i := 0; i < len(args); i++ {
+			a := args[i]
+			if !strings.HasPrefix(a, "-") {
+				arg = a
+				break
+			}
+			if a == "-" {
+				// non-flag but also non-pkg@version
 				return false
 			}
-			pkgArg = args[0]
-			break
-		}
-
-		a, ok := strings.CutPrefix(a, "-")
-		if !ok {
-			// Not a flag argument. Must be a package.
-			pkgArg = a
-			break
-		}
-		a = strings.TrimPrefix(a, "-") // Treat --flag as -flag.
-
-		name, val, hasEq := strings.Cut(a, "=")
-
-		if name == "modcacherw" {
-			if !hasEq {
-				val = "true"
-			}
-			if err := modcacherwVal.Set(val); err != nil {
-				return false
-			}
-			modcacherwSeen = true
-			continue
-		}
-
-		if hasEq {
-			// Already has a value; don't bother parsing it.
-			continue
-		}
-
-		f := run.CmdRun.Flag.Lookup(a)
-		if f == nil {
-			// We don't know whether this flag is a boolean.
-			if os.Args[1] == "run" {
-				// We don't know where to find the pkg@version argument.
-				// For run, the pkg@version can be anywhere on the command line,
-				// because it is preceded by run flags and followed by arguments to the
-				// program being run. Since we don't know whether this flag takes
-				// an argument, we can't reliably identify the end of the run flags.
-				// Just give up and let the user clarify using the "=" form..
-				return false
-			}
-
-			// We would like to let 'go install -newflag pkg@version' work even
-			// across a toolchain switch. To make that work, assume by default that
-			// the pkg@version is the last argument and skip the remaining args unless
-			// we spot a plausible "-modcacherw" flag.
-			for len(args) > 0 {
-				a := args[0]
-				name, _, _ := strings.Cut(a, "=")
-				if name == "-modcacherw" || name == "--modcacherw" {
-					break
+			if a == "--" {
+				if i+1 >= len(args) {
+					return false
 				}
-				if len(args) == 1 && !strings.HasPrefix(a, "-") {
-					pkgArg = a
-				}
-				args = args[1:]
+				arg = args[i+1]
+				break
 			}
-			continue
-		}
-
-		if bf, ok := f.Value.(interface{ IsBoolFlag() bool }); !ok || !bf.IsBoolFlag() {
-			// The next arg is the value for this flag. Skip it.
-			args = args[1:]
-			continue
+			a = strings.TrimPrefix(a, "-")
+			a = strings.TrimPrefix(a, "-")
+			if strings.HasPrefix(a, "-") {
+				// non-flag but also non-pkg@version
+				return false
+			}
+			if strings.Contains(a, "=") {
+				// already has value
+				continue
+			}
+			f := run.CmdRun.Flag.Lookup(a)
+			if f == nil {
+				// Unknown flag. Give up. The command is going to fail in flag parsing.
+				return false
+			}
+			if bf, ok := f.Value.(interface{ IsBoolFlag() bool }); ok && bf.IsBoolFlag() {
+				// Does not take value.
+				continue
+			}
+			i++ // Does take a value; skip it.
 		}
 	}
-
-	if !strings.Contains(pkgArg, "@") || build.IsLocalImport(pkgArg) || filepath.IsAbs(pkgArg) {
+	if !strings.Contains(arg, "@") || build.IsLocalImport(arg) || filepath.IsAbs(arg) {
 		return false
 	}
-	path, version, _ := strings.Cut(pkgArg, "@")
+	path, version, _ := strings.Cut(arg, "@")
 	if path == "" || version == "" || gover.IsToolchain(path) {
 		return false
 	}
 
-	if !modcacherwSeen && base.InGOFLAGS("-modcacherw") {
-		fs := flag.NewFlagSet("goInstallVersion", flag.ExitOnError)
-		fs.Var(modcacherwVal, "modcacherw", modcacherwFlag.Usage)
-		base.SetFromGOFLAGS(fs)
-	}
-
 	// It would be correct to simply return true here, bypassing use
 	// of the current go.mod or go.work, and let "go run" or "go install"
 	// do the rest, including a toolchain switch.

src/cmd/go/internal/vcs/vcs.go

@@ -1204,31 +1204,18 @@ func repoRootFromVCSPaths(importPath string, security web.SecurityMode, vcsPaths
 			var ok bool
 			repoURL, ok = interceptVCSTest(repo, vcs, security)
 			if !ok {
-				scheme, err := func() (string, error) {
+				scheme := vcs.Scheme[0] // default to first scheme
+				if vcs.PingCmd != "" {
+					// If we know how to test schemes, scan to find one.
 					for _, s := range vcs.Scheme {
 						if security == web.SecureOnly && !vcs.isSecureScheme(s) {
 							continue
 						}
-
-						// If we know how to ping URL schemes for this VCS,
-						// check that this repo works.
-						// Otherwise, default to the first scheme
-						// that meets the requested security level.
-						if vcs.PingCmd == "" {
-							return s, nil
-						}
-						if err := vcs.Ping(s, repo); err == nil {
-							return s, nil
+						if vcs.Ping(s, repo) == nil {
+							scheme = s
+							break
 						}
 					}
-					securityFrag := ""
-					if security == web.SecureOnly {
-						securityFrag = "secure "
-					}
-					return "", fmt.Errorf("no %sprotocol found for repository", securityFrag)
-				}()
-				if err != nil {
-					return nil, err
 				}
 				repoURL = scheme + "://" + repo
 			}

src/cmd/go/internal/web/http.go

@@ -212,22 +212,16 @@ func get(security SecurityMode, url *urlpkg.URL) (*Response, error) {
 			}
 		}
 
-		if err != nil {
-			// Per the docs for [net/http.Client.Do], “On error, any Response can be
-			// ignored. A non-nil Response with a non-nil error only occurs when
-			// CheckRedirect fails, and even then the returned Response.Body is
-			// already closed.”
+		if res == nil || res.Body == nil {
 			release()
-			return nil, nil, err
+		} else {
+			body := res.Body
+			res.Body = hookCloser{
+				ReadCloser: body,
+				afterClose: release,
+			}
 		}
 
-		// “If the returned error is nil, the Response will contain a non-nil Body
-		// which the user is expected to close.”
-		body := res.Body
-		res.Body = hookCloser{
-			ReadCloser: body,
-			afterClose: release,
-		}
 		return url, res, err
 	}
 

src/cmd/go/internal/work/security.go

@@ -141,12 +141,6 @@ var validCompilerFlagsWithNextArg = []string{
 	"-x",
 }
 
-var invalidLinkerFlags = []*lazyregexp.Regexp{
-	// On macOS this means the linker loads and executes the next argument.
-	// Have to exclude separately because -lfoo is allowed in general.
-	re(`-lto_library`),
-}
-
 var validLinkerFlags = []*lazyregexp.Regexp{
 	re(`-F([^@\-].*)`),
 	re(`-l([^@\-].*)`),
@@ -237,12 +231,12 @@ var validLinkerFlagsWithNextArg = []string{
 
 func checkCompilerFlags(name, source string, list []string) error {
 	checkOverrides := true
-	return checkFlags(name, source, list, nil, validCompilerFlags, validCompilerFlagsWithNextArg, checkOverrides)
+	return checkFlags(name, source, list, validCompilerFlags, validCompilerFlagsWithNextArg, checkOverrides)
 }
 
 func checkLinkerFlags(name, source string, list []string) error {
 	checkOverrides := true
-	return checkFlags(name, source, list, invalidLinkerFlags, validLinkerFlags, validLinkerFlagsWithNextArg, checkOverrides)
+	return checkFlags(name, source, list, validLinkerFlags, validLinkerFlagsWithNextArg, checkOverrides)
 }
 
 // checkCompilerFlagsForInternalLink returns an error if 'list'
@@ -251,7 +245,7 @@ func checkLinkerFlags(name, source string, list []string) error {
 // external linker).
 func checkCompilerFlagsForInternalLink(name, source string, list []string) error {
 	checkOverrides := false
-	if err := checkFlags(name, source, list, nil, validCompilerFlags, validCompilerFlagsWithNextArg, checkOverrides); err != nil {
+	if err := checkFlags(name, source, list, validCompilerFlags, validCompilerFlagsWithNextArg, checkOverrides); err != nil {
 		return err
 	}
 	// Currently the only flag on the allow list that causes problems
@@ -264,7 +258,7 @@ func checkCompilerFlagsForInternalLink(name, source string, list []string) error
 	return nil
 }
 
-func checkFlags(name, source string, list []string, invalid, valid []*lazyregexp.Regexp, validNext []string, checkOverrides bool) error {
+func checkFlags(name, source string, list []string, valid []*lazyregexp.Regexp, validNext []string, checkOverrides bool) error {
 	// Let users override rules with $CGO_CFLAGS_ALLOW, $CGO_CFLAGS_DISALLOW, etc.
 	var (
 		allow    *regexp.Regexp
@@ -296,11 +290,6 @@ Args:
 		if allow != nil && allow.FindString(arg) == arg {
 			continue Args
 		}
-		for _, re := range invalid {
-			if re.FindString(arg) == arg { // must be complete match
-				goto Bad
-			}
-		}
 		for _, re := range valid {
 			if re.FindString(arg) == arg { // must be complete match
 				continue Args

src/cmd/go/main.go

@@ -175,11 +175,7 @@ func main() {
 		if used > 0 {
 			helpArg += " " + strings.Join(args[:used], " ")
 		}
-		cmdName := cfg.CmdName
-		if cmdName == "" {
-			cmdName = args[0]
-		}
-		fmt.Fprintf(os.Stderr, "go %s: unknown command\nRun 'go help%s' for usage.\n", cmdName, helpArg)
+		fmt.Fprintf(os.Stderr, "go %s: unknown command\nRun 'go help%s' for usage.\n", cfg.CmdName, helpArg)
 		base.SetExitStatus(2)
 		base.Exit()
 	}