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cpu: use xgetbv intrinsic

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Fixes golang/go#53302

Change-Id: I698ef44f90e2ec538ae4a057134c22c102a87ff8
Reviewed-on: https://go-review.googlesource.com/c/sys/+/411635
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
This commit is contained in:
Ian Lance Taylor
2022-06-10 09:47:26 -07:00
committed by Gopher Robot
parent 635b8c9b7f
commit 9f5ed59c13
1 changed files with 12 additions and 17 deletions
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29
cpu/cpu_gccgo_x86.c
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@@ -7,6 +7,7 @@
#include <cpuid.h>
#include <stdint.h>
#include <x86intrin.h>
// Need to wrap __get_cpuid_count because it's declared as static.
int
@@ -17,27 +18,21 @@ gccgoGetCpuidCount(uint32_t leaf, uint32_t subleaf,
return __get_cpuid_count(leaf, subleaf, eax, ebx, ecx, edx);
}
#pragma GCC diagnostic ignored "-Wunknown-pragmas"
#pragma GCC push_options
#pragma GCC target("xsave")
#pragma clang attribute push (__attribute__((target("xsave"))), apply_to=function)
// xgetbv reads the contents of an XCR (Extended Control Register)
// specified in the ECX register into registers EDX:EAX.
// Currently, the only supported value for XCR is 0.
//
// TODO: Replace with a better alternative:
//
// #include <xsaveintrin.h>
//
// #pragma GCC target("xsave")
//
// void gccgoXgetbv(uint32_t *eax, uint32_t *edx) {
// unsigned long long x = _xgetbv(0);
// *eax = x & 0xffffffff;
// *edx = (x >> 32) & 0xffffffff;
// }
//
// Note that _xgetbv is defined starting with GCC 8.
void
gccgoXgetbv(uint32_t *eax, uint32_t *edx)
{
__asm(" xorl %%ecx, %%ecx\n"
" xgetbv"
: "=a"(*eax), "=d"(*edx));
uint64_t v = _xgetbv(0);
*eax = v & 0xffffffff;
*edx = v >> 32;
}
#pragma clang attribute pop
#pragma GCC pop_options