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Work around bug in xgetbv for Visual Studio.

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xgetbv is generating bad code, falsely disabling AVX2 and AVX512.
disable optimization for the function affected on older versions of Visual C 32 bit.

R=brucedawson@chromium.org, dhrosa@google.com, harryjin@google.com
BUG=libyuv:529

Review URL: https://codereview.chromium.org/1503393004 .
This commit is contained in:
Frank Barchard 2015-12-08 18:13:32 -08:00
parent 2657688e70
commit fae1a10545
3 changed files with 24 additions and 14 deletions
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2
README.chromium
View File

@ -1,6 +1,6 @@
Name: libyuv
URL: http://code.google.com/p/libyuv/
Version: 1549
Version: 1550
License: BSD
License File: LICENSE

2
include/libyuv/version.h
View File

@ -11,6 +11,6 @@
#ifndef INCLUDE_LIBYUV_VERSION_H_ // NOLINT
#define INCLUDE_LIBYUV_VERSION_H_
#define LIBYUV_VERSION 1549
#define LIBYUV_VERSION 1550
#endif // INCLUDE_LIBYUV_VERSION_H_ NOLINT

34
source/cpu_id.cc
View File

@ -48,7 +48,7 @@ extern "C" {
!defined(__pnacl__) && !defined(__CLR_VER)
LIBYUV_API
void CpuId(uint32 info_eax, uint32 info_ecx, uint32* cpu_info) {
#if (defined(_MSC_VER) && !defined(__clang__)) && !defined(__clang__)
#if defined(_MSC_VER) && !defined(__clang__)
// Visual C version uses intrinsic or inline x86 assembly.
#if (_MSC_FULL_VER >= 160040219)
__cpuidex((int*)(cpu_info), info_eax, info_ecx);
@ -63,7 +63,7 @@ void CpuId(uint32 info_eax, uint32 info_ecx, uint32* cpu_info) {
mov [edi + 8], ecx
mov [edi + 12], edx
}
#else
#else // Visual C but not x86
if (info_ecx == 0) {
__cpuid((int*)(cpu_info), info_eax);
} else {
@ -71,7 +71,7 @@ void CpuId(uint32 info_eax, uint32 info_ecx, uint32* cpu_info) {
}
#endif
// GCC version uses inline x86 assembly.
#else // (defined(_MSC_VER) && !defined(__clang__)) && !defined(__clang__)
#else // defined(_MSC_VER) && !defined(__clang__)
uint32 info_ebx, info_edx;
asm volatile (
#if defined( __i386__) && defined(__PIC__)
@ -89,7 +89,7 @@ void CpuId(uint32 info_eax, uint32 info_ecx, uint32* cpu_info) {
cpu_info[1] = info_ebx;
cpu_info[2] = info_ecx;
cpu_info[3] = info_edx;
#endif // (defined(_MSC_VER) && !defined(__clang__)) && !defined(__clang__)
#endif // defined(_MSC_VER) && !defined(__clang__)
}
#else // (defined(_M_IX86) || defined(_M_X64) ...
LIBYUV_API
@ -98,7 +98,18 @@ void CpuId(uint32 eax, uint32 ecx, uint32* cpu_info) {
}
#endif
// TODO(fbarchard): Enable xgetbv when validator supports it.
// For VS2010 and earlier emit can be used:
// _asm _emit 0x0f _asm _emit 0x01 _asm _emit 0xd0 // For VS2010 and earlier.
// __asm {
// xor ecx, ecx // xcr 0
// xgetbv
// mov xcr0, eax
// }
// For VS2013 and earlier 32 bit, the _xgetbv(0) optimizer produces bad code.
// https://code.google.com/p/libyuv/issues/detail?id=529
#if defined(_M_IX86) && (_MSC_VER < 1900)
#pragma optimize("g", off)
#endif
#if (defined(_M_IX86) || defined(_M_X64) || \
defined(__i386__) || defined(__x86_64__)) && \
!defined(__pnacl__) && !defined(__CLR_VER) && !defined(__native_client__)
@ -106,20 +117,19 @@ void CpuId(uint32 eax, uint32 ecx, uint32* cpu_info) {
// X86 CPUs have xgetbv to detect OS saves high parts of ymm registers.
int GetXCR0() {
uint32 xcr0 = 0u;
#if (defined(_MSC_VER) && !defined(__clang__)) && (_MSC_FULL_VER >= 160040219)
#if (_MSC_FULL_VER >= 160040219)
xcr0 = (uint32)(_xgetbv(0)); // VS2010 SP1 required.
#elif defined(_M_IX86) && defined(_MSC_VER) && !defined(__clang__)
__asm {
xor ecx, ecx // xcr 0
_asm _emit 0x0f _asm _emit 0x01 _asm _emit 0xd0 // For VS2010 and earlier.
mov xcr0, eax
}
#elif defined(__i386__) || defined(__x86_64__)
uint32 xcr0 = 0u;
asm(".byte 0x0f, 0x01, 0xd0" : "=a" (xcr0) : "c" (0) : "%edx");
#endif // defined(__i386__) || defined(__x86_64__)
return xcr0;
}
#endif // defined(_M_IX86) || defined(_M_X64) ..
// Return optimization to previous setting.
#if defined(_M_IX86) && (_MSC_VER < 1900)
#pragma optimize("g", on)
#endif
// based on libvpx arm_cpudetect.c
// For Arm, but public to allow testing on any CPU