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dsp/cpu: add AVX detection

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currently unused.
https://software.intel.com/en-us/articles/introduction-to-intel-advanced-vector-extensions

similar checks exist in ffmpeg, libyuv. the visual studio inline asm is
based off of libyuv.

Change-Id: I3e233de3492172434e482607a94b99c617f11aad
This commit is contained in:
James Zern 2014-05-16 18:43:11 -07:00
parent 3da924b5b4
commit df08e67e06
2 changed files with 36 additions and 0 deletions
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35
src/dsp/cpu.c
View File

@ -42,6 +42,34 @@ static WEBP_INLINE void GetCPUInfo(int cpu_info[4], int info_type) {
#define GetCPUInfo __cpuid
#endif
#if defined(__i386__) || defined(__x86_64__)
static WEBP_INLINE uint64_t xgetbv(void) {
const uint32_t ecx = 0;
uint32_t eax, edx;
// Use the raw opcode for xgetbv for compatibility with older toolchains.
__asm__ volatile (
".byte 0x0f, 0x01, 0xd0\n"
: "=a"(eax), "=d"(edx) : "c" (ecx));
return ((uint64_t)edx << 32) | eax;
}
#elif defined(_MSC_FULL_VER) && _MSC_FULL_VER >= 160040219 // >= VS2010 SP1
#define xgetbv() _xgetbv(0)
#elif defined(_M_IX86)
static WEBP_INLINE uint64_t xgetbv(void) {
uint32_t eax_, edx_;
__asm {
xor ecx, ecx // ecx = 0
// Use the raw opcode for xgetbv for compatibility with older toolchains.
__asm _emit 0x0f __asm _emit 0x01 __asm _emit 0xd0
mov eax_, eax
mov edx_, edx
}
return ((uint64_t)edx_ << 32) | eax_;
}
#else
#define xgetbv() 0U // no AVX for older x64 or unrecognized toolchains.
#endif
#if defined(__i386__) || defined(__x86_64__) || defined(WEBP_MSC_SSE2)
static int x86CPUInfo(CPUFeature feature) {
int cpu_info[4];
@ -52,6 +80,13 @@ static int x86CPUInfo(CPUFeature feature) {
if (feature == kSSE3) {
return 0 != (cpu_info[2] & 0x00000001);
}
if (feature == kAVX) {
// bits 27 (OSXSAVE) & 28 (256-bit AVX)
if ((cpu_info[2] & 0x18000000) == 0x18000000) {
// XMM state and YMM state enabled by the OS.
return (xgetbv() & 0x6) == 0x6;
}
}
return 0;
}
VP8CPUInfo VP8GetCPUInfo = x86CPUInfo;

1
src/dsp/dsp.h
View File

@ -55,6 +55,7 @@ extern "C" {
typedef enum {
kSSE2,
kSSE3,
kAVX,
kNEON,
kMIPS32
} CPUFeature;