zend_cpuinfo.c

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/*
   +----------------------------------------------------------------------+
   | Zend Engine                                                          |
   +----------------------------------------------------------------------+
   | Copyright (c) Zend Technologies Ltd. (http://www.zend.com)           |
   +----------------------------------------------------------------------+
   | This source file is subject to version 2.00 of the Zend license,     |
   | that is bundled with this package in the file LICENSE, and is        |
   | available through the world-wide-web at the following url:           |
   | http://www.zend.com/license/2_00.txt.                                |
   | If you did not receive a copy of the Zend license and are unable to  |
   | obtain it through the world-wide-web, please send a note to          |
   | license@zend.com so we can mail you a copy immediately.              |
   +----------------------------------------------------------------------+
   | Authors: Xinchen Hui <xinchen.h@zend.com>                            |
   +----------------------------------------------------------------------+
*/
 
#include "zend_cpuinfo.h"
 
typedef struct _zend_cpu_info {
    uint32_t eax;
    uint32_t ebx;
    uint32_t ecx;
    uint32_t edx;
    uint32_t initialized;
} zend_cpu_info;
 
static zend_cpu_info cpuinfo = {0};
 
#if (defined(__GNUC__) || defined(__clang__)) && (defined(__i386__) || defined(__x86_64__))
# if defined(HAVE_CPUID_H) && defined(HAVE_CPUID_COUNT) /* use cpuid.h functions */
#  include <cpuid.h>
static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
    __cpuid_count(func, subfunc, cpuinfo->eax, cpuinfo->ebx, cpuinfo->ecx, cpuinfo->edx);
}
# else /* use inline asm */
static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
#  if defined(__i386__) && (defined(__pic__) || defined(__PIC__))
    /* PIC on i386 uses %ebx, so preserve it. */
    __asm__ __volatile__ (
        "pushl  %%ebx\n"
        "cpuid\n"
        "mov    %%ebx,%1\n"
        "popl   %%ebx"
        : "=a"(cpuinfo->eax), "=r"(cpuinfo->ebx), "=c"(cpuinfo->ecx), "=d"(cpuinfo->edx)
        : "a"(func), "c"(subfunc)
    );
#  else
    __asm__ __volatile__ (
        "cpuid"
        : "=a"(cpuinfo->eax), "=b"(cpuinfo->ebx), "=c"(cpuinfo->ecx), "=d"(cpuinfo->edx)
        : "a"(func), "c"(subfunc)
    );
#  endif
}
# endif
#elif defined(_MSC_VER) && !defined(__clang__) && (defined(_M_X64) || defined(_M_IX86)) /* use MSVC __cpuidex intrin */
# include <intrin.h>
static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
    int regs[4];
 
    __cpuidex(regs, func, subfunc);
 
    cpuinfo->eax = regs[0];
    cpuinfo->ebx = regs[1];
    cpuinfo->ecx = regs[2];
    cpuinfo->edx = regs[3];
}
#else /* fall back to zero */
static void __zend_cpuid(uint32_t func, uint32_t subfunc, zend_cpu_info *cpuinfo) {
    cpuinfo->eax = 0;
}
#endif
 
#if defined(__i386__) || defined(__x86_64__) || defined(_M_X64) || defined(_M_IX86)
/* Function based on compiler-rt implementation. */
static unsigned get_xcr0_eax(void) {
# if defined(__GNUC__) || defined(__clang__)
    // Check xgetbv; this uses a .byte sequence instead of the instruction
    // directly because older assemblers do not include support for xgetbv and
    // there is no easy way to conditionally compile based on the assembler used.
    unsigned eax, edx;
    __asm__(".byte 0x0f, 0x01, 0xd0" : "=a"(eax), "=d"(edx) : "c"(0));
    return eax;
# elif defined(ZEND_WIN32) && defined(_XCR_XFEATURE_ENABLED_MASK)
    return _xgetbv(_XCR_XFEATURE_ENABLED_MASK);
# else
    return 0;
# endif
}
 
static bool is_avx_supported(void) {
    if (!(cpuinfo.ecx & ZEND_CPU_FEATURE_AVX)) {
        /* No support for AVX */
        return 0;
    }
    if (!(cpuinfo.ecx & ZEND_CPU_FEATURE_OSXSAVE)) {
        /* The operating system does not support XSAVE. */
        return 0;
    }
    if ((get_xcr0_eax() & 0x6) != 0x6) {
        /* XCR0 SSE and AVX bits must be set. */
        return 0;
    }
    return 1;
}
#else
static bool is_avx_supported(void) {
    return 0;
}
#endif
 
void zend_cpu_startup(void)
{
    if (!cpuinfo.initialized) {
        zend_cpu_info ebx;
        int max_feature;
 
        cpuinfo.initialized = 1;
        __zend_cpuid(0, 0, &cpuinfo);
        max_feature = cpuinfo.eax;
        if (max_feature == 0) {
            return;
        }
 
        __zend_cpuid(1, 0, &cpuinfo);
 
        /* for avx2 */
        if (max_feature >= 7) {
            __zend_cpuid(7, 0, &ebx);
            cpuinfo.ebx = ebx.ebx;
        } else {
            cpuinfo.ebx = 0;
        }
 
        if (!is_avx_supported()) {
            cpuinfo.edx &= ~ZEND_CPU_FEATURE_AVX;
            cpuinfo.ebx &= ~(ZEND_CPU_FEATURE_AVX2 & ~ZEND_CPU_EBX_MASK);
        }
    }
}
 
ZEND_API int zend_cpu_supports(zend_cpu_feature feature) {
    ZEND_ASSERT(cpuinfo.initialized);
    if (feature & ZEND_CPU_EDX_MASK) {
        return (cpuinfo.edx & (feature & ~ZEND_CPU_EDX_MASK));
    } else if (feature & ZEND_CPU_EBX_MASK) {
        return (cpuinfo.ebx & (feature & ~ZEND_CPU_EBX_MASK));
    } else {
        return (cpuinfo.ecx & feature);
    }
}