pixman/pixman-cpu.c - third_party/pixman - Git at Google

 /*
  * Copyright © 2000 SuSE, Inc.
  * Copyright © 2007 Red Hat, Inc.
  *
  * Permission to use, copy, modify, distribute, and sell this software and its
  * documentation for any purpose is hereby granted without fee, provided that
  * the above copyright notice appear in all copies and that both that
  * copyright notice and this permission notice appear in supporting
  * documentation, and that the name of SuSE not be used in advertising or
  * publicity pertaining to distribution of the software without specific,
  * written prior permission.  SuSE makes no representations about the
  * suitability of this software for any purpose.  It is provided "as is"
  * without express or implied warranty.
  *
  * SuSE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL SuSE
  * BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
  * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
  * OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
  * CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 #ifdef HAVE_CONFIG_H
 #include <config.h>
 #endif

 #include <string.h>

 #if defined(USE_ARM_SIMD) && defined(_MSC_VER)
 /* Needed for EXCEPTION_ILLEGAL_INSTRUCTION */
 #include <windows.h>
 #endif

 #include "pixman-private.h"

 #ifdef USE_VMX

 /* The CPU detection code needs to be in a file not compiled with
  * "-maltivec -mabi=altivec", as gcc would try to save vector register
  * across function calls causing SIGILL on cpus without Altivec/vmx.
  */
 static pixman_bool_t initialized = FALSE;
 static volatile pixman_bool_t have_vmx = TRUE;

 #ifdef __APPLE__
 #include <sys/sysctl.h>

 static pixman_bool_t
 pixman_have_vmx (void)
 {
     if(!initialized) {
         size_t length = sizeof(have_vmx);
         int error =
             sysctlbyname("hw.optional.altivec", &have_vmx, &length, NULL, 0);
         if(error) have_vmx = FALSE;
         initialized = TRUE;
     }
     return have_vmx;
 }

 #elif defined (__linux__)
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
 #include <unistd.h>
 #include <stdio.h>
 #include <linux/auxvec.h>
 #include <asm/cputable.h>

 static pixman_bool_t
 pixman_have_vmx (void)
 {
     if (!initialized) {
 	char fname[64];
 	unsigned long buf[64];
 	ssize_t count = 0;
 	pid_t pid;
 	int fd, i;

 	pid = getpid();
 	snprintf(fname, sizeof(fname)-1, "/proc/%d/auxv", pid);

 	fd = open(fname, O_RDONLY);
 	if (fd >= 0) {
 	    for (i = 0; i <= (count / sizeof(unsigned long)); i += 2) {
 		/* Read more if buf is empty... */
 		if (i == (count / sizeof(unsigned long))) {
 		    count = read(fd, buf, sizeof(buf));
 		    if (count <= 0)
 			break;
 		    i = 0;
 		}

 		if (buf[i] == AT_HWCAP) {
 		    have_vmx = !!(buf[i+1] & PPC_FEATURE_HAS_ALTIVEC);
 		    initialized = TRUE;
 		    break;
 		} else if (buf[i] == AT_NULL) {
 		    break;
 		}
 	    }
 	    close(fd);
 	}
     }
     if (!initialized) {
 	/* Something went wrong. Assume 'no' rather than playing
 	   fragile tricks with catching SIGILL. */
 	have_vmx = FALSE;
 	initialized = TRUE;
     }

     return have_vmx;
 }
 #else /* !__APPLE__ && !__linux__ */
 #include <signal.h>
 #include <setjmp.h>

 static jmp_buf jump_env;

 static void vmx_test(int sig, siginfo_t *si, void *unused) {
     longjmp (jump_env, 1);
 }

 static pixman_bool_t
 pixman_have_vmx (void) {
     struct sigaction sa, osa;
     int jmp_result;
     if (!initialized) {
         sa.sa_flags = SA_SIGINFO;
         sigemptyset(&sa.sa_mask);
         sa.sa_sigaction = vmx_test;
         sigaction(SIGILL, &sa, &osa);
 	jmp_result = setjmp (jump_env);
 	if (jmp_result == 0) {
 	    asm volatile ( "vor 0, 0, 0" );
 	}
         sigaction(SIGILL, &osa, NULL);
 	have_vmx = (jmp_result == 0);
         initialized = TRUE;
     }
     return have_vmx;
 }
 #endif /* __APPLE__ */
 #endif /* USE_VMX */

 #if defined(USE_ARM_SIMD) || defined(USE_ARM_NEON)

 #if defined(_MSC_VER)

 #if defined(USE_ARM_SIMD)
 extern int pixman_msvc_try_arm_simd_op();

 pixman_bool_t
 pixman_have_arm_simd (void)
 {
     static pixman_bool_t initialized = FALSE;
     static pixman_bool_t have_arm_simd = FALSE;

     if (!initialized) {
         __try {
             pixman_msvc_try_arm_simd_op();
             have_arm_simd = TRUE;
         } __except(GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
             have_arm_simd = FALSE;
         }
 	initialized = TRUE;
     }

     return have_arm_simd;
 }
 #endif /* USE_ARM_SIMD */

 #if defined(USE_ARM_NEON)
 extern int pixman_msvc_try_arm_neon_op();

 pixman_bool_t
 pixman_have_arm_neon (void)
 {
     static pixman_bool_t initialized = FALSE;
     static pixman_bool_t have_arm_neon = FALSE;

     if (!initialized) {
         __try {
             pixman_msvc_try_arm_neon_op();
             have_arm_neon = TRUE;
         } __except(GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
             have_arm_neon = FALSE;
         }
 	initialized = TRUE;
     }

     return have_arm_neon;
 }
 #endif /* USE_ARM_NEON */

 #else /* linux ELF */

 #include <stdlib.h>
 #include <unistd.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/mman.h>
 #include <fcntl.h>
 #include <string.h>
 #include <elf.h>

 static pixman_bool_t arm_has_v7 = FALSE;
 static pixman_bool_t arm_has_v6 = FALSE;
 static pixman_bool_t arm_has_vfp = FALSE;
 static pixman_bool_t arm_has_neon = FALSE;
 static pixman_bool_t arm_has_iwmmxt = FALSE;
 static pixman_bool_t arm_tests_initialized = FALSE;

 static void
 pixman_arm_read_auxv() {
     int fd;
     Elf32_auxv_t aux;

     fd = open("/proc/self/auxv", O_RDONLY);
     if (fd >= 0) {
         while (read(fd, &aux, sizeof(Elf32_auxv_t)) == sizeof(Elf32_auxv_t)) {
             if (aux.a_type == AT_HWCAP) {
 		uint32_t hwcap = aux.a_un.a_val;
 		if (getenv("ARM_FORCE_HWCAP"))
 		    hwcap = strtoul(getenv("ARM_FORCE_HWCAP"), NULL, 0);
 		// hardcode these values to avoid depending on specific versions
 		// of the hwcap header, e.g. HWCAP_NEON
 		arm_has_vfp = (hwcap & 64) != 0;
 		arm_has_iwmmxt = (hwcap & 512) != 0;
 		// this flag is only present on kernel 2.6.29
 		arm_has_neon = (hwcap & 4096) != 0;
             } else if (aux.a_type == AT_PLATFORM) {
 		const char *plat = (const char*) aux.a_un.a_val;
 		if (getenv("ARM_FORCE_PLATFORM"))
 		    plat = getenv("ARM_FORCE_PLATFORM");
 		if (strncmp(plat, "v7l", 3) == 0) {
 		    arm_has_v7 = TRUE;
 		    arm_has_v6 = TRUE;
 		} else if (strncmp(plat, "v6l", 3) == 0) {
 		    arm_has_v6 = TRUE;
 		}
             }
         }
         close (fd);

 	// if we don't have 2.6.29, we have to do this hack; set
 	// the env var to trust HWCAP.
 	if (!getenv("ARM_TRUST_HWCAP") && arm_has_v7)
 	    arm_has_neon = TRUE;
     }

     arm_tests_initialized = TRUE;
 }

 #if defined(USE_ARM_SIMD)
 pixman_bool_t
 pixman_have_arm_simd (void)
 {
     if (!arm_tests_initialized)
 	pixman_arm_read_auxv();

     return arm_has_v6;
 }
 #endif /* USE_ARM_SIMD */

 #if defined(USE_ARM_NEON)
 pixman_bool_t
 pixman_have_arm_neon (void)
 {
     if (!arm_tests_initialized)
 	pixman_arm_read_auxv();

     return arm_has_neon;
 }
 #endif /* USE_ARM_NEON */

 #endif /* linux */

 #endif /* USE_ARM_SIMD || USE_ARM_NEON */

 #ifdef USE_MMX
 /* The CPU detection code needs to be in a file not compiled with
  * "-mmmx -msse", as gcc would generate CMOV instructions otherwise
  * that would lead to SIGILL instructions on old CPUs that don't have
  * it.
  */
 #if !defined(__amd64__) && !defined(__x86_64__)

 #ifdef HAVE_GETISAX
 #include <sys/auxv.h>
 #endif

 enum CPUFeatures {
     NoFeatures = 0,
     MMX = 0x1,
     MMX_Extensions = 0x2,
     SSE = 0x6,
     SSE2 = 0x8,
     CMOV = 0x10
 };

 static unsigned int detectCPUFeatures(void) {
     unsigned int features = 0;
     unsigned int result = 0;

 #ifdef HAVE_GETISAX
     if (getisax(&result, 1)) {
         if (result & AV_386_CMOV)
             features |= CMOV;
         if (result & AV_386_MMX)
             features |= MMX;
         if (result & AV_386_AMD_MMX)
             features |= MMX_Extensions;
         if (result & AV_386_SSE)
             features |= SSE;
         if (result & AV_386_SSE2)
             features |= SSE2;
     }
 #else
     char vendor[13];
 #ifdef _MSC_VER
     int vendor0 = 0, vendor1, vendor2;
 #endif
     vendor[0] = 0;
     vendor[12] = 0;

 #ifdef __GNUC__
     /* see p. 118 of amd64 instruction set manual Vol3 */
     /* We need to be careful about the handling of %ebx and
      * %esp here. We can't declare either one as clobbered
      * since they are special registers (%ebx is the "PIC
      * register" holding an offset to global data, %esp the
      * stack pointer), so we need to make sure they have their
      * original values when we access the output operands.
      */
     __asm__ (
 	"pushf\n"
 	"pop %%eax\n"
 	"mov %%eax, %%ecx\n"
 	"xor $0x00200000, %%eax\n"
 	"push %%eax\n"
 	"popf\n"
 	"pushf\n"
 	"pop %%eax\n"
 	"mov $0x0, %%edx\n"
 	"xor %%ecx, %%eax\n"
 	"jz 1f\n"

 	"mov $0x00000000, %%eax\n"
 	"push %%ebx\n"
 	"cpuid\n"
 	"mov %%ebx, %%eax\n"
 	"pop %%ebx\n"
 	"mov %%eax, %1\n"
 	"mov %%edx, %2\n"
 	"mov %%ecx, %3\n"
 	"mov $0x00000001, %%eax\n"
 	"push %%ebx\n"
 	"cpuid\n"
 	"pop %%ebx\n"
 	"1:\n"
 	"mov %%edx, %0\n"
 	: "=r" (result),
 	  "=m" (vendor[0]),
 	  "=m" (vendor[4]),
 	  "=m" (vendor[8])
 	:
 	: "%eax", "%ecx", "%edx"
         );

 #elif defined (_MSC_VER)

     _asm {
       pushfd
       pop eax
       mov ecx, eax
       xor eax, 00200000h
       push eax
       popfd
       pushfd
       pop eax
       mov edx, 0
       xor eax, ecx
       jz nocpuid

       mov eax, 0
       push ebx
       cpuid
       mov eax, ebx
       pop ebx
       mov vendor0, eax
       mov vendor1, edx
       mov vendor2, ecx
       mov eax, 1
       push ebx
       cpuid
       pop ebx
     nocpuid:
       mov result, edx
     }
     memmove (vendor+0, &vendor0, 4);
     memmove (vendor+4, &vendor1, 4);
     memmove (vendor+8, &vendor2, 4);

 #else
 #   error unsupported compiler
 #endif

     features = 0;
     if (result) {
         /* result now contains the standard feature bits */
         if (result & (1 << 15))
             features |= CMOV;
         if (result & (1 << 23))
             features |= MMX;
         if (result & (1 << 25))
             features |= SSE;
         if (result & (1 << 26))
             features |= SSE2;
         if ((features & MMX) && !(features & SSE) &&
             (strcmp(vendor, "AuthenticAMD") == 0 ||
              strcmp(vendor, "Geode by NSC") == 0)) {
             /* check for AMD MMX extensions */
 #ifdef __GNUC__
             __asm__(
 		"	push %%ebx\n"
 		"	mov $0x80000000, %%eax\n"
 		"	cpuid\n"
 		"	xor %%edx, %%edx\n"
 		"	cmp $0x1, %%eax\n"
 		"	jge 2f\n"
 		"	mov $0x80000001, %%eax\n"
 		"	cpuid\n"
 		"2:\n"
 		"	pop %%ebx\n"
 		"	mov %%edx, %0\n"
 		: "=r" (result)
 		:
 		: "%eax", "%ecx", "%edx"
                 );
 #elif defined _MSC_VER
             _asm {
               push ebx
               mov eax, 80000000h
               cpuid
               xor edx, edx
               cmp eax, 1
               jge notamd
               mov eax, 80000001h
               cpuid
             notamd:
               pop ebx
               mov result, edx
             }
 #endif
             if (result & (1<<22))
                 features |= MMX_Extensions;
         }
     }
 #endif /* HAVE_GETISAX */

     return features;
 }

 static pixman_bool_t
 pixman_have_mmx (void)
 {
     static pixman_bool_t initialized = FALSE;
     static pixman_bool_t mmx_present;

     if (!initialized)
     {
         unsigned int features = detectCPUFeatures();
 	mmx_present = (features & (MMX|MMX_Extensions)) == (MMX|MMX_Extensions);
         initialized = TRUE;
     }

     return mmx_present;
 }

 #ifdef USE_SSE2
 static pixman_bool_t
 pixman_have_sse2 (void)
 {
     static pixman_bool_t initialized = FALSE;
     static pixman_bool_t sse2_present;

     if (!initialized)
     {
         unsigned int features = detectCPUFeatures();
         sse2_present = (features & (MMX|MMX_Extensions|SSE|SSE2)) == (MMX|MMX_Extensions|SSE|SSE2);
         initialized = TRUE;
     }

     return sse2_present;
 }
 #endif

 #else /* __amd64__ */
 #ifdef USE_MMX
 #define pixman_have_mmx() TRUE
 #endif
 #ifdef USE_SSE2
 #define pixman_have_sse2() TRUE
 #endif
 #endif /* __amd64__ */
 #endif

 pixman_implementation_t *
 _pixman_choose_implementation (void)
 {
 #ifdef USE_SSE2
     if (pixman_have_sse2 ())
 	return _pixman_implementation_create_sse2 (NULL);
 #endif
 #ifdef USE_MMX
     if (pixman_have_mmx())
 	return _pixman_implementation_create_mmx (NULL);
 #endif

 #ifdef USE_ARM_NEON
     if (pixman_have_arm_neon())
 	return _pixman_implementation_create_arm_neon (NULL);
 #endif
 #ifdef USE_ARM_SIMD
     if (pixman_have_arm_simd())
 	return _pixman_implementation_create_arm_simd (NULL);
 #endif
 #ifdef USE_VMX
     if (pixman_have_vmx())
 	return _pixman_implementation_create_vmx (NULL);
 #endif

     return _pixman_implementation_create_fast_path (NULL);
 }
	/*
	* Copyright © 2000 SuSE, Inc.
	* Copyright © 2007 Red Hat, Inc.
	*
	* Permission to use, copy, modify, distribute, and sell this software and its
	* documentation for any purpose is hereby granted without fee, provided that
	* the above copyright notice appear in all copies and that both that
	* copyright notice and this permission notice appear in supporting
	* documentation, and that the name of SuSE not be used in advertising or
	* publicity pertaining to distribution of the software without specific,
	* written prior permission. SuSE makes no representations about the
	* suitability of this software for any purpose. It is provided "as is"
	* without express or implied warranty.
	*
	* SuSE DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL
	* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO EVENT SHALL SuSE
	* BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
	* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
	* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	*/
	#ifdef HAVE_CONFIG_H
	#include <config.h>
	#endif

	#include <string.h>

	#if defined(USE_ARM_SIMD) && defined(_MSC_VER)
	/* Needed for EXCEPTION_ILLEGAL_INSTRUCTION */
	#include <windows.h>
	#endif

	#include "pixman-private.h"

	#ifdef USE_VMX

	/* The CPU detection code needs to be in a file not compiled with
	* "-maltivec -mabi=altivec", as gcc would try to save vector register
	* across function calls causing SIGILL on cpus without Altivec/vmx.
	*/
	static pixman_bool_t initialized = FALSE;
	static volatile pixman_bool_t have_vmx = TRUE;

	#ifdef __APPLE__
	#include <sys/sysctl.h>

	static pixman_bool_t
	pixman_have_vmx (void)
	{
	if(!initialized) {
	size_t length = sizeof(have_vmx);
	int error =
	sysctlbyname("hw.optional.altivec", &have_vmx, &length, NULL, 0);
	if(error) have_vmx = FALSE;
	initialized = TRUE;
	}
	return have_vmx;
	}

	#elif defined (__linux__)
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <fcntl.h>
	#include <unistd.h>
	#include <stdio.h>
	#include <linux/auxvec.h>
	#include <asm/cputable.h>

	static pixman_bool_t
	pixman_have_vmx (void)
	{
	if (!initialized) {
	char fname[64];
	unsigned long buf[64];
	ssize_t count = 0;
	pid_t pid;
	int fd, i;

	pid = getpid();
	snprintf(fname, sizeof(fname)-1, "/proc/%d/auxv", pid);

	fd = open(fname, O_RDONLY);
	if (fd >= 0) {
	for (i = 0; i <= (count / sizeof(unsigned long)); i += 2) {
	/* Read more if buf is empty... */
	if (i == (count / sizeof(unsigned long))) {
	count = read(fd, buf, sizeof(buf));
	if (count <= 0)
	break;
	i = 0;
	}

	if (buf[i] == AT_HWCAP) {
	have_vmx = !!(buf[i+1] & PPC_FEATURE_HAS_ALTIVEC);
	initialized = TRUE;
	break;
	} else if (buf[i] == AT_NULL) {
	break;
	}
	}
	close(fd);
	}
	}
	if (!initialized) {
	/* Something went wrong. Assume 'no' rather than playing
	fragile tricks with catching SIGILL. */
	have_vmx = FALSE;
	initialized = TRUE;
	}

	return have_vmx;
	}
	#else /* !__APPLE__ && !__linux__ */
	#include <signal.h>
	#include <setjmp.h>

	static jmp_buf jump_env;

	static void vmx_test(int sig, siginfo_t si, void unused) {
	longjmp (jump_env, 1);
	}

	static pixman_bool_t
	pixman_have_vmx (void) {
	struct sigaction sa, osa;
	int jmp_result;
	if (!initialized) {
	sa.sa_flags = SA_SIGINFO;
	sigemptyset(&sa.sa_mask);
	sa.sa_sigaction = vmx_test;
	sigaction(SIGILL, &sa, &osa);
	jmp_result = setjmp (jump_env);
	if (jmp_result == 0) {
	asm volatile ( "vor 0, 0, 0" );
	}
	sigaction(SIGILL, &osa, NULL);
	have_vmx = (jmp_result == 0);
	initialized = TRUE;
	}
	return have_vmx;
	}
	#endif /* __APPLE__ */
	#endif /* USE_VMX */

	#if defined(USE_ARM_SIMD) \|\| defined(USE_ARM_NEON)

	#if defined(_MSC_VER)

	#if defined(USE_ARM_SIMD)
	extern int pixman_msvc_try_arm_simd_op();

	pixman_bool_t
	pixman_have_arm_simd (void)
	{
	static pixman_bool_t initialized = FALSE;
	static pixman_bool_t have_arm_simd = FALSE;

	if (!initialized) {
	__try {
	pixman_msvc_try_arm_simd_op();
	have_arm_simd = TRUE;
	} __except(GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
	have_arm_simd = FALSE;
	}
	initialized = TRUE;
	}

	return have_arm_simd;
	}
	#endif /* USE_ARM_SIMD */

	#if defined(USE_ARM_NEON)
	extern int pixman_msvc_try_arm_neon_op();

	pixman_bool_t
	pixman_have_arm_neon (void)
	{
	static pixman_bool_t initialized = FALSE;
	static pixman_bool_t have_arm_neon = FALSE;

	if (!initialized) {
	__try {
	pixman_msvc_try_arm_neon_op();
	have_arm_neon = TRUE;
	} __except(GetExceptionCode() == EXCEPTION_ILLEGAL_INSTRUCTION) {
	have_arm_neon = FALSE;
	}
	initialized = TRUE;
	}

	return have_arm_neon;
	}
	#endif /* USE_ARM_NEON */

	#else /* linux ELF */

	#include <stdlib.h>
	#include <unistd.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <sys/mman.h>
	#include <fcntl.h>
	#include <string.h>
	#include <elf.h>

	static pixman_bool_t arm_has_v7 = FALSE;
	static pixman_bool_t arm_has_v6 = FALSE;
	static pixman_bool_t arm_has_vfp = FALSE;
	static pixman_bool_t arm_has_neon = FALSE;
	static pixman_bool_t arm_has_iwmmxt = FALSE;
	static pixman_bool_t arm_tests_initialized = FALSE;

	static void
	pixman_arm_read_auxv() {
	int fd;
	Elf32_auxv_t aux;

	fd = open("/proc/self/auxv", O_RDONLY);
	if (fd >= 0) {
	while (read(fd, &aux, sizeof(Elf32_auxv_t)) == sizeof(Elf32_auxv_t)) {
	if (aux.a_type == AT_HWCAP) {
	uint32_t hwcap = aux.a_un.a_val;
	if (getenv("ARM_FORCE_HWCAP"))
	hwcap = strtoul(getenv("ARM_FORCE_HWCAP"), NULL, 0);
	// hardcode these values to avoid depending on specific versions
	// of the hwcap header, e.g. HWCAP_NEON
	arm_has_vfp = (hwcap & 64) != 0;
	arm_has_iwmmxt = (hwcap & 512) != 0;
	// this flag is only present on kernel 2.6.29
	arm_has_neon = (hwcap & 4096) != 0;
	} else if (aux.a_type == AT_PLATFORM) {
	const char plat = (const char) aux.a_un.a_val;
	if (getenv("ARM_FORCE_PLATFORM"))
	plat = getenv("ARM_FORCE_PLATFORM");
	if (strncmp(plat, "v7l", 3) == 0) {
	arm_has_v7 = TRUE;
	arm_has_v6 = TRUE;
	} else if (strncmp(plat, "v6l", 3) == 0) {
	arm_has_v6 = TRUE;
	}
	}
	}
	close (fd);

	// if we don't have 2.6.29, we have to do this hack; set
	// the env var to trust HWCAP.
	if (!getenv("ARM_TRUST_HWCAP") && arm_has_v7)
	arm_has_neon = TRUE;
	}

	arm_tests_initialized = TRUE;
	}

	#if defined(USE_ARM_SIMD)
	pixman_bool_t
	pixman_have_arm_simd (void)
	{
	if (!arm_tests_initialized)
	pixman_arm_read_auxv();

	return arm_has_v6;
	}
	#endif /* USE_ARM_SIMD */

	#if defined(USE_ARM_NEON)
	pixman_bool_t
	pixman_have_arm_neon (void)
	{
	if (!arm_tests_initialized)
	pixman_arm_read_auxv();

	return arm_has_neon;
	}
	#endif /* USE_ARM_NEON */

	#endif /* linux */

	#endif /* USE_ARM_SIMD \|\| USE_ARM_NEON */

	#ifdef USE_MMX
	/* The CPU detection code needs to be in a file not compiled with
	* "-mmmx -msse", as gcc would generate CMOV instructions otherwise
	* that would lead to SIGILL instructions on old CPUs that don't have
	* it.
	*/
	#if !defined(__amd64__) && !defined(__x86_64__)

	#ifdef HAVE_GETISAX
	#include <sys/auxv.h>
	#endif

	enum CPUFeatures {
	NoFeatures = 0,
	MMX = 0x1,
	MMX_Extensions = 0x2,
	SSE = 0x6,
	SSE2 = 0x8,
	CMOV = 0x10
	};

	static unsigned int detectCPUFeatures(void) {
	unsigned int features = 0;
	unsigned int result = 0;

	#ifdef HAVE_GETISAX
	if (getisax(&result, 1)) {
	if (result & AV_386_CMOV)
	features \|= CMOV;
	if (result & AV_386_MMX)
	features \|= MMX;
	if (result & AV_386_AMD_MMX)
	features \|= MMX_Extensions;
	if (result & AV_386_SSE)
	features \|= SSE;
	if (result & AV_386_SSE2)
	features \|= SSE2;
	}
	#else
	char vendor[13];
	#ifdef _MSC_VER
	int vendor0 = 0, vendor1, vendor2;
	#endif
	vendor[0] = 0;
	vendor[12] = 0;

	#ifdef __GNUC__
	/* see p. 118 of amd64 instruction set manual Vol3 */
	/* We need to be careful about the handling of %ebx and
	* %esp here. We can't declare either one as clobbered
	* since they are special registers (%ebx is the "PIC
	* register" holding an offset to global data, %esp the
	* stack pointer), so we need to make sure they have their
	* original values when we access the output operands.
	*/
	__asm__ (
	"pushf\n"
	"pop %%eax\n"
	"mov %%eax, %%ecx\n"
	"xor $0x00200000, %%eax\n"
	"push %%eax\n"
	"popf\n"
	"pushf\n"
	"pop %%eax\n"
	"mov $0x0, %%edx\n"
	"xor %%ecx, %%eax\n"
	"jz 1f\n"

	"mov $0x00000000, %%eax\n"
	"push %%ebx\n"
	"cpuid\n"
	"mov %%ebx, %%eax\n"
	"pop %%ebx\n"
	"mov %%eax, %1\n"
	"mov %%edx, %2\n"
	"mov %%ecx, %3\n"
	"mov $0x00000001, %%eax\n"
	"push %%ebx\n"
	"cpuid\n"
	"pop %%ebx\n"
	"1:\n"
	"mov %%edx, %0\n"
	: "=r" (result),
	"=m" (vendor[0]),
	"=m" (vendor[4]),
	"=m" (vendor[8])
	:
	: "%eax", "%ecx", "%edx"
	);

	#elif defined (_MSC_VER)

	_asm {
	pushfd
	pop eax
	mov ecx, eax
	xor eax, 00200000h
	push eax
	popfd
	pushfd
	pop eax
	mov edx, 0
	xor eax, ecx
	jz nocpuid

	mov eax, 0
	push ebx
	cpuid
	mov eax, ebx
	pop ebx
	mov vendor0, eax
	mov vendor1, edx
	mov vendor2, ecx
	mov eax, 1
	push ebx
	cpuid
	pop ebx
	nocpuid:
	mov result, edx
	}
	memmove (vendor+0, &vendor0, 4);
	memmove (vendor+4, &vendor1, 4);
	memmove (vendor+8, &vendor2, 4);

	#else
	# error unsupported compiler
	#endif

	features = 0;
	if (result) {
	/* result now contains the standard feature bits */
	if (result & (1 << 15))
	features \|= CMOV;
	if (result & (1 << 23))
	features \|= MMX;
	if (result & (1 << 25))
	features \|= SSE;
	if (result & (1 << 26))
	features \|= SSE2;
	if ((features & MMX) && !(features & SSE) &&
	(strcmp(vendor, "AuthenticAMD") == 0 \|\|
	strcmp(vendor, "Geode by NSC") == 0)) {
	/* check for AMD MMX extensions */
	#ifdef __GNUC__
	__asm__(
	" push %%ebx\n"
	" mov $0x80000000, %%eax\n"
	" cpuid\n"
	" xor %%edx, %%edx\n"
	" cmp $0x1, %%eax\n"
	" jge 2f\n"
	" mov $0x80000001, %%eax\n"
	" cpuid\n"
	"2:\n"
	" pop %%ebx\n"
	" mov %%edx, %0\n"
	: "=r" (result)
	:
	: "%eax", "%ecx", "%edx"
	);
	#elif defined _MSC_VER
	_asm {
	push ebx
	mov eax, 80000000h
	cpuid
	xor edx, edx
	cmp eax, 1
	jge notamd
	mov eax, 80000001h
	cpuid
	notamd:
	pop ebx
	mov result, edx
	}
	#endif
	if (result & (1<<22))
	features \|= MMX_Extensions;
	}
	}
	#endif /* HAVE_GETISAX */

	return features;
	}

	static pixman_bool_t
	pixman_have_mmx (void)
	{
	static pixman_bool_t initialized = FALSE;
	static pixman_bool_t mmx_present;

	if (!initialized)
	{
	unsigned int features = detectCPUFeatures();
	mmx_present = (features & (MMX\|MMX_Extensions)) == (MMX\|MMX_Extensions);
	initialized = TRUE;
	}

	return mmx_present;
	}

	#ifdef USE_SSE2
	static pixman_bool_t
	pixman_have_sse2 (void)
	{
	static pixman_bool_t initialized = FALSE;
	static pixman_bool_t sse2_present;

	if (!initialized)
	{
	unsigned int features = detectCPUFeatures();
	sse2_present = (features & (MMX\|MMX_Extensions\|SSE\|SSE2)) == (MMX\|MMX_Extensions\|SSE\|SSE2);
	initialized = TRUE;
	}

	return sse2_present;
	}
	#endif

	#else /* __amd64__ */
	#ifdef USE_MMX
	#define pixman_have_mmx() TRUE
	#endif
	#ifdef USE_SSE2
	#define pixman_have_sse2() TRUE
	#endif
	#endif /* __amd64__ */
	#endif

	pixman_implementation_t *
	_pixman_choose_implementation (void)
	{
	#ifdef USE_SSE2
	if (pixman_have_sse2 ())
	return _pixman_implementation_create_sse2 (NULL);
	#endif
	#ifdef USE_MMX
	if (pixman_have_mmx())
	return _pixman_implementation_create_mmx (NULL);
	#endif

	#ifdef USE_ARM_NEON
	if (pixman_have_arm_neon())
	return _pixman_implementation_create_arm_neon (NULL);
	#endif
	#ifdef USE_ARM_SIMD
	if (pixman_have_arm_simd())
	return _pixman_implementation_create_arm_simd (NULL);
	#endif
	#ifdef USE_VMX
	if (pixman_have_vmx())
	return _pixman_implementation_create_vmx (NULL);
	#endif

	return _pixman_implementation_create_fast_path (NULL);
	}