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dnl @synopsis AX_GCC_X86_CPUID(OP)
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dnl @summary run x86 cpuid instruction OP using gcc inline assembler
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dnl On Pentium and later x86 processors, with gcc or a compiler that
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dnl has a compatible syntax for inline assembly instructions, run
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dnl a small program that executes the cpuid instruction with
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dnl input OP. This can be used to detect the CPU type.
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dnl On output, the values of the eax, ebx, ecx, and edx registers
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dnl are stored as hexadecimal strings as "eax:ebx:ecx:edx" in
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dnl the cache variable ax_cv_gcc_x86_cpuid_OP.
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dnl If the cpuid instruction fails (because you are running a cross-compiler,
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dnl or because you are not using gcc, or because you are on a processor
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dnl that doesn't have this instruction), ax_cv_gcc_x86_cpuid_OP is set
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dnl to the string "unknown".
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dnl This macro mainly exists to be used in AX_GCC_ARCHFLAG.
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dnl @version 2008-12-06
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dnl @license GPLWithACException
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dnl @author Steven G. Johnson <stevenj@alum.mit.edu> and Matteo Frigo.
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AC_DEFUN([AX_GCC_X86_CPUID],
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[AC_REQUIRE([AC_PROG_CC])
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AC_CACHE_CHECK(for x86 cpuid $1 output, ax_cv_gcc_x86_cpuid_$1,
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[AC_RUN_IFELSE([AC_LANG_PROGRAM([#include <stdio.h>], [
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int op = $1, eax, ebx, ecx, edx;
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#if defined(__amd64__) || defined(__amd64) || defined(__x86_64__) || defined(__x86_64)
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__asm__("push %%rbx\n\t"
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: "=a" (eax), "=c" (ecx), "=d" (edx)
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__asm__("push %%rbx\n\t"
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"mov %%rbx, %%rax\n\t"
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: "=a" (ebx), "=c" (ecx), "=d" (edx)
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__asm__("push %%ebx\n\t"
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: "=a" (eax), "=c" (ecx), "=d" (edx)
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__asm__("push %%ebx\n\t"
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"mov %%ebx, %%eax\n\t"
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: "=a" (ebx), "=c" (ecx), "=d" (edx)
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f = fopen("conftest_cpuid", "w"); if (!f) return 1;
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fprintf(f, "%x:%x:%x:%x\n", eax, ebx, ecx, edx);
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[ax_cv_gcc_x86_cpuid_$1=`cat conftest_cpuid`; rm -f conftest_cpuid],
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[ax_cv_gcc_x86_cpuid_$1=unknown; rm -f conftest_cpuid],
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[ax_cv_gcc_x86_cpuid_$1=unknown])])
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m4/ax_gcc_x86_cpuid.m4
