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Fixed bug 2404 - CPU detection not working with MSVC on x64 

Tiemo Jung

All CPU detection functions SDL_Has* will return false, even if it is supported by the CPU, if SDL is compiled with MSVC and the target is x64.

The reason for this is that 'CPU_haveCPUID' will return 0 and macro 'cpuid' in SDL_cpuinfo.c is the fallback implementation, which sets all params to zero.

It is safe to assume that cpuid is supported on a CPU that runs windows x64, so CPU_haveCPUID can just return 1, and the empty macro can be replaced with a small wrap around the __cpuid intrinsic.
Sam Lantinga 2014-02-22 19:10:45 -08:00
parent fea87cc9cf
commit 9cd5f5ceca
1 changed files with 14 additions and 2 deletions
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16
src/cpuinfo/SDL_cpuinfo.c
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@ -98,7 +98,7 @@ CPU_haveCPUID(void)
); );
#elif defined(__GNUC__) && defined(__x86_64__) #elif defined(__GNUC__) && defined(__x86_64__)
/* Technically, if this is being compiled under __x86_64__ then it has /* Technically, if this is being compiled under __x86_64__ then it has
CPUid by definition. But it's nice to be able to prove it. :) */ CPUid by definition. But it's nice to be able to prove it. :) */
__asm__ ( __asm__ (
" pushfq # Get original EFLAGS \n" " pushfq # Get original EFLAGS \n"
" popq %%rax \n" " popq %%rax \n"
@ -131,6 +131,8 @@ CPUid by definition. But it's nice to be able to prove it. :) */
mov has_CPUID,1 ; We have CPUID support mov has_CPUID,1 ; We have CPUID support
done: done:
} }
#elif defined(_MSC_VER) && defined(_M_X64)
has_CPUID = 1;
#elif defined(__sun) && defined(__i386) #elif defined(__sun) && defined(__i386)
__asm ( __asm (
" pushfl \n" " pushfl \n"
@ -191,7 +193,17 @@ done:
__asm mov b, ebx \ __asm mov b, ebx \
__asm mov c, ecx \ __asm mov c, ecx \
__asm mov d, edx \ __asm mov d, edx \
} }
#elif defined(_MSC_VER) && defined(_M_X64)
#define cpuid(func, a, b, c, d) \
{ \
int CPUInfo[4]; \
__cpuid(CPUInfo, func); \
a = CPUInfo[0]; \
b = CPUInfo[1]; \
c = CPUInfo[2]; \
d = CPUInfo[3]; \
}
#else #else
#define cpuid(func, a, b, c, d) \ #define cpuid(func, a, b, c, d) \
a = b = c = d = 0 a = b = c = d = 0