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fix __cpuid() on x86

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The previous version used memory operands that gcc (probably dependent
on optimization flags and/or version) could address relative to the
stack pointer, but pushing %ebx onto the stack changed it. Here, the
address of the regs array is put into %esi and the individual members
are written into directly.
This commit is contained in:
Florian Weimer 2016-03-07 16:45:32 +01:00 committed by Robin Gareus
parent d35e75554f
commit 5a41b86028
1 changed files with 8 additions and 15 deletions
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23
libs/pbd/fpu.cc
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@ -48,32 +48,25 @@ FPU* FPU::_instance (0);
static void
__cpuid(int regs[4], int cpuid_leaf)
{
int eax, ebx, ecx, edx;
asm volatile (
#if defined(__i386__)
"pushl %%ebx;\n\t"
#endif
"movl %4, %%eax;\n\t"
"cpuid;\n\t"
"movl %%eax, %0;\n\t"
"movl %%ebx, %1;\n\t"
"movl %%ecx, %2;\n\t"
"movl %%edx, %3;\n\t"
"movl %%eax, (%1);\n\t"
"movl %%ebx, 4(%1);\n\t"
"movl %%ecx, 8(%1);\n\t"
"movl %%edx, 12(%1);\n\t"
#if defined(__i386__)
"popl %%ebx;\n\t"
#endif
:"=m" (eax), "=m" (ebx), "=m" (ecx), "=m" (edx)
:"r" (cpuid_leaf)
:"%eax",
:"=a" (cpuid_leaf) /* %eax clobbered by CPUID */
:"S" (regs), "a" (cpuid_leaf)
:
#if !defined(__i386__)
"%ebx",
#endif
"%ecx", "%edx");
regs[0] = eax;
regs[1] = ebx;
regs[2] = ecx;
regs[3] = edx;
"%ecx", "%edx", "memory");
}
#endif /* !PLATFORM_WINDOWS */