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x86_64: Correct wrong inline assembly in jit_get_cpu

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* lib/jit_x86.c: Rewrite incorrect inline assembly that could
	truncate a variable in a callee save register. Now it simply
	tells gcc that the register is clobbered, instead of using a
	*32 bit* swap with a temporary variable. The problem only
	happens when compiling with optimization.
This commit is contained in:
pcpa 2014-02-19 15:29:26 -03:00
parent 6e75c0352d
commit dbb9fe1e81
2 changed files with 14 additions and 4 deletions
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10
lib/jit_x86.c
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@ -236,10 +236,11 @@ jit_get_cpu(void)
#endif
/* query %eax = 1 function */
__asm__ volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1"
__asm__ volatile ("cpuid; movl %%ebx, %1"
: "=a" (eax), "=r" (ebx),
"=c" (ecx.cpuid), "=d" (edx.cpuid)
: "0" (1));
: "0" (1)
: "ebx");
jit_cpu.fpu = edx.bits.fpu;
jit_cpu.cmpxchg8b = edx.bits.cmpxchg8b;
@ -261,10 +262,11 @@ jit_get_cpu(void)
#if __WORDSIZE == 64
/* query %eax = 0x80000001 function */
__asm__ volatile ("xchgl %%ebx, %1; cpuid; xchgl %%ebx, %1"
__asm__ volatile ("cpuid; movl %%ebx, %1"
: "=a" (eax), "=r" (ebx),
"=c" (ecx.cpuid), "=d" (edx.cpuid)
: "0" (0x80000001));
: "0" (0x80000001)
: "ebx");
jit_cpu.lahf = ecx.cpuid & 1;
#endif
}