1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
|
--- /usr/local/google/home/waffles/Downloads/C/CpuArch.c 2015-03-25 05:17:41.000000000 -0700
+++ CpuArch.c 2016-02-19 12:42:20.327993932 -0800
@@ -45,7 +45,8 @@
"push %%EDX\n\t"
"popf\n\t"
"andl %%EAX, %0\n\t":
- "=c" (flag) : "c" (flag));
+ "=c" (flag) : "c" (flag):
+ "%eax", "%edx" );
#endif
return flag;
}
@@ -78,8 +79,17 @@
#else
+ // When built using GCC and -fPIC (until GCC 5.0), ebx points to the global
+ // offset table, so the value must be preserved before executing cpuid.
+ // Attempting to explicitly clobber ebx is a compile-time error.
__asm__ __volatile__ (
- #if defined(MY_CPU_X86) && defined(__PIC__)
+ #if defined(MY_CPU_AMD64) && defined(__PIC__)
+ "mov %%rbx, %%rdi\n"
+ "cpuid\n"
+ "xchg %%rdi, %%rbx\n"
+ : "=a" (*a) ,
+ "=D" (*b) ,
+ #elif defined(MY_CPU_X86) && defined(__PIC__)
"mov %%ebx, %%edi;"
"cpuid;"
"xchgl %%ebx, %%edi;"
|
