> On Thu, Nov 01, 2001 at 02:54:37PM -0700, John Regehr wrote:
> > > Don't forget to make sure it's __volatile__, elsewise this is the very
> > > epitome of what would produce dodgy results...
> >
> > Right. So method2 and method2A seem to be broken in multiple ways -
> > forget you ever saw them. Rather, look at this page:
in what way is method2 brocken ??
if you compile method1 and method2A and look at the assembler coee they are
absolutly the same - the only difference on the source level is that its easier
to read "mov" than "0x31" thats all.
---method1---
__inline__ unsigned long long int rdtsc(void)
{
unsigned long long int x;
__asm__ volatile (".byte 0x0f, 0x31" : "=A" (x));
return x;
}
---method2A---
__inline__ unsigned long long int hwtime(void)
{
unsigned long long int x;
__asm__("rdtsc\n\t"
"mov %%edx, %%ecx\n\t"
:"=A" (x));
return x;
}
---assembler code of method1----
.globl rdtsc
.type rdtsc,@function
rdtsc:
pushl %ebp
movl %esp,%ebp
subl $20,%esp
pushl %ebx
---assembler code of method2A----
.globl hwtime
.type hwtime,@function
hwtime:
pushl %ebp
movl %esp,%ebp
subl $20,%esp
pushl %ebx
hofrat
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