> > 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;
> }
>
forgot to put in objdump output in the last post
08048430 <rdtsc>:
8048430: 55 push %ebp
8048431: 89 e5 mov %esp,%ebp
8048433: 83 ec 14 sub $0x14,%esp
8048436: 53 push %ebx
8048437: 0f 31 rdtsc
8048439: 89 c1 mov %eax,%ecx
804843b: 89 d3 mov %edx,%ebx
804843d: 89 4d f8 mov %ecx,0xfffffff8(%ebp)
8048440: 89 5d fc mov %ebx,0xfffffffc(%ebp)
8048443: 8b 4d f8 mov 0xfffffff8(%ebp),%ecx
8048446: 8b 5d fc mov 0xfffffffc(%ebp),%ebx
8048449: 89 c8 mov %ecx,%eax
804844b: 89 da mov %ebx,%edx
804844d: eb 01 jmp 8048450 <rdtsc+0x20>
804844f: 90 nop
8048450: 8b 5d e8 mov 0xffffffe8(%ebp),%ebx
8048453: 89 ec mov %ebp,%esp
8048455: 5d pop %ebp
8048456: c3 ret
8048457: 89 f6 mov %esi,%esi
8048459: 8d bc 27 00 00 00 00 lea 0x0(%edi,1),%edi
08048460 <hwtime>:
8048460: 55 push %ebp
8048461: 89 e5 mov %esp,%ebp
8048463: 83 ec 14 sub $0x14,%esp
8048466: 53 push %ebx
8048467: 0f 31 rdtsc
8048469: 89 d1 mov %edx,%ecx
804846b: 89 c1 mov %eax,%ecx
804846d: 89 d3 mov %edx,%ebx
804846f: 89 4d f8 mov %ecx,0xfffffff8(%ebp)
8048472: 89 5d fc mov %ebx,0xfffffffc(%ebp)
8048475: 8b 4d f8 mov 0xfffffff8(%ebp),%ecx
8048478: 8b 5d fc mov 0xfffffffc(%ebp),%ebx
804847b: 89 c8 mov %ecx,%eax
804847d: 89 da mov %ebx,%edx
804847f: eb 00 jmp 8048481 <hwtime+0x21>
8048481: 8b 5d e8 mov 0xffffffe8(%ebp),%ebx
8048484: 89 ec mov %ebp,%esp
8048486: 5d pop %ebp
8048487: c3 ret
8048488: 90 nop
8048489: 8d b4 26 00 00 00 00 lea 0x0(%esi,1),%esi
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