[LLVMdev] [PATCH] x86/asm: avoid mnemonics without type suffix

Tim Northover t.p.northover at gmail.com
Sun Jul 14 12:30:00 PDT 2013

> And that is why I think you should just consider "bt $x,y" to be
> trivially the same thing and not at all ambiguous. Because there is
> ABSOLUTELY ZERO ambiguity when people write
>    bt $63, mem
> Zero. Nada. None. The semantics are *exactly* the same for btl and btq
> in this case, so why would you want the user to specify one or the
> other?

I don't think you've actually tested that, have you? (x86-64)

int main() {
  long val = 0xffffffff;
  char res;

  asm("btl $63, %1\n\tsetc %0" : "=r"(res) : "m"(val));
  printf("%d\n", res);

  asm("btq $63, %1\n\tsetc %0" : "=r"(res) : "m"(val));
  printf("%d\n", res);


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