[llvm-commits] PATCH: Fix PR8528

[Chris Lattner]

On Nov 3, 2010, at 3:54 PM, İsmail Dönmez wrote:

> Hi;
> 
> Original patch by pdox on #llvm . Asm parser was not handling fist and fistp instructions correctly. Please apply.

Hi Ismail,

This is great detective work!  Just to verify my understanding, the issue is that GAS is treating:
   fistp (%rax)
as an alias for:
  fistps (%rax)
and we're compiling it to:
  fistpl (%rax)

If this is the case, I think that the MC assembler should be changed to *reject* fisp, not to emulate GAS's behavior.  With a simple mem operand, there is nothing to say that "4 bytes" is the right size of the store, it should be diagnosed as an ambiguous instruction.  Reporting it as a bug in the code is much more friendly than miscompiling it of course. :)

What do you think?

-Chris
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