[llvm-commits] PATCH: Fix PR8528

[İsmail Dönmez]

Hi Chris;

On Sat, Nov 6, 2010 at 8:18 AM, Chris Lattner <clattner at apple.com> wrote:

>
> 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)
>
>
You are correct.


> 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?
>

I am no assembly expert but this seems to be another vague gas behaviour. I
guess rejecting this is the correct behaviour indeed.

Regards,
ismail
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