[LLVMdev] [PATCH] Do not generate nopl instruction on CPUs that don't support it.

[Rafael Espíndola]

On 7 November 2013 18:31, Mikulas Patocka
<mikulas at artax.karlin.mff.cuni.cz> wrote:
>
>
> On Tue, 5 Nov 2013, Rafael Espíndola wrote:
>
>> Please include a testcase with the patch.
>
> I'm sending testcase here. Compile it with
> "clang -O2 -march=k6-2 -c loop.c"

The test should be in the patch itself. It can use llvm-mc to check
how the nops are expanded. The trick used by
MachO/x86_32-optimal_nop.s is to use '.align X, 0x90'.

>> gas uses " nopl   0x0(%eax)" for k6_2. Are you sure it is a gas bug?
>
> Yes, it is gas bug. I should report it to binutils maintainers.

Thanks!

Cheers,
Rafael