[llvm] r213892 - [X86] Optimize stackmap shadows on X86.
joerg at britannica.bec.de
Fri Jul 25 01:34:59 PDT 2014
On Thu, Jul 24, 2014 at 04:47:36PM -0700, Lang Hames wrote:
> Oh - I remember now: Branch relaxation only runs during object emission. If
> we waited until relaxation to fix the shadows, then the shadow optimization
> wouldn't run when you're outputting assembly files. The idea that you could
> get different output by passing -S vs -c seemed too non-obvious, so I came
> up with the current solution.
One approach for that would be to introduce a pseudo op for this
purpose. Given that any branch instruction on x86 is likely to depend on
branch relaxation to be computed correctly, this might be the smallest
evil. Put it under an option to just use the largest size when dealing
with external assemblers?
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