[LLVMdev] questions about the mc-relax-all flag

Eli Bendersky
Thu, 06 Dec 2012 03:36:23 -0000

>
> It's more of a debugging tool and stress test of the x86 branch
relaxation than anything. It's definitely not intended to be an
optimization.
>
> "relax-all" says to not just relax instructions that are strictly
required, but to relax every instruction that can be relaxed, whether it's
needed or not.
>
> I'm more inclined to remove the command line options entirely,
especially the clang one.

Hi Jim,

I agree that relax-all will cause all instructions to be relaxed, even
those where the fixup doesn't require it. However, I would like to
challenge the statement that this isn't an optimization. In the link I
posted earlier, Chris and Daniel oppose to removing relax-all
precisely because it makes the assembler run faster.

Had it only been a stress test, removing it would be very reasonable
since at this point I assume the MC assembler is considered to be
stable.

Eli