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

Eli Bendersky eliben at google.com
Wed Dec 5 19:36:23 PST 2012

> 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


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