[PATCH] D94542: [X86] Default to -x86-pad-for-align=false to drop assembler difference with or w/o -g

Thu Jan 14 21:58:25 PST 2021

MaskRay added a comment.

https://bugs.llvm.org/show_bug.cgi?id=42138 was a BranchFolding bug which was probably found by an automating framework. @condy reopened it in #c13 because the symptom looks similar.
I closed 42138 in favor of the X86AsmBackend dedicated https://bugs.llvm.org//show_bug.cgi?id=48742 .

I think it is possible to repair the optimization. But as https://reviews.llvm.org/D75203#2496082 and the previous few comments said, doing it without causing -g vs non-g difference is difficult.
When the optimization gets improved, I have no problem re-enabling -x86-pad-for-align=true. The value of -mbranches-within-32B-boundaries also dilutes over time (it mitigates issues for some Skylake architectures).
(Surprising to me, this feature has been available for one year but I don't see a lot of adoption).

Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D94542/new/

https://reviews.llvm.org/D94542