[PATCH] D36404: Disable jump threading into loop headers

Balaram Makam via Phabricator via llvm-commits llvm-commits at lists.llvm.org
Thu Sep 14 14:09:11 PDT 2017


bmakam added a comment.

> We need to figure out if LSR is doing something reasonable. It's possible that LSR is actually causing the regression, and old jumpthreading is just serving to obscure the loop structure (thus preventing LSR from doing whatever bad thing it's doing).

It seems like LSR is doing the right thing, the difference in codegen is due to loopsimplify that is required in LSR. If LoopSimplify is required in CGP, then running LateJumpThreading right before CGP (https://reviews.llvm.org/D37866) completely recovers the regression.


Repository:
  rL LLVM

https://reviews.llvm.org/D36404





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