[PATCH] D87392: [JumpThreading] Fix an incorrect Modified status

[David Stenberg via Phabricator via llvm-commits]

dstenb created this revision.
dstenb added reviewers: efriedma, kazu, wmi.
Herald added subscribers: llvm-commits, hiraditya.
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This fixes PR47297.

When ProcessBlock() was able to constant fold the terminator's
condition, but not do any more transformations, the function would
return false, which would lead to the JumpThreading pass returning an
incorrect modified status. I assume that we in such cases don't want to
return true from ProcessBlock(), which would trigger another iteration
of the function. Instead, to solve this, this patch introduces a
{Unmodified, Modified, Threaded} tri-state in order to be able to keep
track of the modified status, but still bail out from the ProcessBlock()
loop.

      

This was caught using the check introduced by D80916 <https://reviews.llvm.org/D80916>.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87392

Files:
  llvm/include/llvm/Transforms/Scalar/JumpThreading.h
  llvm/lib/Transforms/Scalar/JumpThreading.cpp
  llvm/test/Transforms/JumpThreading/constant-fold-status.ll

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