[PATCH] D62272: [LoopUtils][SLPVectorizer] clean up management of fast-math-flags

[Sanjay Patel via Phabricator via llvm-commits]

spatel created this revision.
spatel added reviewers: ABataev, hfinkel, RKSimon.
Herald added subscribers: hiraditya, mcrosier.
Herald added a project: LLVM.

Instead of passing around fast-math-flags as a parameter, we can set those using an IRBuilder guard object. This is no-functional-change-intended, but hopefully someone more familiar with this code can try to confirm that.

The motivation is to eventually fix the vectorizers to use and set the correct fast-math-flags for reductions. Examples of that not behaving as expected are:
https://bugs.llvm.org/show_bug.cgi?id=23116 (should be able to reduce with less than 'fast')
https://bugs.llvm.org/show_bug.cgi?id=35538 (possible miscompile for -0.0)
D61802 <https://reviews.llvm.org/D61802> (should be able to reduce with IR-level FMF)


https://reviews.llvm.org/D62272

Files:
  llvm/include/llvm/Transforms/Utils/LoopUtils.h
  llvm/lib/CodeGen/ExpandReductions.cpp
  llvm/lib/Transforms/Utils/LoopUtils.cpp
  llvm/lib/Transforms/Vectorize/SLPVectorizer.cpp

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