[PATCH] D133111: [LICM] Allow load-only scalar promotion in the presence of unwinding

[Nikita Popov via Phabricator via llvm-commits]

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Currently, we bail out of scalar promotion if the loop may unwind and the memory may be visible on unwind. This is because we can't insert stores of the promoted value on unwind edges.

However, nowadays scalar promotion also has support for only promoting loads, while leaving stores in place. This kind of promotion is safe even in the presence of unwinding.

(The next and more interesting step is that we can also allow potentially aliasing reads of the pointer when doing load-only promotion.)


https://reviews.llvm.org/D133111

Files:
  llvm/lib/Transforms/Scalar/LICM.cpp
  llvm/test/Transforms/LICM/guards.ll
  llvm/test/Transforms/LICM/scalar-promote-unwind.ll

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