[PATCH] D59218: [LSR] Fix signed overflow in GenerateCrossUseConstantOffsets.

[Eli Friedman via Phabricator via llvm-commits]

efriedma added inline comments.


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Comment at: llvm/lib/Transforms/Scalar/LoopStrengthReduce.cpp:4142
+          // First + Last = 2 * (First + Last) + (First ^ Last).
+          Imms.lower_bound((First & Last) + (First ^ Last) / 2)};
       for (size_t i = 0, e = array_lengthof(OtherImms); i != e; ++i) {
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Are you sure this formula is right? Alive says it doesn't work correctly for signed values: https://rise4fun.com/Alive/E3V.


Repository:
  rG LLVM Github Monorepo

CHANGES SINCE LAST ACTION
  https://reviews.llvm.org/D59218/new/

https://reviews.llvm.org/D59218