[PATCH] D111319: [GlobalISel] Combine for eliminating redundant operand negations

[Jay Foad via Phabricator via llvm-commits]

foad added inline comments.


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Comment at: llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h:620-622
+  /// Transform (fadd x, fneg(y)) -> (fsub x, y)
+  ///           (fadd fneg(x), y) -> (fsub y, x)
+  ///           (fsub x, fneg(y)) -> (fadd x, y)
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Are these definitely safe. even with signed zeros? Does SelectionDAG do the same?


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Comment at: llvm/include/llvm/CodeGen/GlobalISel/CombinerHelper.h:625
+  ///           (fdiv fneg(x), fneg(y)) -> (fdiv x, y)
+  ///           (fmad fneg(x), fneg(y), z) -> (fma x, y, z)
+  ///           (fma fneg(x), fneg(y), z) -> (fma x, y, z)
----------------
Typo "fma".


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D111319/new/

https://reviews.llvm.org/D111319