[PATCH] D62257: [DAGCombiner][X86][AArch64] (x - C) + y -> (x + y) - C fold

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon accepted this revision.
RKSimon added a comment.
This revision is now accepted and ready to land.

LGTM with one minor



================
Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2457
+  // Hoist one-use subtraction by constant:  (x - C) + y  ->  (x + y) - C
+  if (N0.hasOneUse() && N0.getOpcode() == ISD::SUB &&
+      isConstantOrConstantVector(N0.getOperand(1))) {
----------------
Add a comment explaining that this is necessary because SUB(X,C) -> ADD(X,-C) doesn't work for vectors.


Repository:
  rL LLVM

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  https://reviews.llvm.org/D62257/new/

https://reviews.llvm.org/D62257