[PATCH] D119654: [SDAG] enable binop identity constant folds for add/sub

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


================
Comment at: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:3336
+  if (N1->getOpcode() == ISD::FREEZE && N0.hasOneUse())
+    N1 = N1->getOperand(0);
+
----------------
Is there anyway we can reduce the scope of this initially, its likely that losing freeze like this might have other effects - if we're just after the (sub x, x) -> 0 fold, maybe create a peekThroughFreeze helper:

if (peekThroughFreeze(N0) == peekThroughFreeze(N1))
    return tryFoldToZero(DL, TLI, VT, DAG, LegalOperations);


Repository:
  rG LLVM Github Monorepo

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  https://reviews.llvm.org/D119654/new/

https://reviews.llvm.org/D119654