[PATCH] D46505: [DAGcombine] Teach the combiner about -a = ~a + 1

[Simon Pilgrim via Phabricator via llvm-commits]

RKSimon added inline comments.


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2199
+static SDValue flipBooleanConstant(const SDLoc &DL, EVT VT, SelectionDAG &DAG,
+                                   const TargetLowering &TLI) {
+  switch(TLI.getBooleanContents(VT)) {
----------------
Move this inside flipBoolean() ?


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Comment at: lib/CodeGen/SelectionDAG/DAGCombiner.cpp:2263
 
+  // fold (uaddo (xor a, -1), 1) -> (usub 0, a) and flip carry
+  if (N0.getOpcode() == ISD::XOR &&
----------------
full stop: // fold (uaddo (xor a, -1), 1) -> (usub 0, a) and flip carry.


Repository:
  rL LLVM

https://reviews.llvm.org/D46505