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| author | Chris Lattner <sabre@nondot.org> | 2005-10-17 01:07:11 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2005-10-17 01:07:11 +0000 |
| commit | eeb2bda2fa932045e182879c42baf8954c25c72b (patch) | |
| tree | 4a9a8d4296a127859df629d703ed3c0873c720eb | |
| parent | 17acad625cea650b0c8bbdb8f054d5bf1108cd10 (diff) | |
| download | bcm5719-llvm-eeb2bda2fa932045e182879c42baf8954c25c72b.tar.gz bcm5719-llvm-eeb2bda2fa932045e182879c42baf8954c25c72b.zip | |
add a trivial fold
llvm-svn: 23764
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 5b1d10335cf..69478e3b846 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -532,6 +532,10 @@ SDOperand DAGCombiner::visitSUB(SDNode *N) { ConstantSDNode *N0C = dyn_cast<ConstantSDNode>(N0.Val); ConstantSDNode *N1C = dyn_cast<ConstantSDNode>(N1.Val); + // fold (sub x, x) -> 0 + if (N0 == N1) + return DAG.getConstant(0, N->getValueType(0)); + // fold (sub c1, c2) -> c1-c2 if (N0C && N1C) return DAG.getConstant(N0C->getValue() - N1C->getValue(), |
