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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 | 854077d3a5a42c3286f22fd5f72ee98797ed3d71 (patch) | |
| tree | 0e847ed3b484e46b6664426bc97516cf03ba1a40 /lib | |
| parent | 7a025c8b4dedee6856d9f118386ef0296eddece0 (diff) | |
| download | external_llvm-854077d3a5a42c3286f22fd5f72ee98797ed3d71.zip external_llvm-854077d3a5a42c3286f22fd5f72ee98797ed3d71.tar.gz external_llvm-854077d3a5a42c3286f22fd5f72ee98797ed3d71.tar.bz2 | |
add a trivial fold
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@23764 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 4 |
1 files changed, 4 insertions, 0 deletions
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 5b1d103..69478e3 100644 --- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/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(), |