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| author | Owen Anderson <resistor@mac.com> | 2012-05-07 20:51:25 +0000 |
|---|---|---|
| committer | Owen Anderson <resistor@mac.com> | 2012-05-07 20:51:25 +0000 |
| commit | ab63d84252c6fb85416ddabb040573fe598b39db (patch) | |
| tree | 1315b6f5ab271e9d7c73a589a76f80c9fabe1562 /llvm/lib/CodeGen | |
| parent | f4f80e1f39a2da2de2623eb9d176b77bdbcac009 (diff) | |
| download | llvm-ab63d84252c6fb85416ddabb040573fe598b39db.zip llvm-ab63d84252c6fb85416ddabb040573fe598b39db.tar.gz llvm-ab63d84252c6fb85416ddabb040573fe598b39db.tar.bz2 | |
Teach DAG combine to fold x-x to 0.0 when unsafe FP math is enabled.
llvm-svn: 156324
Diffstat (limited to 'llvm/lib/CodeGen')
| -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 c2b7f6c..753ba93 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -5670,9 +5670,13 @@ SDValue DAGCombiner::visitFSUB(SDNode *N) { GetNegatedExpression(N1, DAG, LegalOperations)); // If 'unsafe math' is enabled, fold + // (fsub x, x) -> 0.0 & // (fsub x, (fadd x, y)) -> (fneg y) & // (fsub x, (fadd y, x)) -> (fneg y) if (DAG.getTarget().Options.UnsafeFPMath) { + if (N0 == N1) + return DAG.getConstantFP(0.0f, VT); + if (N1.getOpcode() == ISD::FADD) { SDValue N10 = N1->getOperand(0); SDValue N11 = N1->getOperand(1); |