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| author | Simon Pilgrim <llvm-dev@redking.me.uk> | 2019-01-13 22:08:26 +0000 |
|---|---|---|
| committer | Simon Pilgrim <llvm-dev@redking.me.uk> | 2019-01-13 22:08:26 +0000 |
| commit | 56ba1db933ea7fc3e993c31fce176bbf8578a64c (patch) | |
| tree | 5c04eaa89447b62795988a159e2d33bac5c47058 /llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | |
| parent | 888fa8680cdd09f0b196c853b4982ddb3a5682c9 (diff) | |
| download | bcm5719-llvm-56ba1db933ea7fc3e993c31fce176bbf8578a64c.tar.gz bcm5719-llvm-56ba1db933ea7fc3e993c31fce176bbf8578a64c.zip | |
[DAGCombiner] If add_sat(x,y) can't overflow -> add(x,y)
NOTE: We need more powerful signed overflow detection in computeOverflowKind
llvm-svn: 351026
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp')
| -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 b3785359f81..6d828d3972d 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -2206,6 +2206,10 @@ SDValue DAGCombiner::visitADDSAT(SDNode *N) { if (isNullConstant(N1)) return N0; + // If it cannot overflow, transform into an add. + if (DAG.computeOverflowKind(N0, N1) == SelectionDAG::OFK_Never) + return DAG.getNode(ISD::ADD, DL, VT, N0, N1); + return SDValue(); } |
