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| author | David Bolvansky <david.bolvansky@gmail.com> | 2018-09-28 18:40:30 +0000 |
|---|---|---|
| committer | David Bolvansky <david.bolvansky@gmail.com> | 2018-09-28 18:40:30 +0000 |
| commit | 8e90bad63d3a448ed680616b393a47d25280fd87 (patch) | |
| tree | 4209890f412dddc242fd4eba5c1e80fa5638f474 /llvm/lib/CodeGen/SelectionDAG | |
| parent | 5ce9dc614d658167ece295ce010e88e949f050fc (diff) | |
| download | bcm5719-llvm-8e90bad63d3a448ed680616b393a47d25280fd87.tar.gz bcm5719-llvm-8e90bad63d3a448ed680616b393a47d25280fd87.zip | |
[DAGCombiner] [NFC] Improve X div/rem 1 fold
Reviewers: spatel
Reviewed By: spatel
Subscribers: llvm-commits
Differential Revision: https://reviews.llvm.org/D52661
llvm-svn: 343349
Diffstat (limited to 'llvm/lib/CodeGen/SelectionDAG')
| -rw-r--r-- | llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp | 13 |
1 files changed, 5 insertions, 8 deletions
diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp index 3f71f154779..09d5eb56e82 100644 --- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp +++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp @@ -3103,6 +3103,7 @@ static SDValue simplifyDivRem(SDNode *N, SelectionDAG &DAG) { unsigned Opc = N->getOpcode(); bool IsDiv = (ISD::SDIV == Opc) || (ISD::UDIV == Opc); + ConstantSDNode *N1C = isConstOrConstSplat(N1); // X / undef -> undef // X % undef -> undef @@ -3125,8 +3126,10 @@ static SDValue simplifyDivRem(SDNode *N, SelectionDAG &DAG) { if (N0 == N1) return DAG.getConstant(IsDiv ? 1 : 0, DL, VT); - // TODO: X / 1 -> X - // TODO: X % 1 -> 0 + // X / 1 -> X + // X % 1 -> 0 + if (N1C && N1C->isOne()) + return IsDiv ? N0 : DAG.getConstant(0, DL, VT); // If this is a boolean op (single-bit element type), we can't have // division-by-zero or remainder-by-zero, so assume the divisor is 1. // Similarly, if we're zero-extending a boolean divisor, then assume it's a 1. @@ -3152,9 +3155,6 @@ SDValue DAGCombiner::visitSDIV(SDNode *N) { ConstantSDNode *N1C = isConstOrConstSplat(N1); if (N0C && N1C && !N0C->isOpaque() && !N1C->isOpaque()) return DAG.FoldConstantArithmetic(ISD::SDIV, DL, VT, N0C, N1C); - // fold (sdiv X, 1) -> X - if (N1C && N1C->isOne()) - return N0; // fold (sdiv X, -1) -> 0-X if (N1C && N1C->isAllOnesValue()) return DAG.getNode(ISD::SUB, DL, VT, DAG.getConstant(0, DL, VT), N0); @@ -3290,9 +3290,6 @@ SDValue DAGCombiner::visitUDIV(SDNode *N) { if (SDValue Folded = DAG.FoldConstantArithmetic(ISD::UDIV, DL, VT, N0C, N1C)) return Folded; - // fold (udiv X, 1) -> X - if (N1C && N1C->isOne()) - return N0; // fold (udiv X, -1) -> select(X == -1, 1, 0) if (N1C && N1C->getAPIntValue().isAllOnesValue()) return DAG.getSelect(DL, VT, DAG.getSetCC(DL, CCVT, N0, N1, ISD::SETEQ), |
