diff options
| author | Chris Lattner <sabre@nondot.org> | 2007-05-19 00:43:44 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2007-05-19 00:43:44 +0000 |
| commit | 2ad913b3428b634f46d6606a150c5d180b528197 (patch) | |
| tree | 80981541884fb490f3b6b558e12f9b1b8c291952 /lib/CodeGen/SelectionDAG/TargetLowering.cpp | |
| parent | 35fbae2b6d47932126d1f9bfeaa76ce1a9dbd292 (diff) | |
Disable the (A == (B-A)) -> 2*A == B xform when the sub has multiple uses (in
this case, the xform introduces an extra operation). This compiles
PowerPC/compare-duplicate.ll into:
_test:
subf r2, r3, r4
cmplw cr0, r2, r3
bne cr0, LBB1_2 ;F
instead of:
_test:
slwi r2, r3, 1
subf r3, r3, r4
cmplw cr0, r4, r2
bne cr0, LBB1_2 ;F
This is target independent of course.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@37246 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/CodeGen/SelectionDAG/TargetLowering.cpp')
| -rw-r--r-- | lib/CodeGen/SelectionDAG/TargetLowering.cpp | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/lib/CodeGen/SelectionDAG/TargetLowering.cpp b/lib/CodeGen/SelectionDAG/TargetLowering.cpp index a2cd12801d..e5883f60c5 100644 --- a/lib/CodeGen/SelectionDAG/TargetLowering.cpp +++ b/lib/CodeGen/SelectionDAG/TargetLowering.cpp @@ -1785,7 +1785,7 @@ TargetLowering::SimplifySetCC(MVT::ValueType VT, SDOperand N0, SDOperand N1, if (DAG.isCommutativeBinOp(N0.getOpcode())) return DAG.getSetCC(VT, N0.getOperand(0), DAG.getConstant(0, N0.getValueType()), Cond); - else { + else if (N0.Val->hasOneUse()) { assert(N0.getOpcode() == ISD::SUB && "Unexpected operation!"); // (Z-X) == X --> Z == X<<1 SDOperand SH = DAG.getNode(ISD::SHL, N1.getValueType(), |