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| author | Chris Lattner <sabre@nondot.org> | 2004-04-26 14:01:59 +0000 |
|---|---|---|
| committer | Chris Lattner <sabre@nondot.org> | 2004-04-26 14:01:59 +0000 |
| commit | e20c334e6546a54e3e53fe54acac47e199eb0cd8 (patch) | |
| tree | b93490e6ea4b10d541c5bb0a6ce49bceaf8c5b2b /llvm/lib/Transforms | |
| parent | e24003a26150be8f109f6e9ebbfd1955fb2edafd (diff) | |
| download | bcm5719-llvm-e20c334e6546a54e3e53fe54acac47e199eb0cd8.tar.gz bcm5719-llvm-e20c334e6546a54e3e53fe54acac47e199eb0cd8.zip | |
Instcombine X/-1 --> 0-X
llvm-svn: 13172
Diffstat (limited to 'llvm/lib/Transforms')
| -rw-r--r-- | llvm/lib/Transforms/Scalar/InstructionCombining.cpp | 6 |
1 files changed, 5 insertions, 1 deletions
diff --git a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp index 52b861da156..e2607c0c1a8 100644 --- a/llvm/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/llvm/lib/Transforms/Scalar/InstructionCombining.cpp @@ -849,11 +849,15 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { } Instruction *InstCombiner::visitDiv(BinaryOperator &I) { - // div X, 1 == X if (ConstantInt *RHS = dyn_cast<ConstantInt>(I.getOperand(1))) { + // div X, 1 == X if (RHS->equalsInt(1)) return ReplaceInstUsesWith(I, I.getOperand(0)); + // div X, -1 == -X + if (RHS->isAllOnesValue()) + return BinaryOperator::createNeg(I.getOperand(0)); + // Check to see if this is an unsigned division with an exact power of 2, // if so, convert to a right shift. if (ConstantUInt *C = dyn_cast<ConstantUInt>(RHS)) |
