diff options
| author | Dan Gohman <gohman@apple.com> | 2009-06-04 17:12:12 +0000 |
|---|---|---|
| committer | Dan Gohman <gohman@apple.com> | 2009-06-04 17:12:12 +0000 |
| commit | 77b81fe487de709d41dfcc97bbb2941ae1bb80af (patch) | |
| tree | 9730d59d8f6ae8de964c38fd56884553c77db692 /lib/Transforms | |
| parent | 68f32cbb1f9e62d5e6047b048c0d7d217b8717e1 (diff) | |
Don't do the X * 0.0 -> 0.0 transformation in instcombine, because
instcombine doesn't know when it's safe. To partially compensate
for this, introduce new code to do this transformation in
dagcombine, which can use UnsafeFPMath.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@72872 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib/Transforms')
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 10 |
1 files changed, 5 insertions, 5 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index e6f854f1a5..8bb16f3de1 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2585,7 +2585,9 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { bool Changed = SimplifyCommutative(I); Value *Op0 = I.getOperand(0); - if (isa<UndefValue>(I.getOperand(1))) // undef * X -> 0 + // TODO: If Op1 is undef and Op0 is finite, return zero. + if (!I.getType()->isFPOrFPVector() && + isa<UndefValue>(I.getOperand(1))) // undef * X -> 0 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType())); // Simplify mul instructions with a constant RHS... @@ -2612,16 +2614,14 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) { ConstantInt::get(Op0->getType(), Val.logBase2())); } } else if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1)) { - if (Op1F->isNullValue()) - return ReplaceInstUsesWith(I, Op1); + // TODO: If Op1 is zero and Op0 is finite, return zero. // "In IEEE floating point, x*1 is not equivalent to x for nans. However, // ANSI says we can drop signals, so we can do this anyway." (from GCC) if (Op1F->isExactlyValue(1.0)) return ReplaceInstUsesWith(I, Op0); // Eliminate 'mul double %X, 1.0' } else if (isa<VectorType>(Op1->getType())) { - if (isa<ConstantAggregateZero>(Op1)) - return ReplaceInstUsesWith(I, Op1); + // TODO: If Op1 is all zeros and Op0 is all finite, return all zeros. if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1)) { if (Op1V->isAllOnesValue()) // X * -1 == 0 - X |