diff options
Diffstat (limited to 'lib/Transforms/Scalar/InstructionCombining.cpp')
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 28 |
1 files changed, 25 insertions, 3 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 5fe95540de..fa615cfc51 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -3553,9 +3553,30 @@ Instruction *InstCombiner::visitCastInst(CastInst &CI) { return new ShiftInst(Instruction::Shl, Op0c, Op1); } break; + case Instruction::SetNE: + case Instruction::SetEQ: + // We if we are just checking for a seteq of a single bit and casting it + // to an integer. If so, shift the bit to the appropriate place then + // cast to integer to avoid the comparison. + if (ConstantInt *Op1C = dyn_cast<ConstantInt>(Op1)) { + // cast (X != 0) to int, cast (X == 1) to int -> X iff X has only the + // low bit set. + bool isSetNE = SrcI->getOpcode() == Instruction::SetNE; + if ((isSetNE && Op1C->getRawValue() == 0) || + (!isSetNE && Op1C->getRawValue() == 1)) { + Constant *Not1 = + ConstantExpr::getNot(ConstantInt::get(Op0->getType(), 1)); + if (MaskedValueIsZero(Op0, cast<ConstantIntegral>(Not1))) { + if (CI.getType() == Op0->getType()) + return ReplaceInstUsesWith(CI, Op0); + else + return new CastInst(Op0, CI.getType()); + } + } + } + break; } } - return 0; } @@ -4603,8 +4624,9 @@ Instruction *InstCombiner::visitAllocationInst(AllocationInst &AI) { // Now that I is pointing to the first non-allocation-inst in the block, // insert our getelementptr instruction... // - std::vector<Value*> Idx(2, Constant::getNullValue(Type::IntTy)); - Value *V = new GetElementPtrInst(New, Idx, New->getName()+".sub", It); + Value *NullIdx = Constant::getNullValue(Type::IntTy); + Value *V = new GetElementPtrInst(New, NullIdx, NullIdx, + New->getName()+".sub", It); // Now make everything use the getelementptr instead of the original // allocation. |