diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 64 |
1 files changed, 63 insertions, 1 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index 9f6e712e25..bb235ca868 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -2149,12 +2149,53 @@ Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS, Instruction::BinaryOps Cond, Instruction &I) { assert(dyn_castGetElementPtr(GEPLHS) && "LHS is not a getelementptr!"); - + + if (CastInst *CI = dyn_cast<CastInst>(RHS)) + if (isa<PointerType>(CI->getOperand(0)->getType())) + RHS = CI->getOperand(0); + Value *PtrBase = GEPLHS->getOperand(0); if (PtrBase == RHS) { // As an optimization, we don't actually have to compute the actual value of // OFFSET if this is a seteq or setne comparison, just return whether each // index is zero or not. + if (Cond == Instruction::SetEQ || Cond == Instruction::SetNE) { + Instruction *InVal = 0; + for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) { + bool EmitIt = true; + if (Constant *C = dyn_cast<Constant>(GEPLHS->getOperand(i))) { + if (isa<UndefValue>(C)) // undef index -> undef. + return ReplaceInstUsesWith(I, UndefValue::get(I.getType())); + if (C->isNullValue()) + EmitIt = false; + else if (isa<ConstantInt>(C)) + return ReplaceInstUsesWith(I, // No comparison is needed here. + ConstantBool::get(Cond == Instruction::SetNE)); + } + + if (EmitIt) { + Instruction *Comp = + new SetCondInst(Cond, GEPLHS->getOperand(i), + Constant::getNullValue(GEPLHS->getOperand(i)->getType())); + if (InVal == 0) + InVal = Comp; + else { + InVal = InsertNewInstBefore(InVal, I); + InsertNewInstBefore(Comp, I); + if (Cond == Instruction::SetNE) // True if any are unequal + InVal = BinaryOperator::createOr(InVal, Comp); + else // True if all are equal + InVal = BinaryOperator::createAnd(InVal, Comp); + } + } + } + + if (InVal) + return InVal; + else + ReplaceInstUsesWith(I, // No comparison is needed here, all indexes = 0 + ConstantBool::get(Cond == Instruction::SetEQ)); + } // Only lower this if the setcc is the only user of the GEP or if we expect // the result to fold to a constant! @@ -2168,6 +2209,27 @@ Instruction *InstCombiner::FoldGEPSetCC(User *GEPLHS, Value *RHS, if (PtrBase != GEPRHS->getOperand(0)) return 0; + // If one of the GEPs has all zero indices, recurse. + bool AllZeros = true; + for (unsigned i = 1, e = GEPLHS->getNumOperands(); i != e; ++i) + if (!isa<Constant>(GEPLHS->getOperand(i)) || + !cast<Constant>(GEPLHS->getOperand(i))->isNullValue()) { + AllZeros = false; + break; + } + if (AllZeros) + return FoldGEPSetCC(GEPRHS, GEPLHS->getOperand(0), + SetCondInst::getSwappedCondition(Cond), I); + AllZeros = true; + for (unsigned i = 1, e = GEPRHS->getNumOperands(); i != e; ++i) + if (!isa<Constant>(GEPRHS->getOperand(i)) || + !cast<Constant>(GEPRHS->getOperand(i))->isNullValue()) { + AllZeros = false; + break; + } + if (AllZeros) + return FoldGEPSetCC(GEPLHS, GEPRHS->getOperand(0), Cond, I); + // Only lower this if the setcc is the only user of the GEP or if we expect // the result to fold to a constant! if ((isa<ConstantExpr>(GEPLHS) || GEPLHS->hasOneUse()) && |