diff options
| -rw-r--r-- | lib/Transforms/Scalar/InstructionCombining.cpp | 86 |
1 files changed, 47 insertions, 39 deletions
diff --git a/lib/Transforms/Scalar/InstructionCombining.cpp b/lib/Transforms/Scalar/InstructionCombining.cpp index ce66a028d6..9e75be7b95 100644 --- a/lib/Transforms/Scalar/InstructionCombining.cpp +++ b/lib/Transforms/Scalar/InstructionCombining.cpp @@ -261,6 +261,17 @@ static const Type *getPromotedType(const Type *Ty) { } } +/// isCast - If the specified operand is a CastInst or a constant expr cast, +/// return the operand value, otherwise return null. +static Value *isCast(Value *V) { + if (CastInst *I = dyn_cast<CastInst>(V)) + return I->getOperand(0); + else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(V)) + if (CE->getOpcode() == Instruction::Cast) + return CE->getOperand(0); + return 0; +} + // SimplifyCommutative - This performs a few simplifications for commutative // operators: // @@ -4682,45 +4693,42 @@ Instruction *InstCombiner::visitGetElementPtrInst(GetElementPtrInst &GEP) { // Replace all uses of the GEP with the new constexpr... return ReplaceInstUsesWith(GEP, CE); } - } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(PtrOp)) { - if (CE->getOpcode() == Instruction::Cast) { - if (HasZeroPointerIndex) { - // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ... - // into : GEP [10 x ubyte]* X, long 0, ... - // - // This occurs when the program declares an array extern like "int X[];" - // - Constant *X = CE->getOperand(0); - const PointerType *CPTy = cast<PointerType>(CE->getType()); - if (const PointerType *XTy = dyn_cast<PointerType>(X->getType())) - if (const ArrayType *XATy = - dyn_cast<ArrayType>(XTy->getElementType())) - if (const ArrayType *CATy = - dyn_cast<ArrayType>(CPTy->getElementType())) - if (CATy->getElementType() == XATy->getElementType()) { - // At this point, we know that the cast source type is a pointer - // to an array of the same type as the destination pointer - // array. Because the array type is never stepped over (there - // is a leading zero) we can fold the cast into this GEP. - GEP.setOperand(0, X); - return &GEP; - } - } else if (GEP.getNumOperands() == 2 && - isa<PointerType>(CE->getOperand(0)->getType())) { - // Transform things like: - // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V - // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast - Constant *X = CE->getOperand(0); - const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType(); - const Type *ResElTy =cast<PointerType>(CE->getType())->getElementType(); - if (isa<ArrayType>(SrcElTy) && - TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) == - TD->getTypeSize(ResElTy)) { - Value *V = InsertNewInstBefore( - new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy), - GEP.getOperand(1), GEP.getName()), GEP); - return new CastInst(V, GEP.getType()); - } + } else if (Value *X = isCast(PtrOp)) { // Is the operand a cast? + if (!isa<PointerType>(X->getType())) { + // Not interesting. Source pointer must be a cast from pointer. + } else if (HasZeroPointerIndex) { + // transform: GEP (cast [10 x ubyte]* X to [0 x ubyte]*), long 0, ... + // into : GEP [10 x ubyte]* X, long 0, ... + // + // This occurs when the program declares an array extern like "int X[];" + // + const PointerType *CPTy = cast<PointerType>(PtrOp->getType()); + const PointerType *XTy = cast<PointerType>(X->getType()); + if (const ArrayType *XATy = + dyn_cast<ArrayType>(XTy->getElementType())) + if (const ArrayType *CATy = + dyn_cast<ArrayType>(CPTy->getElementType())) + if (CATy->getElementType() == XATy->getElementType()) { + // At this point, we know that the cast source type is a pointer + // to an array of the same type as the destination pointer + // array. Because the array type is never stepped over (there + // is a leading zero) we can fold the cast into this GEP. + GEP.setOperand(0, X); + return &GEP; + } + } else if (GEP.getNumOperands() == 2) { + // Transform things like: + // %t = getelementptr ubyte* cast ([2 x sbyte]* %str to ubyte*), uint %V + // into: %t1 = getelementptr [2 x sbyte*]* %str, int 0, uint %V; cast + const Type *SrcElTy = cast<PointerType>(X->getType())->getElementType(); + const Type *ResElTy=cast<PointerType>(PtrOp->getType())->getElementType(); + if (isa<ArrayType>(SrcElTy) && + TD->getTypeSize(cast<ArrayType>(SrcElTy)->getElementType()) == + TD->getTypeSize(ResElTy)) { + Value *V = InsertNewInstBefore( + new GetElementPtrInst(X, Constant::getNullValue(Type::IntTy), + GEP.getOperand(1), GEP.getName()), GEP); + return new CastInst(V, GEP.getType()); } } } |