| //===- TransformInternals.cpp - Implement shared functions for transforms -===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file was developed by the LLVM research group and is distributed under |
| // the University of Illinois Open Source License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file defines shared functions used by the different components of the |
| // Transforms library. |
| // |
| //===----------------------------------------------------------------------===// |
| |
| #include "TransformInternals.h" |
| #include "llvm/Type.h" |
| #include "llvm/Analysis/Expressions.h" |
| #include "llvm/Function.h" |
| #include "llvm/iOther.h" |
| |
| static const Type *getStructOffsetStep(const StructType *STy, uint64_t &Offset, |
| std::vector<Value*> &Indices, |
| const TargetData &TD) { |
| assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!"); |
| const StructLayout *SL = TD.getStructLayout(STy); |
| |
| // This loop terminates always on a 0 <= i < MemberOffsets.size() |
| unsigned i; |
| for (i = 0; i < SL->MemberOffsets.size()-1; ++i) |
| if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1]) |
| break; |
| |
| assert(Offset >= SL->MemberOffsets[i] && |
| (i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1])); |
| |
| // Make sure to save the current index... |
| Indices.push_back(ConstantUInt::get(Type::UByteTy, i)); |
| Offset = SL->MemberOffsets[i]; |
| return STy->getContainedType(i); |
| } |
| |
| |
| // getStructOffsetType - Return a vector of offsets that are to be used to index |
| // into the specified struct type to get as close as possible to index as we |
| // can. Note that it is possible that we cannot get exactly to Offset, in which |
| // case we update offset to be the offset we actually obtained. The resultant |
| // leaf type is returned. |
| // |
| // If StopEarly is set to true (the default), the first object with the |
| // specified type is returned, even if it is a struct type itself. In this |
| // case, this routine will not drill down to the leaf type. Set StopEarly to |
| // false if you want a leaf |
| // |
| const Type *getStructOffsetType(const Type *Ty, unsigned &Offset, |
| std::vector<Value*> &Indices, |
| const TargetData &TD, bool StopEarly) { |
| if (Offset == 0 && StopEarly && !Indices.empty()) |
| return Ty; // Return the leaf type |
| |
| uint64_t ThisOffset; |
| const Type *NextType; |
| if (const StructType *STy = dyn_cast<StructType>(Ty)) { |
| if (STy->getElementTypes().empty()) { |
| Offset = 0; |
| return STy; |
| } |
| |
| ThisOffset = Offset; |
| NextType = getStructOffsetStep(STy, ThisOffset, Indices, TD); |
| } else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) { |
| assert(Offset == 0 || Offset < TD.getTypeSize(ATy) && |
| "Offset not in composite!"); |
| |
| NextType = ATy->getElementType(); |
| unsigned ChildSize = TD.getTypeSize(NextType); |
| Indices.push_back(ConstantSInt::get(Type::LongTy, Offset/ChildSize)); |
| ThisOffset = (Offset/ChildSize)*ChildSize; |
| } else { |
| Offset = 0; // Return the offset that we were able to achieve |
| return Ty; // Return the leaf type |
| } |
| |
| unsigned SubOffs = Offset - ThisOffset; |
| const Type *LeafTy = getStructOffsetType(NextType, SubOffs, |
| Indices, TD, StopEarly); |
| Offset = ThisOffset + SubOffs; |
| return LeafTy; |
| } |
| |
| // ConvertibleToGEP - This function returns true if the specified value V is |
| // a valid index into a pointer of type Ty. If it is valid, Idx is filled in |
| // with the values that would be appropriate to make this a getelementptr |
| // instruction. The type returned is the root type that the GEP would point to |
| // |
| const Type *ConvertibleToGEP(const Type *Ty, Value *OffsetVal, |
| std::vector<Value*> &Indices, |
| const TargetData &TD, |
| BasicBlock::iterator *BI) { |
| const CompositeType *CompTy = dyn_cast<CompositeType>(Ty); |
| if (CompTy == 0) return 0; |
| |
| // See if the cast is of an integer expression that is either a constant, |
| // or a value scaled by some amount with a possible offset. |
| // |
| ExprType Expr = ClassifyExpression(OffsetVal); |
| |
| // Get the offset and scale values if they exists... |
| // A scale of zero with Expr.Var != 0 means a scale of 1. |
| // |
| int64_t Offset = Expr.Offset ? getConstantValue(Expr.Offset) : 0; |
| int64_t Scale = Expr.Scale ? getConstantValue(Expr.Scale) : 0; |
| |
| if (Expr.Var && Scale == 0) Scale = 1; // Scale != 0 if Expr.Var != 0 |
| |
| // Loop over the Scale and Offset values, filling in the Indices vector for |
| // our final getelementptr instruction. |
| // |
| const Type *NextTy = CompTy; |
| do { |
| if (!isa<CompositeType>(NextTy)) |
| return 0; // Type must not be ready for processing... |
| CompTy = cast<CompositeType>(NextTy); |
| |
| if (const StructType *StructTy = dyn_cast<StructType>(CompTy)) { |
| // Step into the appropriate element of the structure... |
| uint64_t ActualOffset = (Offset < 0) ? 0 : (uint64_t)Offset; |
| NextTy = getStructOffsetStep(StructTy, ActualOffset, Indices, TD); |
| Offset -= ActualOffset; |
| } else { |
| const Type *ElTy = cast<SequentialType>(CompTy)->getElementType(); |
| if (!ElTy->isSized() || (isa<PointerType>(CompTy) && !Indices.empty())) |
| return 0; // Type is unreasonable... escape! |
| unsigned ElSize = TD.getTypeSize(ElTy); |
| if (ElSize == 0) return 0; // Avoid division by zero... |
| int64_t ElSizeS = ElSize; |
| |
| // See if the user is indexing into a different cell of this array... |
| if (Scale && (Scale >= ElSizeS || -Scale >= ElSizeS)) { |
| // A scale n*ElSize might occur if we are not stepping through |
| // array by one. In this case, we will have to insert math to munge |
| // the index. |
| // |
| int64_t ScaleAmt = Scale/ElSizeS; |
| if (Scale-ScaleAmt*ElSizeS) |
| return 0; // Didn't scale by a multiple of element size, bail out |
| Scale = 0; // Scale is consumed |
| |
| int64_t Index = Offset/ElSize; // is zero unless Offset > ElSize |
| Offset -= Index*ElSize; // Consume part of the offset |
| |
| if (BI) { // Generate code? |
| BasicBlock *BB = (*BI)->getParent(); |
| if (Expr.Var->getType() != Type::LongTy) |
| Expr.Var = new CastInst(Expr.Var, Type::LongTy, |
| Expr.Var->getName()+"-idxcast", *BI); |
| |
| if (ScaleAmt && ScaleAmt != 1) { |
| // If we have to scale up our index, do so now |
| Value *ScaleAmtVal = ConstantSInt::get(Type::LongTy, ScaleAmt); |
| Expr.Var = BinaryOperator::create(Instruction::Mul, Expr.Var, |
| ScaleAmtVal, |
| Expr.Var->getName()+"-scale",*BI); |
| } |
| |
| if (Index) { // Add an offset to the index |
| Value *IndexAmt = ConstantSInt::get(Type::LongTy, Index); |
| Expr.Var = BinaryOperator::create(Instruction::Add, Expr.Var, |
| IndexAmt, |
| Expr.Var->getName()+"-offset", |
| *BI); |
| } |
| } |
| |
| Indices.push_back(Expr.Var); |
| Expr.Var = 0; |
| } else if (Offset >= (int64_t)ElSize || -Offset >= (int64_t)ElSize) { |
| // Calculate the index that we are entering into the array cell with |
| uint64_t Index = Offset/ElSize; |
| Indices.push_back(ConstantSInt::get(Type::LongTy, Index)); |
| Offset -= (int64_t)(Index*ElSize); // Consume part of the offset |
| |
| } else if (isa<ArrayType>(CompTy) || Indices.empty()) { |
| // Must be indexing a small amount into the first cell of the array |
| // Just index into element zero of the array here. |
| // |
| Indices.push_back(ConstantSInt::get(Type::LongTy, 0)); |
| } else { |
| return 0; // Hrm. wierd, can't handle this case. Bail |
| } |
| NextTy = ElTy; |
| } |
| } while (Offset || Scale); // Go until we're done! |
| |
| return NextTy; |
| } |
