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204 lines
8.3 KiB
C++
204 lines
8.3 KiB
C++
//===- TransformInternals.cpp - Implement shared functions for transforms -===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines shared functions used by the different components of the
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// Transforms library.
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//
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//===----------------------------------------------------------------------===//
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#include "TransformInternals.h"
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#include "llvm/Type.h"
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#include "llvm/Analysis/Expressions.h"
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#include "llvm/Function.h"
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#include "llvm/iOther.h"
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using namespace llvm;
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static const Type *getStructOffsetStep(const StructType *STy, uint64_t &Offset,
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std::vector<Value*> &Indices,
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const TargetData &TD) {
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assert(Offset < TD.getTypeSize(STy) && "Offset not in composite!");
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const StructLayout *SL = TD.getStructLayout(STy);
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// This loop terminates always on a 0 <= i < MemberOffsets.size()
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unsigned i;
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for (i = 0; i < SL->MemberOffsets.size()-1; ++i)
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if (Offset >= SL->MemberOffsets[i] && Offset < SL->MemberOffsets[i+1])
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break;
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assert(Offset >= SL->MemberOffsets[i] &&
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(i == SL->MemberOffsets.size()-1 || Offset < SL->MemberOffsets[i+1]));
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// Make sure to save the current index...
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// FIXME for PR82
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Indices.push_back(ConstantUInt::get(Type::UByteTy, i));
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Offset = SL->MemberOffsets[i];
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return STy->getContainedType(i);
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}
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// getStructOffsetType - Return a vector of offsets that are to be used to index
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// into the specified struct type to get as close as possible to index as we
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// can. Note that it is possible that we cannot get exactly to Offset, in which
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// case we update offset to be the offset we actually obtained. The resultant
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// leaf type is returned.
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//
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// If StopEarly is set to true (the default), the first object with the
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// specified type is returned, even if it is a struct type itself. In this
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// case, this routine will not drill down to the leaf type. Set StopEarly to
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// false if you want a leaf
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//
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const Type *llvm::getStructOffsetType(const Type *Ty, unsigned &Offset,
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std::vector<Value*> &Indices,
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const TargetData &TD, bool StopEarly) {
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if (Offset == 0 && StopEarly && !Indices.empty())
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return Ty; // Return the leaf type
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uint64_t ThisOffset;
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const Type *NextType;
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if (const StructType *STy = dyn_cast<StructType>(Ty)) {
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if (STy->getElementTypes().empty()) {
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Offset = 0;
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return STy;
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}
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ThisOffset = Offset;
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NextType = getStructOffsetStep(STy, ThisOffset, Indices, TD);
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} else if (const ArrayType *ATy = dyn_cast<ArrayType>(Ty)) {
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assert(Offset == 0 || Offset < TD.getTypeSize(ATy) &&
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"Offset not in composite!");
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NextType = ATy->getElementType();
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unsigned ChildSize = TD.getTypeSize(NextType);
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// FIXME for PR82
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Indices.push_back(ConstantSInt::get(Type::LongTy, Offset/ChildSize));
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ThisOffset = (Offset/ChildSize)*ChildSize;
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} else {
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Offset = 0; // Return the offset that we were able to achieve
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return Ty; // Return the leaf type
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}
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unsigned SubOffs = Offset - ThisOffset;
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const Type *LeafTy = getStructOffsetType(NextType, SubOffs,
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Indices, TD, StopEarly);
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Offset = ThisOffset + SubOffs;
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return LeafTy;
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}
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// ConvertibleToGEP - This function returns true if the specified value V is
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// a valid index into a pointer of type Ty. If it is valid, Idx is filled in
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// with the values that would be appropriate to make this a getelementptr
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// instruction. The type returned is the root type that the GEP would point to
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//
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const Type *llvm::ConvertibleToGEP(const Type *Ty, Value *OffsetVal,
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std::vector<Value*> &Indices,
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const TargetData &TD,
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BasicBlock::iterator *BI) {
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const CompositeType *CompTy = dyn_cast<CompositeType>(Ty);
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if (CompTy == 0) return 0;
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// See if the cast is of an integer expression that is either a constant,
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// or a value scaled by some amount with a possible offset.
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//
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ExprType Expr = ClassifyExpr(OffsetVal);
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// Get the offset and scale values if they exists...
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// A scale of zero with Expr.Var != 0 means a scale of 1.
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//
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int64_t Offset = Expr.Offset ? getConstantValue(Expr.Offset) : 0;
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int64_t Scale = Expr.Scale ? getConstantValue(Expr.Scale) : 0;
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if (Expr.Var && Scale == 0) Scale = 1; // Scale != 0 if Expr.Var != 0
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// Loop over the Scale and Offset values, filling in the Indices vector for
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// our final getelementptr instruction.
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//
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const Type *NextTy = CompTy;
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do {
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if (!isa<CompositeType>(NextTy))
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return 0; // Type must not be ready for processing...
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CompTy = cast<CompositeType>(NextTy);
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if (const StructType *StructTy = dyn_cast<StructType>(CompTy)) {
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// Step into the appropriate element of the structure...
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uint64_t ActualOffset = (Offset < 0) ? 0 : (uint64_t)Offset;
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NextTy = getStructOffsetStep(StructTy, ActualOffset, Indices, TD);
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Offset -= ActualOffset;
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} else {
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const Type *ElTy = cast<SequentialType>(CompTy)->getElementType();
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if (!ElTy->isSized() || (isa<PointerType>(CompTy) && !Indices.empty()))
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return 0; // Type is unreasonable... escape!
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unsigned ElSize = TD.getTypeSize(ElTy);
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if (ElSize == 0) return 0; // Avoid division by zero...
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int64_t ElSizeS = ElSize;
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// See if the user is indexing into a different cell of this array...
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if (Scale && (Scale >= ElSizeS || -Scale >= ElSizeS)) {
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// A scale n*ElSize might occur if we are not stepping through
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// array by one. In this case, we will have to insert math to munge
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// the index.
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//
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int64_t ScaleAmt = Scale/ElSizeS;
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if (Scale-ScaleAmt*ElSizeS)
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return 0; // Didn't scale by a multiple of element size, bail out
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Scale = 0; // Scale is consumed
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int64_t Index = Offset/ElSize; // is zero unless Offset > ElSize
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Offset -= Index*ElSize; // Consume part of the offset
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if (BI) { // Generate code?
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BasicBlock *BB = (*BI)->getParent();
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if (Expr.Var->getType() != Type::LongTy) // FIXME for PR82
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Expr.Var = new CastInst(Expr.Var, Type::LongTy, // FIXME for PR82
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Expr.Var->getName()+"-idxcast", *BI);
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if (ScaleAmt && ScaleAmt != 1) {
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// If we have to scale up our index, do so now
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// FIXME for PR82
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Value *ScaleAmtVal = ConstantSInt::get(Type::LongTy, ScaleAmt);
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Expr.Var = BinaryOperator::create(Instruction::Mul, Expr.Var,
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ScaleAmtVal,
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Expr.Var->getName()+"-scale",*BI);
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}
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if (Index) { // Add an offset to the index
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// FIXME for PR82
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Value *IndexAmt = ConstantSInt::get(Type::LongTy, Index);
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Expr.Var = BinaryOperator::create(Instruction::Add, Expr.Var,
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IndexAmt,
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Expr.Var->getName()+"-offset",
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*BI);
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}
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}
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Indices.push_back(Expr.Var);
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Expr.Var = 0;
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} else if (Offset >= (int64_t)ElSize || -Offset >= (int64_t)ElSize) {
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// Calculate the index that we are entering into the array cell with
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uint64_t Index = Offset/ElSize;
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// FIXME for PR82
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Indices.push_back(ConstantSInt::get(Type::LongTy, Index));
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Offset -= (int64_t)(Index*ElSize); // Consume part of the offset
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} else if (isa<ArrayType>(CompTy) || Indices.empty()) {
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// Must be indexing a small amount into the first cell of the array
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// Just index into element zero of the array here.
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//
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// FIXME for PR82
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Indices.push_back(ConstantSInt::get(Type::LongTy, 0));
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} else {
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return 0; // Hrm. wierd, can't handle this case. Bail
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}
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NextTy = ElTy;
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}
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} while (Offset || Scale); // Go until we're done!
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return NextTy;
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}
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