//===- llvm/Transforms/DecomposeMultiDimRefs.cpp - Lower array refs to 1D -===//
//
-// DecomposeMultiDimRefs -
-// Convert multi-dimensional references consisting of any combination
-// of 2 or more array and structure indices into a sequence of
-// instructions (using getelementpr and cast) so that each instruction
-// has at most one index (except structure references,
-// which need an extra leading index of [0]).
+// DecomposeMultiDimRefs - Convert multi-dimensional references consisting of
+// any combination of 2 or more array and structure indices into a sequence of
+// instructions (using getelementpr and cast) so that each instruction has at
+// most one index (except structure references, which need an extra leading
+// index of [0]).
//
//===----------------------------------------------------------------------===//
-#include "llvm/Transforms/Scalar/DecomposeMultiDimRefs.h"
-#include "llvm/Constants.h"
+#include "llvm/Transforms/Scalar.h"
+#include "llvm/DerivedTypes.h"
+#include "llvm/Constant.h"
#include "llvm/iMemory.h"
#include "llvm/iOther.h"
#include "llvm/BasicBlock.h"
-#include "llvm/Function.h"
#include "llvm/Pass.h"
+#include "Support/StatisticReporter.h"
+
+static Statistic<> NumAdded("lowerrefs\t\t- New instructions added");
namespace {
struct DecomposePass : public BasicBlockPass {
+ const char *getPassName() const { return "Decompose Subscripting Exps"; }
+
virtual bool runOnBasicBlock(BasicBlock *BB);
private:
//
bool DecomposePass::runOnBasicBlock(BasicBlock *BB) {
bool Changed = false;
-
for (BasicBlock::iterator II = BB->begin(); II != BB->end(); ) {
if (MemAccessInst *MAI = dyn_cast<MemAccessInst>(*II)) {
if (MAI->getNumOperands() > MAI->getFirstIndexOperandNumber()+1) {
// uses the last ptr2 generated in the loop and a single index.
// If any index is (uint) 0, we omit the getElementPtr instruction.
//
-void DecomposePass::decomposeArrayRef(BasicBlock::iterator &BBI){
- MemAccessInst *memI = cast<MemAccessInst>(*BBI);
- BasicBlock* BB = memI->getParent();
- Value* lastPtr = memI->getPointerOperand();
+void DecomposePass::decomposeArrayRef(BasicBlock::iterator &BBI) {
+ MemAccessInst *MAI = cast<MemAccessInst>(*BBI);
+ BasicBlock *BB = MAI->getParent();
+ Value *LastPtr = MAI->getPointerOperand();
// Remove the instruction from the stream
BB->getInstList().remove(BBI);
- vector<Instruction*> newIvec;
+ vector<Instruction*> NewInsts;
// Process each index except the last one.
//
- User::const_op_iterator OI = memI->idx_begin(), OE = memI->idx_end();
- for (; OI != OE && OI+1 != OE; ++OI) {
- assert(isa<PointerType>(lastPtr->getType()));
+ User::const_op_iterator OI = MAI->idx_begin(), OE = MAI->idx_end();
+ for (; OI+1 != OE; ++OI) {
+ assert(isa<PointerType>(LastPtr->getType()));
// Check for a zero index. This will need a cast instead of
// a getElementPtr, or it may need neither.
- bool indexIsZero = isa<ConstantUInt>(*OI) &&
- cast<Constant>(*OI)->isNullValue();
+ bool indexIsZero = isa<Constant>(*OI) &&
+ cast<Constant>(*OI)->isNullValue() &&
+ (*OI)->getType() == Type::UIntTy;
// Extract the first index. If the ptr is a pointer to a structure
// and the next index is a structure offset (i.e., not an array offset),
// we need to include an initial [0] to index into the pointer.
- vector<Value*> idxVec(1, *OI);
- PointerType* ptrType = cast<PointerType>(lastPtr->getType());
- if (isa<StructType>(ptrType->getElementType())
- && ! ptrType->indexValid(*OI))
- idxVec.insert(idxVec.begin(), ConstantUInt::get(Type::UIntTy, 0));
-
+ //
+ vector<Value*> Indices;
+ PointerType *PtrTy = cast<PointerType>(LastPtr->getType());
+ if (isa<StructType>(PtrTy->getElementType())
+ && !PtrTy->indexValid(*OI))
+ Indices.push_back(Constant::getNullValue(Type::UIntTy));
+ Indices.push_back(*OI);
+
// Get the type obtained by applying the first index.
// It must be a structure or array.
- const Type* nextType = MemAccessInst::getIndexedType(lastPtr->getType(),
- idxVec, true);
- assert(isa<StructType>(nextType) || isa<ArrayType>(nextType));
+ const Type *NextTy = MemAccessInst::getIndexedType(LastPtr->getType(),
+ Indices, true);
+ assert(isa<CompositeType>(NextTy));
// Get a pointer to the structure or to the elements of the array.
- const Type* nextPtrType =
- PointerType::get(isa<StructType>(nextType) ? nextType
- : cast<ArrayType>(nextType)->getElementType());
+ const Type *NextPtrTy =
+ PointerType::get(isa<StructType>(NextTy) ? NextTy
+ : cast<ArrayType>(NextTy)->getElementType());
- // Instruction 1: nextPtr1 = GetElementPtr lastPtr, idxVec
+ // Instruction 1: nextPtr1 = GetElementPtr LastPtr, Indices
// This is not needed if the index is zero.
- Value *gepValue;
- if (indexIsZero)
- gepValue = lastPtr;
- else {
- gepValue = new GetElementPtrInst(lastPtr, idxVec,"ptr1");
- newIvec.push_back(cast<Instruction>(gepValue));
+ if (!indexIsZero) {
+ LastPtr = new GetElementPtrInst(LastPtr, Indices, "ptr1");
+ NewInsts.push_back(cast<Instruction>(LastPtr));
+ ++NumAdded;
}
- // Instruction 2: nextPtr2 = cast nextPtr1 to nextPtrType
+ // Instruction 2: nextPtr2 = cast nextPtr1 to NextPtrTy
// This is not needed if the two types are identical.
- Value *castInst;
- if (gepValue->getType() == nextPtrType)
- castInst = gepValue;
- else {
- castInst = new CastInst(gepValue, nextPtrType, "ptr2");
- newIvec.push_back(cast<Instruction>(castInst));
+ //
+ if (LastPtr->getType() != NextPtrTy) {
+ LastPtr = new CastInst(LastPtr, NextPtrTy, "ptr2");
+ NewInsts.push_back(cast<Instruction>(LastPtr));
+ ++NumAdded;
}
-
- lastPtr = castInst;
}
//
// Now create a new instruction to replace the original one
//
- PointerType *ptrType = cast<PointerType>(lastPtr->getType());
+ PointerType *PtrTy = cast<PointerType>(LastPtr->getType());
// First, get the final index vector. As above, we may need an initial [0].
- vector<Value*> idxVec(1, *OI);
- if (isa<StructType>(ptrType->getElementType())
- && !ptrType->indexValid(*OI))
- idxVec.insert(idxVec.begin(), Constant::getNullValue(Type::UIntTy));
-
- Instruction* newInst = NULL;
- switch(memI->getOpcode()) {
+ vector<Value*> Indices;
+ if (isa<StructType>(PtrTy->getElementType())
+ && !PtrTy->indexValid(*OI))
+ Indices.push_back(Constant::getNullValue(Type::UIntTy));
+
+ Indices.push_back(*OI);
+
+ Instruction *NewI = 0;
+ switch(MAI->getOpcode()) {
case Instruction::Load:
- newInst = new LoadInst(lastPtr, idxVec, memI->getName());
+ NewI = new LoadInst(LastPtr, Indices, MAI->getName());
break;
case Instruction::Store:
- newInst = new StoreInst(memI->getOperand(0), lastPtr, idxVec);
+ NewI = new StoreInst(MAI->getOperand(0), LastPtr, Indices);
break;
case Instruction::GetElementPtr:
- newInst = new GetElementPtrInst(lastPtr, idxVec, memI->getName());
+ NewI = new GetElementPtrInst(LastPtr, Indices, MAI->getName());
break;
default:
assert(0 && "Unrecognized memory access instruction");
}
- newIvec.push_back(newInst);
+ NewInsts.push_back(NewI);
// Replace all uses of the old instruction with the new
- memI->replaceAllUsesWith(newInst);
+ MAI->replaceAllUsesWith(NewI);
// Now delete the old instruction...
- delete memI;
-
- // Convert our iterator into an index... that cannot get invalidated
- unsigned ItOffs = BBI-BB->begin();
+ delete MAI;
// Insert all of the new instructions...
- BB->getInstList().insert(BBI, newIvec.begin(), newIvec.end());
+ BBI = BB->getInstList().insert(BBI, NewInsts.begin(), NewInsts.end());
// Advance the iterator to the instruction following the one just inserted...
- BBI = BB->begin() + (ItOffs+newIvec.size());
+ BBI += NewInsts.size();
}
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