//===- llvm/Transforms/DecomposeMultiDimRefs.cpp - Lower array refs to 1D -===//
+//
+// 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.
+//
+//===----------------------------------------------------------------------===//
//
// DecomposeMultiDimRefs - Convert multi-dimensional references consisting of
// any combination of 2 or more array and structure indices into a sequence of
#include "llvm/iOther.h"
#include "llvm/BasicBlock.h"
#include "llvm/Pass.h"
-#include "Support/StatisticReporter.h"
-
-static Statistic<> NumAdded("lowerrefs\t\t- New instructions added");
+#include "Support/Statistic.h"
namespace {
+ Statistic<> NumAdded("lowerrefs", "# of getelementptr instructions added");
+
struct DecomposePass : public BasicBlockPass {
virtual bool runOnBasicBlock(BasicBlock &BB);
-
- private:
- static bool decomposeArrayRef(BasicBlock::iterator &BBI);
};
-
- RegisterOpt<DecomposePass> X("lowerrefs", "Decompose multi-dimensional "
- "structure/array references");
}
-Pass
+RegisterOpt<DecomposePass> X("lowerrefs", "Decompose multi-dimensional "
+ "structure/array references");
+
+FunctionPass
*createDecomposeMultiDimRefsPass()
{
return new DecomposePass();
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->getNumIndices() >= 2) {
- Changed = decomposeArrayRef(II) || Changed; // always modifies II
- continue;
- }
- ++II;
- }
- return Changed;
+ bool changed = false;
+ for (BasicBlock::iterator II = BB.begin(); II != BB.end(); )
+ if (GetElementPtrInst *gep = dyn_cast<GetElementPtrInst>(II++)) // pre-inc
+ if (gep->getNumIndices() >= 2)
+ changed |= DecomposeArrayRef(gep); // always modifies II
+ return changed;
}
-// Check for a constant (uint) 0.
-inline bool
-IsZero(Value* idx)
-{
- return (isa<ConstantInt>(idx) && cast<ConstantInt>(idx)->isNullValue());
-}
-// For any MemAccessInst with 2 or more array and structure indices:
+// Function: DecomposeArrayRef()
+//
+// For any GetElementPtrInst with 2 or more array and structure indices:
//
// opCode CompositeType* P, [uint|ubyte] idx1, ..., [uint|ubyte] idxN
//
// Return value: true if the instruction was replaced; false otherwise.
//
bool
-DecomposePass::decomposeArrayRef(BasicBlock::iterator &BBI)
+DecomposeArrayRef(GetElementPtrInst* GEP)
{
- MemAccessInst &MAI = cast<MemAccessInst>(*BBI);
-
- // If this instr two or fewer arguments and the first argument is 0,
- // the decomposed version is identical to the instruction itself.
- // This is common enough that it is worth checking for explicitly...
- if (MAI.getNumIndices() == 0 ||
- (MAI.getNumIndices() <= 2 && IsZero(*MAI.idx_begin()))) {
- ++BBI;
+ if (GEP->getNumIndices() < 2)
return false;
- }
- BasicBlock *BB = MAI.getParent();
- Value *LastPtr = MAI.getPointerOperand();
-
- // Remove the instruction from the stream
- BB->getInstList().remove(BBI);
+ BasicBlock *BB = GEP->getParent();
+ Value *LastPtr = GEP->getPointerOperand();
+ Instruction *InsertPoint = GEP->getNext(); // Insert before the next insn
// The vector of new instructions to be created
std::vector<Instruction*> NewInsts;
// Process each index except the last one.
- User::const_op_iterator OI = MAI.idx_begin(), OE = MAI.idx_end();
+ User::const_op_iterator OI = GEP->idx_begin(), OE = GEP->idx_end();
for (; OI+1 != OE; ++OI) {
std::vector<Value*> Indices;
// If this is the first index and is 0, skip it and move on!
- if (OI == MAI.idx_begin()) {
- if (IsZero(*OI)) continue;
- } else
- // Not the first index: include initial [0] to deref the last ptr
- Indices.push_back(Constant::getNullValue(Type::UIntTy));
+ if (OI == GEP->idx_begin()) {
+ if (*OI == ConstantInt::getNullValue((*OI)->getType()))
+ continue;
+ }
+ else // Not the first index: include initial [0] to deref the last ptr
+ Indices.push_back(Constant::getNullValue(Type::LongTy));
Indices.push_back(*OI);
// New Instruction: nextPtr1 = GetElementPtr LastPtr, Indices
- LastPtr = new GetElementPtrInst(LastPtr, Indices, "ptr1");
- NewInsts.push_back(cast<Instruction>(LastPtr));
+ LastPtr = new GetElementPtrInst(LastPtr, Indices, "ptr1", InsertPoint);
++NumAdded;
}
// Get the final index vector, including an initial [0] as before.
std::vector<Value*> Indices;
- Indices.push_back(Constant::getNullValue(Type::UIntTy));
+ Indices.push_back(Constant::getNullValue(Type::LongTy));
Indices.push_back(*OI);
- Instruction *NewI = 0;
- switch(MAI.getOpcode()) {
- case Instruction::Load:
- NewI = new LoadInst(LastPtr, Indices, MAI.getName());
- break;
- case Instruction::Store:
- NewI = new StoreInst(MAI.getOperand(0), LastPtr, Indices);
- break;
- case Instruction::GetElementPtr:
- NewI = new GetElementPtrInst(LastPtr, Indices, MAI.getName());
- break;
- default:
- assert(0 && "Unrecognized memory access instruction");
- }
- NewInsts.push_back(NewI);
+ Value *NewVal = new GetElementPtrInst(LastPtr, Indices, GEP->getName(),
+ InsertPoint);
// Replace all uses of the old instruction with the new
- MAI.replaceAllUsesWith(NewI);
-
- // Now delete the old instruction...
- delete &MAI;
+ GEP->replaceAllUsesWith(NewVal);
- // Insert all of the new instructions...
- BB->getInstList().insert(BBI, NewInsts.begin(), NewInsts.end());
+ // Now remove and delete the old instruction...
+ BB->getInstList().erase(GEP);
- // Advance the iterator to the instruction following the one just inserted...
- BBI = NewInsts.back();
- ++BBI;
return true;
}
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