+++ /dev/null
-//===- llvm/Transforms/DecomposeArrayRefs.cpp - Lower array refs to 1D -----=//
-//
-// DecomposeArrayRefs -
-// Convert multi-dimensional array references into a sequence of
-// instructions (using getelementpr and cast) so that each instruction
-// has at most one array offset.
-//
-//===---------------------------------------------------------------------===//
-
-#include "llvm/Transforms/DecomposeArrayRefs.h"
-#include "llvm/iMemory.h"
-#include "llvm/iOther.h"
-#include "llvm/BasicBlock.h"
-#include "llvm/Method.h"
-#include "llvm/Pass.h"
-
-
-//
-// This function repeats until we have a one-dim. reference: {
-// // For an N-dim array ref, where N > 1, insert:
-// aptr1 = getElementPtr [N-dim array] * lastPtr, uint firstIndex
-// aptr2 = cast [N-dim-arry] * aptr to [<N-1>-dim-array] *
-// }
-// Then it replaces the original instruction with an equivalent one that
-// uses the last aptr2 generated in the loop and a single index.
-//
-static BasicBlock::reverse_iterator
-decomposeArrayRef(BasicBlock::reverse_iterator& BBI)
-{
- MemAccessInst *memI = cast<MemAccessInst>(*BBI);
- BasicBlock* BB = memI->getParent();
- Value* lastPtr = memI->getPointerOperand();
- vector<Instruction*> newIvec;
-
- MemAccessInst::const_op_iterator OI = memI->idx_begin();
- for (MemAccessInst::const_op_iterator OE = memI->idx_end(); OI != OE; ++OI)
- {
- if (OI+1 == OE) // skip the last operand
- break;
-
- assert(isa<PointerType>(lastPtr->getType()));
- vector<Value*> idxVec(1, *OI);
-
- // The first index does not change the type of the pointer
- // since all pointers are treated as potential arrays (i.e.,
- // int *X is either a scalar X[0] or an array at X[i]).
- //
- const Type* nextPtrType;
- // if (OI == memI->idx_begin())
- // nextPtrType = lastPtr->getType();
- // else
- // {
- const Type* nextArrayType =
- MemAccessInst::getIndexedType(lastPtr->getType(), idxVec,
- /*allowCompositeLeaf*/ true);
- nextPtrType = PointerType::get(cast<SequentialType>(nextArrayType)
- ->getElementType());
- // }
-
- Instruction* gepInst = new GetElementPtrInst(lastPtr, idxVec, "aptr1");
- Instruction* castInst = new CastInst(gepInst, nextPtrType, "aptr2");
- lastPtr = castInst;
-
- newIvec.push_back(gepInst);
- newIvec.push_back(castInst);
- }
-
- // Now create a new instruction to replace the original one
- assert(lastPtr != memI->getPointerOperand() && "the above loop did not execute?");
- assert(isa<PointerType>(lastPtr->getType()));
- vector<Value*> idxVec(1, *OI);
- const std::string newInstName = memI->hasName()? memI->getName()
- : string("oneDimRef");
- Instruction* newInst = NULL;
-
- switch(memI->getOpcode())
- {
- case Instruction::Load:
- newInst = new LoadInst(lastPtr, idxVec /*, newInstName */); break;
- case Instruction::Store:
- newInst = new StoreInst(memI->getOperand(0),
- lastPtr, idxVec /*, newInstName */); break;
- break;
- case Instruction::GetElementPtr:
- newInst = new GetElementPtrInst(lastPtr, idxVec /*, newInstName */); break;
- default:
- assert(0 && "Unrecognized memory access instruction"); break;
- }
-
- newIvec.push_back(newInst);
-
- // Replace all uses of the old instruction with the new
- memI->replaceAllUsesWith(newInst);
-
- // Insert the instructions created in reverse order. insert is destructive
- // so we always have to use the new pointer returned by insert.
- BasicBlock::iterator newI = BBI.base(); // gives ptr to instr. after memI
- --newI; // step back to memI
- for (int i = newIvec.size()-1; i >= 0; i--)
- newI = BB->getInstList().insert(newI, newIvec[i]);
-
- // Now delete the old instruction and return a pointer to the first new one
- BB->getInstList().remove(memI);
- delete memI;
-
- BasicBlock::reverse_iterator retI(newI); // reverse ptr to instr before newI
- return --retI; // reverse pointer to newI
-}
-
-
-//---------------------------------------------------------------------------
-// Entry point for decomposing multi-dimensional array references
-//---------------------------------------------------------------------------
-
-static bool
-doDecomposeArrayRefs(Method *M)
-{
- bool changed = false;
-
- for (Method::iterator BI = M->begin(), BE = M->end(); BI != BE; ++BI)
- for (BasicBlock::reverse_iterator newI, II=(*BI)->rbegin();
- II != (*BI)->rend(); II = ++newI)
- {
- newI = II;
- if (MemAccessInst *memI = dyn_cast<MemAccessInst>(*II))
- { // Check for a multi-dimensional array access
- const PointerType* ptrType =
- cast<PointerType>(memI->getPointerOperand()->getType());
- if (isa<ArrayType>(ptrType->getElementType()) &&
- memI->getNumOperands() > 1+ memI->getFirstIndexOperandNumber())
- {
- newI = decomposeArrayRef(II);
- changed = true;
- }
- }
- }
-
- return changed;
-}
-
-
-namespace {
- struct DecomposeArrayRefsPass : public MethodPass {
- virtual bool runOnMethod(Method *M) { return doDecomposeArrayRefs(M); }
- };
-}
-
-Pass *createDecomposeArrayRefsPass() { return new DecomposeArrayRefsPass(); }