diff --git a/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp b/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp index e079c749e37..67f79d5d228 100644 --- a/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp +++ b/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp @@ -107,9 +107,10 @@ GetConstantValueAsSignedInt(const Value *V, // Function: FoldGetElemChain // // Purpose: -// Fold a chain of GetElementPtr instructions into an equivalent -// (Pointer, IndexVector) pair. Returns the pointer Value, and -// stores the resulting IndexVector in argument chainIdxVec. +// Fold a chain of GetElementPtr instructions containing only +// structure offsets into an equivalent (Pointer, IndexVector) pair. +// Returns the pointer Value, and stores the resulting IndexVector +// in argument chainIdxVec. //--------------------------------------------------------------------------- Value* @@ -120,11 +121,13 @@ FoldGetElemChain(const InstructionNode* getElemInstrNode, getElemInstrNode->getInstruction(); // Initialize return values from the incoming instruction - Value* ptrVal = getElemInst->getPointerOperand(); - chainIdxVec = getElemInst->copyIndices(); + Value* ptrVal = NULL; + assert(chainIdxVec.size() == 0); - // Now chase the chain of getElementInstr instructions, if any - InstrTreeNode* ptrChild = getElemInstrNode->leftChild(); + // Now chase the chain of getElementInstr instructions, if any. + // Check for any array indices and stop there. + // + const InstrTreeNode* ptrChild = getElemInstrNode; while (ptrChild->getOpLabel() == Instruction::GetElementPtr || ptrChild->getOpLabel() == GetElemPtrIdx) { @@ -132,10 +135,32 @@ FoldGetElemChain(const InstructionNode* getElemInstrNode, getElemInst = (MemAccessInst*) ((InstructionNode*) ptrChild)->getInstruction(); const vector& idxVec = getElemInst->copyIndices(); + bool allStructureOffsets = true; - // Get the pointer value out of ptrChild and *prepend* its index vector - ptrVal = getElemInst->getPointerOperand(); - chainIdxVec.insert(chainIdxVec.begin(), idxVec.begin(), idxVec.end()); + // If it is a struct* access, the first offset must be array index [0], + // and all other offsets must be structure (not array) offsets + if (!isa(idxVec.front()) || + cast(idxVec.front())->getValue() != 0) + allStructureOffsets = false; + + if (allStructureOffsets) + for (unsigned int i=1; i < idxVec.size(); i++) + if (idxVec[i]->getType() == Type::UIntTy) + { + allStructureOffsets = false; + break; + } + + if (allStructureOffsets) + { // Get pointer value out of ptrChild and *prepend* its index vector + ptrVal = getElemInst->getPointerOperand(); + chainIdxVec.insert(chainIdxVec.begin(), + idxVec.begin()+1, idxVec.end()); + ((InstructionNode*) ptrChild)->markFoldedIntoParent(); + // mark so no code is generated + } + else // cannot fold this getElementPtr instr. or any further ones + break; ptrChild = ptrChild->leftChild(); }