Major overhaul to FoldGetElemPtr to handle mixed array and struct refs.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@1968 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp b/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp
index e079c74..67f79d5 100644
--- a/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp
+++ b/lib/CodeGen/InstrSelection/InstrSelectionSupport.cpp
@@ -107,9 +107,10 @@
// 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 @@
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 @@
getElemInst = (MemAccessInst*)
((InstructionNode*) ptrChild)->getInstruction();
const vector<Value*>& 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<ConstantUInt>(idxVec.front()) ||
+ cast<ConstantUInt>(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();
}