When combining consecutive stores allow loads in between the stores, if the loads do not alias.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@168832 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
index 37d7731..5659069 100644
--- a/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -291,6 +291,10 @@
unsigned SrcValueAlign2,
const MDNode *TBAAInfo2) const;
+ /// isAlias - Return true if there is any possibility that the two addresses
+ /// overlap.
+ bool isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1);
+
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool FindAliasInfo(SDNode *N,
@@ -7552,7 +7556,14 @@
if (BasePtr.first.getOpcode() == ISD::UNDEF)
return false;
+ // Save the LoadSDNodes that we find in the chain.
+ // We need to make sure that these nodes do not interfere with
+ // any of the store nodes.
+ SmallVector<LSBaseSDNode*, 8> AliasLoadNodes;
+
+ // Save the StoreSDNodes that we find in the chain.
SmallVector<MemOpLink, 8> StoreNodes;
+
// Walk up the chain and look for nodes with offsets from the same
// base pointer. Stop when reaching an instruction with a different kind
// or instruction which has a different base pointer.
@@ -7596,8 +7607,26 @@
// We found a potential memory operand to merge.
StoreNodes.push_back(MemOpLink(Index, Ptr.second, Seq++));
- // Move up the chain to the next memory operation.
- Index = dyn_cast<StoreSDNode>(Index->getChain().getNode());
+ // Find the next memory operand in the chain. If the next operand in the
+ // chain is a store then move up and continue the scan with the next
+ // memory operand. If the next operand is a load save it and use alias
+ // information to check if it interferes with anything.
+ SDNode *NextInChain = Index->getChain().getNode();
+ while (1) {
+ if (isa<StoreSDNode>(NextInChain)) {
+ // We found a store node. Use it for the next iteration.
+ Index = cast<StoreSDNode>(NextInChain);
+ break;
+ } else if (LoadSDNode *Ldn = dyn_cast<LoadSDNode>(NextInChain)) {
+ // Save the load node for later. Continue the scan.
+ AliasLoadNodes.push_back(Ldn);
+ NextInChain = Ldn->getChain().getNode();
+ continue;
+ } else {
+ Index = NULL;
+ break;
+ }
+ }
}
// Check if there is anything to merge.
@@ -7612,11 +7641,23 @@
// store memory address.
unsigned LastConsecutiveStore = 0;
int64_t StartAddress = StoreNodes[0].OffsetFromBase;
- for (unsigned i=1; i<StoreNodes.size(); ++i) {
+ for (unsigned i = 1, e = StoreNodes.size(); i < e; ++i) {
int64_t CurrAddress = StoreNodes[i].OffsetFromBase;
if (CurrAddress - StartAddress != (ElementSizeBytes * i))
break;
+ bool Alias = false;
+ // Check if this store interferes with any of the loads that we found.
+ for (unsigned ld = 0, lde = AliasLoadNodes.size(); ld < lde; ++ld)
+ if (isAlias(AliasLoadNodes[ld], StoreNodes[i].MemNode)) {
+ Alias = true;
+ break;
+ }
+
+ // We found a load that alias with this store. Stop the sequence.
+ if (Alias)
+ break;
+
// Mark this node as useful.
LastConsecutiveStore = i;
}
@@ -9680,6 +9721,23 @@
return true;
}
+bool DAGCombiner::isAlias(LSBaseSDNode *Op0, LSBaseSDNode *Op1) {
+ SDValue Ptr0, Ptr1;
+ int64_t Size0, Size1;
+ const Value *SrcValue0, *SrcValue1;
+ int SrcValueOffset0, SrcValueOffset1;
+ unsigned SrcValueAlign0, SrcValueAlign1;
+ const MDNode *SrcTBAAInfo0, *SrcTBAAInfo1;
+ FindAliasInfo(Op0, Ptr0, Size0, SrcValue0, SrcValueOffset0,
+ SrcValueAlign0, SrcTBAAInfo0);
+ FindAliasInfo(Op1, Ptr1, Size1, SrcValue1, SrcValueOffset1,
+ SrcValueAlign1, SrcTBAAInfo1);
+ return isAlias(Ptr0, Size0, SrcValue0, SrcValueOffset0,
+ SrcValueAlign0, SrcTBAAInfo0,
+ Ptr1, Size1, SrcValue1, SrcValueOffset1,
+ SrcValueAlign1, SrcTBAAInfo1);
+}
+
/// FindAliasInfo - Extracts the relevant alias information from the memory
/// node. Returns true if the operand was a load.
bool DAGCombiner::FindAliasInfo(SDNode *N,