Changes in directory llvm/lib/CodeGen/SelectionDAG:
DAGCombiner.cpp updated: 1.247 -> 1.248
---
Log message:
When forming a pre-indexed store, make sure ptr isn't the same or is a pred of
value being stored. It would cause a cycle.
---
Diffs of the changes: (+16 -7)
DAGCombiner.cpp | 23 ++++++++++++++++-------
1 files changed, 16 insertions(+), 7 deletions(-)
Index: llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
diff -u llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.247
llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.248
--- llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp:1.247 Thu Nov 9 13:10:46 2006
+++ llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp Fri Nov 10 02:28:11 2006
@@ -214,11 +214,20 @@
ISD::MemIndexedMode AM = ISD::UNINDEXED;
if (TLI.getPreIndexedAddressParts(N, BasePtr, Offset, AM, DAG)) {
// Try turning it into a pre-indexed load / store except when
- // 1) Another use of base ptr is a predecessor of N. If ptr is folded
+ // 1) If N is a store and the ptr is either the same as or is a
+ // predecessor of the value being stored.
+ // 2) Another use of base ptr is a predecessor of N. If ptr is folded
// that would create a cycle.
- // 2) All uses are load / store ops that use it as base ptr.
+ // 3) All uses are load / store ops that use it as base ptr.
- // Now check for #1 and #2.
+ // Checking #1.
+ if (!isLoad) {
+ SDOperand Val = cast<StoreSDNode>(N)->getValue();
+ if (Val == Ptr || Ptr.Val->isPredecessor(Val.Val))
+ return false;
+ }
+
+ // Now check for #2 and #3.
bool RealUse = false;
for (SDNode::use_iterator I = Ptr.Val->use_begin(),
E = Ptr.Val->use_end(); I != E; ++I) {
@@ -323,12 +332,12 @@
continue;
// Try turning it into a post-indexed load / store except when
- // 1) Op must be independent of N, i.e. Op is neither a predecessor
+ // 1) All uses are load / store ops that use it as base ptr.
+ // 2) Op must be independent of N, i.e. Op is neither a predecessor
// nor a successor of N. Otherwise, if Op is folded that would
// create a cycle.
- // 2) All uses are load / store ops that use it as base ptr.
- // Check for #3.
+ // Check for #1.
bool TryNext = false;
for (SDNode::use_iterator II = BasePtr.Val->use_begin(),
EE = BasePtr.Val->use_end(); II != EE; ++II) {
@@ -359,7 +368,7 @@
if (TryNext)
continue;
- // Check for #1
+ // Check for #2
if (!Op->isPredecessor(N) && !N->isPredecessor(Op)) {
SDOperand Result = isLoad
? DAG.getIndexedLoad(SDOperand(N,0), BasePtr, Offset, AM)
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