When determining the set of interesting reuse factors, consider
strides in foreign loops. This helps locate reuse opportunities
with existing induction variables in foreign loops and reduces
the need for inserting new ones. This fixes rdar://7657764.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@96629 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Transforms/Scalar/LoopStrengthReduce.cpp b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
index b0b0934..0c2f1d6 100644
--- a/lib/Transforms/Scalar/LoopStrengthReduce.cpp
+++ b/lib/Transforms/Scalar/LoopStrengthReduce.cpp
@@ -1690,21 +1690,29 @@
void LSRInstance::CollectInterestingTypesAndFactors() {
SmallSetVector<const SCEV *, 4> Strides;
- // Collect interesting types and factors.
+ // Collect interesting types and strides.
for (IVUsers::const_iterator UI = IU.begin(), E = IU.end(); UI != E; ++UI) {
const SCEV *Stride = UI->getStride();
// Collect interesting types.
Types.insert(SE.getEffectiveSCEVType(Stride->getType()));
- // Collect interesting factors.
+ // Add the stride for this loop.
+ Strides.insert(Stride);
+
+ // Add strides for other mentioned loops.
+ for (const SCEVAddRecExpr *AR = dyn_cast<SCEVAddRecExpr>(UI->getOffset());
+ AR; AR = dyn_cast<SCEVAddRecExpr>(AR->getStart()))
+ Strides.insert(AR->getStepRecurrence(SE));
+ }
+
+ // Compute interesting factors from the set of interesting strides.
+ for (SmallSetVector<const SCEV *, 4>::const_iterator
+ I = Strides.begin(), E = Strides.end(); I != E; ++I)
for (SmallSetVector<const SCEV *, 4>::const_iterator NewStrideIter =
- Strides.begin(), SEnd = Strides.end(); NewStrideIter != SEnd;
- ++NewStrideIter) {
- const SCEV *OldStride = Stride;
+ next(I); NewStrideIter != E; ++NewStrideIter) {
+ const SCEV *OldStride = *I;
const SCEV *NewStride = *NewStrideIter;
- if (OldStride == NewStride)
- continue;
if (SE.getTypeSizeInBits(OldStride->getType()) !=
SE.getTypeSizeInBits(NewStride->getType())) {
@@ -1726,8 +1734,6 @@
Factors.insert(Factor->getValue()->getValue().getSExtValue());
}
}
- Strides.insert(Stride);
- }
// If all uses use the same type, don't bother looking for truncation-based
// reuse.