[LICM] Only recompute LCSSA when we actually promoted something.
We want to recompute LCSSA only when we actually promoted a value.
This means we only need to look at changes made by promotion when
deciding whether to recompute it or not, not at regular sinking/hoisting.
(This was what the code was documented as doing, just not what it did)
Hopefully NFC.
llvm-svn: 290726
diff --git a/llvm/lib/Transforms/Scalar/LICM.cpp b/llvm/lib/Transforms/Scalar/LICM.cpp
index c981a8f..30a7037 100644
--- a/llvm/lib/Transforms/Scalar/LICM.cpp
+++ b/llvm/lib/Transforms/Scalar/LICM.cpp
@@ -255,9 +255,11 @@
SmallVector<Instruction *, 8> InsertPts;
PredIteratorCache PIC;
+ bool Promoted = false;
+
// Loop over all of the alias sets in the tracker object.
for (AliasSet &AS : *CurAST)
- Changed |= promoteLoopAccessesToScalars(
+ Promoted |= promoteLoopAccessesToScalars(
AS, ExitBlocks, InsertPts, PIC, LI, DT, TLI, L, CurAST, &SafetyInfo);
// Once we have promoted values across the loop body we have to recursively
@@ -266,9 +268,10 @@
// FIXME: This is really heavy handed. It would be a bit better to use an
// SSAUpdater strategy during promotion that was LCSSA aware and reformed
// it as it went.
- if (Changed) {
+ if (Promoted)
formLCSSARecursively(*L, *DT, LI, SE);
- }
+
+ Changed |= Promoted;
}
// Check that neither this loop nor its parent have had LCSSA broken. LICM is