[LCSSA] Post-process PHI-nodes created by SSAUpdate when constructing LCSSA form.
Summary:
SSAUpdate might insert PHI-nodes inside loops, which can break LCSSA
form unless we fix it up.
This fixes PR28424.
Reviewers: sanjoy, chandlerc, hfinkel
Subscribers: uabelho, llvm-commits
Differential Revision: http://reviews.llvm.org/D21997
llvm-svn: 275883
diff --git a/llvm/lib/Transforms/Utils/LCSSA.cpp b/llvm/lib/Transforms/Utils/LCSSA.cpp
index 9658966..bee6e24 100644
--- a/llvm/lib/Transforms/Utils/LCSSA.cpp
+++ b/llvm/lib/Transforms/Utils/LCSSA.cpp
@@ -115,7 +115,8 @@
SmallVector<PHINode *, 16> AddedPHIs;
SmallVector<PHINode *, 8> PostProcessPHIs;
- SSAUpdater SSAUpdate;
+ SmallVector<PHINode *, 4> InsertedPHIs;
+ SSAUpdater SSAUpdate(&InsertedPHIs);
SSAUpdate.Initialize(I->getType(), I->getName());
// Insert the LCSSA phi's into all of the exit blocks dominated by the
@@ -184,6 +185,14 @@
// Otherwise, do full PHI insertion.
SSAUpdate.RewriteUse(*UseToRewrite);
+
+ // SSAUpdater might have inserted phi-nodes inside other loops. We'll need
+ // to post-process them to keep LCSSA form.
+ for (PHINode *InsertedPN : InsertedPHIs) {
+ if (auto *OtherLoop = LI.getLoopFor(InsertedPN->getParent()))
+ if (!L->contains(OtherLoop))
+ PostProcessPHIs.push_back(InsertedPN);
+ }
}
// Post process PHI instructions that were inserted into another disjoint