[MemorySSA] Fix existing phis when inserting defs.
Summary:
When inserting a new Def, and inserting Phis in the IDF when needed,
also mark the already existing Phis in the IDF as non-optimized, since
these may need fixing as well.
In the test attached, there is a Phi in the IDF that happens to be
trivial, and is wrongfully removed by the call to getLastDef that
follows. This is a valid situation and the existing IDF Phis need to
marked as "may need fixing" as well.
Resolves PR43044.
Reviewers: george.burgess.iv
Subscribers: Prazek, sanjoy.google, llvm-commits
Tags: #llvm
Differential Revision: https://reviews.llvm.org/D66495
llvm-svn: 369464
diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
index 87818c5..e63a9b8 100644
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -341,16 +341,20 @@
IDFs.setDefiningBlocks(DefiningBlocks);
IDFs.calculate(IDFBlocks);
SmallVector<AssertingVH<MemoryPhi>, 4> NewInsertedPHIs;
- for (auto *BBIDF : IDFBlocks)
- if (!MSSA->getMemoryAccess(BBIDF)) {
- auto *MPhi = MSSA->createMemoryPhi(BBIDF);
+ for (auto *BBIDF : IDFBlocks) {
+ auto *MPhi = MSSA->getMemoryAccess(BBIDF);
+ if (!MPhi) {
+ MPhi = MSSA->createMemoryPhi(BBIDF);
NewInsertedPHIs.push_back(MPhi);
- // Add the phis created into the IDF blocks to NonOptPhis, so they are
- // not optimized out as trivial by the call to getPreviousDefFromEnd
- // below. Once they are complete, all these Phis are added to the
- // FixupList, and removed from NonOptPhis inside fixupDefs().
- NonOptPhis.insert(MPhi);
}
+ // Add the phis created into the IDF blocks to NonOptPhis, so they are
+ // not optimized out as trivial by the call to getPreviousDefFromEnd
+ // below. Once they are complete, all these Phis are added to the
+ // FixupList, and removed from NonOptPhis inside fixupDefs().
+ // Existing Phis in IDF may need fixing as well, and potentially be
+ // trivial before this insertion, hence add all IDF Phis. See PR43044.
+ NonOptPhis.insert(MPhi);
+ }
for (auto &MPhi : NewInsertedPHIs) {
auto *BBIDF = MPhi->getBlock();