https://github.com/dtcxzyw created https://github.com/llvm/llvm-project/pull/139370
Closes https://github.com/llvm/llvm-project/issues/139103.
Closes https://github.com/llvm/llvm-project/issues/139289.
Closes https://github.com/llvm/llvm-project/issues/139308.
>From 7f78ed5851c683c35dc7a48c2fc347dc08b6157f Mon Sep 17 00:00:00 2001
From: Yingwei Zheng <dtcxzyw2333 at gmail.com>
Date: Sat, 10 May 2025 17:31:14 +0800
Subject: [PATCH] [MemorySSAUpdater] Fix iterator invalidation bug in
`applyInsertUpdates`
---
llvm/lib/Analysis/MemorySSAUpdater.cpp | 8 +++-
llvm/test/Analysis/MemorySSA/pr139103.ll | 49 ++++++++++++++++++++++++
2 files changed, 56 insertions(+), 1 deletion(-)
create mode 100644 llvm/test/Analysis/MemorySSA/pr139103.ll
diff --git a/llvm/lib/Analysis/MemorySSAUpdater.cpp b/llvm/lib/Analysis/MemorySSAUpdater.cpp
index aa9f0b6e100c4..ecfecb03c3757 100644
--- a/llvm/lib/Analysis/MemorySSAUpdater.cpp
+++ b/llvm/lib/Analysis/MemorySSAUpdater.cpp
@@ -1119,6 +1119,9 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
if (auto DefsList = MSSA->getWritableBlockDefs(BlockWithDefsToReplace)) {
for (auto &DefToReplaceUses : *DefsList) {
BasicBlock *DominatingBlock = DefToReplaceUses.getBlock();
+ // We defer resetting optimized accesses until all uses are replaced, to
+ // avoid invalidating the iterator.
+ SmallVector<MemoryUseOrDef *, 4> ResetOptimized;
for (Use &U : llvm::make_early_inc_range(DefToReplaceUses.uses())) {
MemoryAccess *Usr = cast<MemoryAccess>(U.getUser());
if (MemoryPhi *UsrPhi = dyn_cast<MemoryPhi>(Usr)) {
@@ -1135,10 +1138,13 @@ void MemorySSAUpdater::applyInsertUpdates(ArrayRef<CFGUpdate> Updates,
assert(IDom && "Block must have a valid IDom.");
U.set(GetLastDef(IDom->getBlock()));
}
- cast<MemoryUseOrDef>(Usr)->resetOptimized();
+ ResetOptimized.push_back(cast<MemoryUseOrDef>(Usr));
}
}
}
+
+ for (auto *Usr : ResetOptimized)
+ Usr->resetOptimized();
}
}
}
diff --git a/llvm/test/Analysis/MemorySSA/pr139103.ll b/llvm/test/Analysis/MemorySSA/pr139103.ll
new file mode 100644
index 0000000000000..252731c4c3bde
--- /dev/null
+++ b/llvm/test/Analysis/MemorySSA/pr139103.ll
@@ -0,0 +1,49 @@
+; RUN: opt -disable-output -passes="loop-mssa(licm,loop-rotate,licm,simple-loop-unswitch<nontrivial>),print<memoryssa>" -verify-memoryssa < %s 2>&1 | FileCheck %s
+
+; Make sure that we update MSSA correctly in this case.
+
+; CHECK-LABEL: MemorySSA for function: test
+; CHECK: for.header2.preheader:
+; CHECK-NEXT: 11 = MemoryPhi({entry.split,liveOnEntry},{for.header,9})
+; CHECK: for.body.us:
+; CHECK-NEXT: 7 = MemoryPhi({for.header2.preheader.split.us,11},{for.header2.us,9})
+; CHECK-NEXT: 8 = MemoryDef(7)->7
+; CHECK-NEXT: store i32 0, ptr %p, align 4
+; CHECK-NEXT: 9 = MemoryDef(8)->8
+; CHECK-NEXT: store i8 0, ptr %p, align 1
+
+define void @test(ptr %p, i1 %cond) {
+entry:
+ br label %for.header
+
+for.header:
+ br i1 false, label %exit.loopexit1, label %for.header2.preheader
+
+for.header2.preheader:
+ br label %for.body
+
+for.header2:
+ br i1 false, label %for.latch, label %for.body
+
+for.body:
+ store i32 0, ptr %p, align 4
+ store i8 0, ptr %p, align 1
+ br i1 %cond, label %for.header2, label %exit.loopexit
+
+for.latch:
+ br i1 false, label %for.inc, label %exit.loopexit1
+
+for.inc:
+ br label %for.header
+
+exit.loopexit:
+ br label %exit
+
+exit.loopexit1:
+ br label %exit
+
+exit:
+ ret void
+}
+;; NOTE: These prefixes are unused and the list is autogenerated. Do not add tests below this line:
+; CHECK: {{.*}}