[PATCH] D87137: [EarlyCSE] Explicitly require AAResultsWrapperPass.

[Florian Hahn via Phabricator via llvm-commits]

fhahn created this revision.
fhahn added reviewers: asbirlea, george.burgess.iv, efriedma.
Herald added a subscriber: hiraditya.
Herald added a project: LLVM.
fhahn requested review of this revision.

The MemorySSAWrapperPass depends on AAResultsWrapperPass and if
MemorySSA is preserved but AAResultsWrapperPass is not, this could lead
to a crash when updating the last user of the MemorySSAWrapperPass.

Alternatively AAResultsWrapperPass could be marked preserved by GVN, but
I am not sure if that would be safe. I am not sure what is required in
order to preserve AAResultsWrapperPass. At the moment, it seems like a
couple of passes that do similar transforms to GVN are preserving it.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D87137

Files:
  llvm/lib/Transforms/Scalar/EarlyCSE.cpp
  llvm/lib/Transforms/Scalar/GVN.cpp
  llvm/test/Transforms/EarlyCSE/reuse-preserved-memoryssa.ll


Index: llvm/test/Transforms/EarlyCSE/reuse-preserved-memoryssa.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/EarlyCSE/reuse-preserved-memoryssa.ll
@@ -0,0 +1,7 @@
+; RUN: opt -memoryssa -gvn -early-cse-memssa %s -S | FileCheck %s
+
+; CHECK: define void @foo(
+
+define void @foo() {
+  ret void
+}
Index: llvm/lib/Transforms/Scalar/GVN.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/GVN.cpp
+++ llvm/lib/Transforms/Scalar/GVN.cpp
@@ -2850,7 +2850,6 @@
     if (Impl.isMemDepEnabled())
       AU.addRequired<MemoryDependenceWrapperPass>();
     AU.addRequired<AAResultsWrapperPass>();
-
     AU.addPreserved<DominatorTreeWrapperPass>();
     AU.addPreserved<GlobalsAAWrapperPass>();
     AU.addPreserved<TargetLibraryInfoWrapperPass>();
Index: llvm/lib/Transforms/Scalar/EarlyCSE.cpp
===================================================================
--- llvm/lib/Transforms/Scalar/EarlyCSE.cpp
+++ llvm/lib/Transforms/Scalar/EarlyCSE.cpp
@@ -1463,6 +1463,7 @@
     AU.addRequired<TargetLibraryInfoWrapperPass>();
     AU.addRequired<TargetTransformInfoWrapperPass>();
     if (UseMemorySSA) {
+      AU.addRequired<AAResultsWrapperPass>();
       AU.addRequired<MemorySSAWrapperPass>();
       AU.addPreserved<MemorySSAWrapperPass>();
     }
@@ -1504,6 +1505,7 @@
                       "Early CSE w/ MemorySSA", false, false)
 INITIALIZE_PASS_DEPENDENCY(TargetTransformInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(AssumptionCacheTracker)
+INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(TargetLibraryInfoWrapperPass)
 INITIALIZE_PASS_DEPENDENCY(MemorySSAWrapperPass)


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