[llvm-branch-commits] [llvm] 675be65 - Require chained analyses in BasicAA and AAResults to be transitive

[Bjorn Pettersson via llvm-branch-commits]

Author: Bjorn Pettersson
Date: 2021-01-11T11:50:07+01:00
New Revision: 675be651062476cd0cd4b491b35c275bb03d7b2c

URL: https://github.com/llvm/llvm-project/commit/675be651062476cd0cd4b491b35c275bb03d7b2c
DIFF: https://github.com/llvm/llvm-project/commit/675be651062476cd0cd4b491b35c275bb03d7b2c.diff

LOG: Require chained analyses in BasicAA and AAResults to be transitive

This patch fixes a bug that could result in miscompiles (at least
in an OOT target). The problem could be seen by adding checks that
the DominatorTree used in BasicAliasAnalysis and ValueTracking was
valid (e.g. by adding DT->verify() call before every DT dereference
and then running all tests in test/CodeGen).

Problem was that the LegacyPassManager calculated "last user"
incorrectly for passes such as the DominatorTree when not telling
the pass manager that there was a transitive dependency between
the different analyses. And then it could happen that an incorrect
dominator tree was used when doing alias analysis (which was a pretty
serious bug as the alias analysis result could be invalid).

Fixes: https://bugs.llvm.org/show_bug.cgi?id=48709

Reviewed By: nikic

Differential Revision: https://reviews.llvm.org/D94138

Added: 
    

Modified: 
    llvm/lib/Analysis/AliasAnalysis.cpp
    llvm/lib/Analysis/BasicAliasAnalysis.cpp
    llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp
    llvm/lib/Transforms/Scalar/GVNHoist.cpp

Removed: 
    


################################################################################
diff  --git a/llvm/lib/Analysis/AliasAnalysis.cpp b/llvm/lib/Analysis/AliasAnalysis.cpp
index f5b62ef06a23..fae7a84332fd 100644
--- a/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -883,8 +883,8 @@ bool AAResultsWrapperPass::runOnFunction(Function &F) {
 
 void AAResultsWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
-  AU.addRequired<BasicAAWrapperPass>();
-  AU.addRequired<TargetLibraryInfoWrapperPass>();
+  AU.addRequiredTransitive<BasicAAWrapperPass>();
+  AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
 
   // We also need to mark all the alias analysis passes we will potentially
   // probe in runOnFunction as used here to ensure the legacy pass manager

diff  --git a/llvm/lib/Analysis/BasicAliasAnalysis.cpp b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
index 1440906944eb..313a85ccc4de 100644
--- a/llvm/lib/Analysis/BasicAliasAnalysis.cpp
+++ b/llvm/lib/Analysis/BasicAliasAnalysis.cpp
@@ -1899,9 +1899,9 @@ bool BasicAAWrapperPass::runOnFunction(Function &F) {
 
 void BasicAAWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.setPreservesAll();
-  AU.addRequired<AssumptionCacheTracker>();
-  AU.addRequired<DominatorTreeWrapperPass>();
-  AU.addRequired<TargetLibraryInfoWrapperPass>();
+  AU.addRequiredTransitive<AssumptionCacheTracker>();
+  AU.addRequiredTransitive<DominatorTreeWrapperPass>();
+  AU.addRequiredTransitive<TargetLibraryInfoWrapperPass>();
   AU.addUsedIfAvailable<PhiValuesWrapperPass>();
 }
 

diff  --git a/llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp b/llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp
index 68c79d2a113f..76cc8f402c5a 100644
--- a/llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp
+++ b/llvm/lib/Target/Hexagon/HexagonLoopIdiomRecognition.cpp
@@ -165,7 +165,6 @@ class HexagonLoopIdiomRecognizeLegacyPass : public LoopPass {
     AU.addRequiredID(LoopSimplifyID);
     AU.addRequiredID(LCSSAID);
     AU.addRequired<AAResultsWrapperPass>();
-    AU.addPreserved<AAResultsWrapperPass>();
     AU.addRequired<ScalarEvolutionWrapperPass>();
     AU.addRequired<DominatorTreeWrapperPass>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();

diff  --git a/llvm/lib/Transforms/Scalar/GVNHoist.cpp b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
index e2b40942f300..8d0bd5674964 100644
--- a/llvm/lib/Transforms/Scalar/GVNHoist.cpp
+++ b/llvm/lib/Transforms/Scalar/GVNHoist.cpp
@@ -547,7 +547,6 @@ class GVNHoistLegacyPass : public FunctionPass {
     AU.addPreserved<DominatorTreeWrapperPass>();
     AU.addPreserved<MemorySSAWrapperPass>();
     AU.addPreserved<GlobalsAAWrapperPass>();
-    AU.addPreserved<AAResultsWrapperPass>();
   }
 };