Add an "addUsedAAAnalyses" helper function

Summary:
Passes that call `getAnalysisIfAvailable<T>` also need to call
`addUsedIfAvailable<T>` in `getAnalysisUsage` to indicate to the
legacy pass manager that it uses `T`.  This contract was being
violated by passes that used `createLegacyPMAAResults`.  This change
fixes this by exposing a helper in AliasAnalysis.h,
`addUsedAAAnalyses`, that is complementary to createLegacyPMAAResults
and does the right thing when called from `getAnalysisUsage`.

Reviewers: chandlerc

Subscribers: mcrosier, llvm-commits

Differential Revision: http://reviews.llvm.org/D17010

llvm-svn: 260183

include/llvm/Analysis/AliasAnalysis.h

@@ -1057,8 +1057,16 @@ ImmutablePass *createExternalAAWrapperPass(
 /// A helper for the legacy pass manager to create a \c AAResults
 /// object populated to the best of our ability for a particular function when
 /// inside of a \c ModulePass or a \c CallGraphSCCPass.
+///
+/// If a \c ModulePass or a \c CallGraphSCCPass calls \p
+/// createLegacyPMAAResults, it also needs to call \p addUsedAAAnalyses in \p
+/// getAnalysisUsage.
 AAResults createLegacyPMAAResults(Pass &P, Function &F, BasicAAResult &BAR);
 
+/// A helper for the legacy pass manager to populate \p AU to add uses to make
+/// sure the analyses required by \p createLegacyPMAAResults are available.
+void addUsedAAAnalyses(AnalysisUsage &AU);
+
 } // End llvm namespace
 
 #endif

lib/Analysis/AliasAnalysis.cpp

@@ -563,3 +563,14 @@ bool llvm::isIdentifiedObject(const Value *V) {
 bool llvm::isIdentifiedFunctionLocal(const Value *V) {
   return isa<AllocaInst>(V) || isNoAliasCall(V) || isNoAliasArgument(V);
 }
+
+void llvm::addUsedAAAnalyses(AnalysisUsage &AU) {
+  // This function needs to be in sync with llvm::createLegacyPMAAResults -- if
+  // more alias analyses are added to llvm::createLegacyPMAAResults, they need
+  // to be added here also.
+  AU.addUsedIfAvailable<ScopedNoAliasAAWrapperPass>();
+  AU.addUsedIfAvailable<TypeBasedAAWrapperPass>();
+  AU.addUsedIfAvailable<objcarc::ObjCARCAAWrapperPass>();
+  AU.addUsedIfAvailable<GlobalsAAWrapperPass>();
+  AU.addUsedIfAvailable<CFLAAWrapperPass>();
+}

lib/Transforms/IPO/ArgumentPromotion.cpp

@@ -68,6 +68,7 @@ namespace {
     void getAnalysisUsage(AnalysisUsage &AU) const override {
       AU.addRequired<AssumptionCacheTracker>();
       AU.addRequired<TargetLibraryInfoWrapperPass>();
+      addUsedAAAnalyses(AU);
       CallGraphSCCPass::getAnalysisUsage(AU);
     }
 

lib/Transforms/IPO/FunctionAttrs.cpp

@@ -64,6 +64,7 @@ struct PostOrderFunctionAttrs : public CallGraphSCCPass {
     AU.setPreservesCFG();
     AU.addRequired<AssumptionCacheTracker>();
     AU.addRequired<TargetLibraryInfoWrapperPass>();
+    addUsedAAAnalyses(AU);
     CallGraphSCCPass::getAnalysisUsage(AU);
   }
 

lib/Transforms/IPO/Inliner.cpp

@@ -58,6 +58,7 @@ Inliner::Inliner(char &ID, bool InsertLifetime)
 void Inliner::getAnalysisUsage(AnalysisUsage &AU) const {
   AU.addRequired<AssumptionCacheTracker>();
   AU.addRequired<TargetLibraryInfoWrapperPass>();
+  addUsedAAAnalyses(AU);
   CallGraphSCCPass::getAnalysisUsage(AU);
 }
 

test/Analysis/alias-analysis-uses.ll

@@ -0,0 +1,10 @@
+; RUN: opt -debug-pass=Executions -globals-aa -functionattrs -disable-output < %s 2>&1 | FileCheck %s
+
+; CHECK: Executing Pass 'Globals Alias Analysis'
+; CHECK-NOT: Freeing Pass 'Globals Alias Analysis'
+; CHECK: Executing Pass 'Deduce function attributes'
+; CHECK: Freeing Pass 'Globals Alias Analysis'
+
+define void @test(i8* %p) {
+  ret void
+}