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

1 files changed, 8 insertions, 0 deletions

diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index e2ca0ab1229..d63e7b0ddad 100644
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/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