PM: Check that loop passes preserve a basic set of analyses

A loop pass that didn't preserve this entire set of passes wouldn't
play well with other loop passes, since these are generally a basic
requirement to do any interesting transformations to a loop.

Adds a helper to get the set of analyses a loop pass should preserve,
and checks that any loop pass we run satisfies the requirement.

llvm-svn: 268444

1 files changed, 19 insertions, 0 deletions

diff --git a/llvm/lib/Analysis/LoopPassManager.cpp b/llvm/lib/Analysis/LoopPassManager.cpp
index 76210fa89c0..8bac19a5821 100644
--- a/llvm/lib/Analysis/LoopPassManager.cpp
+++ b/llvm/lib/Analysis/LoopPassManager.cpp
@@ -8,6 +8,12 @@
 //===----------------------------------------------------------------------===//
 
 #include "llvm/Analysis/LoopPassManager.h"
+#include "llvm/Analysis/BasicAliasAnalysis.h"
+#include "llvm/Analysis/GlobalsModRef.h"
+#include "llvm/Analysis/LoopInfo.h"
+#include "llvm/Analysis/ScalarEvolution.h"
+#include "llvm/Analysis/ScalarEvolutionAliasAnalysis.h"
+#include "llvm/IR/Dominators.h"
 
 using namespace llvm;
 
@@ -18,3 +24,16 @@ template class AnalysisManager<Loop>;
 template class InnerAnalysisManagerProxy<LoopAnalysisManager, Function>;
 template class OuterAnalysisManagerProxy<FunctionAnalysisManager, Loop>;
 }
+
+PreservedAnalyses llvm::getLoopPassPreservedAnalyses() {
+  PreservedAnalyses PA;
+  PA.preserve<DominatorTreeAnalysis>();
+  PA.preserve<LoopAnalysis>();
+  PA.preserve<ScalarEvolutionAnalysis>();
+  // TODO: What we really want to do here is preserve an AA category, but that
+  // concept doesn't exist yet.
+  PA.preserve<BasicAA>();
+  PA.preserve<GlobalsAA>();
+  PA.preserve<SCEVAA>();
+  return PA;
+}