[AliasAnalysis/NewPassManager] Invalidate AAManager less often.

Summary:
This is a redo of D60914.

The objective is to not invalidate AAManager, which is stateless, unless
there is an explicit invalidate in one of the AAResults.

To achieve this, this patch adds an API to PAC, to check precisely this:
is this analysis not invalidated explicitly == is this analysis not abandoned == is this analysis stateless, so preserved without explicitly being marked as preserved by everyone

Reviewers: chandlerc

Subscribers: mehdi_amini, jlebar, george.burgess.iv, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D61284

llvm-svn: 359622

include/llvm/Analysis/AliasAnalysis.h

@@ -1096,6 +1096,11 @@ bool isIdentifiedFunctionLocal(const Value *V);
 /// This manager effectively wraps the AnalysisManager for registering alias
 /// analyses. When you register your alias analysis with this manager, it will
 /// ensure the analysis itself is registered with its AnalysisManager.
+///
+/// The result of this analysis is only invalidated if one of the particular
+/// aggregated AA results end up being invalidated. This removes the need to
+/// explicitly preserve the results of `AAManager`. Note that analyses should no
+/// longer be registered once the `AAManager` is run.
 class AAManager : public AnalysisInfoMixin<AAManager> {
 public:
   using Result = AAResults;

include/llvm/IR/PassManager.h

@@ -286,6 +286,13 @@ public:
                               PA.PreservedIDs.count(ID));
     }
 
+    /// Return true if the checker's analysis was not abandoned, i.e. it was not
+    /// explicitly invalidated. Even if the analysis is not explicitly
+    /// preserved, if the analysis is known stateless, then it is preserved.
+    bool preservedWhenStateless() {
+      return !IsAbandoned;
+    }
+
     /// Returns true if the checker's analysis was not abandoned and either
     ///  - \p AnalysisSetT is explicitly preserved or
     ///  - all analyses are preserved.

lib/Analysis/AliasAnalysis.cpp

@@ -79,12 +79,16 @@ AAResults::~AAResults() {
 
 bool AAResults::invalidate(Function &F, const PreservedAnalyses &PA,
                            FunctionAnalysisManager::Invalidator &Inv) {
-  // Check if the AA manager itself has been invalidated.
+  // AAResults preserves the AAManager by default, due to the stateless nature
+  // of AliasAnalysis. There is no need to check whether it has been preserved
+  // explicitly. Check if any module dependency was invalidated and caused the
+  // AAManager to be invalidated. Invalidate ourselves in that case.
   auto PAC = PA.getChecker<AAManager>();
-  if (!PAC.preserved() && !PAC.preservedSet<AllAnalysesOn<Function>>())
-    return true; // The manager needs to be blown away, clear everything.
+  if (!PAC.preservedWhenStateless())
+    return true;
 
-  // Check all of the dependencies registered.
+  // Check if any of the function dependencies were invalidated, and invalidate
+  // ourselves in that case.
   for (AnalysisKey *ID : AADeps)
     if (Inv.invalidate(ID, F, PA))
       return true;

test/Analysis/MemoryDependenceAnalysis/invalidation.ll

@@ -1,17 +1,16 @@
 ; Test that memdep gets invalidated when the analyses it depends on are
 ; invalidated.
 ;
-; Check AA specifically.
+; Check AA. AA is stateless, there's nothing to invalidate.
 ; RUN: opt -disable-output -debug-pass-manager -aa-pipeline='basic-aa' %s 2>&1 \
 ; RUN:     -passes='require<memdep>,invalidate<aa>,gvn' \
 ; RUN:     | FileCheck %s --check-prefix=CHECK-AA-INVALIDATE
 ; CHECK-AA-INVALIDATE: Running pass: RequireAnalysisPass
 ; CHECK-AA-INVALIDATE: Running analysis: MemoryDependenceAnalysis
 ; CHECK-AA-INVALIDATE: Running pass: InvalidateAnalysisPass
-; CHECK-AA-INVALIDATE: Invalidating analysis: AAManager
-; CHECK-AA-INVALIDATE: Invalidating analysis: MemoryDependenceAnalysis
+; CHECK-NOT-AA-INVALIDATE: Invalidating analysis: MemoryDependenceAnalysis
 ; CHECK-AA-INVALIDATE: Running pass: GVN
-; CHECK-AA-INVALIDATE: Running analysis: MemoryDependenceAnalysis
+; CHECK-NOT-AA-INVALIDATE: Running analysis: MemoryDependenceAnalysis
 ;
 ; Check domtree specifically.
 ; RUN: opt -disable-output -debug-pass-manager %s 2>&1 \

test/Other/new-pass-manager.ll

@@ -355,13 +355,11 @@
 ; CHECK-AA-MODULE-INVALIDATE: Running analysis: AAManager
 ; CHECK-AA-MODULE-INVALIDATE: Finished llvm::Function pass manager run
 ; CHECK-AA-MODULE-INVALIDATE: Running pass: InvalidateAnalysisPass
-; CHECK-AA-MODULE-INVALIDATE: Invalidating analysis: AAManager
 ; CHECK-AA-MODULE-INVALIDATE: Invalidating analysis: GlobalsAA
 ; CHECK-AA-MODULE-INVALIDATE: Running pass: RequireAnalysisPass
 ; CHECK-AA-MODULE-INVALIDATE: Running analysis: GlobalsAA
 ; CHECK-AA-MODULE-INVALIDATE: Starting llvm::Function pass manager run
 ; CHECK-AA-MODULE-INVALIDATE: Running pass: AAEvaluator
-; CHECK-AA-MODULE-INVALIDATE: Running analysis: AAManager
 ; CHECK-AA-MODULE-INVALIDATE: Finished llvm::Function pass manager run
 ; CHECK-AA-MODULE-INVALIDATE: Finished llvm::Module pass manager run
 

unittests/Transforms/Scalar/LoopPassManagerTest.cpp

@@ -572,7 +572,6 @@ TEST_F(LoopPassManagerTest, InvalidationOfBundledAnalyses) {
   // invalidation and running.
   EXPECT_CALL(MFPHandle, run(HasName("f"), _))
       .WillOnce(Return(getLoopPassPreservedAnalyses()));
-  EXPECT_CALL(MLAHandle, invalidate(_, _, _)).Times(3);
   EXPECT_CALL(MLAHandle, run(HasName("loop.0.0"), _, _));
   EXPECT_CALL(MLAHandle, run(HasName("loop.0.1"), _, _));
   EXPECT_CALL(MLAHandle, run(HasName("loop.0"), _, _));