[GlobalsModRef] Add invalidate method

[asbirlea]

Summary

Add invalidate method to GlobalsAA.

[MaskRay]

llvm/lib/Analysis/GlobalsModRef.cpp

813

M can be omitted as well.

[tejohnson]

Is this a bugfix and should there be a test case?

[asbirlea]

Not a bug fix, but a prerequisite for a change I'm working on for the new pass manager, requiring all passes to have an invalidate method.
I sent it for review to get another pair of eyes on the invalidate implementation in case I missed something.

[tejohnson]

In D72818#1824398, @asbirlea wrote:

Not a bug fix, but a prerequisite for a change I'm working on for the new pass manager, requiring all passes to have an invalidate method.
I sent it for review to get another pair of eyes on the invalidate implementation in case I missed something.

Ok thanks. Can you add a comment to it explaining the rationale, I see that the existing invalidate methods tend to comment on when/why they are invalidated.
I'm unfortunately not very familiar with this aspect of the pass manager, but the change seems reasonable (I assume we were never invalidating before?).

[asbirlea]

Address comment.

[asbirlea]

Add comment explaining invalidate rational.
GlobalsAA is stateless and is preserved, unless it's explicitly invalidated.

[tejohnson]

LGTM. Thanks for the explanation.

[thakis]

This breaks check-clang everywhere, see e.g. http://45.33.8.238/linux/7798/step_7.txt

llvm/include/llvm/Analysis/GlobalsModRef.h

class GlobalsAAResult : public AAResultBase<GlobalsAAResult> {
   explicit GlobalsAAResult(
       const DataLayout &DL,
       std::function<const TargetLibraryInfo &(Function &F)> GetTLI);
 
 public:
   GlobalsAAResult(GlobalsAAResult &&Arg);
   ~GlobalsAAResult();
 
+  bool invalidate(Module &M, const PreservedAnalyses &PA,
+                  ModuleAnalysisManager::Invalidator &);
+
   static GlobalsAAResult
   analyzeModule(Module &M,
                 std::function<const TargetLibraryInfo &(Function &F)> GetTLI,
                 CallGraph &CG);
 
   //------------------------------------------------
   // Implement the AliasAnalysis API
   //

llvm/lib/Analysis/GlobalsModRef.cpp

do {
     // false.
     return false;
   } while (!Inputs.empty());
 
   // If all the inputs to V were definitively no-alias, then V is no-alias.
   return true;
 }
 
+bool GlobalsAAResult::invalidate(Module &, const PreservedAnalyses &PA,
+                                 ModuleAnalysisManager::Invalidator &) {
+  // Check whether the analysis has been explicitly invalidated. Otherwise, it's
+  // stateless and remains preserved.
+  auto PAC = PA.getChecker<GlobalsAA>();
+  return !PAC.preservedWhenStateless();
+}
+
 /// alias - If one of the pointers is to a global that we are tracking, and the
 /// other is some random pointer, we know there cannot be an alias, because the
 /// address of the global isn't taken.
 AliasResult GlobalsAAResult::alias(const MemoryLocation &LocA,
                                    const MemoryLocation &LocB,
                                    AAQueryInfo &AAQI) {
   // Get the base object these pointers point to.
   const Value *UV1 = GetUnderlyingObject(LocA.Ptr, DL);