[AA] Change RunEarly to be a Boolean Flag in ExternalAAWrapper

[Chengjunp]

Change the previous runEarly virtual function in ExternalAAWrapper to be a boolean flag.

[llvmbot]

@llvm/pr-subscribers-llvm-analysis

@llvm/pr-subscribers-backend-nvptx

Author: Chengjun (Chengjunp)

Changes

Change the previous runEarly virtual function in ExternalAAWrapper to be a boolean flag.

---

Full diff: https://github.com/llvm/llvm-project/pull/139158.diff

3 Files Affected:

• (modified) llvm/include/llvm/Analysis/AliasAnalysis.h (+9-4)
• (modified) llvm/lib/Analysis/AliasAnalysis.cpp (+2-2)
• (modified) llvm/lib/Target/NVPTX/NVPTXAliasAnalysis.h (+3-3)

diff --git a/llvm/include/llvm/Analysis/AliasAnalysis.h b/llvm/include/llvm/Analysis/AliasAnalysis.h
index d23b81854c9ea..fad8bf7c8faea 100644
--- a/llvm/include/llvm/Analysis/AliasAnalysis.h
+++ b/llvm/include/llvm/Analysis/AliasAnalysis.h
@@ -1013,17 +1013,22 @@ struct ExternalAAWrapperPass : ImmutablePass {
 
   explicit ExternalAAWrapperPass(CallbackT CB);
 
-  /// Returns whether this external AA should run before Basic AA.
+  /// Flag indicating whether this external AA should run before Basic AA.
   ///
-  /// By default, external AA passes are run after Basic AA. If this returns
-  /// true, the external AA will be run before Basic AA during alias analysis.
+  /// This flag is for LegacyPassManager only. To run an external AA early
+  /// with the NewPassManager, override the registerEarlyDefaultAliasAnalyses
+  /// method on the target machine.
+  ///
+  /// By default, external AA passes are run after Basic AA. If this flag is
+  /// set to true, the external AA will be run before Basic AA during alias
+  /// analysis.
   ///
   /// For some targets, we prefer to run the external AA early to improve
   /// compile time as it has more target-specific information. This is
   /// particularly useful when the external AA can provide more precise results
   /// than Basic AA so that Basic AA does not need to spend time recomputing
   /// them.
-  virtual bool runEarly() { return false; }
+  bool RunEarly = false;
 
   void getAnalysisUsage(AnalysisUsage &AU) const override {
     AU.setPreservesAll();
diff --git a/llvm/lib/Analysis/AliasAnalysis.cpp b/llvm/lib/Analysis/AliasAnalysis.cpp
index 27bd179a58ede..20c8ce67acbac 100644
--- a/llvm/lib/Analysis/AliasAnalysis.cpp
+++ b/llvm/lib/Analysis/AliasAnalysis.cpp
@@ -741,7 +741,7 @@ bool AAResultsWrapperPass::runOnFunction(Function &F) {
 
   // Add any target-specific alias analyses that should be run early.
   auto *ExtWrapperPass = getAnalysisIfAvailable<ExternalAAWrapperPass>();
-  if (ExtWrapperPass && ExtWrapperPass->runEarly() && ExtWrapperPass->CB) {
+  if (ExtWrapperPass && ExtWrapperPass->RunEarly && ExtWrapperPass->CB) {
     LLVM_DEBUG(dbgs() << "AAResults register Early ExternalAA: "
                       << ExtWrapperPass->getPassName() << "\n");
     ExtWrapperPass->CB(*this, F, *AAR);
@@ -777,7 +777,7 @@ bool AAResultsWrapperPass::runOnFunction(Function &F) {
 
   // If available, run an external AA providing callback over the results as
   // well.
-  if (ExtWrapperPass && !ExtWrapperPass->runEarly() && ExtWrapperPass->CB) {
+  if (ExtWrapperPass && !ExtWrapperPass->RunEarly && ExtWrapperPass->CB) {
     LLVM_DEBUG(dbgs() << "AAResults register Late ExternalAA: "
                       << ExtWrapperPass->getPassName() << "\n");
     ExtWrapperPass->CB(*this, F, *AAR);
diff --git a/llvm/lib/Target/NVPTX/NVPTXAliasAnalysis.h b/llvm/lib/Target/NVPTX/NVPTXAliasAnalysis.h
index 430fcd741c1b6..e706f1ebc00fa 100644
--- a/llvm/lib/Target/NVPTX/NVPTXAliasAnalysis.h
+++ b/llvm/lib/Target/NVPTX/NVPTXAliasAnalysis.h
@@ -90,14 +90,14 @@ class NVPTXExternalAAWrapper : public ExternalAAWrapperPass {
 public:
   static char ID;
 
-  bool runEarly() override { return true; }
-
   NVPTXExternalAAWrapper()
       : ExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
           if (auto *WrapperPass =
                   P.getAnalysisIfAvailable<NVPTXAAWrapperPass>())
             AAR.addAAResult(WrapperPass->getResult());
-        }) {}
+        }) {
+    RunEarly = true;
+  }
 
   StringRef getPassName() const override {
     return "NVPTX Address space based Alias Analysis Wrapper";

[arsenm]

Make it a constructor argument (which you could hide under an EarlyExternalAA and LateExternalAA wrapper class)

[Chengjunp]

Could you further explain how to "hide" RunEarly under an EarlyExternalAA and LateExternalAA wrapper class?

Do you mean making the constructor of ExternalAAWrapperPass to be

explicit ExternalAAWrapperPass(CallbackT CB, bool RunEarly = false);

and having

  NVPTXExternalAAWrapper()
      : ExternalAAWrapperPass([](Pass &P, Function &, AAResults &AAR) {
          if (auto *WrapperPass =
                  P.getAnalysisIfAvailable<NVPTXAAWrapperPass>())
            AAR.addAAResult(WrapperPass->getResult());
        }, /*RunEarly=*/true) {}

?

[Prince781]

which you could hide under an EarlyExternalAA and LateExternalAA wrapper class

What's the intent of doing this? To make it possible to use isa<> to determine whether an AA should run early?

[arsenm]

Do you mean making the constructor of ExternalAAWrapperPass to be

Yes

What's the intent of doing this? To make it possible to use isa<> to determine whether an AA should run early?

No, passes don't do the RTTI thing. This is the minimal amount of typing for a pass to swap between the two forms