[NewPM] Use the default AA pipeline by default

We almost always want to use the default AA pipeline. It's very easy for
users of PassBuilder to forget to customize the AAManager to use the
default AA pipeline (for example, the NewPM C API forgets to do this).

If somebody wants a custom AA pipeline, similar to what is being done
now with the default AA pipeline registration, they can

  FAM.registerPass([&] { return std::move(MyAA); });

before calling

  PB.registerFunctionAnalyses(FAM);

For example, LTOBackend.cpp and NewPMDriver.cpp do this.

Reviewed By: asbirlea

Differential Revision: https://reviews.llvm.org/D113210

clang/lib/CodeGen/BackendUtil.cpp

@@ -1312,9 +1312,6 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
   get##Ext##PluginInfo().RegisterPassBuilderCallbacks(PB);
 #include "llvm/Support/Extension.def"
 
-  // Register the AA manager first so that our version is the one used.
-  FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
-
   // Register the target library analysis directly and give it a customized
   // preset TLI.
   Triple TargetTriple(TheModule->getTargetTriple());

llvm/lib/LTO/LTOBackend.cpp

@@ -251,18 +251,16 @@ static void runNewPMPasses(const Config &Conf, Module &Mod, TargetMachine *TM,
     TLII->disableAllFunctions();
   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
 
-  AAManager AA;
   // Parse a custom AA pipeline if asked to.
   if (!Conf.AAPipeline.empty()) {
+    AAManager AA;
     if (auto Err = PB.parseAAPipeline(AA, Conf.AAPipeline)) {
       report_fatal_error(Twine("unable to parse AA pipeline description '") +
                          Conf.AAPipeline + "': " + toString(std::move(Err)));
     }
-  } else {
-    AA = PB.buildDefaultAAPipeline();
+    // Register the AA manager first so that our version is the one used.
+    FAM.registerPass([&] { return std::move(AA); });
   }
-  // Register the AA manager first so that our version is the one used.
-  FAM.registerPass([&] { return std::move(AA); });
 
   // Register all the basic analyses with the managers.
   PB.registerModuleAnalyses(MAM);

llvm/lib/LTO/ThinLTOCodeGenerator.cpp

@@ -291,11 +291,6 @@ static void optimizeModuleNewPM(Module &TheModule, TargetMachine &TM,
     TLII->disableAllFunctions();
   FAM.registerPass([&] { return TargetLibraryAnalysis(*TLII); });
 
-  AAManager AA = PB.buildDefaultAAPipeline();
-
-  // Register the AA manager first so that our version is the one used.
-  FAM.registerPass([&] { return std::move(AA); });
-
   // Register all the basic analyses with the managers.
   PB.registerModuleAnalyses(MAM);
   PB.registerCGSCCAnalyses(CGAM);

llvm/lib/Passes/PassBuilder.cpp

@@ -413,6 +413,11 @@ void PassBuilder::registerCGSCCAnalyses(CGSCCAnalysisManager &CGAM) {
 }
 
 void PassBuilder::registerFunctionAnalyses(FunctionAnalysisManager &FAM) {
+  // We almost always want the default alias analysis pipeline.
+  // If a user wants a different one, they can register their own before calling
+  // registerFunctionAnalyses().
+  FAM.registerPass([&] { return buildDefaultAAPipeline(); });
+
 #define FUNCTION_ANALYSIS(NAME, CREATE_PASS)                                   \
   FAM.registerPass([&] { return CREATE_PASS; });
 #include "PassRegistry.def"

llvm/tools/llvm-opt-fuzzer/llvm-opt-fuzzer.cpp

@@ -144,7 +144,6 @@ extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
   ModulePassManager MPM;
   ModuleAnalysisManager MAM;
 
-  FAM.registerPass([&] { return PB.buildDefaultAAPipeline(); });
   PB.registerModuleAnalyses(MAM);
   PB.registerCGSCCAnalyses(CGAM);
   PB.registerFunctionAnalyses(FAM);