[NFC][InstrProf] Refactor InstrProfiling lowering pass (#74970)

Akin other passes - refactored the name to `InstrProfilingLoweringPass` to better communicate what it does, and split the pass part and the transformation part to avoid needing to initialize object state during `::run`.

A subsequent PR will move `InstrLowering` to the .cpp file and rename it to `InstrLowerer`.

Author: mtrofin

clang/lib/CodeGen/BackendUtil.cpp

@@ -982,7 +982,7 @@ void EmitAssemblyHelper::RunOptimizationPipeline(
             getInstrProfOptions(CodeGenOpts, LangOpts))
       PB.registerPipelineStartEPCallback(
           [Options](ModulePassManager &MPM, OptimizationLevel Level) {
-            MPM.addPass(InstrProfiling(*Options, false));
+            MPM.addPass(InstrProfilingLoweringPass(*Options, false));
           });
 
     // TODO: Consider passing the MemoryProfileOutput to the pass builder via

clang/test/CodeGen/pgo-instrumentation.c

@@ -3,15 +3,15 @@
 // Ensure Pass PGOInstrumentationGenPass is invoked.
 // RUN: %clang_cc1 -O2 -fprofile-instrument=llvm %s  -fdebug-pass-manager -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=CHECK-PGOGENPASS-INVOKED-INSTR-GEN --check-prefix=CHECK-INSTRPROF
 // CHECK-PGOGENPASS-INVOKED-INSTR-GEN: Running pass: PGOInstrumentationGen on
-// CHECK-INSTRPROF: Running pass: InstrProfiling on
+// CHECK-INSTRPROF: Running pass: InstrProfilingLoweringPass on
 //
 // Ensure Pass PGOInstrumentationGenPass is not invoked.
 // RUN: %clang_cc1 -O2 -fprofile-instrument=clang %s -fdebug-pass-manager -emit-llvm -o - 2>&1 | FileCheck %s -check-prefix=CHECK-PGOGENPASS-INVOKED-INSTR-GEN-CLANG
 // CHECK-PGOGENPASS-INVOKED-INSTR-GEN-CLANG-NOT: Running pass: PGOInstrumentationGen on
 
 // RUN: %clang_cc1 -O2 -fprofile-instrument=clang %s -fdebug-pass-manager -emit-llvm -o - 2>&1 | FileCheck %s --check-prefix=CHECK-CLANG-INSTRPROF
 // RUN: %clang_cc1 -O0 -fprofile-instrument=clang %s -fdebug-pass-manager -emit-llvm -o - 2>&1 | FileCheck %s --check-prefix=CHECK-CLANG-INSTRPROF
-// CHECK-CLANG-INSTRPROF: Running pass: InstrProfiling on
+// CHECK-CLANG-INSTRPROF: Running pass: InstrProfilingLoweringPass on
 
 // Ensure Pass PGOInstrumentationUsePass is invoked.
 // RUN: llvm-profdata merge -o %t.profdata %S/Inputs/pgotestir.profraw

llvm/include/llvm/Transforms/Instrumentation.h

@@ -52,7 +52,8 @@ Comdat *getOrCreateFunctionComdat(Function &F, Triple &T);
 // Place global in a large section for x86-64 ELF binaries to mitigate
 // relocation overflow pressure. This can be be used for metadata globals that
 // aren't directly accessed by code, which has no performance impact.
-void setGlobalVariableLargeSection(Triple &TargetTriple, GlobalVariable &GV);
+void setGlobalVariableLargeSection(const Triple &TargetTriple,
+                                   GlobalVariable &GV);
 
 // Insert GCOV profiling instrumentation
 struct GCOVOptions {

llvm/include/llvm/Transforms/Instrumentation/InstrProfiling.h

@@ -31,31 +31,46 @@ using LoadStorePair = std::pair<Instruction *, Instruction *>;
 /// Instrumentation based profiling lowering pass. This pass lowers
 /// the profile instrumented code generated by FE or the IR based
 /// instrumentation pass.
-class InstrProfiling : public PassInfoMixin<InstrProfiling> {
+class InstrProfilingLoweringPass
+    : public PassInfoMixin<InstrProfilingLoweringPass> {
+  const InstrProfOptions Options;
+  // Is this lowering for the context-sensitive instrumentation.
+  const bool IsCS = false;
+
 public:
-  InstrProfiling() : IsCS(false) {}
-  InstrProfiling(const InstrProfOptions &Options, bool IsCS = false)
+  InstrProfilingLoweringPass() = default;
+  InstrProfilingLoweringPass(const InstrProfOptions &Options, bool IsCS = false)
       : Options(Options), IsCS(IsCS) {}
 
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
-  bool run(Module &M,
-           std::function<const TargetLibraryInfo &(Function &F)> GetTLI);
+};
+
+class InstrProfiling final {
+public:
+  InstrProfiling(Module &M, const InstrProfOptions &Options,
+                 std::function<const TargetLibraryInfo &(Function &F)> GetTLI,
+                 bool IsCS)
+      : M(M), Options(Options), TT(Triple(M.getTargetTriple())), IsCS(IsCS),
+        GetTLI(GetTLI) {}
+
+  bool lower();
 
 private:
-  InstrProfOptions Options;
-  Module *M;
-  Triple TT;
+  Module &M;
+  const InstrProfOptions Options;
+  const Triple TT;
+  // Is this lowering for the context-sensitive instrumentation.
+  const bool IsCS;
+
   std::function<const TargetLibraryInfo &(Function &F)> GetTLI;
   struct PerFunctionProfileData {
-    uint32_t NumValueSites[IPVK_Last + 1];
+    uint32_t NumValueSites[IPVK_Last + 1] = {};
     GlobalVariable *RegionCounters = nullptr;
     GlobalVariable *DataVar = nullptr;
     GlobalVariable *RegionBitmaps = nullptr;
     uint32_t NumBitmapBytes = 0;
 
-    PerFunctionProfileData() {
-      memset(NumValueSites, 0, sizeof(uint32_t) * (IPVK_Last + 1));
-    }
+    PerFunctionProfileData() = default;
   };
   DenseMap<GlobalVariable *, PerFunctionProfileData> ProfileDataMap;
   /// If runtime relocation is enabled, this maps functions to the load
@@ -64,11 +79,8 @@ class InstrProfiling : public PassInfoMixin<InstrProfiling> {
   std::vector<GlobalValue *> CompilerUsedVars;
   std::vector<GlobalValue *> UsedVars;
   std::vector<GlobalVariable *> ReferencedNames;
-  GlobalVariable *NamesVar;
-  size_t NamesSize;
-
-  // Is this lowering for the context-sensitive instrumentation.
-  bool IsCS;
+  GlobalVariable *NamesVar = nullptr;
+  size_t NamesSize = 0;
 
   // vector of counter load/store pairs to be register promoted.
   std::vector<LoadStorePair> PromotionCandidates;

llvm/lib/Passes/PassBuilderPipelines.cpp

@@ -810,7 +810,7 @@ void PassBuilder::addPGOInstrPasses(ModulePassManager &MPM,
   Options.DoCounterPromotion = true;
   Options.UseBFIInPromotion = IsCS;
   Options.Atomic = AtomicCounterUpdate;
-  MPM.addPass(InstrProfiling(Options, IsCS));
+  MPM.addPass(InstrProfilingLoweringPass(Options, IsCS));
 }
 
 void PassBuilder::addPGOInstrPassesForO0(
@@ -837,7 +837,7 @@ void PassBuilder::addPGOInstrPassesForO0(
   Options.DoCounterPromotion = false;
   Options.UseBFIInPromotion = IsCS;
   Options.Atomic = AtomicCounterUpdate;
-  MPM.addPass(InstrProfiling(Options, IsCS));
+  MPM.addPass(InstrProfilingLoweringPass(Options, IsCS));
 }
 
 static InlineParams getInlineParamsFromOptLevel(OptimizationLevel Level) {

llvm/lib/Passes/PassRegistry.def

@@ -77,7 +77,7 @@ MODULE_PASS("inliner-wrapper-no-mandatory-first",
             ModuleInlinerWrapperPass(getInlineParams(), false))
 MODULE_PASS("insert-gcov-profiling", GCOVProfilerPass())
 MODULE_PASS("instrorderfile", InstrOrderFilePass())
-MODULE_PASS("instrprof", InstrProfiling())
+MODULE_PASS("instrprof", InstrProfilingLoweringPass())
 MODULE_PASS("internalize", InternalizePass())
 MODULE_PASS("invalidate<all>", InvalidateAllAnalysesPass())
 MODULE_PASS("iroutliner", IROutlinerPass())