[PATCH] D15853: [PGO]: Simplify coverage data lowering code

[David Li via cfe-commits]

davidxl updated this revision to Diff 44127.
davidxl added a comment.

Update patch to reduce overhead: Only record names for unused functions.


http://reviews.llvm.org/D15853

Files:
  lib/CodeGen/CodeGenPGO.cpp
  lib/CodeGen/CoverageMappingGen.cpp
  lib/CodeGen/CoverageMappingGen.h

Index: lib/CodeGen/CoverageMappingGen.h
===================================================================
--- lib/CodeGen/CoverageMappingGen.h
+++ lib/CodeGen/CoverageMappingGen.h
@@ -54,6 +54,7 @@
   CoverageSourceInfo &SourceInfo;
   llvm::SmallDenseMap<const FileEntry *, unsigned, 8> FileEntries;
   std::vector<llvm::Constant *> FunctionRecords;
+  std::vector<llvm::Constant *> FunctionNames;
   llvm::StructType *FunctionRecordTy;
   std::string CoverageMappings;
 
@@ -70,7 +71,8 @@
   void addFunctionMappingRecord(llvm::GlobalVariable *FunctionName,
                                 StringRef FunctionNameValue,
                                 uint64_t FunctionHash,
-                                const std::string &CoverageMapping);
+                                const std::string &CoverageMapping,
+                                bool isUsed = true);
 
   /// \brief Emit the coverage mapping data for a translation unit.
   void emit();
Index: lib/CodeGen/CoverageMappingGen.cpp
===================================================================
--- lib/CodeGen/CoverageMappingGen.cpp
+++ lib/CodeGen/CoverageMappingGen.cpp
@@ -910,11 +910,11 @@
 }
 
 void CoverageMappingModuleGen::addFunctionMappingRecord(
-    llvm::GlobalVariable *NamePtr, StringRef NameValue,
-    uint64_t FuncHash, const std::string &CoverageMapping) {
+    llvm::GlobalVariable *NamePtr, StringRef NameValue, uint64_t FuncHash,
+    const std::string &CoverageMapping, bool isUsed) {
   llvm::LLVMContext &Ctx = CGM.getLLVMContext();
   if (!FunctionRecordTy) {
-    #define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) LLVMType,
+#define COVMAP_FUNC_RECORD(Type, LLVMType, Name, Init) LLVMType,
     llvm::Type *FunctionRecordTypes[] = {
       #include "llvm/ProfileData/InstrProfData.inc"
     };
@@ -929,6 +929,9 @@
   };
   FunctionRecords.push_back(llvm::ConstantStruct::get(
       FunctionRecordTy, makeArrayRef(FunctionRecordVals)));
+  if (!isUsed)
+    FunctionNames.push_back(
+        llvm::ConstantExpr::getBitCast(NamePtr, llvm::Type::getInt8PtrTy(Ctx)));
   CoverageMappings += CoverageMapping;
 
   if (CGM.getCodeGenOpts().DumpCoverageMapping) {
@@ -1023,6 +1026,17 @@
 
   // Make sure the data doesn't get deleted.
   CGM.addUsedGlobal(CovData);
+  // Create the deferred function records array
+  if (!FunctionNames.empty()) {
+    auto NamesArrTy = llvm::ArrayType::get(llvm::Type::getInt8PtrTy(Ctx),
+                                           FunctionNames.size());
+    auto NamesArrVal = llvm::ConstantArray::get(NamesArrTy, FunctionNames);
+    // This variable will *NOT* be emitted to the object file. It is used
+    // to pass the list of names referenced to codegen.
+    new llvm::GlobalVariable(CGM.getModule(), NamesArrTy, true,
+                             llvm::GlobalValue::InternalLinkage, NamesArrVal,
+                             llvm::getCoverageNamesVarName());
+  }
 }
 
 unsigned CoverageMappingModuleGen::getFileID(const FileEntry *File) {
Index: lib/CodeGen/CodeGenPGO.cpp
===================================================================
--- lib/CodeGen/CodeGenPGO.cpp
+++ lib/CodeGen/CodeGenPGO.cpp
@@ -699,7 +699,7 @@
 
   setFuncName(Name, Linkage);
   CGM.getCoverageMapping()->addFunctionMappingRecord(
-      FuncNameVar, FuncName, FunctionHash, CoverageMapping);
+      FuncNameVar, FuncName, FunctionHash, CoverageMapping, false);
 }
 
 void CodeGenPGO::computeRegionCounts(const Decl *D) {


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