[Coverage] Respect function linkage in PGO name variables

Fix a crash in emitBuiltinCall() which occurs because we drop function
linkage information when creating SILCoverageMaps.

include/swift/SIL/SILCoverageMap.h

@@ -60,6 +60,9 @@ private:
   // The mangled name of the function covered by this mapping.
   StringRef Name;
 
+  // Whether or not the covered function may have external linkage.
+  bool External;
+
   // The coverage hash of the function covered by this mapping.
   uint64_t Hash;
 
@@ -80,14 +83,14 @@ private:
   SILCoverageMap &operator=(const SILCoverageMap &) = delete;
 
   /// Private constructor. Create these using SILCoverageMap::create.
-  SILCoverageMap(uint64_t Hash);
+  SILCoverageMap(uint64_t Hash, bool External);
 
 public:
   ~SILCoverageMap();
 
   static SILCoverageMap *
-  create(SILModule &M, StringRef Filename, StringRef Name, uint64_t Hash,
-         ArrayRef<MappedRegion> MappedRegions,
+  create(SILModule &M, StringRef Filename, StringRef Name, bool External,
+         uint64_t Hash, ArrayRef<MappedRegion> MappedRegions,
          ArrayRef<llvm::coverage::CounterExpression> Expressions);
 
   /// Return the name of the source file where this mapping is found.
@@ -96,6 +99,9 @@ public:
   /// Return the mangled name of the function this mapping covers.
   StringRef getName() const { return Name; }
 
+  /// Check whether the covered function may have external linkage.
+  bool isPossiblyUsedExternally() const { return External; }
+
   /// Return the coverage hash for function this mapping covers.
   uint64_t getHash() const { return Hash; }
 

lib/IRGen/GenCoverage.cpp

@@ -104,7 +104,10 @@ void IRGenModule::emitCoverageMapping() {
     W.write(OS);
 
     std::string NameValue = llvm::getPGOFuncName(
-        M.getName(), llvm::GlobalValue::LinkOnceAnyLinkage, M.getFile());
+        M.getName(),
+        M.isPossiblyUsedExternally() ? llvm::GlobalValue::ExternalLinkage
+                                     : llvm::GlobalValue::PrivateLinkage,
+        M.getFile());
     llvm::GlobalVariable *NamePtr = llvm::createPGOFuncNameVar(
         *getModule(), llvm::GlobalValue::LinkOnceAnyLinkage, NameValue);
 

lib/IRGen/GenFunc.cpp

@@ -1806,27 +1806,30 @@ void irgen::emitBuiltinCall(IRGenFunction &IGF, Identifier FnId,
   // At that stage, the function name GV used by the profiling pass is hidden.
   // Fix the intrinsic call here by pointing it to the correct GV.
   if (IID == llvm::Intrinsic::instrprof_increment) {
-    // Extract the function name.
+    // Extract the PGO function name.
     auto *NameGEP = cast<llvm::User>(args.claimNext());
-    auto *NameGV = cast<llvm::GlobalVariable>(NameGEP->getOperand(0));
-    auto *NameC = NameGV->getInitializer();
-    StringRef Name = cast<llvm::ConstantDataArray>(NameC)->getRawDataValues();
+    auto *NameGV = dyn_cast<llvm::GlobalVariable>(NameGEP->stripPointerCasts());
+    if (NameGV) {
+      auto *NameC = NameGV->getInitializer();
+      StringRef Name = cast<llvm::ConstantDataArray>(NameC)->getRawDataValues();
+      StringRef PGOFuncName = Name.rtrim(StringRef("\0", 1));
 
-    // Find the existing function name pointer.
-    std::string NameValue = llvm::getInstrProfNameVarPrefix();
-    NameValue += Name;
-    StringRef ProfName = StringRef(NameValue).rtrim(StringRef("\0", 1));
-    auto *FuncNamePtr = IGF.IGM.Module.getNamedGlobal(ProfName);
-    assert(FuncNamePtr && "No function name pointer for counter update");
+      // Point the increment call to the right function name variable.
+      std::string PGOFuncNameVar = llvm::getPGOFuncNameVarName(
+          PGOFuncName, llvm::GlobalValue::LinkOnceAnyLinkage);
+      auto *FuncNamePtr = IGF.IGM.Module.getNamedGlobal(PGOFuncNameVar);
 
-    // Create a GEP into the function name.
-    llvm::SmallVector<llvm::Value *, 2> Indices(2, NameGEP->getOperand(1));
-    auto *FuncName = llvm::GetElementPtrInst::CreateInBounds(
-        FuncNamePtr, makeArrayRef(Indices), "", IGF.Builder.GetInsertBlock());
+      if (FuncNamePtr) {
+        llvm::SmallVector<llvm::Value *, 2> Indices(2, NameGEP->getOperand(1));
+        NameGEP = llvm::GetElementPtrInst::CreateInBounds(
+            FuncNamePtr, makeArrayRef(Indices), "",
+            IGF.Builder.GetInsertBlock());
+      }
+    }
 
     // Replace the placeholder value with the new GEP.
     Explosion replacement;
-    replacement.add(FuncName);
+    replacement.add(NameGEP);
     replacement.add(args.claimAll());
     args = std::move(replacement);
   }

lib/Parse/ParseSIL.cpp

@@ -4613,8 +4613,9 @@ bool Parser::parseSILCoverageMap() {
                      LBraceLoc);
 
   if (!BodyHasError)
-    SILCoverageMap::create(*SIL->M, Filename.str(), FuncName.str(), Hash,
-                           Regions, Builder.getExpressions());
+    SILCoverageMap::create(*SIL->M, Filename.str(), FuncName.str(),
+                           Func->isPossiblyUsedExternally(), Hash, Regions,
+                           Builder.getExpressions());
   return false;
 }
 

lib/SIL/SILCoverageMap.cpp

@@ -24,10 +24,11 @@ using llvm::coverage::CounterExpression;
 
 SILCoverageMap *
 SILCoverageMap::create(SILModule &M, StringRef Filename, StringRef Name,
-                       uint64_t Hash, ArrayRef<MappedRegion> MappedRegions,
+                       bool External, uint64_t Hash,
+                       ArrayRef<MappedRegion> MappedRegions,
                        ArrayRef<CounterExpression> Expressions) {
   void *Buf = M.allocate(sizeof(SILCoverageMap), alignof(SILCoverageMap));
-  SILCoverageMap *CM = ::new (Buf) SILCoverageMap(Hash);
+  SILCoverageMap *CM = ::new (Buf) SILCoverageMap(Hash, External);
 
   // Store a copy of the name so that we own the lifetime.
   char *AllocatedName = (char *)M.allocate(Filename.size(), alignof(char));
@@ -56,7 +57,8 @@ SILCoverageMap::create(SILModule &M, StringRef Filename, StringRef Name,
   return CM;
 }
 
-SILCoverageMap::SILCoverageMap(uint64_t Hash) : Hash(Hash) {}
+SILCoverageMap::SILCoverageMap(uint64_t Hash, bool External)
+    : Hash(Hash), External(External) {}
 
 SILCoverageMap::~SILCoverageMap() {}
 

lib/SILGen/SILGenProfiling.cpp

@@ -17,9 +17,12 @@
 #include "swift/AST/ASTWalker.h"
 #include "swift/Basic/Fallthrough.h"
 #include "swift/Parse/Lexer.h"
+#include "swift/SIL/FormalLinkage.h"
 #include "llvm/IR/Intrinsics.h"
+#include "llvm/IR/GlobalValue.h"
 #include "llvm/ProfileData/CoverageMapping.h"
 #include "llvm/ProfileData/CoverageMappingWriter.h"
+#include "llvm/ProfileData/InstrProf.h"
 
 #include <forward_list>
 
@@ -408,12 +411,11 @@ public:
   /// \brief Generate the coverage counter mapping regions from collected
   /// source regions.
   SILCoverageMap *
-  emitSourceRegions(SILModule &M, StringRef Name, uint64_t Hash,
-                    llvm::DenseMap<ASTNode, unsigned> &CounterIndices) {
+  emitSourceRegions(SILModule &M, StringRef Name, bool External, uint64_t Hash,
+                    llvm::DenseMap<ASTNode, unsigned> &CounterIndices,
+                    StringRef Filename) {
     if (SourceRegions.empty())
       return nullptr;
-    StringRef Filename = SM.getIdentifierForBuffer(
-        SM.findBufferContainingLoc(SourceRegions.front().getStartLoc()));
 
     llvm::coverage::CounterExpressionBuilder Builder;
     std::vector<SILCoverageMap::MappedRegion> Regions;
@@ -428,7 +430,7 @@ public:
       Regions.emplace_back(Start.first, Start.second, End.first, End.second,
                            Region.getCounter().expand(Builder, CounterIndices));
     }
-    return SILCoverageMap::create(M, Filename, Name, Hash, Regions,
+    return SILCoverageMap::create(M, Filename, Name, External, Hash, Regions,
                                   Builder.getExpressions());
   }
 
@@ -633,8 +635,21 @@ static void walkForProfiling(AbstractFunctionDecl *Root, ASTWalker &Walker) {
   }
 }
 
+static llvm::GlobalValue::LinkageTypes
+getEquivalentPGOLinkage(FormalLinkage Linkage) {
+  return (Linkage == FormalLinkage::HiddenUnique ||
+          Linkage == FormalLinkage::HiddenNonUnique ||
+          Linkage == FormalLinkage::Private)
+             ? llvm::GlobalValue::PrivateLinkage
+             : llvm::GlobalValue::ExternalLinkage;
+}
+
 void SILGenProfiling::assignRegionCounters(AbstractFunctionDecl *Root) {
   CurrentFuncName = SILDeclRef(Root).mangle();
+  CurrentFuncLinkage = getDeclLinkage(Root);
+
+  if (auto *ParentFile = Root->getParentSourceFile())
+    CurrentFileName = ParentFile->getFilename();
 
   MapRegionCounters Mapper(RegionCounterMap);
   walkForProfiling(Root, Mapper);
@@ -646,8 +661,10 @@ void SILGenProfiling::assignRegionCounters(AbstractFunctionDecl *Root) {
   if (EmitCoverageMapping) {
     CoverageMapping Coverage(SGM.M.getASTContext().SourceMgr);
     walkForProfiling(Root, Coverage);
-    Coverage.emitSourceRegions(SGM.M, CurrentFuncName, FunctionHash,
-                               RegionCounterMap);
+    Coverage.emitSourceRegions(SGM.M, CurrentFuncName,
+                               !llvm::GlobalValue::isLocalLinkage(
+                                   getEquivalentPGOLinkage(CurrentFuncLinkage)),
+                               FunctionHash, RegionCounterMap, CurrentFileName);
   }
 }
 
@@ -672,11 +689,15 @@ void SILGenProfiling::emitCounterIncrement(SILGenBuilder &Builder,ASTNode Node){
   auto Int32Ty = SGM.Types.getLoweredType(BuiltinIntegerType::get(32, C));
   auto Int64Ty = SGM.Types.getLoweredType(BuiltinIntegerType::get(64, C));
 
+  std::string PGOFuncName = llvm::getPGOFuncName(
+      CurrentFuncName, getEquivalentPGOLinkage(CurrentFuncLinkage),
+      CurrentFileName);
+
   SILLocation Loc = getLocation(Node);
   SILValue Args[] = {
       // The intrinsic must refer to the function profiling name var, which is
       // inaccessible during SILGen. Rely on irgen to rewrite the function name.
-      Builder.createStringLiteral(Loc, StringRef(CurrentFuncName),
+      Builder.createStringLiteral(Loc, StringRef(PGOFuncName),
                                   StringLiteralInst::Encoding::UTF8),
       Builder.createIntegerLiteral(Loc, Int64Ty, FunctionHash),
       Builder.createIntegerLiteral(Loc, Int32Ty, NumRegionCounters),

lib/SILGen/SILGenProfiling.h

@@ -16,6 +16,7 @@
 #include "llvm/ADT/DenseMap.h"
 #include "swift/AST/ASTNode.h"
 #include "swift/AST/Stmt.h"
+#include "swift/SIL/FormalLinkage.h"
 
 namespace swift {
 
@@ -41,6 +42,8 @@ private:
 
   // The current function's name and counter data.
   std::string CurrentFuncName;
+  StringRef CurrentFileName;
+  FormalLinkage CurrentFuncLinkage;
   unsigned NumRegionCounters;
   uint64_t FunctionHash;
   llvm::DenseMap<ASTNode, unsigned> RegionCounterMap;

test/IRGen/coverage.swift

@@ -0,0 +1,20 @@
+// RUN: %target-swift-frontend %s -profile-generate -profile-coverage-mapping -emit-sil -o - | FileCheck %s --check-prefix=SIL
+// RUN: %target-swift-frontend %s -profile-generate -profile-coverage-mapping -emit-ir -o - | FileCheck %s --check-prefix=IR
+
+// SIL-DAG: sil hidden @_TF8coverage2f1FT_T_
+// SIL-DAG: string_literal utf8 "_TF8coverage2f1FT_T_"
+// IR: @__profn__TF8coverage2f1FT_T_ {{.*}} c"_TF8coverage2f1FT_T_", section "__DATA,__llvm_prf_names"
+internal func f1() {}
+
+// SIL-DAG: sil private @_TF8coverageP33_[[F2HASH:[_a-zA-Z0-9]+]]
+// SIL-DAG: string_literal utf8 "{{.*}}coverage.swift:_TF8coverageP33_[[F2HASH]]"
+// IR: @"__profn_{{.*}}coverage.swift:_TF8coverageP33_[[F2HASH:[_a-zA-Z0-9]+]]" {{.*}} c"{{.*}}coverage.swift:_TF8coverageP33_[[F2HASH]]", section "__DATA,__llvm_prf_names"
+private func f2() {}
+
+// SIL-DAG: sil @_TF8coverage2f3FT_T_
+// SIL-DAG: string_literal utf8 "_TF8coverage2f3FT_T_"
+// IR: @__profn__TF8coverage2f3FT_T_ {{.*}} c"_TF8coverage2f3FT_T_", section "__DATA,__llvm_prf_names"
+public func f3() {
+  f1();
+  f2();
+}