[Modules] Preserve source order for the map of late parsed templates.

Clang was inserting these into a dense map. While it never iterated the
dense map during normal compilation, it did when emitting a module. Fix
this by using a standard MapVector to preserve the order in which we
encounter the late parsed templates.

I suspect this still isn't ideal, as we don't seem to remove things from
this map even when we mark the templates as no longer late parsed. But
I don't know enough about this particular extension to craft a nice,
subtle test case covering this. I've managed to get the stress test to
at least do some late parsing and demonstrate the core problem here.
This patch fixes the test and provides deterministic behavior which is
a strict improvement over the prior state.

I've cleaned up some of the code here as well to be explicit about
inserting when that is what is actually going on.

llvm-svn: 233264

9 files changed, 25 insertions, 17 deletions

diff --git a/clang/include/clang/Sema/ExternalSemaSource.h b/clang/include/clang/Sema/ExternalSemaSource.h
index 1083784fb7f..430cef7846b 100644
--- a/clang/include/clang/Sema/ExternalSemaSource.h
+++ b/clang/include/clang/Sema/ExternalSemaSource.h
@@ -182,7 +182,7 @@ public:
   /// external source should take care not to introduce the same map entries
   /// repeatedly.
   virtual void ReadLateParsedTemplates(
-      llvm::DenseMap<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {}
+      llvm::MapVector<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {}
 
   /// \copydoc Sema::CorrectTypo
   /// \note LookupKind must correspond to a valid Sema::LookupNameKind
diff --git a/clang/include/clang/Sema/MultiplexExternalSemaSource.h b/clang/include/clang/Sema/MultiplexExternalSemaSource.h
index 7a57abc0106..5f717891032 100644
--- a/clang/include/clang/Sema/MultiplexExternalSemaSource.h
+++ b/clang/include/clang/Sema/MultiplexExternalSemaSource.h
@@ -331,8 +331,8 @@ public:
   /// external source should take care not to introduce the same map entries
   /// repeatedly.
   void ReadLateParsedTemplates(
-                         llvm::DenseMap<const FunctionDecl *,
-                                        LateParsedTemplate *> &LPTMap) override;
+      llvm::MapVector<const FunctionDecl *, LateParsedTemplate *> &LPTMap)
+      override;
 
   /// \copydoc ExternalSemaSource::CorrectTypo
   /// \note Returns the first nonempty correction.
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index dde928ff914..21fe2e493c2 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -455,8 +455,8 @@ public:
   SmallVector<std::pair<CXXMethodDecl*, const FunctionProtoType*>, 2>
     DelayedDefaultedMemberExceptionSpecs;
 
-  typedef llvm::DenseMap<const FunctionDecl *, LateParsedTemplate *>
-  LateParsedTemplateMapT;
+  typedef llvm::MapVector<const FunctionDecl *, LateParsedTemplate *>
+      LateParsedTemplateMapT;
   LateParsedTemplateMapT LateParsedTemplateMap;
 
   /// \brief Callback to the parser to parse templated functions when needed.
diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index 1471910db47..f8366f7621a 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -1832,8 +1832,8 @@ public:
                                            SourceLocation> > &Pending) override;
 
   void ReadLateParsedTemplates(
-                         llvm::DenseMap<const FunctionDecl *,
-                                        LateParsedTemplate *> &LPTMap) override;
+      llvm::MapVector<const FunctionDecl *, LateParsedTemplate *> &LPTMap)
+      override;
 
   /// \brief Load a selector from disk, registering its ID if it exists.
   void LoadSelector(Selector Sel);
diff --git a/clang/lib/Sema/MultiplexExternalSemaSource.cpp b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
index bd7e785780b..51a12746fdd 100644
--- a/clang/lib/Sema/MultiplexExternalSemaSource.cpp
+++ b/clang/lib/Sema/MultiplexExternalSemaSource.cpp
@@ -276,7 +276,7 @@ void MultiplexExternalSemaSource::ReadPendingInstantiations(
 }
 
 void MultiplexExternalSemaSource::ReadLateParsedTemplates(
-    llvm::DenseMap<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {
+    llvm::MapVector<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {
   for (size_t i = 0; i < Sources.size(); ++i)
     Sources[i]->ReadLateParsedTemplates(LPTMap);
 }
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
index fad15bbc4f6..805709dab80 100644
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -8305,7 +8305,7 @@ void Sema::MarkAsLateParsedTemplate(FunctionDecl *FD, Decl *FnD,
   // Take tokens to avoid allocations
   LPT->Toks.swap(Toks);
   LPT->D = FnD;
-  LateParsedTemplateMap[FD] = LPT;
+  LateParsedTemplateMap.insert(std::make_pair(FD, LPT));
 
   FD->setLateTemplateParsed(true);
 }
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index 2273979883a..4d5141bf921 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -7453,7 +7453,7 @@ void ASTReader::ReadPendingInstantiations(
 }
 
 void ASTReader::ReadLateParsedTemplates(
-    llvm::DenseMap<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {
+    llvm::MapVector<const FunctionDecl *, LateParsedTemplate *> &LPTMap) {
   for (unsigned Idx = 0, N = LateParsedTemplates.size(); Idx < N;
        /* In loop */) {
     FunctionDecl *FD = cast<FunctionDecl>(GetDecl(LateParsedTemplates[Idx++]));
@@ -7469,7 +7469,7 @@ void ASTReader::ReadLateParsedTemplates(
     for (unsigned T = 0; T < TokN; ++T)
       LT->Toks.push_back(ReadToken(*F, LateParsedTemplates, Idx));
 
-    LPTMap[FD] = LT;
+    LPTMap.insert(std::make_pair(FD, LT));
   }
 
   LateParsedTemplates.clear();
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 7227a97e7b9..679419c9c5a 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -4089,11 +4089,10 @@ void ASTWriter::WriteLateParsedTemplates(Sema &SemaRef) {
     return;
 
   RecordData Record;
-  for (Sema::LateParsedTemplateMapT::iterator It = LPTMap.begin(),
-                                              ItEnd = LPTMap.end();
-       It != ItEnd; ++It) {
-    LateParsedTemplate *LPT = It->second;
-    AddDeclRef(It->first, Record);
+  for (auto LPTMapEntry : LPTMap) {
+    const FunctionDecl *FD = LPTMapEntry.first;
+    LateParsedTemplate *LPT = LPTMapEntry.second;
+    AddDeclRef(FD, Record);
     AddDeclRef(LPT->D, Record);
     Record.push_back(LPT->Toks.size());
 
diff --git a/clang/test/Modules/stress1.cpp b/clang/test/Modules/stress1.cpp
index e03e538a3ce..df690aa7e65 100644
--- a/clang/test/Modules/stress1.cpp
+++ b/clang/test/Modules/stress1.cpp
@@ -17,13 +17,22 @@
 //
 // RUN: diff %t/m00.pcm %t/m00_check.pcm
 //
-// RUN: %clang_cc1 -fmodules -x c++ -std=c++11 \
+// RUN: %clang_cc1 -fmodules -x c++ -std=c++11 -fdelayed-template-parsing \
 // RUN:   -I Inputs/stress1 \
 // RUN:   -fno-implicit-modules -fno-modules-implicit-maps \
 // RUN:   -fmodule-map-file-home-is-cwd \
 // RUN:   -emit-module -fmodule-name=m01 -o %t/m01.pcm \
 // RUN:   Inputs/stress1/module.modulemap
 //
+// RUN: %clang_cc1 -fmodules -x c++ -std=c++11 -fdelayed-template-parsing \
+// RUN:   -I Inputs/stress1 \
+// RUN:   -fno-implicit-modules -fno-modules-implicit-maps \
+// RUN:   -fmodule-map-file-home-is-cwd \
+// RUN:   -emit-module -fmodule-name=m01 -o %t/m01_check.pcm \
+// RUN:   Inputs/stress1/module.modulemap
+//
+// RUN: diff %t/m01.pcm %t/m01_check.pcm
+//
 // RUN: %clang_cc1 -fmodules -x c++ -std=c++11 \
 // RUN:   -I Inputs/stress1 \
 // RUN:   -fno-implicit-modules -fno-modules-implicit-maps \