r303432 - [modules] Further delay calling DeclMustBeEmitted until it's safe.

[Vassil Vassilev via cfe-commits]

Author: vvassilev
Date: Fri May 19 11:46:06 2017
New Revision: 303432

URL: http://llvm.org/viewvc/llvm-project?rev=303432&view=rev
Log:
[modules] Further delay calling DeclMustBeEmitted until it's safe.

As discussed in D30793, we have some unsafe calls to isConsumerInterestedIn().
This patch implements Richard's suggestion (from the inline comment) that we
should track if we just deserialized an declaration. If we just deserialized,
we can skip the unsafe call because we know it's interesting. If we didn't just
deserialize the declaration, calling isConsumerInterestedIn() should be safe.

We tried to create a test case for this but we were not successful.

Patch by Raphael Isemann (D32499)!

Modified:
    cfe/trunk/include/clang/Serialization/ASTReader.h
    cfe/trunk/lib/Serialization/ASTReader.cpp
    cfe/trunk/lib/Serialization/ASTReaderDecl.cpp

Modified: cfe/trunk/include/clang/Serialization/ASTReader.h
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/include/clang/Serialization/ASTReader.h?rev=303432&r1=303431&r2=303432&view=diff
==============================================================================
--- cfe/trunk/include/clang/Serialization/ASTReader.h (original)
+++ cfe/trunk/include/clang/Serialization/ASTReader.h Fri May 19 11:46:06 2017
@@ -478,10 +478,18 @@ private:
   /// in the chain.
   DeclUpdateOffsetsMap DeclUpdateOffsets;
 
+  struct PendingUpdateRecord {
+    Decl *D;
+    serialization::GlobalDeclID ID;
+    // Whether the declaration was just deserialized.
+    bool JustLoaded;
+    PendingUpdateRecord(serialization::GlobalDeclID ID, Decl *D,
+                        bool JustLoaded)
+        : D(D), ID(ID), JustLoaded(JustLoaded) {}
+  };
   /// \brief Declaration updates for already-loaded declarations that we need
   /// to apply once we finish processing an import.
-  llvm::SmallVector<std::pair<serialization::GlobalDeclID, Decl*>, 16>
-      PendingUpdateRecords;
+  llvm::SmallVector<PendingUpdateRecord, 16> PendingUpdateRecords;
 
   enum class PendingFakeDefinitionKind { NotFake, Fake, FakeLoaded };
 
@@ -1279,7 +1287,7 @@ private:
 
   RecordLocation DeclCursorForID(serialization::DeclID ID,
                                  SourceLocation &Location);
-  void loadDeclUpdateRecords(serialization::DeclID ID, Decl *D);
+  void loadDeclUpdateRecords(PendingUpdateRecord &Record);
   void loadPendingDeclChain(Decl *D, uint64_t LocalOffset);
   void loadObjCCategories(serialization::GlobalDeclID ID, ObjCInterfaceDecl *D,
                           unsigned PreviousGeneration = 0);

Modified: cfe/trunk/lib/Serialization/ASTReader.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReader.cpp?rev=303432&r1=303431&r2=303432&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReader.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReader.cpp Fri May 19 11:46:06 2017
@@ -2756,7 +2756,8 @@ ASTReader::ReadASTBlock(ModuleFile &F, u
       // If we've already loaded the decl, perform the updates when we finish
       // loading this block.
       if (Decl *D = GetExistingDecl(ID))
-        PendingUpdateRecords.push_back(std::make_pair(ID, D));
+        PendingUpdateRecords.push_back(
+            PendingUpdateRecord(ID, D, /*JustLoaded=*/false));
       break;
     }
 
@@ -3086,7 +3087,8 @@ ASTReader::ReadASTBlock(ModuleFile &F, u
         // If we've already loaded the decl, perform the updates when we finish
         // loading this block.
         if (Decl *D = GetExistingDecl(ID))
-          PendingUpdateRecords.push_back(std::make_pair(ID, D));
+          PendingUpdateRecords.push_back(
+              PendingUpdateRecord(ID, D, /*JustLoaded=*/false));
       }
       break;
     }
@@ -8956,7 +8958,7 @@ void ASTReader::finishPendingActions() {
     while (!PendingUpdateRecords.empty()) {
       auto Update = PendingUpdateRecords.pop_back_val();
       ReadingKindTracker ReadingKind(Read_Decl, *this);
-      loadDeclUpdateRecords(Update.first, Update.second);
+      loadDeclUpdateRecords(Update);
     }
   }
 

Modified: cfe/trunk/lib/Serialization/ASTReaderDecl.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTReaderDecl.cpp?rev=303432&r1=303431&r2=303432&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTReaderDecl.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTReaderDecl.cpp Fri May 19 11:46:06 2017
@@ -3612,7 +3612,8 @@ Decl *ASTReader::ReadDeclRecord(DeclID I
   assert(Record.getIdx() == Record.size());
 
   // Load any relevant update records.
-  PendingUpdateRecords.push_back(std::make_pair(ID, D));
+  PendingUpdateRecords.push_back(
+      PendingUpdateRecord(ID, D, /*JustLoaded=*/true));
 
   // Load the categories after recursive loading is finished.
   if (ObjCInterfaceDecl *Class = dyn_cast<ObjCInterfaceDecl>(D))
@@ -3657,20 +3658,24 @@ void ASTReader::PassInterestingDeclsToCo
   }
 }
 
-void ASTReader::loadDeclUpdateRecords(serialization::DeclID ID, Decl *D) {
+void ASTReader::loadDeclUpdateRecords(PendingUpdateRecord &Record) {
   // The declaration may have been modified by files later in the chain.
   // If this is the case, read the record containing the updates from each file
   // and pass it to ASTDeclReader to make the modifications.
+  serialization::GlobalDeclID ID = Record.ID;
+  Decl *D = Record.D;
   ProcessingUpdatesRAIIObj ProcessingUpdates(*this);
   DeclUpdateOffsetsMap::iterator UpdI = DeclUpdateOffsets.find(ID);
   if (UpdI != DeclUpdateOffsets.end()) {
     auto UpdateOffsets = std::move(UpdI->second);
     DeclUpdateOffsets.erase(UpdI);
 
-    // FIXME: This call to isConsumerInterestedIn is not safe because
-    // we could be deserializing declarations at the moment. We should
-    // delay calling this in the same way as done in D30793.
-    bool WasInteresting = isConsumerInterestedIn(Context, D, false);
+    // Check if this decl was interesting to the consumer. If we just loaded
+    // the declaration, then we know it was interesting and we skip the call
+    // to isConsumerInterestedIn because it is unsafe to call in the
+    // current ASTReader state.
+    bool WasInteresting =
+        Record.JustLoaded || isConsumerInterestedIn(Context, D, false);
     for (auto &FileAndOffset : UpdateOffsets) {
       ModuleFile *F = FileAndOffset.first;
       uint64_t Offset = FileAndOffset.second;