2 files changed, 28 insertions, 0 deletions
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 55cb670f427e..b7bbb9dc7be1 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -2925,6 +2925,21 @@ ASTReader::ReadASTBlock(ModuleFile &F, unsigned ClientLoadCapabilities) {
       }
       break;
 
+    case PP_CONDITIONAL_STACK:
+      if (!Record.empty()) {
+        SmallVector<PPConditionalInfo, 4> ConditionalStack;
+        for (unsigned Idx = 0, N = Record.size() - 1; Idx < N; /* in loop */) {
+          auto Loc = ReadSourceLocation(F, Record, Idx);
+          bool WasSkipping = Record[Idx++];
+          bool FoundNonSkip = Record[Idx++];
+          bool FoundElse = Record[Idx++];
+          ConditionalStack.push_back(
+              {Loc, WasSkipping, FoundNonSkip, FoundElse});
+        }
+        PP.setReplayablePreambleConditionalStack(ConditionalStack);
+      }
+      break;
+
     case PP_COUNTER_VALUE:
       if (!Record.empty() && Listener)
         Listener->ReadCounter(F, Record[0]);
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index b3556371c9b8..c931b13f65f3 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -1093,6 +1093,7 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(UNUSED_LOCAL_TYPEDEF_NAME_CANDIDATES);
   RECORD(DELETE_EXPRS_TO_ANALYZE);
   RECORD(CUDA_PRAGMA_FORCE_HOST_DEVICE_DEPTH);
+  RECORD(PP_CONDITIONAL_STACK);
 
   // SourceManager Block.
   BLOCK(SOURCE_MANAGER_BLOCK);
@@ -2302,6 +2303,18 @@ void ASTWriter::WritePreprocessor(const Preprocessor &PP, bool IsModule) {
     Stream.EmitRecord(PP_COUNTER_VALUE, Record);
   }
 
+  if (PP.isRecordingPreamble() && PP.hasRecordedPreamble()) {
+    assert(!IsModule);
+    for (const auto &Cond : PP.getPreambleConditionalStack()) {
+      AddSourceLocation(Cond.IfLoc, Record);
+      Record.push_back(Cond.WasSkipping);
+      Record.push_back(Cond.FoundNonSkip);
+      Record.push_back(Cond.FoundElse);
+    }
+    Stream.EmitRecord(PP_CONDITIONAL_STACK, Record);
+    Record.clear();
+  }
+
   // Enter the preprocessor block.
   Stream.EnterSubblock(PREPROCESSOR_BLOCK_ID, 3);