[Modules] Sort the file IDs prior to building the flattened array of

DeclIDs so that in addition to be grouped by file, the order of these
groups is stable.

Found by inspection, no test case. Not sure this can be observed without
a randomized seed for the hash table, but we shouldn't be relying on the
hash table layout under any circumstances.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@233339 91177308-0d34-0410-b5e6-96231b3b80d8

diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index 655c9fd28b5f905134f95b14b88e538e11bfce61..990a565e5036fd5f471717e99ad9af5872a092bb 100644 (file)
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -2857,15 +2857,18 @@ void ASTWriter::WriteFileDeclIDsMap() {
   using namespace llvm;
   RecordData Record;
 
+  SmallVector<std::pair<FileID, DeclIDInFileInfo *>, 64> SortedFileDeclIDs(
+      FileDeclIDs.begin(), FileDeclIDs.end());
+  std::sort(SortedFileDeclIDs.begin(), SortedFileDeclIDs.end(),
+            llvm::less_first());
+
   // Join the vectors of DeclIDs from all files.
-  SmallVector<DeclID, 256> FileSortedIDs;
-  for (FileDeclIDsTy::iterator
-         FI = FileDeclIDs.begin(), FE = FileDeclIDs.end(); FI != FE; ++FI) {
-    DeclIDInFileInfo &Info = *FI->second;
-    Info.FirstDeclIndex = FileSortedIDs.size();
-    for (LocDeclIDsTy::iterator
-           DI = Info.DeclIDs.begin(), DE = Info.DeclIDs.end(); DI != DE; ++DI)
-      FileSortedIDs.push_back(DI->second);
+  SmallVector<DeclID, 256> FileGroupedDeclIDs;
+  for (auto &FileDeclEntry : SortedFileDeclIDs) {
+    DeclIDInFileInfo &Info = *FileDeclEntry.second;
+    Info.FirstDeclIndex = FileGroupedDeclIDs.size();
+    for (auto &LocDeclEntry : Info.DeclIDs)
+      FileGroupedDeclIDs.push_back(LocDeclEntry.second);
   }
 
   BitCodeAbbrev *Abbrev = new BitCodeAbbrev();
@@ -2874,8 +2877,8 @@ void ASTWriter::WriteFileDeclIDsMap() {
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob));
   unsigned AbbrevCode = Stream.EmitAbbrev(Abbrev);
   Record.push_back(FILE_SORTED_DECLS);
-  Record.push_back(FileSortedIDs.size());
-  Stream.EmitRecordWithBlob(AbbrevCode, Record, data(FileSortedIDs));
+  Record.push_back(FileGroupedDeclIDs.size());
+  Stream.EmitRecordWithBlob(AbbrevCode, Record, data(FileGroupedDeclIDs));
 }
 
 void ASTWriter::WriteComments() {