r233339 - [Modules] Sort the file IDs prior to building the flattened array of

[Chandler Carruth]

Author: chandlerc
Date: Thu Mar 26 19:31:20 2015
New Revision: 233339

URL: http://llvm.org/viewvc/llvm-project?rev=233339&view=rev
Log:
[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.

Modified:
    cfe/trunk/lib/Serialization/ASTWriter.cpp

Modified: cfe/trunk/lib/Serialization/ASTWriter.cpp
URL: http://llvm.org/viewvc/llvm-project/cfe/trunk/lib/Serialization/ASTWriter.cpp?rev=233339&r1=233338&r2=233339&view=diff
==============================================================================
--- cfe/trunk/lib/Serialization/ASTWriter.cpp (original)
+++ cfe/trunk/lib/Serialization/ASTWriter.cpp Thu Mar 26 19:31:20 2015
@@ -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() {