[modules] When encoding SourceLocations in bitcode, rotate the 'is macro' flag

bit from the top bit to the bottom bit, so that we don't need 6 VBR6 hunks for
each macro location. Reduces libstdc++ module size by about 1%.

llvm-svn: 264540

1 files changed, 10 insertions, 7 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 89a54a18d3d..a828d350c04 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -1912,7 +1912,7 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
     Record.push_back(SLoc->getOffset() - 2);
     if (SLoc->isFile()) {
       const SrcMgr::FileInfo &File = SLoc->getFile();
-      Record.push_back(File.getIncludeLoc().getRawEncoding());
+      AddSourceLocation(File.getIncludeLoc(), Record);
       Record.push_back(File.getFileCharacteristic()); // FIXME: stable encoding
       Record.push_back(File.hasLineDirectives());
 
@@ -1984,10 +1984,12 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
     } else {
       // The source location entry is a macro expansion.
       const SrcMgr::ExpansionInfo &Expansion = SLoc->getExpansion();
-      Record.push_back(Expansion.getSpellingLoc().getRawEncoding());
-      Record.push_back(Expansion.getExpansionLocStart().getRawEncoding());
-      Record.push_back(Expansion.isMacroArgExpansion() ? 0
-                             : Expansion.getExpansionLocEnd().getRawEncoding());
+      AddSourceLocation(Expansion.getSpellingLoc(), Record);
+      AddSourceLocation(Expansion.getExpansionLocStart(), Record);
+      AddSourceLocation(Expansion.isMacroArgExpansion()
+                            ? SourceLocation()
+                            : Expansion.getExpansionLocEnd(),
+                        Record);
 
       // Compute the token length for this macro expansion.
       unsigned NextOffset = SourceMgr.getNextLocalOffset();
@@ -2669,7 +2671,7 @@ void ASTWriter::WritePragmaDiagnosticMappings(const DiagnosticsEngine &Diag,
     if (point.Loc.isInvalid())
       continue;
 
-    Record.push_back(point.Loc.getRawEncoding());
+    AddSourceLocation(point.Loc, Record);
     unsigned &DiagStateID = DiagStateIDMap[point.State];
     Record.push_back(DiagStateID);
     
@@ -4782,7 +4784,8 @@ void ASTWriter::WriteDeclUpdatesBlocks(RecordDataImpl &OffsetsRecord) {
 }
 
 void ASTWriter::AddSourceLocation(SourceLocation Loc, RecordDataImpl &Record) {
-  Record.push_back(Loc.getRawEncoding());
+  uint32_t Raw = Loc.getRawEncoding();
+  Record.push_back((Raw << 1) | (Raw >> 31));
 }
 
 void ASTWriter::AddSourceRange(SourceRange Range, RecordDataImpl &Record) {