1 files changed, 38 insertions, 16 deletions

diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index 3e153327923..985bcb05b4d 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -50,6 +50,7 @@
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Bitcode/BitstreamWriter.h"
+#include "llvm/Support/Compression.h"
 #include "llvm/Support/EndianStream.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -962,6 +963,7 @@ void ASTWriter::WriteBlockInfoBlock() {
   RECORD(SM_SLOC_FILE_ENTRY);
   RECORD(SM_SLOC_BUFFER_ENTRY);
   RECORD(SM_SLOC_BUFFER_BLOB);
+  RECORD(SM_SLOC_BUFFER_BLOB_COMPRESSED);
   RECORD(SM_SLOC_EXPANSION_ENTRY);
 
   // Preprocessor Block.
@@ -1631,11 +1633,15 @@ static unsigned CreateSLocBufferAbbrev(llvm::BitstreamWriter &Stream) {
 
 /// \brief Create an abbreviation for the SLocEntry that refers to a
 /// buffer's blob.
-static unsigned CreateSLocBufferBlobAbbrev(llvm::BitstreamWriter &Stream) {
+static unsigned CreateSLocBufferBlobAbbrev(llvm::BitstreamWriter &Stream,
+                                           bool Compressed) {
   using namespace llvm;
 
   auto *Abbrev = new BitCodeAbbrev();
-  Abbrev->Add(BitCodeAbbrevOp(SM_SLOC_BUFFER_BLOB));
+  Abbrev->Add(BitCodeAbbrevOp(Compressed ? SM_SLOC_BUFFER_BLOB_COMPRESSED
+                                         : SM_SLOC_BUFFER_BLOB));
+  if (Compressed)
+    Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::VBR, 8)); // Uncompressed size
   Abbrev->Add(BitCodeAbbrevOp(BitCodeAbbrevOp::Blob)); // Blob
   return Stream.EmitAbbrev(Abbrev);
 }
@@ -1857,12 +1863,14 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
   RecordData Record;
 
   // Enter the source manager block.
-  Stream.EnterSubblock(SOURCE_MANAGER_BLOCK_ID, 3);
+  Stream.EnterSubblock(SOURCE_MANAGER_BLOCK_ID, 4);
 
   // Abbreviations for the various kinds of source-location entries.
   unsigned SLocFileAbbrv = CreateSLocFileAbbrev(Stream);
   unsigned SLocBufferAbbrv = CreateSLocBufferAbbrev(Stream);
-  unsigned SLocBufferBlobAbbrv = CreateSLocBufferBlobAbbrev(Stream);
+  unsigned SLocBufferBlobAbbrv = CreateSLocBufferBlobAbbrev(Stream, false);
+  unsigned SLocBufferBlobCompressedAbbrv =
+      CreateSLocBufferBlobAbbrev(Stream, true);
   unsigned SLocExpansionAbbrv = CreateSLocExpansionAbbrev(Stream);
 
   // Write out the source location entry table. We skip the first
@@ -1902,6 +1910,7 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
       Record.push_back(File.hasLineDirectives());
 
       const SrcMgr::ContentCache *Content = File.getContentCache();
+      bool EmitBlob = false;
       if (Content->OrigEntry) {
         assert(Content->OrigEntry == Content->ContentsEntry &&
                "Writing to AST an overridden file is not supported");
@@ -1923,14 +1932,8 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
         
         Stream.EmitRecordWithAbbrev(SLocFileAbbrv, Record);
         
-        if (Content->BufferOverridden || Content->IsTransient) {
-          RecordData::value_type Record[] = {SM_SLOC_BUFFER_BLOB};
-          const llvm::MemoryBuffer *Buffer
-            = Content->getBuffer(PP.getDiagnostics(), PP.getSourceManager());
-          Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record,
-                                    StringRef(Buffer->getBufferStart(),
-                                              Buffer->getBufferSize() + 1));          
-        }
+        if (Content->BufferOverridden || Content->IsTransient)
+          EmitBlob = true;
       } else {
         // The source location entry is a buffer. The blob associated
         // with this entry contains the contents of the buffer.
@@ -1943,15 +1946,34 @@ void ASTWriter::WriteSourceManagerBlock(SourceManager &SourceMgr,
         const char *Name = Buffer->getBufferIdentifier();
         Stream.EmitRecordWithBlob(SLocBufferAbbrv, Record,
                                   StringRef(Name, strlen(Name) + 1));
-        RecordData::value_type Record[] = {SM_SLOC_BUFFER_BLOB};
-        Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record,
-                                  StringRef(Buffer->getBufferStart(),
-                                                  Buffer->getBufferSize() + 1));
+        EmitBlob = true;
 
         if (strcmp(Name, "<built-in>") == 0) {
           PreloadSLocs.push_back(SLocEntryOffsets.size());
         }
       }
+
+      if (EmitBlob) {
+        // Include the implicit terminating null character in the on-disk buffer
+        // if we're writing it uncompressed.
+        const llvm::MemoryBuffer *Buffer =
+            Content->getBuffer(PP.getDiagnostics(), PP.getSourceManager());
+        StringRef Blob(Buffer->getBufferStart(), Buffer->getBufferSize() + 1);
+
+        // Compress the buffer if possible. We expect that almost all PCM
+        // consumers will not want its contents.
+        SmallString<0> CompressedBuffer;
+        if (llvm::zlib::compress(Blob.drop_back(1), CompressedBuffer) ==
+            llvm::zlib::StatusOK) {
+          RecordData::value_type Record[] = {SM_SLOC_BUFFER_BLOB_COMPRESSED,
+                                             Blob.size() - 1};
+          Stream.EmitRecordWithBlob(SLocBufferBlobCompressedAbbrv, Record,
+                                    CompressedBuffer);
+        } else {
+          RecordData::value_type Record[] = {SM_SLOC_BUFFER_BLOB};
+          Stream.EmitRecordWithBlob(SLocBufferBlobAbbrv, Record, Blob);
+        }
+      }
     } else {
       // The source location entry is a macro expansion.
       const SrcMgr::ExpansionInfo &Expansion = SLoc->getExpansion();