[modules] Compress files embedded into a .pcm file, to reduce the disk usage of -fembed-all-files mode.

llvm-svn: 259976

1 files changed, 32 insertions, 21 deletions

diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index dbfc5c31db1..1c62b4e57b0 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -48,6 +48,7 @@
 #include "llvm/ADT/Hashing.h"
 #include "llvm/ADT/StringExtras.h"
 #include "llvm/Bitcode/BitstreamReader.h"
+#include "llvm/Support/Compression.h"
 #include "llvm/Support/ErrorHandling.h"
 #include "llvm/Support/FileSystem.h"
 #include "llvm/Support/MemoryBuffer.h"
@@ -1203,6 +1204,32 @@ bool ASTReader::ReadSLocEntry(int ID) {
     return true;
   }
 
+  // Local helper to read the (possibly-compressed) buffer data following the
+  // entry record.
+  auto ReadBuffer = [this](
+      BitstreamCursor &SLocEntryCursor,
+      StringRef Name) -> std::unique_ptr<llvm::MemoryBuffer> {
+    RecordData Record;
+    StringRef Blob;
+    unsigned Code = SLocEntryCursor.ReadCode();
+    unsigned RecCode = SLocEntryCursor.readRecord(Code, Record, &Blob);
+
+    if (RecCode == SM_SLOC_BUFFER_BLOB_COMPRESSED) {
+      SmallString<0> Uncompressed;
+      if (llvm::zlib::uncompress(Blob, Uncompressed, Record[0]) !=
+          llvm::zlib::StatusOK) {
+        Error("could not decompress embedded file contents");
+        return nullptr;
+      }
+      return llvm::MemoryBuffer::getMemBufferCopy(Uncompressed, Name);
+    } else if (RecCode == SM_SLOC_BUFFER_BLOB) {
+      return llvm::MemoryBuffer::getMemBuffer(Blob.drop_back(1), Name, true);
+    } else {
+      Error("AST record has invalid code");
+      return nullptr;
+    }
+  };
+
   ModuleFile *F = GlobalSLocEntryMap.find(-ID)->second;
   F->SLocEntryCursor.JumpToBit(F->SLocEntryOffsets[ID - F->SLocEntryBaseID]);
   BitstreamCursor &SLocEntryCursor = F->SLocEntryCursor;
@@ -1258,24 +1285,16 @@ bool ASTReader::ReadSLocEntry(int ID) {
       FileDeclIDs[FID] = FileDeclsInfo(F, llvm::makeArrayRef(FirstDecl,
                                                              NumFileDecls));
     }
-    
+
     const SrcMgr::ContentCache *ContentCache
       = SourceMgr.getOrCreateContentCache(File,
                               /*isSystemFile=*/FileCharacter != SrcMgr::C_User);
     if (OverriddenBuffer && !ContentCache->BufferOverridden &&
         ContentCache->ContentsEntry == ContentCache->OrigEntry &&
         !ContentCache->getRawBuffer()) {
-      unsigned Code = SLocEntryCursor.ReadCode();
-      Record.clear();
-      unsigned RecCode = SLocEntryCursor.readRecord(Code, Record, &Blob);
-      
-      if (RecCode != SM_SLOC_BUFFER_BLOB) {
-        Error("AST record has invalid code");
+      auto Buffer = ReadBuffer(SLocEntryCursor, File->getName());
+      if (!Buffer)
         return true;
-      }
-      
-      std::unique_ptr<llvm::MemoryBuffer> Buffer
-        = llvm::MemoryBuffer::getMemBuffer(Blob.drop_back(1), File->getName());
       SourceMgr.overrideFileContents(File, std::move(Buffer));
     }
 
@@ -1292,18 +1311,10 @@ bool ASTReader::ReadSLocEntry(int ID) {
         (F->Kind == MK_ImplicitModule || F->Kind == MK_ExplicitModule)) {
       IncludeLoc = getImportLocation(F);
     }
-    unsigned Code = SLocEntryCursor.ReadCode();
-    Record.clear();
-    unsigned RecCode
-      = SLocEntryCursor.readRecord(Code, Record, &Blob);
 
-    if (RecCode != SM_SLOC_BUFFER_BLOB) {
-      Error("AST record has invalid code");
+    auto Buffer = ReadBuffer(SLocEntryCursor, Name);
+    if (!Buffer)
       return true;
-    }
-
-    std::unique_ptr<llvm::MemoryBuffer> Buffer =
-        llvm::MemoryBuffer::getMemBuffer(Blob.drop_back(1), Name);
     SourceMgr.createFileID(std::move(Buffer), FileCharacter, ID,
                            BaseOffset + Offset, IncludeLoc);
     break;