[pdb] Allow zero-copy read support for symbol streams.

This reduces the amount of memory used by llvm-pdbdump by roughly
1/3 of the size of the PDB file.

Differential Revision: http://reviews.llvm.org/D20724
Reviewed By: ruiu

llvm-svn: 271025

1 files changed, 10 insertions, 3 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp b/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
index 38d3f2f..404208a 100644
--- a/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Raw/ModStream.cpp
@@ -9,6 +9,7 @@
 
 #include "llvm/DebugInfo/PDB/Raw/ModStream.h"
 
+#include "llvm/DebugInfo/CodeView/RecordIterator.h"
 #include "llvm/DebugInfo/CodeView/StreamReader.h"
 #include "llvm/DebugInfo/PDB/Raw/ModInfo.h"
 #include "llvm/DebugInfo/PDB/Raw/RawError.h"
@@ -32,8 +33,14 @@ Error ModStream::reload() {
     return llvm::make_error<RawError>(raw_error_code::corrupt_file,
                                       "Module has both C11 and C13 line info");
 
-  if (auto EC = SymbolsSubstream.load(Reader, SymbolSize))
+  codeview::StreamRef S;
+
+  uint32_t SymbolSubstreamSig = 0;
+  if (auto EC = Reader.readInteger(SymbolSubstreamSig))
+    return EC;
+  if (auto EC = Reader.readArray(SymbolsSubstream, SymbolSize - 4))
     return EC;
+
   if (auto EC = Reader.readStreamRef(LinesSubstream, C11Size))
     return EC;
   if (auto EC = Reader.readStreamRef(C13LinesSubstream, C13Size))
@@ -51,6 +58,6 @@ Error ModStream::reload() {
   return Error::success();
 }
 
-iterator_range<codeview::SymbolIterator> ModStream::symbols() const {
-  return codeview::makeSymbolRange(SymbolsSubstream.data().slice(4), nullptr);
+iterator_range<codeview::CVSymbolArray::Iterator> ModStream::symbols() const {
+  return llvm::make_range(SymbolsSubstream.begin(), SymbolsSubstream.end());
 }