[DebugInfo][PDB] Don't write empty debug streams

Before, empty debug streams were written as 8 bytes (4 bytes signature + 4 bytes for the GlobalRefs count).

With this patch, unused empty streams aren't emitted anymore. Modules now encode 65535 as an 'unused stream' value, by convention.
Also fix the * Linker * contrib section which wasn't correctly emitted previously.

Differential Revision: https://reviews.llvm.org/D59502

llvm-svn: 356395

1 files changed, 12 insertions, 4 deletions

diff --git a/llvm/lib/DebugInfo/PDB/Native/ModuleDebugStream.cpp b/llvm/lib/DebugInfo/PDB/Native/ModuleDebugStream.cpp
index 649ff7c..1445f0b 100644
--- a/llvm/lib/DebugInfo/PDB/Native/ModuleDebugStream.cpp
+++ b/llvm/lib/DebugInfo/PDB/Native/ModuleDebugStream.cpp
@@ -14,6 +14,7 @@
 #include "llvm/DebugInfo/CodeView/SymbolRecord.h"
 #include "llvm/DebugInfo/CodeView/SymbolRecordHelpers.h"
 #include "llvm/DebugInfo/PDB/Native/DbiModuleDescriptor.h"
+#include "llvm/DebugInfo/PDB/Native/RawConstants.h"
 #include "llvm/DebugInfo/PDB/Native/RawError.h"
 #include "llvm/Support/BinaryStreamReader.h"
 #include "llvm/Support/BinaryStreamRef.h"
@@ -36,6 +37,17 @@ ModuleDebugStreamRef::~ModuleDebugStreamRef() = default;
 Error ModuleDebugStreamRef::reload() {
   BinaryStreamReader Reader(*Stream);
 
+  if (Mod.getModuleStreamIndex() != llvm::pdb::kInvalidStreamIndex) {
+    if (Error E = reloadSerialize(Reader))
+      return E;
+  }
+  if (Reader.bytesRemaining() > 0)
+    return make_error<RawError>(raw_error_code::corrupt_file,
+                                "Unexpected bytes in module stream.");
+  return Error::success();
+}
+
+Error ModuleDebugStreamRef::reloadSerialize(BinaryStreamReader &Reader) {
   uint32_t SymbolSize = Mod.getSymbolDebugInfoByteSize();
   uint32_t C11Size = Mod.getC11LineInfoByteSize();
   uint32_t C13Size = Mod.getC13LineInfoByteSize();
@@ -71,10 +83,6 @@ Error ModuleDebugStreamRef::reload() {
     return EC;
   if (auto EC = Reader.readSubstream(GlobalRefsSubstream, GlobalRefsSize))
     return EC;
-  if (Reader.bytesRemaining() > 0)
-    return make_error<RawError>(raw_error_code::corrupt_file,
-                                "Unexpected bytes in module stream.");
-
   return Error::success();
 }