[Debuginfo][COFF] Minimal serialization support for precompiled types records

This change adds support for the LF_PRECOMP and LF_ENDPRECOMP records required
to read/write Microsoft precompiled types .objs.
See https://en.wikipedia.org/wiki/Precompiled_header#Microsoft_Visual_C_and_C++

This also adds handling for the .debug$P section, which is actually a .debug$T
section in disguise, found only in precompiled .objs.

Differential Revision: https://reviews.llvm.org/D45283

llvm-svn: 329613

2 files changed, 3 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
index fa3fd17d629..f8cd01abddd 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -524,7 +524,7 @@ void CodeViewDebug::emitTypeInformation() {
   if (TypeTable.empty())
     return;
 
-  // Start the .debug$T section with 0x4.
+  // Start the .debug$T or .debug$P section with 0x4.
   OS.SwitchSection(Asm->getObjFileLowering().getCOFFDebugTypesSection());
   emitCodeViewMagicVersion();
 
diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 236a70ef15d..e58c4c666f2 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -239,7 +239,8 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
   }
 
   /// Emit the magic version number at the start of a CodeView type or symbol
-  /// section. Appears at the front of every .debug$S or .debug$T section.
+  /// section. Appears at the front of every .debug$S or .debug$T or .debug$P
+  /// section.
   void emitCodeViewMagicVersion();
 
   void emitTypeInformation();