Re-land "[codeview] Emit information about global variables"

This reverts commit r271962 and reinstantes r271957.

MSVC's linker doesn't appear to like it if you have an empty symbol
substream, so only open a symbol substream if we're going to emit
something about globals into it.

Makes check-asan pass.

llvm-svn: 271965

1 files changed, 11 insertions, 0 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
index 208ff33b964..69c9c966f93 100644
--- a/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -169,6 +169,17 @@ class LLVM_LIBRARY_VISIBILITY CodeViewDebug : public DebugHandlerBase {
 
   void emitDebugInfoForFunction(const Function *GV, FunctionInfo &FI);
 
+  void emitDebugInfoForGlobals();
+
+  void emitDebugInfoForGlobal(const DIGlobalVariable *DIGV, MCSymbol *GVSym);
+
+  /// Opens a subsection of the given kind in a .debug$S codeview section.
+  /// Returns an end label for use with endCVSubsection when the subsection is
+  /// finished.
+  MCSymbol *beginCVSubsection(codeview::ModuleSubstreamKind Kind);
+
+  void endCVSubsection(MCSymbol *EndLabel);
+
   void emitInlinedCallSite(const FunctionInfo &FI, const DILocation *InlinedAt,
                            const InlineSite &Site);