[DebugInfo] Generate DWARF debug information for labels.

There are two forms for label debug information in DWARF format.

1. Labels in a non-inlined function:

DW_TAG_label
  DW_AT_name
  DW_AT_decl_file
  DW_AT_decl_line
  DW_AT_low_pc

2. Labels in an inlined function:

DW_TAG_label
  DW_AT_abstract_origin
  DW_AT_low_pc

We will collect label information from DBG_LABEL. Before every DBG_LABEL,
we will generate a temporary symbol to denote the location of the label.
The symbol could be used to get DW_AT_low_pc afterwards. So, we create a
mapping between 'inlined label' and DBG_LABEL MachineInstr in DebugHandlerBase.
The DBG_LABEL in the mapping is used to query the symbol before it.

The AbstractLabels in DwarfCompileUnit is used to process labels in inlined
functions.

We also keep a mapping between scope and labels in DwarfFile to help to
generate correct tree structure of DIEs.

Differential Revision: https://reviews.llvm.org/D45556

Patch by Hsiangkai Wang.

llvm-svn: 337799

1 files changed, 4 insertions, 1 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
index 1ccefe32be7..4b0ce0e3f03 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugHandlerBase.h
@@ -16,7 +16,7 @@
 #define LLVM_LIB_CODEGEN_ASMPRINTER_DEBUGHANDLERBASE_H
 
 #include "AsmPrinterHandler.h"
-#include "DbgValueHistoryCalculator.h"
+#include "DbgEntityHistoryCalculator.h"
 #include "llvm/ADT/Optional.h"
 #include "llvm/CodeGen/LexicalScopes.h"
 #include "llvm/CodeGen/MachineInstr.h"
@@ -82,6 +82,9 @@ protected:
   /// variable.  Variables are listed in order of appearance.
   DbgValueHistoryMap DbgValues;
 
+  /// Mapping of inlined labels and DBG_LABEL machine instruction.
+  DbgLabelInstrMap DbgLabels;
+
   /// Maps instruction with label emitted before instruction.
   /// FIXME: Make this private from DwarfDebug, we have the necessary accessors
   /// for it.