[DebugInfo] Introduce DW_OP_LLVM_convert

Introduce a DW_OP_LLVM_convert Dwarf expression pseudo op that allows
for a convenient way to perform type conversions on the Dwarf expression
stack. As an additional bonus it paves the way for using other Dwarf
v5 ops that need to reference a base_type.

The new DW_OP_LLVM_convert is used from lib/Transforms/Utils/Local.cpp
to perform sext/zext on debug values but mainly the patch is about
preparing terrain for adding other Dwarf v5 ops that need to reference a
base_type.

For Dwarf v5 the op maps to DW_OP_convert and for earlier versions a
complex shift & mask pattern is generated to emulate sext/zext.

Differential Revision: https://reviews.llvm.org/D56587

llvm-svn: 356442

1 files changed, 4 insertions, 2 deletions

diff --git a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
index f0d50a47640..ec5040f6c10 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -682,10 +682,12 @@ public:
   /// Emit an entry for the debug loc section. This can be used to
   /// handle an entry that's going to be emitted into the debug loc section.
   void emitDebugLocEntry(ByteStreamer &Streamer,
-                         const DebugLocStream::Entry &Entry);
+                         const DebugLocStream::Entry &Entry,
+                         const DwarfCompileUnit *CU);
 
   /// Emit the location for a debug loc entry, including the size header.
-  void emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry);
+  void emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
+                                 const DwarfCompileUnit *CU);
 
   /// Find the MDNode for the given reference.
   template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {