[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/DebugLocEntry.h b/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
index 40360ba4d34..256a41be237 100644
--- a/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
+++ b/llvm/lib/CodeGen/AsmPrinter/DebugLocEntry.h
@@ -148,8 +148,10 @@ public:
   }
 
   /// Lower this entry into a DWARF expression.
-  void finalize(const AsmPrinter &AP, DebugLocStream::ListBuilder &List,
-                const DIBasicType *BT);
+  void finalize(const AsmPrinter &AP,
+                DebugLocStream::ListBuilder &List,
+                const DIBasicType *BT,
+                DwarfCompileUnit &TheCU);
 };
 
 /// Compare two Values for equality.