[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.

This is a recommit of r356442 with trivial fixes for the failing tests.

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

llvm-svn: 356451

1 files changed, 3 insertions, 0 deletions

diff --git a/llvm/lib/BinaryFormat/Dwarf.cpp b/llvm/lib/BinaryFormat/Dwarf.cpp
index 73f04a3ed28..b6d4d5b0730 100644
--- a/llvm/lib/BinaryFormat/Dwarf.cpp
+++ b/llvm/lib/BinaryFormat/Dwarf.cpp
@@ -143,6 +143,8 @@ StringRef llvm::dwarf::OperationEncodingString(unsigned Encoding) {
   case DW_OP_##NAME:                                                           \
     return "DW_OP_" #NAME;
 #include "llvm/BinaryFormat/Dwarf.def"
+  case DW_OP_LLVM_convert:
+    return "DW_OP_LLVM_convert";
   case DW_OP_LLVM_fragment:
     return "DW_OP_LLVM_fragment";
   }
@@ -153,6 +155,7 @@ unsigned llvm::dwarf::getOperationEncoding(StringRef OperationEncodingString) {
 #define HANDLE_DW_OP(ID, NAME, VERSION, VENDOR)                                \
   .Case("DW_OP_" #NAME, DW_OP_##NAME)
 #include "llvm/BinaryFormat/Dwarf.def"
+      .Case("DW_OP_LLVM_convert", DW_OP_LLVM_convert)
       .Case("DW_OP_LLVM_fragment", DW_OP_LLVM_fragment)
       .Default(0);
 }