[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, 9 insertions, 0 deletions

diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 5a875fee07b..71315f3c0fb 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -4838,6 +4838,15 @@ bool LLParser::ParseDIExpression(MDNode *&Result, bool IsDistinct) {
         return TokError(Twine("invalid DWARF op '") + Lex.getStrVal() + "'");
       }
 
+      if (Lex.getKind() == lltok::DwarfAttEncoding) {
+        if (unsigned Op = dwarf::getAttributeEncoding(Lex.getStrVal())) {
+          Lex.Lex();
+          Elements.push_back(Op);
+          continue;
+        }
+        return TokError(Twine("invalid DWARF attribute encoding '") + Lex.getStrVal() + "'");
+      }
+
       if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
         return TokError("expected unsigned integer");