AsmParser/Writer: Handle symbolic constants in DI 'flags:'

Parse (and write) symbolic constants in debug info `flags:` fields.
This prevents a readability (and CHECK-ability) regression with the new
debug info hierarchy.

Old (well, current) assembly, with pretty-printing:

    !{!"...\\0016387", ...} ; ... [public] [rvalue reference]

Flags field without this change:

   !MDDerivedType(flags: 16387, ...)

Flags field with this change:

   !MDDerivedType(flags: DIFlagPublic | DIFlagRValueReference, ...)

As discussed in the review thread, this isn't a final state.  Most of
these flags correspond to `DW_AT_` symbolic constants, and we might
eventually want to support arbitrary attributes in some form.  However,
as it stands now, some of the flags correspond to other concepts (like
`FlagStaticMember`); until things are refactored this is the simplest
way to move forward without regressing assembly.

llvm-svn: 230111

1 files changed, 6 insertions, 0 deletions

diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index 656b1692182..3bf090a4b33 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -241,6 +241,7 @@ lltok::Kind LLLexer::LexToken() {
   case ')': return lltok::rparen;
   case ',': return lltok::comma;
   case '*': return lltok::star;
+  case '|': return lltok::bar;
   }
 }
 
@@ -760,6 +761,11 @@ lltok::Kind LLLexer::LexIdentifier() {
   DWKEYWORD(OP, DwarfOp);
 #undef DWKEYWORD
 
+  if (Keyword.startswith("DIFlag")) {
+    StrVal.assign(Keyword.begin(), Keyword.end());
+    return lltok::DIFlag;
+  }
+
   // Check for [us]0x[0-9A-Fa-f]+ which are Hexadecimal constant generated by
   // the CFE to avoid forcing it to deal with 64-bit numbers.
   if ((TokStart[0] == 'u' || TokStart[0] == 's') &&