3 files changed, 42 insertions, 5 deletions
diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index 63eb96324fa..2fd9861c517 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -748,6 +748,7 @@ lltok::Kind LLLexer::LexIdentifier() {
   DWKEYWORD(ATE, DwarfAttEncoding);
   DWKEYWORD(VIRTUALITY, DwarfVirtuality);
   DWKEYWORD(LANG, DwarfLang);
+  DWKEYWORD(OP, DwarfOp);
 #undef DWKEYWORD
 
   // Check for [us]0x[0-9A-Fa-f]+ which are Hexadecimal constant generated by
diff --git a/llvm/lib/AsmParser/LLParser.cpp b/llvm/lib/AsmParser/LLParser.cpp
index 48dbaeeb76a..dc8367c5626 100644
--- a/llvm/lib/AsmParser/LLParser.cpp
+++ b/llvm/lib/AsmParser/LLParser.cpp
@@ -3599,9 +3599,44 @@ bool LLParser::ParseMDLocalVariable(MDNode *&Result, bool IsDistinct) {
   return false;
 }
 
+/// ParseMDExpression:
+///   ::= !MDExpression(0, 7, -1)
 bool LLParser::ParseMDExpression(MDNode *&Result, bool IsDistinct) {
-  return TokError("unimplemented parser");
+  assert(Lex.getKind() == lltok::MetadataVar && "Expected metadata type name");
+  Lex.Lex();
+
+  if (ParseToken(lltok::lparen, "expected '(' here"))
+    return true;
+
+  SmallVector<uint64_t, 8> Elements;
+  if (Lex.getKind() != lltok::rparen)
+    do {
+      if (Lex.getKind() == lltok::DwarfOp) {
+        if (unsigned Op = dwarf::getOperationEncoding(Lex.getStrVal())) {
+          Lex.Lex();
+          Elements.push_back(Op);
+          continue;
+        }
+        return TokError(Twine("invalid DWARF op '") + Lex.getStrVal() + "'");
+      }
+
+      if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
+        return TokError("expected unsigned integer");
+
+      auto &U = Lex.getAPSIntVal();
+      if (U.ugt(UINT64_MAX))
+        return TokError("element too large, limit is " + Twine(UINT64_MAX));
+      Elements.push_back(U.getZExtValue());
+      Lex.Lex();
+    } while (EatIfPresent(lltok::comma));
+
+  if (ParseToken(lltok::rparen, "expected ')' here"))
+    return true;
+
+  Result = GET_OR_DISTINCT(MDExpression, (Context, Elements));
+  return false;
 }
+
 bool LLParser::ParseMDObjCProperty(MDNode *&Result, bool IsDistinct) {
   return TokError("unimplemented parser");
 }
diff --git a/llvm/lib/AsmParser/LLToken.h b/llvm/lib/AsmParser/LLToken.h
index ff894df5db4..57218dafbb9 100644
--- a/llvm/lib/AsmParser/LLToken.h
+++ b/llvm/lib/AsmParser/LLToken.h
@@ -198,10 +198,11 @@ namespace lltok {
     LocalVar,          // %foo %"foo"
     MetadataVar,       // !foo
     StringConstant,    // "foo"
-    DwarfTag,          // DW_TAG_foo (includes "DW_TAG_")
-    DwarfAttEncoding,  // DW_ATE_foo (includes "DW_ATE_")
-    DwarfVirtuality,   // DW_VIRTUALITY_foo (includes "DW_VIRTUALITY_")
-    DwarfLang,         // DW_LANG_foo (includes "DW_LANG_")
+    DwarfTag,          // DW_TAG_foo
+    DwarfAttEncoding,  // DW_ATE_foo
+    DwarfVirtuality,   // DW_VIRTUALITY_foo
+    DwarfLang,         // DW_LANG_foo
+    DwarfOp,           // DW_OP_foo
 
     // Type valued tokens (TyVal).
     Type,