[LLVM][AsmParser] Add support for C style comments (#111554)

Add support for C style comments in LLVM assembly.

---------

Co-authored-by: Nikita Popov <github@npopov.com>

1 files changed, 28 insertions, 1 deletions

diff --git a/llvm/lib/AsmParser/LLLexer.cpp b/llvm/lib/AsmParser/LLLexer.cpp
index 56abd03..1b8e033 100644
--- a/llvm/lib/AsmParser/LLLexer.cpp
+++ b/llvm/lib/AsmParser/LLLexer.cpp
@@ -200,7 +200,6 @@ lltok::Kind LLLexer::LexToken() {
       // Handle letters: [a-zA-Z_]
       if (isalpha(static_cast<unsigned char>(CurChar)) || CurChar == '_')
         return LexIdentifier();
-
       return lltok::Error;
     case EOF: return lltok::Eof;
     case 0:
@@ -251,6 +250,12 @@ lltok::Kind LLLexer::LexToken() {
     case ',': return lltok::comma;
     case '*': return lltok::star;
     case '|': return lltok::bar;
+    case '/':
+      if (getNextChar() != '*')
+        return lltok::Error;
+      if (SkipCComment())
+        return lltok::Error;
+      continue;
     }
   }
 }
@@ -262,6 +267,28 @@ void LLLexer::SkipLineComment() {
   }
 }
 
+/// This skips C-style /**/ comments. Returns true if there
+/// was an error.
+bool LLLexer::SkipCComment() {
+  while (true) {
+    int CurChar = getNextChar();
+    switch (CurChar) {
+    case EOF:
+      LexError("unterminated comment");
+      return true;
+    case '*':
+      // End of the comment?
+      CurChar = getNextChar();
+      if (CurChar == '/')
+        return false;
+      if (CurChar == EOF) {
+        LexError("unterminated comment");
+        return true;
+      }
+    }
+  }
+}
+
 /// Lex all tokens that start with an @ character.
 ///   GlobalVar   @\"[^\"]*\"
 ///   GlobalVar   @[-a-zA-Z$._][-a-zA-Z$._0-9]*