Simplify script lexer.

[ruiu]

Summary

Simplify script lexer.

[grimar]

LGTM, thanks !

lld/ELF/ScriptLexer.cpp

if (S.startswith("\"")) {
         return;
       }
 
       Vec.push_back(S.take_front(E + 1));
       S = S.substr(E + 1);
       continue;
     }
 
+    // ">foo" is parsed to ">" and "foo", but ">>" is parsed to ">>".
+    if (S.startswith("<<") || S.startswith("<=") || S.startswith(">>") ||
+        S.startswith(">=")) {
+      Vec.push_back(S.substr(0, 2));
+      S = S.substr(2);
+      continue;
+    }
+
     // Unquoted token. This is more relaxed than tokens in C-like language,
     // so that you can write "file-name.cpp" as one bare token, for example.
     size_t Pos = S.find_first_not_of(
         "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz"
-        "0123456789_.$/\\~=+[]*?-!<>^:");
+        "0123456789_.$/\\~=+[]*?-!^:");
 
     // A character that cannot start a word (which is usually a
     // punctuation) forms a single character token.
     if (Pos == 0)
       Pos = 1;
     Vec.push_back(S.substr(0, Pos));
     S = S.substr(Pos);
   }

lld/ELF/ScriptParser.cpp

if (Tok == ";") {
       Cmd->SectionCommands.push_back(readInputSectionDescription(Tok));
     } else {
       setError("unknown command " + Tok);
     }
   }
 
   if (consume(">"))
     Cmd->MemoryRegionName = next();
-  else if (peek().startswith(">"))
-    Cmd->MemoryRegionName = next().drop_front();
 
   Cmd->Phdrs = readOutputSectionPhdrs();
 
   if (consume("="))
     Cmd->Filler = parseFill(next());
   else if (peek().startswith("="))
     Cmd->Filler = parseFill(next().drop_front());