Revert "[Parser] Start to parse instructions (#4789)"

This reverts commit 5aa2e18.

Author: aheejin

scripts/gen-s-parser.py

@@ -693,7 +693,7 @@ def insert(self, inst, expr):
         self.do_insert(inst, inst, expr)
 
 
-def instruction_parser(new_parser=False):
+def instruction_parser():
     """Build a trie out of all the instructions, then emit it as C++ code."""
     trie = Node()
     inst_length = 0
@@ -703,23 +703,12 @@ def instruction_parser(new_parser=False):
 
     printer = CodePrinter()
 
-    if not new_parser:
-        printer.print_line("char op[{}] = {{'\\0'}};".format(inst_length + 1))
-        printer.print_line("strncpy(op, s[0]->c_str(), {});".format(inst_length))
+    printer.print_line("char op[{}] = {{'\\0'}};".format(inst_length + 1))
+    printer.print_line("strncpy(op, s[0]->c_str(), {});".format(inst_length))
 
     def print_leaf(expr, inst):
-        if new_parser:
-            expr = expr.replace("()", "(ctx)")
-            expr = expr.replace("(s", "(ctx, in")
-            printer.print_line("if (op == \"{inst}\"sv) {{".format(inst=inst))
-            with printer.indent():
-                printer.print_line("auto ret = {expr};".format(expr=expr))
-                printer.print_line("CHECK_ERR(ret);")
-                printer.print_line("return *ret;")
-            printer.print_line("}")
-        else:
-            printer.print_line("if (strcmp(op, \"{inst}\") == 0) {{ return {expr}; }}"
-                               .format(inst=inst, expr=expr))
+        printer.print_line("if (strcmp(op, \"{inst}\") == 0) {{ return {expr}; }}"
+                           .format(inst=inst, expr=expr))
         printer.print_line("goto parse_error;")
 
     def emit(node, idx=0):
@@ -748,10 +737,7 @@ def emit(node, idx=0):
     emit(trie)
     printer.print_line("parse_error:")
     with printer.indent():
-        if new_parser:
-            printer.print_line("return in.err(\"unrecognized instruction\");")
-        else:
-            printer.print_line("throw ParseException(std::string(op), s.line, s.col);")
+        printer.print_line("throw ParseException(std::string(op), s.line, s.col);")
 
 
 def print_header():
@@ -777,8 +763,6 @@ def main():
         sys.exit(1)
     print_header()
     generate_with_guard(instruction_parser, "INSTRUCTION_PARSER")
-    print()
-    generate_with_guard(lambda: instruction_parser(True), "NEW_INSTRUCTION_PARSER")
     print_footer()