Experimental parser: remove unnecessary reads

tools/lexer_generator/code_generator.jinja

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 187 matching lines @@
 {% endmacro -%}
 
 
 {%- macro do_dfa_state(node_number_chain) -%}
 
   {%- set node_number = node_number_chain|first -%}
   {%- set state = dfa_states[node_number] -%}
 
   {{ write_label('state_entry', node_number_chain) }}
 
+  READ_CURSOR();
+
   {% if debug_print %}
     fprintf(stderr,
             "state {{state.node_number}}, start %d, cursor %d\n",
             start_ - buffer_,
             cursor_ - buffer_);
   {% endif -%}
 
   {%- set entry_action = state.entry_action -%}
   {%- if entry_action %}
     {{ dispatch_entry_action(entry_action[0], entry_action[1]) }}
@@ skipping 70 matching lines @@
 
 #define DO_TOKEN(T) {                 \
   next_.beg_pos = start_ - buffer_;   \
   next_.end_pos = cursor_ - buffer_;  \
   next_.token = T;                    \
   RESET_START();                      \
 }
 
 #define FORWARD() {                               \
   cursor_++;                                      \
-  READ_CURSOR();                                  \
 }
 
 #define BACKWARD(n) {                             \
   cursor_ -= n;                                   \
-  READ_CURSOR();                                  \
 }
 
 #define READ_CURSOR() {                           \
   if (cursor_ >= buffer_end_) primary_char = 0;   \
   else primary_char = *(cursor_);                 \
 }
 
 #ifdef DEBUG
 #define CRASH() { ((void(*)())0)(); }
 #else
 #define CRASH() { }
 #endif
 
 namespace v8 {
 namespace internal {
 template<>
 void ExperimentalScanner<{{char_type}}>::Scan() {
 
   // Setup environment.
   next_.has_escapes = false;
   Token::Value stored_token;
   const {{char_type}} * marker;
   {{char_type}} primary_char;
-  READ_CURSOR();
 
 {# first node is start node #}
 {% for dfa_state in dfa_states -%}
   {%- if not dfa_state['inline'] %}
     {{ do_dfa_state([dfa_state['node_number']]) }}
   {%- endif -%}
 {%- endfor %}
 
   // Execute the default action.
   default_action:
 {%- if debug_print %}
     fprintf(stderr, "default action\n");
 {% endif -%}
     {{dispatch_match_action(default_action[0], default_action[1])}}
   CRASH();
 
   if (false) {
     // force use of stored_token
     stored_token = Token::ILLEGAL;
     // force use of marker
     marker = NULL;
     // force use of state_entry_0
     goto state_entry_0;
   }
 }
 } }