Re: [PATCH 14/40] Introduce CP_OPERATOR_STR/CP_OPERATOR_LEN and use throughout

[Pedro Alves <palves at redhat dot com>]

On 07/14/2017 07:04 PM, Keith Seitz wrote:
> On 06/02/2017 05:22 AM, Pedro Alves wrote:
>> I ran into LENGTH_OF_OPERATOR in cp-support.c and wanted to use it
>> elsewhere, so I moved it to cp-support.h.  Since there's already
>> CP_ANONYMOUS_NAMESPACE_STR/CP_ANONYMOUS_NAMESPACE_LEN there, I
>> followed the same naming pattern for the new symbols.
> 
> Looks pretty straightforward (even?) to me, but I do notice that there are still one or two places that could be updated:
> 
> c-exp.y:2281:    {"operator", OPERATOR, OP_NULL, FLAG_CXX},
> cp-name-parser.y:1839:      if (strncmp (tokstart, "operator", 8) == 0)

I had left these two because looking at the context around them, I'm
thinking that using the macro would obfuscate more than help.  c-exp.y has:

...
    {"new", NEW, OP_NULL, FLAG_CXX},
    {"delete", DELETE, OP_NULL, FLAG_CXX},
    {"operator", OPERATOR, OP_NULL, FLAG_CXX},

    {"and", ANDAND, BINOP_END, FLAG_CXX},
    {"and_eq", ASSIGN_MODIFY, BINOP_BITWISE_AND, FLAG_CXX},
    {"bitand", '&', OP_NULL, FLAG_CXX},
...

And cp-name-parser.y has:

...
    case 8:
      HANDLE_SPECIAL ("typeinfo for ", DEMANGLE_COMPONENT_TYPEINFO);
      HANDLE_SPECIAL ("typeinfo fn for ", DEMANGLE_COMPONENT_TYPEINFO_FN);
      HANDLE_SPECIAL ("typeinfo name for ", DEMANGLE_COMPONENT_TYPEINFO_NAME);
      if (strncmp (tokstart, "operator", 8) == 0)
	return OPERATOR;
      if (strncmp (tokstart, "restrict", 8) == 0)
	return RESTRICT;
      if (strncmp (tokstart, "unsigned", 8) == 0)
	return UNSIGNED;
      if (strncmp (tokstart, "template", 8) == 0)
	return TEMPLATE;
...

Note all those "8"s match the size in the switch case.  (Likewise
the other switch cases.)

Given that nowadays compilers optimize strlen("string literal") to a
constant, this cp-name-parser.y case might be tweaked as:

      if (startswith (tokstart, "operator"))
	return OPERATOR;
      if (startswith (tokstart, "restrict"))
	return RESTRICT;
      if (startswith (tokstart, "unsigned"))
	return UNSIGNED;
      if (startswith (tokstart, "template"))
	return TEMPLATE;

etc.

So for now, I've pushed the patch as it was.

Thanks,
Pedro Alves