This is the mail archive of the
gdb-patches@sourceware.org
mailing list for the GDB project.
Re: [RFA] C++-ify parser_state
- From: Simon Marchi <simon dot marchi at ericsson dot com>
- To: Tom Tromey <tom at tromey dot com>, <gdb-patches at sourceware dot org>
- Date: Mon, 27 Nov 2017 11:40:52 -0500
- Subject: Re: [RFA] C++-ify parser_state
- Authentication-results: sourceware.org; auth=none
- Authentication-results: spf=none (sender IP is ) smtp.mailfrom=simon dot marchi at ericsson dot com;
- References: <20171126174047.23943-1-tom@tromey.com>
- Spamdiagnosticmetadata: NSPM
- Spamdiagnosticoutput: 1:99
Hi Tom,
I think this looks good. I have some suggestions to clean things a further
bit, you are free to take them or leave them
On 2017-11-26 12:40 PM, Tom Tromey wrote:
> +expression_up
> +parser_state::release ()
> {
> /* Record the actual number of expression elements, and then
> reallocate the expression memory so that we free up any
> excess elements. */
>
> - ps->expout->nelts = ps->expout_ptr;
> - ps->expout = (struct expression *)
> - xrealloc (ps->expout,
> + expout->nelts = expout_ptr;
> + expout = (struct expression *)
> + xrealloc (expout,
> sizeof (struct expression)
> - + EXP_ELEM_TO_BYTES (ps->expout_ptr));
> + + EXP_ELEM_TO_BYTES (expout_ptr));
> +
> + expression_up result (expout);
> + /* Ensure that we don't free it in the destructor. */
> + expout = nullptr;
> + return result;
If expout was an expression_up, we could just std::move it here, and
wouldn't need an explicit destructor.
> }
>
> /* This page contains the functions for adding data to the struct expression
> @@ -1118,7 +1127,6 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
> int comma, int void_context_p, int *out_subexp)
> {
> const struct language_defn *lang = NULL;
> - struct parser_state ps;
> int subexp;
>
> lexptr = *stringptr;
> @@ -1194,7 +1202,7 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
> and others called from *.y) ensure CURRENT_LANGUAGE gets restored
> to the value matching SELECTED_FRAME as set by get_current_arch. */
>
> - initialize_expout (&ps, 10, lang, get_current_arch ());
> + parser_state ps (10, lang, get_current_arch ());
>
> scoped_restore_current_language lang_saver;
> set_language (lang->la_language);
> @@ -1207,33 +1215,32 @@ parse_exp_in_context_1 (const char **stringptr, CORE_ADDR pc,
> CATCH (except, RETURN_MASK_ALL)
> {
> if (! parse_completion)
> - {
> - xfree (ps.expout);
> - throw_exception (except);
> - }
> + throw_exception (except);
> }
> END_CATCH
>
> - reallocate_expout (&ps);
> + /* We have to operate on an "expression *", due to la_post_parser,
> + which explains this funny-looking double release. */
> + struct expression *result = ps.release ().release ();
>
> /* Convert expression from postfix form as generated by yacc
> parser, to a prefix form. */
>
> if (expressiondebug)
> - dump_raw_expression (ps.expout, gdb_stdlog,
> + dump_raw_expression (result, gdb_stdlog,
> "before conversion to prefix form");
>
> - subexp = prefixify_expression (ps.expout);
> + subexp = prefixify_expression (result);
> if (out_subexp)
> *out_subexp = subexp;
>
> - lang->la_post_parser (&ps.expout, void_context_p);
> + lang->la_post_parser (&result, void_context_p);
Passing a pointer or reference to the unique_ptr would allow
the implementations of la_post_parser to modify it directly,
and avoid the .release ().release ().
> --- a/gdb/stap-probe.c
> +++ b/gdb/stap-probe.c
> @@ -1146,25 +1146,17 @@ static expression_up
> stap_parse_argument (const char **arg, struct type *atype,
> struct gdbarch *gdbarch)
> {
> - struct stap_parse_info p;
> - struct cleanup *back_to;
> -
> /* We need to initialize the expression buffer, in order to begin
> our parsing efforts. We use language_c here because we may need
> to do pointer arithmetics. */
> - initialize_expout (&p.pstate, 10, language_def (language_c), gdbarch);
> - back_to = make_cleanup (free_current_contents, &p.pstate.expout);
> + struct stap_parse_info p (10, language_def (language_c), gdbarch);
>
> p.saved_arg = *arg;
> p.arg = *arg;
> p.arg_type = atype;
> - p.gdbarch = gdbarch;
> - p.inside_paren_p = 0;
Why not pass the other arguments to the constructor (*arg and atype)?
Simon