Hi,
> On Dec 9, 2021, at 12:13 PM, Qing Zhao via Gcc-patches
> <gcc-patches@gcc.gnu.org> wrote:
>>
>>> + return;
>>> +
>>> + /* Get the variable declaration location from the def_stmt. */
>>> + var_decl_loc = gimple_location (def_stmt);
>>> +
>>> + /* The LHS of the call is a temporary variable, we use it as a
>>> + placeholder to record the information on whether the warning
>>> + has been issued or not. */
>>> + repl_var = gimple_call_lhs (def_stmt);
>>> + }
>>> }
>>> - if (var == NULL_TREE)
>>> + if (var == NULL_TREE && var_name == NULL_TREE)
>>> return;
>>> /* Avoid warning if we've already done so or if the warning has been
>>> @@ -207,36 +245,56 @@ warn_uninit (opt_code opt, tree t, tree var, const
>>> char *gmsgid,
>>> if (((warning_suppressed_p (context, OPT_Wuninitialized)
>>> || (gimple_assign_single_p (context)
>>> && get_no_uninit_warning (gimple_assign_rhs1 (context)))))
>>> - || get_no_uninit_warning (var))
>>> + || (var && get_no_uninit_warning (var))
>>> + || (repl_var && get_no_uninit_warning (repl_var)))
>>> return;
>>> /* Use either the location of the read statement or that of the PHI
>>> argument, or that of the uninitialized variable, in that order,
>>> whichever is valid. */
>>> - location_t location;
>>> + location_t location = UNKNOWN_LOCATION;
>>> if (gimple_has_location (context))
>>> location = gimple_location (context);
>>> else if (phi_arg_loc != UNKNOWN_LOCATION)
>>> location = phi_arg_loc;
>>> - else
>>> + else if (var)
>>> location = DECL_SOURCE_LOCATION (var);
>>> + else if (var_name)
>>> + location = var_decl_loc;
>>> +
>>> location = linemap_resolve_location (line_table, location,
>>> LRK_SPELLING_LOCATION, NULL);
>>> auto_diagnostic_group d;
>>> - if (!warning_at (location, opt, gmsgid, var))
>>> + char *gmsgid_final = XNEWVEC (char, strlen (gmsgid) + 5);
>>> + gmsgid_final[0] = 0;
>>> + if (var)
>>> + strcat (gmsgid_final, "%qD ");
>>> + else if (var_name)
>>> + strcat (gmsgid_final, "%qs ");
>>> + strcat (gmsgid_final, gmsgid);
>>> +
>>> + if (var && !warning_at (location, opt, gmsgid_final, var))
>>> + return;
>>> + else if (var_name && !warning_at (location, opt, gmsgid_final,
>>> var_name_str))
>>> return;
>>
>> Dynamically creating the string seems quite cumbersome here, and
>> it leaks the allocated block. I wonder if it might be better to
>> remove the gmsgid argument from the function and assign it to
>> one of the literals based on the other arguments.
>>
>> Since only one of var and var_name is used, I also wonder if
>> the %qs form could be used for both to simplify the overall
>> logic. (I.e., get the IDENTIFIER_POINTER string from var and
>> use it instead of %qD).
Looks like that using “%qs” + get the IDENTIFIER_POINTER string from var did
not work very well for the following testing case:
1 /* PR tree-optimization/45083 */
2 /* { dg-do compile } */
3 /* { dg-options "-O2 -Wuninitialized" } */
4
5 struct S { char *a; unsigned b; unsigned c; };
6 extern int foo (const char *);
7 extern void bar (int, int);
8
9 static void
10 baz (void)
11 {
12 struct S cs[1]; /* { dg-message "was declared here" } */
13 switch (cs->b) /* { dg-warning "cs\[^\n\r\]*\\.b\[^\n\r\]*is used
uninitialized" } */
14 {
15 case 101:
16 if (foo (cs->a)) /* { dg-warning "cs\[^\n\r\]*\\.a\[^\n\r\]*may be
used uninitialized" } */
17 bar (cs->c, cs->b); /* { dg-warning
"cs\[^\n\r\]*\\.c\[^\n\r\]*may be used uninitialized" } */
18 }
19 }
20
21 void
22 test (void)
23 {
24 baz ();
25 }
For the uninitialized usages at line 13, 16, 17: the IDENTIFIER_POINTER string
of var are:
cs$0$b, cs$0$a ,cs$0$c
However, with %qD, they are printed as cs[0].b, cs[0].a, cs[0].c
But with %qs, they are printed as cs$0$b, cs$0$a ,cs$0$c.
Looks like that %qD does not simplify print out the IDENTIFIER_POINTER string
directly, it specially handle it for some cases.
I tried to see how %qD specially handle the strings, but didn’t get it so far.
Do you know where the %qD handle this case specially?
Thanks.
Qing
> Both are good suggestions, I will try to update the code based on this.
>
> Thanks again.
>
> Qing
>>
>
