[Bug c/79691] -Wformat-truncation suppressed by (and only by) -Og

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79691

Martin Sebor  changed:

   What|Removed |Added

 Status|ASSIGNED|RESOLVED
 Resolution|--- |FIXED

--- Comment #4 from Martin Sebor  ---
Fixed in r245782.

[Bug c/79691] -Wformat-truncation suppressed by (and only by) -Og

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79691

--- Comment #3 from Martin Sebor  ---
Author: msebor
Date: Tue Feb 28 16:59:16 2017
New Revision: 245782

URL: https://gcc.gnu.org/viewcvs?rev=245782&root=gcc&view=rev
Log:
PR tree-optimization/79691 - -Wformat-truncation suppressed by (and only by)
-Og

gcc/ChangeLog:

PR tree-optimization/79691
* passes.def (pass_all_optimizations_g): Enable pass_sprintf_length.

gcc/testsuite/ChangeLog:

PR tree-optimization/79691
* gcc.dg/tree-ssa/pr79691.c: New test.


Added:
trunk/gcc/testsuite/gcc.dg/tree-ssa/pr79691.c
Modified:
trunk/gcc/ChangeLog
trunk/gcc/passes.def
trunk/gcc/testsuite/ChangeLog

[Bug c/79691] -Wformat-truncation suppressed by (and only by) -Og

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79691

--- Comment #2 from Martin Sebor  ---
Patch posted for review:
https://gcc.gnu.org/ml/gcc-patches/2017-02/msg01480.html

[Bug c/79691] -Wformat-truncation suppressed by (and only by) -Og

[msebor at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=79691

Martin Sebor  changed:

   What|Removed |Added

   Keywords||diagnostic,
   ||missed-optimization
 Status|UNCONFIRMED |ASSIGNED
   Last reconfirmed||2017-02-23
 CC||msebor at gcc dot gnu.org
   Assignee|unassigned at gcc dot gnu.org  |msebor at gcc dot 
gnu.org
 Ever confirmed|0   |1

--- Comment #1 from Martin Sebor  ---
Confirmed for the missing diagnostic
(https://gcc.gnu.org/ml/gcc/2017-02/msg00105.html).

It's a also a missed optimization because, as can be seen in the test case
below, the sprintf return value optimization isn't done:

$ (set -x && cat t.c && for O in 1 g; do gcc -O$O -S -Wall -Wextra -Wpedantic
-fdump-tree-optimized=/dev/stdout t.c; done)
+ cat t.c
int f (void)
{
  return __builtin_snprintf (0, 0, "%i", 123);
} 
+ for O in 1 g
+ gcc -O1 -S -Wall -Wextra -Wpedantic -fdump-tree-optimized=/dev/stdout t.c

;; Function f (f, funcdef_no=0, decl_uid=1795, cgraph_uid=0, symbol_order=0)

f ()
{
   [100.00%]:
  return 3;

}


+ for O in 1 g
+ gcc -Og -S -Wall -Wextra -Wpedantic -fdump-tree-optimized=/dev/stdout t.c

;; Function f (f, funcdef_no=0, decl_uid=1795, cgraph_uid=0, symbol_order=0)

f ()
{
  int _3;

   [100.00%]:
  _3 = __builtin_snprintf (0B, 0, "%i", 123);
  return _3;

}