[Bug tree-optimization/38943] New: Optimization removes trapping instruction

[Bug tree-optimization/38943] New: Optimization removes trapping instruction

[ubizjak at gmail dot com]

Following test:

--cut here--
#define _GNU_SOURCE
#include <fenv.h>
#include <signal.h>
#include <stdlib.h>

static void foo (int sig)
{
  exit (0);
}

float __attribute__((noinline)) test (float x) { return 2.0f / x; };

int main()
{
  signal (SIGFPE, foo);

  feclearexcept (FE_ALL_EXCEPT);
  feenableexcept (FE_INEXACT);

  test (3.0f);

  abort ();
}
--cut here--

aborts when compiled with optimizations, since the call to a procedure with a
trapping insn is removed.

$ gcc -O2 -fnon-call-exceptions -ftrapping-math -lm sf.c
$ ./a.out
Aborted

$ gcc -lm sf.c
$ ./a.out
$ [...works OK...]

A wild guess is to blame tree optimizers, since in 123t.optimized we already
have the call removed:

main ()
{
<bb 2>:
  signal (8, foo);
  feclearexcept (61);
  feenableexcept (32);
  abort ();

}


-- 
           Summary: Optimization removes trapping instruction
           Product: gcc
           Version: 4.4.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ubizjak at gmail dot com
 GCC build triplet: i686-pc-linux-gnu
  GCC host triplet: i686-pc-linux-gnu
GCC target triplet:


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38943

[Bug tree-optimization/38943] Optimization removes trapping instruction

[rguenth at gcc dot gnu dot org]

------- Comment #1 from rguenth at gcc dot gnu dot org  2009-01-23 09:21 -------
FENV access is not implemented.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
 GCC target triplet|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38943