[Bug tree-optimization/26608] New: address of local variables are said to escape even though it is obvious they don't

[Bug tree-optimization/26608] New: address of local variables are said to escape even though it is obvious they don't

[pinskia at gcc dot gnu dot org]

Testcase:
int *d1;
int g(int *b)
{
  d1 = b;
}
int f(int a, int b, int c)
{
  int i, j;
  int *d;
  if (a)
    d = &i;
  else
    d = &j;
  i = 2;
  j = 3;
  g(&b);
  if (i!=2)
   link_error();
  if (j!=3)
   link_error();
  return *d;
}
int main(void)
{
  f(1, 2,3);
  return 0;
}

This should link with optimize but right now i and j are said to be call
clobbered for some reason.


-- 
           Summary: address of local variables are said to escape even
                    though it is obvious they don't
           Product: gcc
           Version: 4.2.0
            Status: UNCONFIRMED
          Keywords: missed-optimization, alias
          Severity: normal
          Priority: P3
         Component: tree-optimization
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: pinskia at gcc dot gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26608

Re: [Bug tree-optimization/26608] New: address of local variables are said to escape even though it is obvious they don't

[Daniel Berlin]

On Wed, 2006-03-08 at 18:59 +0000, pinskia at gcc dot gnu dot org wrote:
> Testcase:
> int *d1;
> int g(int *b)
> {
>   d1 = b;
> }
> int f(int a, int b, int c)
> {
>   int i, j;
>   int *d;
>   if (a)
>     d = &i;
>   else
>     d = &j;
>   i = 2;
>   j = 3;
>   g(&b);
>   if (i!=2)
>    link_error();
>   if (j!=3)
>    link_error();
>   return *d;
> }
> int main(void)
> {
>   f(1, 2,3);
>   return 0;
> }
> 
> This should link with optimize but right now i and j are said to be call
> clobbered for some reason.

What does the dump say.
My guess is that it believes that they are returned from the call, even
though they are not.

> 
> 

[Bug tree-optimization/26608] address of local variables are said to escape even though it is obvious they don't

[dberlin at dberlin dot org]

------- Comment #1 from dberlin at gcc dot gnu dot org  2006-03-08 19:44 -------
Subject: Re:   New: address of local variables
        are said to escape even though it is obvious they don't

On Wed, 2006-03-08 at 18:59 +0000, pinskia at gcc dot gnu dot org wrote:
> Testcase:
> int *d1;
> int g(int *b)
> {
>   d1 = b;
> }
> int f(int a, int b, int c)
> {
>   int i, j;
>   int *d;
>   if (a)
>     d = &i;
>   else
>     d = &j;
>   i = 2;
>   j = 3;
>   g(&b);
>   if (i!=2)
>    link_error();
>   if (j!=3)
>    link_error();
>   return *d;
> }
> int main(void)
> {
>   f(1, 2,3);
>   return 0;
> }
> 
> This should link with optimize but right now i and j are said to be call
> clobbered for some reason.

What does the dump say.
My guess is that it believes that they are returned from the call, even
though they are not.

> 
> 


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26608

[Bug tree-optimization/26608] address of local variables are said to escape even though it is obvious they don't

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-03-08 19:47 -------
Variable: i, UID 1520, int, is aliased, is addressable, default def: i_3

Variable: j, UID 1521, int, is aliased, is addressable, default def: j_5

Variable: b, UID 1516, int, is aliased, is addressable, call clobbered (,
passed to call )

Variable: SMT.30, UID 1569, int, is addressable, call clobbered (, passed to
call ), may aliases: { i j b }

Hmm, it does not say why i and j are thought to be call clobbered but it looks
like it is because the SMT is call clobbered.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26608

[Bug tree-optimization/26608] address of local variables are said to escape even though it is obvious they don't

[pinskia at gcc dot gnu dot org]

------- Comment #3 from pinskia at gcc dot gnu dot org  2006-09-12 06:37 -------
Confirmed.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|normal                      |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   Last reconfirmed|0000-00-00 00:00:00         |2006-09-12 06:37:43
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26608

[Bug tree-optimization/26608] address of local variables are said to escape even though it is obvious they don't

[rguenth at gcc dot gnu dot org]

------- Comment #4 from rguenth at gcc dot gnu dot org  2009-04-03 12:24 -------
Works with 4.3.  Very similar to PR23086.


-- 

rguenth at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.3.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=26608