[Bug optimization/9624] Stack space allocation too gratuitious

[Bug optimization/9624] Stack space allocation too gratuitious

[pinskia at physics dot uc dot edu]

PLEASE REPLY TO gcc-bugzilla@gcc.gnu.org ONLY, *NOT* gcc-bugs@gcc.gnu.org.

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|0000-00-00 00:00:00         |2003-07-28 00:23:36
               date|                            |


------- Additional Comments From pinskia at physics dot uc dot edu  2003-07-28 00:23 -------
On the tree-ssa branch, gcc gcc does not allocate space for buf at all but it does not fix 
the problem if you use buf, the space allocated is still too gratuitious.

[Bug optimization/9624] Stack space allocation too gratuitious

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2003-11-25 08:48 -------
This looks like an aligment issue.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2003-07-28 00:23:36         |2003-11-25 08:48:12
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624

[Bug optimization/9624] Stack space allocation too gratuitious

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-01-09 02:44 -------
*** Bug 13623 has been marked as a duplicate of this bug. ***

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |anupamk at speakeasy dot net


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624

[Bug rtl-optimization/9624] Stack space allocation too gratuitious

[bisqwit at iki dot fi]

------- Additional Comments From bisqwit at iki dot fi  2004-09-08 11:29 -------
Alignment indeed rounds up the size, but consider this code:
  void xxx(void)
  {
      unsigned x[12451];
  }
No matter which optimization settings you run it at (even with
-fomit-frame-pointer), gcc will still emit code that allocates 49804+ bytes from
stack and immediately releases it. On x86, for example, it does this:
  _Z3xxxv:
      subl $49820, %esp
      addl $49820, %esp
      ret

Same thing also happens for unused local structs and classes.
The stack space isn't freed.

This does not happen with simple variables (ints and such), probably because the
compiler treats them as register variables by default and only allocates stack
space when it has no other choice.


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624

[Bug rtl-optimization/9624] Stack space allocation too gratuitious

[bisqwit at iki dot fi]

------- Additional Comments From bisqwit at iki dot fi  2004-09-08 11:31 -------
Err, meant "needlessly allocated" in comment #6, not "not freed".


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624

[Bug rtl-optimization/9624] Stack space allocation too gratuitious

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-09-08 18:27 -------
I should note that on the mainline now, we don't allocate the stack space for unused arrays.

-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624

[Bug rtl-optimization/9624] Stack space allocation too gratuitious

[rth at gcc dot gnu dot org]

------- Additional Comments From rth at gcc dot gnu dot org  2004-09-13 10:08 -------
Indeed, fixed for 4.0.  Will not be fixed in previous versions.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=9624