[Bug c/11761] New: [tree-ssa] arrays inside classes not optimised away

[Bug c/11761] New: [tree-ssa] arrays inside classes not optimised away

[stefaandr at hotmail dot com]

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761

           Summary: [tree-ssa] arrays inside classes not optimised away
           Product: gcc
           Version: tree-ssa
            Status: UNCONFIRMED
          Severity: minor
          Priority: P2
         Component: c
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: stefaandr at hotmail dot com
                CC: gcc-bugs at gcc dot gnu dot org
 GCC build triplet: i386-redhat-linux
  GCC host triplet: i386-redhat-linux
GCC target triplet: i386-redhat-linux

Follow-up of 9059, in which arrays weren't optimised away, which is currently
fixed in tree-ssa.  In the 3 lines of code hereunder the unused array is inside
a class, which again seems to leave the array unbothered.  If the array is
replaced by a regular int or similar, it is optimised away though.

extern void t();
struct p { int a[5]; p() { a[3] = 1234; } };
int main() { p p1; t(); };

Reading specs from /esat/quendi/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.5-tree-ssa/specs
Configured with: ../gcc/configure --prefix=/esat/quendi/gcc --enable-languages=c,c++
Thread model: posix
gcc version 3.5-tree-ssa 20030731 (merged 20030722)
 /esat/quendi/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.5-tree-ssa/cc1plus -quiet -v
-D_GNU_SOURCE t4.cpp -quiet -dumpbase t4.cpp -mtune=pentiumpro -auxbase-strip
t4.s -O3 -version -o t4.s
ignoring nonexistent directory "/esat/quendi/gcc/i686-pc-linux-gnu/include"
#include "..." search starts here:
#include <...> search starts here:
 /esat/quendi/gcc/include/c++/3.5-tree-ssa
 /esat/quendi/gcc/include/c++/3.5-tree-ssa/i686-pc-linux-gnu
 /esat/quendi/gcc/include/c++/3.5-tree-ssa/backward
 /usr/local/include
 /esat/quendi/gcc/include
 /esat/quendi/gcc/lib/gcc-lib/i686-pc-linux-gnu/3.5-tree-ssa/include
 /usr/include
End of search list.
GNU C++ version 3.5-tree-ssa 20030731 (merged 20030722) (i686-pc-linux-gnu)
        compiled by GNU C version 3.3.
GGC heuristics: --param ggc-min-expand=55 --param ggc-min-heapsize=48056

[Bug c/11761] [tree-ssa] arrays inside classes not optimised away

[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=11761


pinskia at physics dot uc dot edu changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Severity|minor                       |enhancement
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|                            |1
           Keywords|                            |pessimizes-code
   Last reconfirmed|0000-00-00 00:00:00         |2003-08-01 15:12:27
               date|                            |
   Target Milestone|3.4                         |tree-ssa


------- Additional Comments From pinskia at physics dot uc dot edu  2003-08-01 15:12 -------
I can confirm this on tree-ssa branch (20030801).
output from -fdump-tree-all:
int main() ()
{
  {
    struct p p1;

    {
      struct p * const this;

      this = (struct p * const)&p1;
      this->a[3] = 1234
    };
    t ()
  };
  return 0;
}

Looks like the store in this->a[3] is not being optimized away so the variable this is not being 
optimized away which causes p1 not be optimize away.

[Bug c/11761] [tree-ssa] arrays inside classes not optimised away

[dnovillo at redhat dot com]

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761



------- Additional Comments From dnovillo at redhat dot com  2003-08-01 15:23 -------
Subject: Re:  [tree-ssa] arrays inside classes not optimised
	away


Right.  Tree SSA does not deal with arrays yet.

There are plans for scalarization and dead storage elimination that
should be able to deal with cases like this.


Diego.

[Bug optimization/11761] [tree-ssa] arrays inside classes not optimised away

[pinskia at gcc dot gnu dot org]

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

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761


pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|2003-08-15 03:44:04         |2003-10-26 20:32:09
               date|                            |


------- Additional Comments From pinskia at gcc dot gnu dot org  2003-10-26 20:32 -------
This is semi fixed, now gcc just has to remove p1:
;; Function int main() (main)

int main() ()
{
  {
    struct p p1;

    {
      (void)0
    };
    t ();
  };
  return 0;;
}

[Bug optimization/11761] arrays inside classes not optimised away

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-01-17 04:32 -------
Not really a tree-ssa specific problem, just the infrostructor is there to fix this problem.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
            Summary|[tree-ssa] arrays inside    |arrays inside classes not
                   |classes not optimised away  |optimised away
            Version|tree-ssa                    |3.4.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761

[Bug optimization/11761] arrays inside classes not optimised away

[dnovillo at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
         AssignedTo|unassigned at gcc dot gnu   |dnovillo at gcc dot gnu dot
                   |dot org                     |org
             Status|NEW                         |ASSIGNED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761

[Bug optimization/11761] arrays inside classes not optimised away

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2004-01-17 20:26 -------
Subject: Bug 11761

CVSROOT:	/cvs/gcc
Module name:	gcc
Branch: 	tree-ssa-20020619-branch
Changes by:	dnovillo@gcc.gnu.org	2004-01-17 20:26:21

Modified files:
	gcc            : ChangeLog.tree-ssa Makefile.in tree-dfa.c 
	                 tree-flow.h tree-simple.c tree-ssa.c 

Log message:
	2004-01-17  Jan Hubicka  <jh@suse.cz>
	
	PR optimization/11761
	* Makefile.in: Remove tree-simple.c from GTYized files.
	* tree-dfa.c (find_addressable_vars): Parse nontrivial ADDR_EXPRs.
	(discover_nonconstant_array_refs_r): New static function.
	(discover_nonconstant_array_refs): New global function.
	* tree-flow.h (discover_nonconstant_array_refs): Declare.
	* tree-simple.c (types_checked, types_in_memory): Kill.
	(struct_needs_to_live_in_memory): Kill.
	(needs_to_live_in_memory): aggregates are safe.
	* tree-ssa.c (rewrite_out_of_ssa): Call the new function.

Patches:
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/ChangeLog.tree-ssa.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.1.2.1093&r2=1.1.2.1094
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/Makefile.in.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.903.2.168&r2=1.903.2.169
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-dfa.c.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.1.4.210&r2=1.1.4.211
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-flow.h.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.1.4.182&r2=1.1.4.183
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-simple.c.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.1.4.68&r2=1.1.4.69
http://gcc.gnu.org/cgi-bin/cvsweb.cgi/gcc/gcc/tree-ssa.c.diff?cvsroot=gcc&only_with_tag=tree-ssa-20020619-branch&r1=1.1.4.187&r2=1.1.4.188



-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761

[Bug optimization/11761] arrays inside classes not optimised away

[dnovillo at gcc dot gnu dot org]

------- Additional Comments From dnovillo at gcc dot gnu dot org  2004-01-17 20:31 -------

Fixed in tree-ssa.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|ASSIGNED                    |SUSPENDED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761

[Bug optimization (tree-ssa)/11761] arrays inside classes not optimised away

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-05-13 11:22 -------
Fixed for 3.5.0 by the merge of the tree-ssa.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |RESOLVED
          Component|optimization (RTL)          |optimization (tree-ssa)
         Resolution|                            |FIXED
   Target Milestone|tree-ssa                    |3.5.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=11761