[Bug other/16801] New: PowerPC - forward store motion opportunity

[Bug other/16801] New: PowerPC - forward store motion opportunity

[gcc-bugzilla at gcc dot gnu dot org]

Description:
A non-optimal code sequence is illustrated.  There exists an opportunity to perform forward store motion.  Duplicate using gcc 3.5 and command line:

gcc -O3 -m64 -c test.c

Testcase:
typedef struct {
    unsigned int e;
} str;
char *q;

void foo (char *p) {

  while (1) {
    q = p - ((str *)p)->e;
    if (((str *)q)->e) break;
    p = q;
  }

}

Assembly:
 .foo:
	lwz 0,0(3)
	ld 11,.LC0@toc(2)
	subf 3,0,3
	std 3,0(11)
	lwz 0,0(3)
	cmpwi 7,0,0
	bnelr- 7
	mr 9,3
.L4:
	lwz 0,0(9)
	subf 9,0,9
	std 9,0(11) <-- candidate for forward store motion out of the loop.
	lwz 0,0(9)
	cmpwi 7,0,0
	beq+ 7,.L4
	blr



-- 
           Summary: PowerPC - forward store motion opportunity
           Product: gcc
           Version: 3.5.0
            Status: UNCONFIRMED
          Severity: enhancement
          Priority: P1
         Component: other
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: steinmtz at us dot ibm dot com
                CC: gcc-bugs at gcc dot gnu dot org,steinmtz at us dot ibm
                    dot com
 GCC build triplet: powerpc64-linux
  GCC host triplet: powerpc64-linux
GCC target triplet: powerpc64-linux


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug target/16801] PowerPC - forward store motion opportunity

[bangerth at dealii dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
          Component|other                       |target


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug target/16801] PowerPC - forward store motion opportunity

[falk at debian dot org]

------- Additional Comments From falk at debian dot org  2004-07-28 18:42 -------
This works for me on alphev68-linux with the lno branch. Can you please
try there?


-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |WAITING


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug tree-optimization/16801] PowerPC - forward store motion opportunity

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-07-29 04:53 -------
Fixed on the lno so suspendeding.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|WAITING                     |SUSPENDED
          Component|target                      |tree-optimization
           Keywords|                            |missed-optimization
   Target Milestone|---                         |lno


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug tree-optimization/16801] PowerPC - forward store motion opportunity

[pinskia at gcc dot gnu dot org]

------- Additional Comments From pinskia at gcc dot gnu dot org  2004-09-24 13:14 -------
Actually this is not fixed on the lno at all.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|SUSPENDED                   |NEW
     Ever Confirmed|                            |1
   Last reconfirmed|0000-00-00 00:00:00         |2004-09-24 13:14:38
               date|                            |
   Target Milestone|lno                         |---


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug tree-optimization/16801] PowerPC - forward store motion opportunity

[nathan at gcc dot gnu dot org]

------- Additional Comments From nathan at gcc dot gnu dot org  2004-11-11 17:27 -------
This is fixed on FSF HEAD 2004-11-11.  Probably due to some
better alias analysis

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|NEW                         |RESOLVED
         Resolution|                            |FIXED


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801

[Bug tree-optimization/16801] PowerPC - forward store motion opportunity

[pinskia at gcc dot gnu dot org]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |4.0.0


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=16801