[Bug regression/28173] New: 4.1.1 misses constant folding .

[Bug regression/28173] New: 4.1.1 misses constant folding .

[ramana dot radhakrishnan at codito dot com]

A performance regression from 3.4.6 to 4.1.1 for m68k-elf.
combine used to take care of this in 3.4.6   . 

A backport of the patch for Bug #24427 works .  If its allowed, I'll put it up
. 

This is the test case . 

#include <stdio.h>
int i;
int main (void)
{

          if ( ((i & ~1) | 1) != ( i | 1))
                      printf ("abc");
}

3.4.6 generated 

       .file   "fail.c"
        .text
        .align  2
        .globl  foo
        .type   foo, @function
foo:
        link.w %a6,#0
        unlk %a6
        rts
        .size   foo, .-foo
        .comm   i,4,2
        .ident  "GCC: (GNU) 3.4.6"



4.1.2 pre-release generates      

.file   "fail.c"
        .section        .rodata.str1.1,"aMS",@progbits,1
.LC0:
        .string "abc"
        .text
        .align  2
        .globl  main
        .type   main, @function
main:
        link.w %fp,#0
        move.l %d2,-(%sp)
        move.l i,%d1
        moveq #-2,%d0
        and.l %d1,%d0
        moveq #1,%d2
        or.l %d2,%d0
        or.l %d2,%d1
        cmp.l %d0,%d1
        jbeq .L5
        pea .LC0
        jbsr printf
        addq.l #4,%sp
.L5:
        move.l -4(%fp),%d2
        unlk %fp
        rts
        .size   main, .-main
        .comm   i,4,2
        .ident  "GCC: (GNU) 4.1.2 20060623 (prerelease)"


-- 
           Summary: 4.1.1 misses constant folding .
           Product: gcc
           Version: 4.1.2
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: regression
        AssignedTo: unassigned at gcc dot gnu dot org
        ReportedBy: ramana dot radhakrishnan at codito dot com
  GCC host triplet: i686-linux
GCC target triplet: m68k-elf


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug regression/28173] [4.1 Regression] 4.1.1 misses constant folding .

[pinskia at gcc dot gnu dot org]

-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Keywords|                            |missed-optimization
            Summary|4.1.1 misses constant       |[4.1 Regression] 4.1.1
                   |folding .                   |misses constant folding .
   Target Milestone|---                         |4.1.2


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.1 Regression] 4.1.1 misses constant folding .

[bangerth at dealii dot org]

------- Comment #1 from bangerth at dealii dot org  2006-09-13 03:39 -------
Confirmed. I see the same behavior on x86_64-linux-unknown-gnu. This
is a regression from 3.4.x that is present in at least the 4.0.x and 4.1.x
release branches (don't know about mainline).

W.


-- 

bangerth at dealii dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |bangerth at dealii dot org
             Status|UNCONFIRMED                 |NEW
     Ever Confirmed|0                           |1
   GCC host triplet|i686-linux                  |
 GCC target triplet|m68k-elf                    |
      Known to fail|                            |4.0.3 4.1.1
      Known to work|                            |3.4.6
           Priority|P3                          |P2
   Last reconfirmed|0000-00-00 00:00:00         |2006-09-13 03:39:04
               date|                            |


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[pinskia at gcc dot gnu dot org]

------- Comment #2 from pinskia at gcc dot gnu dot org  2006-09-13 03:59 -------
This is not a regression on the mainline because of PR 24427.


-- 

pinskia at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
  BugsThisDependsOn|                            |24427
            Summary|[4.0/4.1/4.2? regression]   |[4.0/4.1 regression] misses
                   |misses constant folding     |constant folding


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[ebotcazou at gcc dot gnu dot org]

------- Comment #3 from ebotcazou at gcc dot gnu dot org  2006-09-13 08:24 -------
Roger, could you comment on Ramana's proposition?  Thanks in advance.


-- 

ebotcazou at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |sayle at gcc dot gnu dot
                   |                            |org, ebotcazou at gcc dot
                   |                            |gnu dot org


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[mmitchel at gcc dot gnu dot org]

-- 

mmitchel at gcc dot gnu dot org changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|4.1.2                       |4.1.3


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[sayle at gcc dot gnu dot org]

------- Comment #4 from sayle at gcc dot gnu dot org  2007-02-18 17:10 -------
Subject: Bug 28173

Author: sayle
Date: Sun Feb 18 17:10:19 2007
New Revision: 122100

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=122100
Log:

        Backport from mainline.
        PR middle-end/24427
        PR rtl-optimization/28173
        * fold-const.c (fold_binary) <BIT_IOR_EXPR>: Transform (X&C1)|C2
        into (X,C2) if C1 is a subset of the bits of C2.  Transform
        (X&C1)|C2 into X|C2 if C1|C2 == ~0.  Canonicalize (X&C1)|C2 as
        (X&(C1&~C2))|C2.
        <BIT_AND_EXPR>: Canonicalize (X|C1)&C2 as (X&C2)|(C1&C2).

        * gcc.dg/tree-ssa/andor-1.c: New test case.


Added:
    branches/gcc-4_1-branch/gcc/testsuite/gcc.dg/tree-ssa/andor-1.c
Modified:
    branches/gcc-4_1-branch/gcc/ChangeLog
    branches/gcc-4_1-branch/gcc/fold-const.c
    branches/gcc-4_1-branch/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[sayle at gcc dot gnu dot org]

------- Comment #5 from sayle at gcc dot gnu dot org  2007-02-19 00:54 -------
Subject: Bug 28173

Author: sayle
Date: Mon Feb 19 00:54:29 2007
New Revision: 122116

URL: http://gcc.gnu.org/viewcvs?root=gcc&view=rev&rev=122116
Log:

        PR rtl-optimization/28173
        * simplify-rtx.c (simplify_binary_operation_1) <IOR>:  Optimize
        (X & C1) | C2 as C2 when (C1 & C2) == C1 and X has no side-effects.
        Optimize (X & C1) | C2 as X | C2 when (C1 | C2) == ~0.
        Canonicalize (X & C1) | C2 as (X & (C1 & ~C2)) | C2.
        <AND>: Canonicalize (X | C1) & C2 as (X & C2) | (C1 & C2).

        * gcc.target/i386/andor-1.c: New test case.


Added:
    trunk/gcc/testsuite/gcc.target/i386/andor-1.c
Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/simplify-rtx.c
    trunk/gcc/testsuite/ChangeLog


-- 


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173

[Bug rtl-optimization/28173] [4.0/4.1 regression] misses constant folding

[roger at eyesopen dot com]

------- Comment #6 from roger at eyesopen dot com  2007-03-08 01:55 -------
I suspect this problem is now fully resolved.  The patch for PR24427 has been
backported to the gcc-4_1-branch, and additionally on mainline, simplify-rtx.c
has been enhanced to also perform the missed-optimization at the RTL level.
Given that the 4.0 branch is now closed, I believe this is sufficient to close
this PR.


-- 

roger at eyesopen dot com changed:

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


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=28173