[Bug middle-end/49959] New: ABS pattern is not recognized

[Bug middle-end/49959] New: ABS pattern is not recognized

[enkovich.gnu at gmail dot com]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

           Summary: ABS pattern is not recognized
           Product: gcc
           Version: 4.7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P3
         Component: middle-end
        AssignedTo: unassigned@gcc.gnu.org
        ReportedBy: enkovich.gnu@gmail.com


Created attachment 24900
  --> http://gcc.gnu.org/bugzilla/attachment.cgi?id=24900
Simple test where ABS pattern is not recognized

Here is optimization opportunity for ABS pattern recognizer which does not
catch all cases.

Here is a simple test for ABS computation:

#define ABS(X)    (((X)>0)?(X):-(X))
int
test_abs(int *cur)
{
  unsigned long sad = 0;
  sad = ABS(cur[0]);
  return sad;
}

GIMPLE for the test is good (phase optimized):

test_abs (int * cur)
{
  int D.2783;
  int D.2782;

<bb 2>:
  D.2782_3 = *cur_2(D);
  D.2783_4 = ABS_EXPR <D.2782_3>;
  return D.2783_4;
}

Now try to make a minor change in test:
#define ABS(X)    (((X)>0)?(X):-(X))
int
test_abs(int *cur)
{
  unsigned long sad = 0;
  sad += ABS(cur[0]);
  return sad;
}

GIMPLE becomes worse:

test_abs (int * cur)
{
  int D.2788;
  int D.2787;
  int D.2783;
  long unsigned int iftmp.0;

<bb 2>:
  D.2783_4 = *cur_3(D);
  if (D.2783_4 > 0)
    goto <bb 3>;
  else
    goto <bb 4>;

<bb 3>:
  iftmp.0_6 = (long unsigned int) D.2783_4;
  goto <bb 5>;

<bb 4>:
  D.2787_8 = -D.2783_4;
  iftmp.0_9 = (long unsigned int) D.2787_8;

<bb 5>:
  # iftmp.0_1 = PHI <iftmp.0_6(3), iftmp.0_9(4)>
  D.2788_11 = (int) iftmp.0_1;
  return D.2788_11;
}

Compiler used for tests:

Target: x86_64-unknown-linux-gnu
Configured with: ../gcc/configure --prefix=/export/gcc-build
--enable-languages=c,c++,fortran
Thread model: posix
gcc version 4.7.0 20110707 (experimental) (GCC)
COLLECT_GCC_OPTIONS='-v' '-save-temps' '-O2' '-S' '-mtune=generic'
'-march=x86-64'

[Bug tree-optimization/49959] ABS pattern is not recognized

[rguenth at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

Richard Guenther <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |NEW
   Last reconfirmed|                            |2011.08.03 12:49:46
          Component|middle-end                  |tree-optimization
     Ever Confirmed|0                           |1

--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2011-08-03 12:49:46 UTC ---
Confirmed.

[Bug tree-optimization/49959] ABS pattern is not recognized

[pinskia at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> 2012-01-21 08:03:40 UTC ---
If we had a pass which was able to convert:
<bb 3>:
  iftmp.0_6 = (long unsigned int) D.1708_4;
  goto <bb 5>;

<bb 4>:
  D.1712_8 = -D.1708_4;
  iftmp.0_9 = (long unsigned int) D.1712_8;

<bb 5>:
  # iftmp.0_1 = PHI <iftmp.0_6(3), iftmp.0_9(4)>

Into:

<bb 3>:
  goto <bb 5>;

<bb 4>:
  D.1712_8 = -D.1708_4;

<bb 5>:
  # t_N = PHI<D.1708_4(3), D.1712_8(4)>
  iftmp.0_1 = (long unsigned int)t_n;

And then PHIOPT would recognize it.  So this is really the code commoning.

[Bug tree-optimization/49959] ABS pattern is not recognized

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org
             Status|NEW                         |ASSIGNED
           Severity|normal                      |enhancement
           See Also|                            |https://gcc.gnu.org/bugzill
                   |                            |a/show_bug.cgi?id=59424
           Keywords|                            |missed-optimization

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
I have a fix.
This is related to PR 59424 (part of that fixes this one).

[Bug tree-optimization/49959] ABS pattern is not recognized

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Note Pre is able to remove the casts since GCC 8.
So the original testcase is fixed but if you change it to:
#define ABS(X)    (((X)>0)?(X):-(X))
unsigned long
test_abs(int *cur)
{
  unsigned long sad = 0;
  sad += ABS(cur[0]);
  return sad;
}

We still have the same issue as before.

[Bug tree-optimization/49959] ABS pattern is not recognized

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Created attachment 55016
  --> https://gcc.gnu.org/bugzilla/attachment.cgi?id=55016&action=edit
Patch

For some reason it didn't make it to the mailing list yet. Will figure out why
in a few. patches 2 and 3 did make it though.

[Bug tree-optimization/49959] ABS pattern is not recognized

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

--- Comment #6 from CVS Commits <cvs-commit at gcc dot gnu.org> ---
The trunk branch has been updated by Andrew Pinski <pinskia@gcc.gnu.org>:

https://gcc.gnu.org/g:69f1a8af45d8a42003c21489019ddfb01d88d30d

commit r14-573-g69f1a8af45d8a42003c21489019ddfb01d88d30d
Author: Andrew Pinski <apinski@marvell.com>
Date:   Wed Apr 26 14:55:46 2023 -0700

    PHIOPT: Add diamond bb form to factor_out_conditional_conversion

    So the function factor_out_conditional_conversion already supports
    diamond shaped bb forms, just need to be called for such a thing.

    harden-cond-comp.c needed to be changed as we would optimize out the
    conversion now and that causes the compare hardening not needing to
    split the block which it was testing. So change it such that there
    would be no chance of optimization.

    Also add two testcases that showed the improvement. PR 103771 is
    solved in ifconvert also for the vectorizer but now it is solved
    in a general sense.

    OK? Bootstrapped and tested on x86_64-linux-gnu with no regressions.

            PR tree-optimization/49959
            PR tree-optimization/103771

    gcc/ChangeLog:

            * tree-ssa-phiopt.cc (pass_phiopt::execute): Support
            Diamond shapped bb form for factor_out_conditional_conversion.

    gcc/testsuite/ChangeLog:

            * c-c++-common/torture/harden-cond-comp.c: Change testcase
            slightly to avoid the new phiopt optimization.
            * gcc.dg/tree-ssa/abs-2.c: New test.
            * gcc.dg/tree-ssa/pr103771.c: New test.

[Bug tree-optimization/49959] ABS pattern is not recognized

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=49959

Andrew Pinski <pinskia at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|---                         |14.0

--- Comment #7 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.