[Bug tree-optimization/103228] New: [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[Bug tree-optimization/103228] New: [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

            Bug ID: 103228
           Summary: [9/10/11/12 Regression] missed optimization with |^ at
                    the gimple level
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: tree-optimization
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

Take:
int f(int a, int b)
{
  b|=1u;
  b|=2;
  return b;
}

----- CUT ---
This no longer gets optimized at the gimple level but it did in 4.7.x.
This is also true for ^.

I Noticed this while writing testcases for PR 103216.

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Target Milestone|---                         |9.5
      Known to fail|                            |11.1.0, 4.8.1
      Known to work|                            |4.7.4
           Keywords|                            |TREE

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
   Last reconfirmed|                            |2021-11-15
     Ever confirmed|0                           |1
             Status|UNCONFIRMED                 |ASSIGNED
           Assignee|unassigned at gcc dot gnu.org      |pinskia at gcc dot gnu.org

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Turns out I had a patch for this bug ran into another bug which just happened
to be fixed on the trunk.  So I assigning it to me. I don't know if it will be
accepted for stage 3 or not since I won't be able to submit it today.

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
The patch to fix this is located in PR 60669 comment #2 .

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

--- Comment #3 from Richard Biener <rguenth at gcc dot gnu.org> ---
Possibly some STRIP_NOPS gone "missing" during fold-const.c -> match.pd move of
some patterns.

But then reassoc, for bit ops, should eventually learn to look through sign
conversions, re-instantiating them on the leafs and result when required
(maybe optimizing for the number of conversions somehow, or simply prefering
unsigned).

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[rguenth at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
           Priority|P3                          |P2

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

--- Comment #4 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
(In reply to Richard Biener from comment #3)
> Possibly some STRIP_NOPS gone "missing" during fold-const.c -> match.pd move
> of some patterns.

Well match.pd has:
/* Try to fold (type) X op CST -> (type) (X op ((type-x) CST))
   when profitable.
   For bitwise binary operations apply operand conversions to the
   binary operation result instead of to the operands.  This allows
   to combine successive conversions and bitwise binary operations.
   We combine the above two cases by using a conditional convert.  */

Just the check for precision was < and not <= :
       && (/* That's a good idea if the conversion widens the operand, thus
              after hoisting the conversion the operation will be narrower.  */
           TYPE_PRECISION (TREE_TYPE (@0)) < TYPE_PRECISION (type)

I am going to test changing < to <=.
Note the atomic changed (PR 103194) might have some conflict with this.

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

--- Comment #5 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:3200de91bc70bfd6d4b7b40e769bc82756b9b555

commit r12-5291-g3200de91bc70bfd6d4b7b40e769bc82756b9b555
Author: Andrew Pinski <apinski@marvell.com>
Date:   Mon Nov 15 22:55:09 2021 +0000

    tree-optimization: [PR103245] Improve detection of abs pattern using
multiplication

    So while working on PR 103228 (and a few others), I noticed the testcase
for PR 94785
    was failing. The problem is that the nop_convert moved from being inside
the IOR to be
    outside of it. I also noticed the patch for PR 103228 was not needed to
reproduce the
    issue either.
    This patch combines the two patterns together for the abs match when using
multiplication
    and adds a few places where nop_convert are optional.

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

            PR tree-optimization/103245

    gcc/ChangeLog:

            * match.pd: Combine the abs pattern matching using multiplication.
            Adding optional nop_convert too.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/pr103245-1.c: New test.

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228
Bug 103228 depends on bug 103245, which changed state.

Bug 103245 Summary: Failure to detect abs pattern using multiplication with slightly different casts for unsigned case
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103245

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

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
                URL|                            |https://gcc.gnu.org/piperma
                   |                            |il/gcc-patches/2021-Novembe
                   |                            |r/584551.html
           Keywords|                            |patch

--- Comment #6 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Patch posted:
https://gcc.gnu.org/pipermail/gcc-patches/2021-November/584551.html

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

--- Comment #7 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:32221357007666124409ec3ee0d3a1cf263ebc9e

commit r12-5358-g32221357007666124409ec3ee0d3a1cf263ebc9e
Author: Andrew Pinski <apinski@marvell.com>
Date:   Mon Nov 15 09:31:20 2021 +0000

    Fix PR tree-optimization/103228 and 103228: folding of (type) X op CST
where type is a nop convert

    Currently we fold (type) X op CST into (type) (X op ((type-x) CST)) when
the conversion widens
    but not when the conversion is a nop. For the same reason why we move the
widening conversion
    (the possibility of removing an extra conversion), we should do the same if
the conversion is a
    nop.

    Committed as approved with the comment change.

            PR tree-optimization/103228
            PR tree-optimization/55177

    gcc/ChangeLog:

            * match.pd ((type) X bitop CST): Also do this
            transformation for nop conversions.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/pr103228-1.c: New test.
            * gcc.dg/tree-ssa/pr55177-1.c: New test.

[Bug tree-optimization/103228] [9/10/11/12 Regression] missed optimization with |^ at the gimple level

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=103228

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

           What    |Removed                     |Added
----------------------------------------------------------------------------
         Resolution|---                         |FIXED
             Status|ASSIGNED                    |RESOLVED
   Target Milestone|9.5                         |12.0

--- Comment #8 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed in GCC 12, not worth the backport really.