[Bug middle-end/100798] New: a?~t:t and (-(!!a))^t don't produce the same assembly code

[Bug middle-end/100798] New: a?~t:t and (-(!!a))^t don't produce the same assembly code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

            Bug ID: 100798
           Summary: a?~t:t and (-(!!a))^t don't produce the same assembly
                    code
           Product: gcc
           Version: 12.0
            Status: UNCONFIRMED
          Keywords: missed-optimization
          Severity: normal
          Priority: P3
         Component: middle-end
          Assignee: unassigned at gcc dot gnu.org
          Reporter: pinskia at gcc dot gnu.org
  Target Milestone: ---

While working on non GCC code, I notice these two functions don't produce the
assembly code:
int f(int a, int t)
{
  return (a=='s' ? ~t : t);
}

int f1(int a, int t)
{
  int t1 = -(a=='s');
  return (t1 ^ t);
}

For aarch64, the first case produce the best, while on x86_64, I don't know
which is better, sete or cmov.

Note LLVM produces the same code for both, for aarch64, the csinv and
sete/neg/xor for x86_64.

[Bug middle-end/100798] a?~t:t and (-(!!a))^t don't produce the same assembly code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

--- Comment #1 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
To produce the same code we could do a match pattern:
(simplify
 (cond @0 (bit_not @1) @1)
 (bit_xor (neg (convert @0)) @1))

[Bug middle-end/100798] a?~t:t and (-(!!a))^t don't produce the same assembly code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

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
     Ever confirmed|0                           |1
   Last reconfirmed|                            |2023-08-07
             Status|UNCONFIRMED                 |ASSIGNED

--- Comment #2 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
.

[Bug middle-end/100798] a?~t:t and (-(!!a))^t don't produce the same assembly code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

--- Comment #3 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Patch posted:
https://gcc.gnu.org/pipermail/gcc-patches/2023-August/626580.html

[Bug middle-end/100798] a?~t:t and (-(!!a))^t don't produce the same assembly code

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

--- Comment #4 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:7fb65f102851248bafa0815401d8bdcea6d7626c

commit r14-3110-g7fb65f102851248bafa0815401d8bdcea6d7626c
Author: Andrew Pinski <apinski@marvell.com>
Date:   Mon Aug 7 10:47:09 2023 -0700

    MATCH: [PR110937/PR100798] (a ? ~b : b) should be optimized to b ^ -(a)

    This adds a simple match pattern for this case.
    I noticed it a couple of different places.
    One while I was looking at code generation of a parser and
    also while I was looking at locations where bitwise_inverted_equal_p
    should be used more.

    Committed as approved after bootstrapped and tested on x86_64-linux-gnu
with no regressions.

            PR tree-optimization/110937
            PR tree-optimization/100798

    gcc/ChangeLog:

            * match.pd (`a ? ~b : b`): Handle this
            case.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/bool-14.c: New test.
            * gcc.dg/tree-ssa/bool-15.c: New test.
            * gcc.dg/tree-ssa/phi-opt-33.c: New test.
            * gcc.dg/tree-ssa/20030709-2.c: Update testcase
            so `a ? -1 : 0` is not used to hit the match
            pattern.

[Bug middle-end/100798] a?~t:t and (-(!!a))^t don't produce the same assembly code

[pinskia at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=100798

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

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

--- Comment #5 from Andrew Pinski <pinskia at gcc dot gnu.org> ---
Fixed.