[Bug tree-optimization/122843] [16 Regression] Excessive compile time with flags -O2 -fpeel-loops -march=znver3

[cvs-commit at gcc dot gnu.org]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=122843

--- Comment #19 from GCC 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:50df2b188450457580b5ff4ac1d524fcc74de9bc

commit r16-6727-g50df2b188450457580b5ff4ac1d524fcc74de9bc
Author: Andrew Pinski <andrew.pinski@oss.qualcomm.com>
Date:   Sat Jan 10 23:17:12 2026 -0800

    match: Simplify `(T1)(a bit_op (T2)b)` to `((T1)a bit_op b)` When b is T1
type and truncating from T2 [PR122845]

    This adds the simpliciation of:
    ```
      <unnamed-signed:3> _1;

      _2 = (signed char) _1;
      _3 = _2 ^ -47;
      _4 = (<unnamed-signed:3>) _3;
    ```

    to:
    ```
      <unnamed-signed:3> _n;
      _4 = _1 ^ -47;
    ```

    This also fixes PR 122843 by optimizing out the xor such that we get:
    ```
      _1 = b.a;
      _21 = (<unnamed-signed:3>) t_23(D);
      // t_23 in the original testcase was 200 so this is reduced to 0
      _5 = _1 ^ _21;
      # .MEM_24 = VDEF <.MEM_13>
      b.a = _5;
    ```
    And then there is no cast catch this pattern:
    `(bit_xor (convert1? (bit_xor:c @0 @1)) (convert2? (bit_xor:c @0 @2)))`
    As we get:
    ```
      _21 = (<unnamed-signed:3>) t_23(D);
      _5 = _1 ^ _21;
      _22 = (<unnamed-signed:3>) t_23(D);
      _7 = _5 ^ _22;
      _25 = (<unnamed-signed:3>) t_23(D);
      _8 = _7 ^ _25;
      _26 = (<unnamed-signed:3>) t_23(D);
      _9 = _7 ^ _26;
    ```
    After unrolling and then fre will optimize away all of those xor.

    Bootstrapped and tested on x86_64-linux-gnu.

            PR tree-optimization/122845
            PR tree-optimization/122843
    gcc/ChangeLog:

            * match.pd (`(T1)(a bit_op (T2)b)`): Also
            simplify if T1 is the same type as b and T2 is wider
            type than T1.

    gcc/testsuite/ChangeLog:

            * gcc.dg/tree-ssa/bitops-12.c: New test.
            * gcc.dg/tree-ssa/bitops-13.c: New test.
            * gcc.dg/store_merging_18.c: xfail store merging.

    Signed-off-by: Andrew Pinski <andrew.pinski@oss.qualcomm.com>