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From: "sjames at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
To: gcc-bugs@gcc.gnu.org
Subject: [Bug tree-optimization/114396] [13/14 Regression] Vector: Runtime
 mismatch at -O2 with -fwrapv
Date: Wed, 20 Mar 2024 11:41:18 +0000
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https://gcc.gnu.org/bugzilla/show_bug.cgi?id=3D114396

Sam James <sjames at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |liuhongt at gcc dot gnu.org

--- Comment #12 from Sam James <sjames at gcc dot gnu.org> ---
(In reply to Sam James from comment #11)
> Bisecting.

commit r13-7988-g82919cf4cb2321
Author: liuhongt <hongtao.liu@intel.com>
Date:   Wed Oct 18 10:08:24 2023 +0800

    Avoid compile time hog on vect_peel_nonlinear_iv_init for nonlinear
induction vec_step_op_mul when iteration count is too big.

    There's loop in vect_peel_nonlinear_iv_init to get init_expr *
    pow (step_expr, skip_niters). When skipn_iters is too big, compile time
    hogs. To avoid that, optimize init_expr * pow (step_expr, skip_niters) =
to
    init_expr << (exact_log2 (step_expr) * skip_niters) when step_expr is
    pow of 2, otherwise give up vectorization when skip_niters >=3D
    TYPE_PRECISION (TREE_TYPE (init_expr)).=