On Wed, Sep 21, 2022 at 1:41 AM liuhongt via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> When init_expr is INTEGER_CST or REAL_CST, can_vec_perm_const_p is not
> necessary since there's no real vec_perm needed, but
> vec_gen_perm_mask_checked will gcc_assert (can_vec_perm_const_p). So
> it's better to use vec_gen_perm_mask_any in
> vect_create_nonlinear_iv_init.
and the VEC_PERM build will fold the permute away?
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk?
OK.
Thanks,
Richard.
> gcc/ChangeLog:
>
> PR tree-optimization/106963
> * tree-vect-loop.cc (vect_create_nonlinear_iv_init): Use
> vec_gen_perm_mask_any instead of vec_gen_perm_mask_check.
>
> gcc/testsuite/ChangeLog:
>
> * gcc.target/i386/pr106963.c: New test.
> ---
> gcc/testsuite/gcc.target/i386/pr106963.c | 14 ++++++++++++++
> gcc/tree-vect-loop.cc | 5 ++++-
> 2 files changed, 18 insertions(+), 1 deletion(-)
> create mode 100644 gcc/testsuite/gcc.target/i386/pr106963.c
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr106963.c
> b/gcc/testsuite/gcc.target/i386/pr106963.c
> new file mode 100644
> index 00000000000..9f2d20e2523
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr106963.c
> @@ -0,0 +1,14 @@
> +/* { dg-do compile } */
> +/* { dg-options "-O2 -mavx -mno-avx2" } */
> +
> +void
> +foo_neg_const (int *a)
> +{
> + int i, b = 1;
> +
> + for (i = 0; i < 1000; i++)
> + {
> + a[i] = b;
> + b = -b;
> + }
> +}
> diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> index 9c434b66c5b..aabdc6f2d81 100644
> --- a/gcc/tree-vect-loop.cc
> +++ b/gcc/tree-vect-loop.cc
> @@ -8356,8 +8356,11 @@ vect_create_nonlinear_iv_init (gimple_seq* stmts, tree
> init_expr,
> sel[2 * i + 1] = i + nunits;
> }
> vec_perm_indices indices (sel, 2, nunits);
> + /* Don't use vect_gen_perm_mask_checked since can_vec_perm_const_p may
> + fail when vec_init is const vector. In that situation vec_perm is
> not
> + really needed. */
> tree perm_mask_even
> - = vect_gen_perm_mask_checked (vectype, indices);
> + = vect_gen_perm_mask_any (vectype, indices);
> vec_init = gimple_build (stmts, VEC_PERM_EXPR,
> vectype,
> vec_init, vec_neg,
> --
> 2.18.1
>
