Re: [PATCH] [vect]Use intermiediate integer type for float_expr/fix_trunc_expr when direct optab is not existed.

[Richard Biener <richard.guenther@gmail.com>]

On Fri, Jun 2, 2023 at 3:01 AM liuhongt via Gcc-patches
<gcc-patches@gcc.gnu.org> wrote:
>
> We have already use intermidate type in case WIDEN, but not for NONE,
> this patch extended that.
>
> I didn't do that in pattern recog since we need to know whether the
> stmt belongs to any slp_node to decide the vectype, the related optabs
> are checked according to vectype_in and vectype_out. For non-slp case,
> vec_pack/unpack are always used when lhs has different size from rhs,
> for slp case, sometimes vec_pack/unpack is used, somethings
> direct conversion is used.
>
> Bootstrapped and regtested on x86_64-pc-linux-gnu{-m32,}.
> Ok for trunk?
>
> gcc/ChangeLog:
>
>         PR target/110018
>         * tree-vect-stmts.cc (vectorizable_conversion): Use
>         intermiediate integer type for float_expr/fix_trunc_expr when
>         direct optab is not existed.
>
> gcc/testsuite/ChangeLog:
>
>         * gcc.target/i386/pr110018-1.c: New test.
> ---
>  gcc/testsuite/gcc.target/i386/pr110018-1.c | 94 ++++++++++++++++++++++
>  gcc/tree-vect-stmts.cc                     | 56 ++++++++++++-
>  2 files changed, 149 insertions(+), 1 deletion(-)
>  create mode 100644 gcc/testsuite/gcc.target/i386/pr110018-1.c
>
> diff --git a/gcc/testsuite/gcc.target/i386/pr110018-1.c b/gcc/testsuite/gcc.target/i386/pr110018-1.c
> new file mode 100644
> index 00000000000..b1baffd7af1
> --- /dev/null
> +++ b/gcc/testsuite/gcc.target/i386/pr110018-1.c
> @@ -0,0 +1,94 @@
> +/* { dg-do compile } */
> +/* { dg-options "-mavx512fp16 -mavx512vl -O2 -mavx512dq" } */
> +/* { dg-final { scan-assembler-times {(?n)vcvttp[dsh]2[dqw]} 5 } } */
> +/* { dg-final { scan-assembler-times {(?n)vcvt[dqw]*2p[dsh]} 5 } } */
> +
> +void
> +foo (double* __restrict a, char* b)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +}
> +
> +void
> +foo1 (float* __restrict a, char* b)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +}
> +
> +void
> +foo2 (_Float16* __restrict a, char* b)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +  a[4] = b[4];
> +  a[5] = b[5];
> +  a[6] = b[6];
> +  a[7] = b[7];
> +}
> +
> +void
> +foo3 (double* __restrict a, short* b)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +}
> +
> +void
> +foo4 (float* __restrict a, char* b)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +}
> +
> +void
> +foo5 (double* __restrict b, char* a)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +}
> +
> +void
> +foo6 (float* __restrict b, char* a)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +}
> +
> +void
> +foo7 (_Float16* __restrict b, char* a)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +  a[4] = b[4];
> +  a[5] = b[5];
> +  a[6] = b[6];
> +  a[7] = b[7];
> +}
> +
> +void
> +foo8 (double* __restrict b, short* a)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +}
> +
> +void
> +foo9 (float* __restrict b, char* a)
> +{
> +  a[0] = b[0];
> +  a[1] = b[1];
> +  a[2] = b[2];
> +  a[3] = b[3];
> +}
> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> index bd3b07a3aa1..1118c89686d 100644
> --- a/gcc/tree-vect-stmts.cc
> +++ b/gcc/tree-vect-stmts.cc
> @@ -5162,6 +5162,49 @@ vectorizable_conversion (vec_info *vinfo,
>         return false;
>        if (supportable_convert_operation (code, vectype_out, vectype_in, &code1))
>         break;

A comment would be nice here.  Like

   /* For conversions between float and smaller integer types try whether we can
      use intermediate signed integer types to support the conversion.  */

> +      if ((code == FLOAT_EXPR
> +          && GET_MODE_SIZE (lhs_mode) > GET_MODE_SIZE (rhs_mode))
> +         || (code == FIX_TRUNC_EXPR
> +             && GET_MODE_SIZE (rhs_mode) > GET_MODE_SIZE (lhs_mode)))
> +       {
> +         bool float_expr_p = code == FLOAT_EXPR;
> +         scalar_mode imode = float_expr_p ? rhs_mode : lhs_mode;
> +         fltsz = GET_MODE_SIZE (float_expr_p ? lhs_mode : rhs_mode);
> +         code1 = float_expr_p ? code : NOP_EXPR;
> +         codecvt1 = float_expr_p ? NOP_EXPR : code;
> +         FOR_EACH_2XWIDER_MODE (rhs_mode_iter, imode)
> +           {
> +             imode = rhs_mode_iter.require ();
> +             if (GET_MODE_SIZE (imode) > fltsz)
> +               break;
> +
> +             cvt_type
> +               = build_nonstandard_integer_type (GET_MODE_BITSIZE (imode),
> +                                                 0);
> +             cvt_type = get_vectype_for_scalar_type (vinfo, cvt_type,
> +                                                     slp_node);
> +             /* This should only happened for SLP as long as loop vectorizer
> +                only supports same-sized vector.  */
> +             if (cvt_type == NULL_TREE
> +                 || maybe_ne (TYPE_VECTOR_SUBPARTS (cvt_type), nunits_in)
> +                 || !supportable_convert_operation (code1, vectype_out,
> +                                                    cvt_type, &code1)
> +                 || !supportable_convert_operation (codecvt1, cvt_type,
> +                                                    vectype_in, &codecvt1))
> +               continue;
> +
> +             found_mode = true;
> +             break;
> +           }
> +
> +         if (found_mode)
> +           {
> +             multi_step_cvt++;
> +             interm_types.safe_push (cvt_type);
> +             cvt_type = NULL_TREE;
> +             break;
> +           }
> +       }
>        /* FALLTHRU */
>      unsupported:
>        if (dump_enabled_p ())
> @@ -5381,7 +5424,18 @@ vectorizable_conversion (vec_info *vinfo,
>         {
>           /* Arguments are ready, create the new vector stmt.  */
>           gcc_assert (TREE_CODE_LENGTH (code1) == unary_op);
> -         gassign *new_stmt = gimple_build_assign (vec_dest, code1, vop0);
> +         gassign* new_stmt;
> +         if (multi_step_cvt)
> +           {
> +             gcc_assert (multi_step_cvt == 1);
> +             new_stmt = gimple_build_assign (vec_dest, codecvt1, vop0);
> +             new_temp = make_ssa_name (vec_dest, new_stmt);

I wonder how you get away with using vec_dest both for the final and the
intermediate conversion and not involve interm_types[0]?

Otherwise looks good.

Thanks,
Richard.

> +             gimple_assign_set_lhs (new_stmt, new_temp);
> +             vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
> +             vop0 = new_temp;
> +             vec_dest = vec_dsts[0];
> +           }
> +         new_stmt = gimple_build_assign (vec_dest, code1, vop0);
>           new_temp = make_ssa_name (vec_dest, new_stmt);
>           gimple_assign_set_lhs (new_stmt, new_temp);
>           vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
> --
> 2.39.1.388.g2fc9e9ca3c
>