RE: [PATCH v2 1/3] Vect: Support loop len in vectorizable early exit

["Li, Pan2" <pan2.li@intel.com>]

Committed, thanks Richard.

Pan

-----Original Message-----
From: Richard Biener <richard.guenther@gmail.com> 
Sent: Thursday, May 16, 2024 8:13 PM
To: Tamar Christina <Tamar.Christina@arm.com>
Cc: Li, Pan2 <pan2.li@intel.com>; gcc-patches@gcc.gnu.org; juzhe.zhong@rivai.ai; kito.cheng@gmail.com; Richard Sandiford <Richard.Sandiford@arm.com>
Subject: Re: [PATCH v2 1/3] Vect: Support loop len in vectorizable early exit

On Thu, May 16, 2024 at 8:50 AM Tamar Christina <Tamar.Christina@arm.com> wrote:
>
> > -----Original Message-----
> > From: pan2.li@intel.com <pan2.li@intel.com>
> > Sent: Thursday, May 16, 2024 5:06 AM
> > To: gcc-patches@gcc.gnu.org
> > Cc: juzhe.zhong@rivai.ai; kito.cheng@gmail.com; Tamar Christina
> > <Tamar.Christina@arm.com>; richard.guenther@gmail.com; Richard Sandiford
> > <Richard.Sandiford@arm.com>; Pan Li <pan2.li@intel.com>
> > Subject: [PATCH v2 1/3] Vect: Support loop len in vectorizable early exit
> >
> > From: Pan Li <pan2.li@intel.com>
> >
> > This patch adds early break auto-vectorization support for target which
> > use length on partial vectorization.  Consider this following example:
> >
> > unsigned vect_a[802];
> > unsigned vect_b[802];
> >
> > void test (unsigned x, int n)
> > {
> >   for (int i = 0; i < n; i++)
> >   {
> >     vect_b[i] = x + i;
> >
> >     if (vect_a[i] > x)
> >       break;
> >
> >     vect_a[i] = x;
> >   }
> > }
> >
> > We use VCOND_MASK_LEN to simulate the generate (mask && i < len + bias).
> > And then the IR of RVV looks like below:
> >
> >   ...
> >   _87 = .SELECT_VL (ivtmp_85, POLY_INT_CST [32, 32]);
> >   _55 = (int) _87;
> >   ...
> >   mask_patt_6.13_69 = vect_cst__62 < vect__3.12_67;
> >   vec_len_mask_72 = .VCOND_MASK_LEN (mask_patt_6.13_69, { -1, ... }, \
> >     {0, ... }, _87, 0);
> >   if (vec_len_mask_72 != { 0, ... })
> >     goto <bb 6>; [5.50%]
> >   else
> >     goto <bb 7>; [94.50%]
> >
> > The below tests are passed for this patch:
> > 1. The riscv fully regression tests.
> > 2. The x86 bootstrap tests.
> > 3. The x86 fully regression tests.
> >
> > gcc/ChangeLog:
> >
> >       * tree-vect-stmts.cc (vectorizable_early_exit): Add loop len
> >       handling for one or multiple stmt.
> >
> > gcc/ChangeLog:
> >
> >       * tree-vect-loop.cc (vect_gen_loop_len_mask): New func to gen
> >       the loop len mask.
> >       * tree-vect-stmts.cc (vectorizable_early_exit): Invoke the
> >       vect_gen_loop_len_mask for 1 or more stmt(s).
> >       * tree-vectorizer.h (vect_gen_loop_len_mask): New func decl
> >       for vect_gen_loop_len_mask.
> >
>
> Thanks, this version looks good to me!
>
> You'll need Richi's review still.

OK.

Thanks,
Richard.

> Cheers,
> Tamar
>
> > Signed-off-by: Pan Li <pan2.li@intel.com>
> > ---
> >  gcc/tree-vect-loop.cc  | 27 +++++++++++++++++++++++++++
> >  gcc/tree-vect-stmts.cc | 17 +++++++++++++++--
> >  gcc/tree-vectorizer.h  |  4 ++++
> >  3 files changed, 46 insertions(+), 2 deletions(-)
> >
> > diff --git a/gcc/tree-vect-loop.cc b/gcc/tree-vect-loop.cc
> > index 361aec06488..83c0544b6aa 100644
> > --- a/gcc/tree-vect-loop.cc
> > +++ b/gcc/tree-vect-loop.cc
> > @@ -11416,6 +11416,33 @@ vect_get_loop_len (loop_vec_info loop_vinfo,
> > gimple_stmt_iterator *gsi,
> >    return loop_len;
> >  }
> >
> > +/* Generate the tree for the loop len mask and return it.  Given the lens,
> > +   nvectors, vectype, index and factor to gen the len mask as below.
> > +
> > +   tree len_mask = VCOND_MASK_LEN (compare_mask, ones, zero, len, bias)
> > +*/
> > +tree
> > +vect_gen_loop_len_mask (loop_vec_info loop_vinfo, gimple_stmt_iterator *gsi,
> > +                     gimple_stmt_iterator *cond_gsi, vec_loop_lens *lens,
> > +                     unsigned int nvectors, tree vectype, tree stmt,
> > +                     unsigned int index, unsigned int factor)
> > +{
> > +  tree all_one_mask = build_all_ones_cst (vectype);
> > +  tree all_zero_mask = build_zero_cst (vectype);
> > +  tree len = vect_get_loop_len (loop_vinfo, gsi, lens, nvectors, vectype, index,
> > +                             factor);
> > +  tree bias = build_int_cst (intQI_type_node,
> > +                          LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS
> > (loop_vinfo));
> > +  tree len_mask = make_temp_ssa_name (TREE_TYPE (stmt), NULL,
> > "vec_len_mask");
> > +  gcall *call = gimple_build_call_internal (IFN_VCOND_MASK_LEN, 5, stmt,
> > +                                         all_one_mask, all_zero_mask, len,
> > +                                         bias);
> > +  gimple_call_set_lhs (call, len_mask);
> > +  gsi_insert_before (cond_gsi, call, GSI_SAME_STMT);
> > +
> > +  return len_mask;
> > +}
> > +
> >  /* Scale profiling counters by estimation for LOOP which is vectorized
> >     by factor VF.
> >     If FLAT is true, the loop we started with had unrealistically flat
> > diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
> > index b8a71605f1b..672959501bb 100644
> > --- a/gcc/tree-vect-stmts.cc
> > +++ b/gcc/tree-vect-stmts.cc
> > @@ -12895,7 +12895,9 @@ vectorizable_early_exit (vec_info *vinfo,
> > stmt_vec_info stmt_info,
> >      ncopies = vect_get_num_copies (loop_vinfo, vectype);
> >
> >    vec_loop_masks *masks = &LOOP_VINFO_MASKS (loop_vinfo);
> > +  vec_loop_lens *lens = &LOOP_VINFO_LENS (loop_vinfo);
> >    bool masked_loop_p = LOOP_VINFO_FULLY_MASKED_P (loop_vinfo);
> > +  bool len_loop_p = LOOP_VINFO_FULLY_WITH_LENGTH_P (loop_vinfo);
> >
> >    /* Now build the new conditional.  Pattern gimple_conds get dropped during
> >       codegen so we must replace the original insn.  */
> > @@ -12959,12 +12961,11 @@ vectorizable_early_exit (vec_info *vinfo,
> > stmt_vec_info stmt_info,
> >       {
> >         if (direct_internal_fn_supported_p (IFN_VCOND_MASK_LEN, vectype,
> >                                             OPTIMIZE_FOR_SPEED))
> > -         return false;
> > +         vect_record_loop_len (loop_vinfo, lens, ncopies, vectype, 1);
> >         else
> >           vect_record_loop_mask (loop_vinfo, masks, ncopies, vectype, NULL);
> >       }
> >
> > -
> >        return true;
> >      }
> >
> > @@ -13017,6 +13018,15 @@ vectorizable_early_exit (vec_info *vinfo,
> > stmt_vec_info stmt_info,
> >                                 stmts[i], &cond_gsi);
> >           workset.quick_push (stmt_mask);
> >         }
> > +      else if (len_loop_p)
> > +     for (unsigned i = 0; i < stmts.length (); i++)
> > +       {
> > +         tree len_mask = vect_gen_loop_len_mask (loop_vinfo, gsi, &cond_gsi,
> > +                                                 lens, ncopies, vectype,
> > +                                                 stmts[i], i, 1);
> > +
> > +         workset.quick_push (len_mask);
> > +       }
> >        else
> >       workset.splice (stmts);
> >
> > @@ -13041,6 +13051,9 @@ vectorizable_early_exit (vec_info *vinfo,
> > stmt_vec_info stmt_info,
> >         new_temp = prepare_vec_mask (loop_vinfo, TREE_TYPE (mask), mask,
> >                                      new_temp, &cond_gsi);
> >       }
> > +      else if (len_loop_p)
> > +     new_temp = vect_gen_loop_len_mask (loop_vinfo, gsi, &cond_gsi, lens,
> > +                                        ncopies, vectype, new_temp, 0, 1);
> >      }
> >
> >    gcc_assert (new_temp);
> > diff --git a/gcc/tree-vectorizer.h b/gcc/tree-vectorizer.h
> > index db44d730b70..93bc30ef660 100644
> > --- a/gcc/tree-vectorizer.h
> > +++ b/gcc/tree-vectorizer.h
> > @@ -2408,6 +2408,10 @@ extern void vect_record_loop_len (loop_vec_info,
> > vec_loop_lens *, unsigned int,
> >  extern tree vect_get_loop_len (loop_vec_info, gimple_stmt_iterator *,
> >                              vec_loop_lens *, unsigned int, tree,
> >                              unsigned int, unsigned int);
> > +extern tree vect_gen_loop_len_mask (loop_vec_info, gimple_stmt_iterator *,
> > +                                 gimple_stmt_iterator *, vec_loop_lens *,
> > +                                 unsigned int, tree, tree, unsigned int,
> > +                                 unsigned int);
> >  extern gimple_seq vect_gen_len (tree, tree, tree, tree);
> >  extern stmt_vec_info info_for_reduction (vec_info *, stmt_vec_info);
> >  extern bool reduction_fn_for_scalar_code (code_helper, internal_fn *);
> > --
> > 2.34.1
>