Re: [PATCH] vect: Move VMAT_GATHER_SCATTER handlings from final loop nest

["Kewen.Lin" <linkw@linux.ibm.com>]

Hi Richard,

on 2023/8/14 20:20, Richard Sandiford wrote:
> Thanks for the clean-ups.  But...
> 
> "Kewen.Lin" <linkw@linux.ibm.com> writes:
>> Hi,
>>
>> Following Richi's suggestion [1], this patch is to move the
>> handlings on VMAT_GATHER_SCATTER in the final loop nest
>> of function vectorizable_load to its own loop.  Basically
>> it duplicates the final loop nest, clean up some useless
>> set up code for the case of VMAT_GATHER_SCATTER, remove some
>> unreachable code.  Also remove the corresponding handlings
>> in the final loop nest.
>>
>> Bootstrapped and regtested on x86_64-redhat-linux,
>> aarch64-linux-gnu and powerpc64{,le}-linux-gnu.
>>
>> [1] https://gcc.gnu.org/pipermail/gcc-patches/2023-June/623329.html
>>
>> Is it ok for trunk?
>>
>> BR,
>> Kewen
>> -----
>>
>> gcc/ChangeLog:
>>
>> 	* tree-vect-stmts.cc (vectorizable_load): Move the handlings on
>> 	VMAT_GATHER_SCATTER in the final loop nest to its own loop,
>> 	and update the final nest accordingly.
>> ---
>>  gcc/tree-vect-stmts.cc | 361 +++++++++++++++++++++++++----------------
>>  1 file changed, 219 insertions(+), 142 deletions(-)
> 
> ...that seems like quite a lot of +s.  Is there nothing we can do to
> avoid the cut-&-paste?

Thanks for the comments!  I'm not sure if I get your question, if we
want to move out the handlings of VMAT_GATHER_SCATTER, the new +s seem
inevitable?  Your concern is mainly about git blame history?

BR,
Kewen

> 
> Richard
> 
>>
>> diff --git a/gcc/tree-vect-stmts.cc b/gcc/tree-vect-stmts.cc
>> index c361e16cb7b..5e514eca19b 100644
>> --- a/gcc/tree-vect-stmts.cc
>> +++ b/gcc/tree-vect-stmts.cc
>> @@ -10455,6 +10455,218 @@ vectorizable_load (vec_info *vinfo,
>>        return true;
>>      }
>>
>> +  if (memory_access_type == VMAT_GATHER_SCATTER)
>> +    {
>> +      gcc_assert (alignment_support_scheme == dr_aligned
>> +		  || alignment_support_scheme == dr_unaligned_supported);
>> +      gcc_assert (!grouped_load && !slp_perm);
>> +
>> +      unsigned int inside_cost = 0, prologue_cost = 0;
>> +      for (j = 0; j < ncopies; j++)
>> +	{
>> +	  /* 1. Create the vector or array pointer update chain.  */
>> +	  if (j == 0 && !costing_p)
>> +	    {
>> +	      if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +		vect_get_gather_scatter_ops (loop_vinfo, loop, stmt_info,
>> +					     slp_node, &gs_info, &dataref_ptr,
>> +					     &vec_offsets);
>> +	      else
>> +		dataref_ptr
>> +		  = vect_create_data_ref_ptr (vinfo, first_stmt_info, aggr_type,
>> +					      at_loop, offset, &dummy, gsi,
>> +					      &ptr_incr, false, bump);
>> +	    }
>> +	  else if (!costing_p)
>> +	    {
>> +	      gcc_assert (!LOOP_VINFO_USING_SELECT_VL_P (loop_vinfo));
>> +	      if (!STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +		dataref_ptr = bump_vector_ptr (vinfo, dataref_ptr, ptr_incr,
>> +					       gsi, stmt_info, bump);
>> +	    }
>> +
>> +	  if (mask && !costing_p)
>> +	    vec_mask = vec_masks[j];
>> +
>> +	  gimple *new_stmt = NULL;
>> +	  for (i = 0; i < vec_num; i++)
>> +	    {
>> +	      tree final_mask = NULL_TREE;
>> +	      tree final_len = NULL_TREE;
>> +	      tree bias = NULL_TREE;
>> +	      if (!costing_p)
>> +		{
>> +		  if (loop_masks)
>> +		    final_mask
>> +		      = vect_get_loop_mask (loop_vinfo, gsi, loop_masks,
>> +					    vec_num * ncopies, vectype,
>> +					    vec_num * j + i);
>> +		  if (vec_mask)
>> +		    final_mask = prepare_vec_mask (loop_vinfo, mask_vectype,
>> +						   final_mask, vec_mask, gsi);
>> +
>> +		  if (i > 0 && !STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +		    dataref_ptr = bump_vector_ptr (vinfo, dataref_ptr, ptr_incr,
>> +						   gsi, stmt_info, bump);
>> +		}
>> +
>> +	      /* 2. Create the vector-load in the loop.  */
>> +	      unsigned HOST_WIDE_INT align;
>> +	      if (gs_info.ifn != IFN_LAST)
>> +		{
>> +		  if (costing_p)
>> +		    {
>> +		      unsigned int cnunits = vect_nunits_for_cost (vectype);
>> +		      inside_cost
>> +			= record_stmt_cost (cost_vec, cnunits, scalar_load,
>> +					    stmt_info, 0, vect_body);
>> +		      continue;
>> +		    }
>> +		  if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +		    vec_offset = vec_offsets[vec_num * j + i];
>> +		  tree zero = build_zero_cst (vectype);
>> +		  tree scale = size_int (gs_info.scale);
>> +
>> +		  if (gs_info.ifn == IFN_MASK_LEN_GATHER_LOAD)
>> +		    {
>> +		      if (loop_lens)
>> +			final_len
>> +			  = vect_get_loop_len (loop_vinfo, gsi, loop_lens,
>> +					       vec_num * ncopies, vectype,
>> +					       vec_num * j + i, 1);
>> +		      else
>> +			final_len
>> +			  = build_int_cst (sizetype,
>> +					   TYPE_VECTOR_SUBPARTS (vectype));
>> +		      signed char biasval
>> +			= LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
>> +		      bias = build_int_cst (intQI_type_node, biasval);
>> +		      if (!final_mask)
>> +			{
>> +			  mask_vectype = truth_type_for (vectype);
>> +			  final_mask = build_minus_one_cst (mask_vectype);
>> +			}
>> +		    }
>> +
>> +		  gcall *call;
>> +		  if (final_len && final_mask)
>> +		    call
>> +		      = gimple_build_call_internal (IFN_MASK_LEN_GATHER_LOAD, 7,
>> +						    dataref_ptr, vec_offset,
>> +						    scale, zero, final_mask,
>> +						    final_len, bias);
>> +		  else if (final_mask)
>> +		    call = gimple_build_call_internal (IFN_MASK_GATHER_LOAD, 5,
>> +						       dataref_ptr, vec_offset,
>> +						       scale, zero, final_mask);
>> +		  else
>> +		    call = gimple_build_call_internal (IFN_GATHER_LOAD, 4,
>> +						       dataref_ptr, vec_offset,
>> +						       scale, zero);
>> +		  gimple_call_set_nothrow (call, true);
>> +		  new_stmt = call;
>> +		  data_ref = NULL_TREE;
>> +		}
>> +	      else
>> +		{
>> +		  /* Emulated gather-scatter.  */
>> +		  gcc_assert (!final_mask);
>> +		  unsigned HOST_WIDE_INT const_nunits = nunits.to_constant ();
>> +		  if (costing_p)
>> +		    {
>> +		      /* For emulated gathers N offset vector element
>> +			 offset add is consumed by the load).  */
>> +		      inside_cost = record_stmt_cost (cost_vec, const_nunits,
>> +						      vec_to_scalar, stmt_info,
>> +						      0, vect_body);
>> +		      /* N scalar loads plus gathering them into a
>> +			 vector.  */
>> +		      inside_cost
>> +			= record_stmt_cost (cost_vec, const_nunits, scalar_load,
>> +					    stmt_info, 0, vect_body);
>> +		      inside_cost
>> +			= record_stmt_cost (cost_vec, 1, vec_construct,
>> +					    stmt_info, 0, vect_body);
>> +		      continue;
>> +		    }
>> +		  unsigned HOST_WIDE_INT const_offset_nunits
>> +		    = TYPE_VECTOR_SUBPARTS (gs_info.offset_vectype)
>> +			.to_constant ();
>> +		  vec<constructor_elt, va_gc> *ctor_elts;
>> +		  vec_alloc (ctor_elts, const_nunits);
>> +		  gimple_seq stmts = NULL;
>> +		  /* We support offset vectors with more elements
>> +		     than the data vector for now.  */
>> +		  unsigned HOST_WIDE_INT factor
>> +		    = const_offset_nunits / const_nunits;
>> +		  vec_offset = vec_offsets[j / factor];
>> +		  unsigned elt_offset = (j % factor) * const_nunits;
>> +		  tree idx_type = TREE_TYPE (TREE_TYPE (vec_offset));
>> +		  tree scale = size_int (gs_info.scale);
>> +		  align = get_object_alignment (DR_REF (first_dr_info->dr));
>> +		  tree ltype = build_aligned_type (TREE_TYPE (vectype), align);
>> +		  for (unsigned k = 0; k < const_nunits; ++k)
>> +		    {
>> +		      tree boff = size_binop (MULT_EXPR, TYPE_SIZE (idx_type),
>> +					      bitsize_int (k + elt_offset));
>> +		      tree idx
>> +			= gimple_build (&stmts, BIT_FIELD_REF, idx_type,
>> +					vec_offset, TYPE_SIZE (idx_type), boff);
>> +		      idx = gimple_convert (&stmts, sizetype, idx);
>> +		      idx = gimple_build (&stmts, MULT_EXPR, sizetype, idx,
>> +					  scale);
>> +		      tree ptr = gimple_build (&stmts, PLUS_EXPR,
>> +					       TREE_TYPE (dataref_ptr),
>> +					       dataref_ptr, idx);
>> +		      ptr = gimple_convert (&stmts, ptr_type_node, ptr);
>> +		      tree elt = make_ssa_name (TREE_TYPE (vectype));
>> +		      tree ref = build2 (MEM_REF, ltype, ptr,
>> +					 build_int_cst (ref_type, 0));
>> +		      new_stmt = gimple_build_assign (elt, ref);
>> +		      gimple_set_vuse (new_stmt, gimple_vuse (gsi_stmt (*gsi)));
>> +		      gimple_seq_add_stmt (&stmts, new_stmt);
>> +		      CONSTRUCTOR_APPEND_ELT (ctor_elts, NULL_TREE, elt);
>> +		    }
>> +		  gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
>> +		  new_stmt = gimple_build_assign (
>> +		    NULL_TREE, build_constructor (vectype, ctor_elts));
>> +		  data_ref = NULL_TREE;
>> +		}
>> +
>> +	      vec_dest = vect_create_destination_var (scalar_dest, vectype);
>> +	      /* DATA_REF is null if we've already built the statement.  */
>> +	      if (data_ref)
>> +		{
>> +		  vect_copy_ref_info (data_ref, DR_REF (first_dr_info->dr));
>> +		  new_stmt = gimple_build_assign (vec_dest, data_ref);
>> +		}
>> +	      new_temp = make_ssa_name (vec_dest, new_stmt);
>> +	      gimple_set_lhs (new_stmt, new_temp);
>> +	      vect_finish_stmt_generation (vinfo, stmt_info, new_stmt, gsi);
>> +
>> +	      /* Store vector loads in the corresponding SLP_NODE.  */
>> +	      if (slp)
>> +		slp_node->push_vec_def (new_stmt);
>> +	    }
>> +
>> +	  if (!slp && !costing_p)
>> +	    STMT_VINFO_VEC_STMTS (stmt_info).safe_push (new_stmt);
>> +	}
>> +
>> +      if (!slp && !costing_p)
>> +	*vec_stmt = STMT_VINFO_VEC_STMTS (stmt_info)[0];
>> +
>> +      if (costing_p)
>> +	{
>> +	  if (dump_enabled_p ())
>> +	    dump_printf_loc (MSG_NOTE, vect_location,
>> +			     "vect_model_load_cost: inside_cost = %u, "
>> +			     "prologue_cost = %u .\n",
>> +			     inside_cost, prologue_cost);
>> +	}
>> +      return true;
>> +    }
>> +
>>    poly_uint64 group_elt = 0;
>>    unsigned int inside_cost = 0, prologue_cost = 0;
>>    for (j = 0; j < ncopies; j++)
>> @@ -10504,12 +10716,6 @@ vectorizable_load (vec_info *vinfo,
>>  		  gcc_assert (!compute_in_loop);
>>  		}
>>  	    }
>> -	  else if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> -	    {
>> -	      vect_get_gather_scatter_ops (loop_vinfo, loop, stmt_info,
>> -					   slp_node, &gs_info, &dataref_ptr,
>> -					   &vec_offsets);
>> -	    }
>>  	  else
>>  	    dataref_ptr
>>  	      = vect_create_data_ref_ptr (vinfo, first_stmt_info, aggr_type,
>> @@ -10525,7 +10731,7 @@ vectorizable_load (vec_info *vinfo,
>>  	  if (dataref_offset)
>>  	    dataref_offset = int_const_binop (PLUS_EXPR, dataref_offset,
>>  					      bump);
>> -	  else if (!STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +	  else
>>  	    dataref_ptr = bump_vector_ptr (vinfo, dataref_ptr, ptr_incr, gsi,
>>  					   stmt_info, bump);
>>  	  if (mask)
>> @@ -10551,7 +10757,7 @@ vectorizable_load (vec_info *vinfo,
>>  		final_mask = prepare_vec_mask (loop_vinfo, mask_vectype,
>>  					       final_mask, vec_mask, gsi);
>>
>> -	      if (i > 0 && !STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> +	      if (i > 0)
>>  		dataref_ptr = bump_vector_ptr (vinfo, dataref_ptr, ptr_incr,
>>  					       gsi, stmt_info, bump);
>>  	    }
>> @@ -10562,139 +10768,11 @@ vectorizable_load (vec_info *vinfo,
>>  	    case dr_aligned:
>>  	    case dr_unaligned_supported:
>>  	      {
>> -		unsigned int misalign;
>> -		unsigned HOST_WIDE_INT align;
>> -
>> -		if (memory_access_type == VMAT_GATHER_SCATTER
>> -		    && gs_info.ifn != IFN_LAST)
>> -		  {
>> -		    if (costing_p)
>> -		      {
>> -			unsigned int cnunits = vect_nunits_for_cost (vectype);
>> -			inside_cost
>> -			  = record_stmt_cost (cost_vec, cnunits, scalar_load,
>> -					      stmt_info, 0, vect_body);
>> -			break;
>> -		      }
>> -		    if (STMT_VINFO_GATHER_SCATTER_P (stmt_info))
>> -		      vec_offset = vec_offsets[vec_num * j + i];
>> -		    tree zero = build_zero_cst (vectype);
>> -		    tree scale = size_int (gs_info.scale);
>> -
>> -		    if (gs_info.ifn == IFN_MASK_LEN_GATHER_LOAD)
>> -		      {
>> -			if (loop_lens)
>> -			  final_len
>> -			    = vect_get_loop_len (loop_vinfo, gsi, loop_lens,
>> -						 vec_num * ncopies, vectype,
>> -						 vec_num * j + i, 1);
>> -			else
>> -			  final_len
>> -			    = build_int_cst (sizetype,
>> -					     TYPE_VECTOR_SUBPARTS (vectype));
>> -			signed char biasval
>> -			  = LOOP_VINFO_PARTIAL_LOAD_STORE_BIAS (loop_vinfo);
>> -			bias = build_int_cst (intQI_type_node, biasval);
>> -			if (!final_mask)
>> -			  {
>> -			    mask_vectype = truth_type_for (vectype);
>> -			    final_mask = build_minus_one_cst (mask_vectype);
>> -			  }
>> -		      }
>> -
>> -		    gcall *call;
>> -		    if (final_len && final_mask)
>> -		      call = gimple_build_call_internal (
>> -			IFN_MASK_LEN_GATHER_LOAD, 7, dataref_ptr, vec_offset,
>> -			scale, zero, final_mask, final_len, bias);
>> -		    else if (final_mask)
>> -		      call
>> -			= gimple_build_call_internal (IFN_MASK_GATHER_LOAD, 5,
>> -						      dataref_ptr, vec_offset,
>> -						      scale, zero, final_mask);
>> -		    else
>> -		      call
>> -			= gimple_build_call_internal (IFN_GATHER_LOAD, 4,
>> -						      dataref_ptr, vec_offset,
>> -						      scale, zero);
>> -		    gimple_call_set_nothrow (call, true);
>> -		    new_stmt = call;
>> -		    data_ref = NULL_TREE;
>> -		    break;
>> -		  }
>> -		else if (memory_access_type == VMAT_GATHER_SCATTER)
>> -		  {
>> -		    /* Emulated gather-scatter.  */
>> -		    gcc_assert (!final_mask);
>> -		    unsigned HOST_WIDE_INT const_nunits = nunits.to_constant ();
>> -		    if (costing_p)
>> -		      {
>> -			/* For emulated gathers N offset vector element
>> -			   offset add is consumed by the load).  */
>> -			inside_cost
>> -			  = record_stmt_cost (cost_vec, const_nunits,
>> -					      vec_to_scalar, stmt_info, 0,
>> -					      vect_body);
>> -			/* N scalar loads plus gathering them into a
>> -			   vector.  */
>> -			inside_cost = record_stmt_cost (cost_vec, const_nunits,
>> -							scalar_load, stmt_info,
>> -							0, vect_body);
>> -			inside_cost
>> -			  = record_stmt_cost (cost_vec, 1, vec_construct,
>> -					      stmt_info, 0, vect_body);
>> -			break;
>> -		      }
>> -		    unsigned HOST_WIDE_INT const_offset_nunits
>> -		      = TYPE_VECTOR_SUBPARTS (gs_info.offset_vectype)
>> -			  .to_constant ();
>> -		    vec<constructor_elt, va_gc> *ctor_elts;
>> -		    vec_alloc (ctor_elts, const_nunits);
>> -		    gimple_seq stmts = NULL;
>> -		    /* We support offset vectors with more elements
>> -		       than the data vector for now.  */
>> -		    unsigned HOST_WIDE_INT factor
>> -		      = const_offset_nunits / const_nunits;
>> -		    vec_offset = vec_offsets[j / factor];
>> -		    unsigned elt_offset = (j % factor) * const_nunits;
>> -		    tree idx_type = TREE_TYPE (TREE_TYPE (vec_offset));
>> -		    tree scale = size_int (gs_info.scale);
>> -		    align = get_object_alignment (DR_REF (first_dr_info->dr));
>> -		    tree ltype
>> -		      = build_aligned_type (TREE_TYPE (vectype), align);
>> -		    for (unsigned k = 0; k < const_nunits; ++k)
>> -		      {
>> -			tree boff = size_binop (MULT_EXPR, TYPE_SIZE (idx_type),
>> -						bitsize_int (k + elt_offset));
>> -			tree idx = gimple_build (&stmts, BIT_FIELD_REF,
>> -						 idx_type, vec_offset,
>> -						 TYPE_SIZE (idx_type), boff);
>> -			idx = gimple_convert (&stmts, sizetype, idx);
>> -			idx = gimple_build (&stmts, MULT_EXPR, sizetype, idx,
>> -					    scale);
>> -			tree ptr = gimple_build (&stmts, PLUS_EXPR,
>> -						 TREE_TYPE (dataref_ptr),
>> -						 dataref_ptr, idx);
>> -			ptr = gimple_convert (&stmts, ptr_type_node, ptr);
>> -			tree elt = make_ssa_name (TREE_TYPE (vectype));
>> -			tree ref = build2 (MEM_REF, ltype, ptr,
>> -					   build_int_cst (ref_type, 0));
>> -			new_stmt = gimple_build_assign (elt, ref);
>> -			gimple_set_vuse (new_stmt,
>> -					 gimple_vuse (gsi_stmt (*gsi)));
>> -			gimple_seq_add_stmt (&stmts, new_stmt);
>> -			CONSTRUCTOR_APPEND_ELT (ctor_elts, NULL_TREE, elt);
>> -		      }
>> -		    gsi_insert_seq_before (gsi, stmts, GSI_SAME_STMT);
>> -		    new_stmt = gimple_build_assign (
>> -		      NULL_TREE, build_constructor (vectype, ctor_elts));
>> -		    data_ref = NULL_TREE;
>> -		    break;
>> -		  }
>> -
>>  		if (costing_p)
>>  		  break;
>>
>> +		unsigned int misalign;
>> +		unsigned HOST_WIDE_INT align;
>>  		align = known_alignment (DR_TARGET_ALIGNMENT (first_dr_info));
>>  		if (alignment_support_scheme == dr_aligned)
>>  		  misalign = 0;
>> @@ -11156,10 +11234,9 @@ vectorizable_load (vec_info *vinfo,
>>
>>    if (costing_p)
>>      {
>> -      gcc_assert (memory_access_type != VMAT_INVARIANT
>> -		  && memory_access_type != VMAT_ELEMENTWISE
>> -		  && memory_access_type != VMAT_STRIDED_SLP
>> -		  && memory_access_type != VMAT_LOAD_STORE_LANES);
>> +      gcc_assert (memory_access_type == VMAT_CONTIGUOUS
>> +		  || memory_access_type == VMAT_CONTIGUOUS_REVERSE
>> +		  || memory_access_type == VMAT_CONTIGUOUS_PERMUTE);
>>        if (dump_enabled_p ())
>>  	dump_printf_loc (MSG_NOTE, vect_location,
>>  			 "vect_model_load_cost: inside_cost = %u, "
>> --
>> 2.39.1