[3/4] Make more use of rtx_vector_builder

This patch makes various bits of CONST_VECTOR-building code use
rtx_vector_builder, operating directly on a specific encoding.


2017-12-28  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* expr.c: Include rtx-vector-builder.h.
	(const_vector_mask_from_tree): Use rtx_vector_builder and operate
	directly on the tree encoding.
	(const_vector_from_tree): Likewise.
	* optabs.c: Include rtx-vector-builder.h.
	(expand_vec_perm_var): Use rtx_vector_builder and create a repeating
	sequence of "u" values.
	* vec-perm-indices.c: Include rtx-vector-builder.h.
	(vec_perm_indices_to_rtx): Use rtx_vector_builder and operate
	directly on the vec_perm_indices encoding.

On Thu, Dec 28, 2017 at 9:53 PM, Richard Sandiford
<richard.sandiford@linaro.org> wrote:
> This patch makes various bits of CONST_VECTOR-building code use
> rtx_vector_builder, operating directly on a specific encoding.

Ok.

Richard.

>
> 2017-12-28  Richard Sandiford  <richard.sandiford@linaro.org>
>
> gcc/
>         * expr.c: Include rtx-vector-builder.h.
>         (const_vector_mask_from_tree): Use rtx_vector_builder and operate
>         directly on the tree encoding.
>         (const_vector_from_tree): Likewise.
>         * optabs.c: Include rtx-vector-builder.h.
>         (expand_vec_perm_var): Use rtx_vector_builder and create a repeating
>         sequence of "u" values.
>         * vec-perm-indices.c: Include rtx-vector-builder.h.
>         (vec_perm_indices_to_rtx): Use rtx_vector_builder and operate
>         directly on the vec_perm_indices encoding.
>
> Index: gcc/expr.c
> ===================================================================
> --- gcc/expr.c  2017-12-22 12:58:44.518127920 +0000
> +++ gcc/expr.c  2017-12-22 13:09:48.535709302 +0000
> @@ -61,6 +61,7 @@ Software Foundation; either version 3, o
>  #include "tree-chkp.h"
>  #include "rtl-chkp.h"
>  #include "ccmp.h"
> +#include "rtx-vector-builder.h"
>
>
>  /* If this is nonzero, we do not bother generating VOLATILE
> @@ -11761,32 +11762,25 @@ try_tablejump (tree index_type, tree ind
>  static rtx
>  const_vector_mask_from_tree (tree exp)
>  {
> -  rtvec v;
> -  unsigned i, units;
> -  tree elt;
> -  machine_mode inner, mode;
> -
> -  mode = TYPE_MODE (TREE_TYPE (exp));
> -  units = VECTOR_CST_NELTS (exp);
> -  inner = GET_MODE_INNER (mode);
> -
> -  v = rtvec_alloc (units);
> +  machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
> +  machine_mode inner = GET_MODE_INNER (mode);
>
> -  for (i = 0; i < units; ++i)
> +  rtx_vector_builder builder (mode, VECTOR_CST_NPATTERNS (exp),
> +                             VECTOR_CST_NELTS_PER_PATTERN (exp));
> +  unsigned int count = builder.encoded_nelts ();
> +  for (unsigned int i = 0; i < count; ++i)
>      {
> -      elt = VECTOR_CST_ELT (exp, i);
> -
> +      tree elt = VECTOR_CST_ELT (exp, i);
>        gcc_assert (TREE_CODE (elt) == INTEGER_CST);
>        if (integer_zerop (elt))
> -       RTVEC_ELT (v, i) = CONST0_RTX (inner);
> +       builder.quick_push (CONST0_RTX (inner));
>        else if (integer_onep (elt)
>                || integer_minus_onep (elt))
> -       RTVEC_ELT (v, i) = CONSTM1_RTX (inner);
> +       builder.quick_push (CONSTM1_RTX (inner));
>        else
>         gcc_unreachable ();
>      }
> -
> -  return gen_rtx_CONST_VECTOR (mode, v);
> +  return builder.build ();
>  }
>
>  /* EXP is a VECTOR_CST in which each element is either all-zeros or all-ones.
> @@ -11816,12 +11810,7 @@ const_scalar_mask_from_tree (scalar_int_
>  static rtx
>  const_vector_from_tree (tree exp)
>  {
> -  rtvec v;
> -  unsigned i, units;
> -  tree elt;
> -  machine_mode inner, mode;
> -
> -  mode = TYPE_MODE (TREE_TYPE (exp));
> +  machine_mode mode = TYPE_MODE (TREE_TYPE (exp));
>
>    if (initializer_zerop (exp))
>      return CONST0_RTX (mode);
> @@ -11829,27 +11818,25 @@ const_vector_from_tree (tree exp)
>    if (VECTOR_BOOLEAN_TYPE_P (TREE_TYPE (exp)))
>      return const_vector_mask_from_tree (exp);
>
> -  units = VECTOR_CST_NELTS (exp);
> -  inner = GET_MODE_INNER (mode);
> -
> -  v = rtvec_alloc (units);
> +  machine_mode inner = GET_MODE_INNER (mode);
>
> -  for (i = 0; i < units; ++i)
> +  rtx_vector_builder builder (mode, VECTOR_CST_NPATTERNS (exp),
> +                             VECTOR_CST_NELTS_PER_PATTERN (exp));
> +  unsigned int count = builder.encoded_nelts ();
> +  for (unsigned int i = 0; i < count; ++i)
>      {
> -      elt = VECTOR_CST_ELT (exp, i);
> -
> +      tree elt = VECTOR_CST_ELT (exp, i);
>        if (TREE_CODE (elt) == REAL_CST)
> -       RTVEC_ELT (v, i) = const_double_from_real_value (TREE_REAL_CST (elt),
> -                                                        inner);
> +       builder.quick_push (const_double_from_real_value (TREE_REAL_CST (elt),
> +                                                         inner));
>        else if (TREE_CODE (elt) == FIXED_CST)
> -       RTVEC_ELT (v, i) = CONST_FIXED_FROM_FIXED_VALUE (TREE_FIXED_CST (elt),
> -                                                        inner);
> +       builder.quick_push (CONST_FIXED_FROM_FIXED_VALUE (TREE_FIXED_CST (elt),
> +                                                         inner));
>        else
> -       RTVEC_ELT (v, i) = immed_wide_int_const (wi::to_poly_wide (elt),
> -                                                inner);
> +       builder.quick_push (immed_wide_int_const (wi::to_poly_wide (elt),
> +                                                 inner));
>      }
> -
> -  return gen_rtx_CONST_VECTOR (mode, v);
> +  return builder.build ();
>  }
>
>  /* Build a decl for a personality function given a language prefix.  */
> Index: gcc/optabs.c
> ===================================================================
> --- gcc/optabs.c        2017-12-22 13:06:03.092620276 +0000
> +++ gcc/optabs.c        2017-12-22 13:09:48.535709302 +0000
> @@ -33,6 +33,7 @@ Software Foundation; either version 3, o
>  #include "emit-rtl.h"
>  #include "recog.h"
>  #include "diagnostic-core.h"
> +#include "rtx-vector-builder.h"
>
>  /* Include insn-config.h before expr.h so that HAVE_conditional_move
>     is properly defined.  */
> @@ -5609,7 +5610,6 @@ expand_vec_perm_var (machine_mode mode,
>    enum insn_code icode;
>    unsigned int i, w, u;
>    rtx tmp, sel_qi;
> -  rtvec vec;
>
>    w = GET_MODE_SIZE (mode);
>    u = GET_MODE_UNIT_SIZE (mode);
> @@ -5661,10 +5661,10 @@ expand_vec_perm_var (machine_mode mode,
>    /* Add the byte offset to each byte element.  */
>    /* Note that the definition of the indicies here is memory ordering,
>       so there should be no difference between big and little endian.  */
> -  vec = rtvec_alloc (w);
> -  for (i = 0; i < w; ++i)
> -    RTVEC_ELT (vec, i) = GEN_INT (i % u);
> -  tmp = gen_rtx_CONST_VECTOR (qimode, vec);
> +  rtx_vector_builder byte_indices (qimode, u, 1);
> +  for (i = 0; i < u; ++i)
> +    byte_indices.quick_push (GEN_INT (i));
> +  tmp = byte_indices.build ();
>    sel_qi = expand_simple_binop (qimode, PLUS, sel, tmp,
>                                 sel, 0, OPTAB_DIRECT);
>    gcc_assert (sel_qi != NULL);
> Index: gcc/vec-perm-indices.c
> ===================================================================
> --- gcc/vec-perm-indices.c      2017-12-22 13:05:20.155253154 +0000
> +++ gcc/vec-perm-indices.c      2017-12-22 13:09:48.535709302 +0000
> @@ -29,6 +29,7 @@ Software Foundation; either version 3, o
>  #include "memmodel.h"
>  #include "emit-rtl.h"
>  #include "selftest.h"
> +#include "rtx-vector-builder.h"
>
>  /* Switch to a new permutation vector that selects between NINPUTS vector
>     inputs that have NELTS_PER_INPUT elements each.  Take the elements of the
> @@ -223,11 +224,12 @@ vec_perm_indices_to_rtx (machine_mode mo
>  {
>    gcc_assert (GET_MODE_CLASS (mode) == MODE_VECTOR_INT
>               && GET_MODE_NUNITS (mode) == indices.length ());
> -  unsigned int nelts = indices.length ();
> -  rtvec v = rtvec_alloc (nelts);
> -  for (unsigned int i = 0; i < nelts; ++i)
> -    RTVEC_ELT (v, i) = gen_int_mode (indices[i], GET_MODE_INNER (mode));
> -  return gen_rtx_CONST_VECTOR (mode, v);
> +  rtx_vector_builder sel (mode, indices.encoding ().npatterns (),
> +                         indices.encoding ().nelts_per_pattern ());
> +  unsigned int encoded_nelts = sel.encoded_nelts ();
> +  for (unsigned int i = 0; i < encoded_nelts; i++)
> +    sel.quick_push (gen_int_mode (indices[i], GET_MODE_INNER (mode)));
> +  return sel.build ();
>  }
>
>  #if CHECKING_P