Split can_vec_perm_p into can_vec_perm_{var,const}_p

This patch splits can_vec_perm_p into two functions: can_vec_perm_var_p
for testing permute operations with variable selection vectors, and
can_vec_perm_const_p for testing permute operations with specific
constant selection vectors.  This means that we can pass the constant
selection vector by reference.

Constant permutes can still use a variable permute as a fallback.
A later patch adds a check to makre sure that we don't truncate the
vector indices when doing this.

However, have_whole_vector_shift checked:

  if (direct_optab_handler (vec_perm_const_optab, mode) == CODE_FOR_nothing)
    return false;

which had the effect of disallowing the fallback to variable permutes.
I'm not sure whether that was the intention or whether it was just
supposed to short-cut the loop on targets that don't support permutes.
(But then why bother?  The first check in the loop would fail and
we'd bail out straightaway.)

The patch adds a parameter for disallowing the fallback.  I think it
makes sense to do this for the following code in the VEC_PERM_EXPR
folder:

	  /* Some targets are deficient and fail to expand a single
	     argument permutation while still allowing an equivalent
	     2-argument version.  */
	  if (need_mask_canon && arg2 == op2
	      && !can_vec_perm_p (TYPE_MODE (type), false, &sel)
	      && can_vec_perm_p (TYPE_MODE (type), false, &sel2))

since it's really testing whether the expand_vec_perm_const code expects
a particular form.

2018-01-02  Richard Sandiford  <richard.sandiford@linaro.org>

gcc/
	* optabs-query.h (can_vec_perm_p): Delete.
	(can_vec_perm_var_p, can_vec_perm_const_p): Declare.
	* optabs-query.c (can_vec_perm_p): Split into...
	(can_vec_perm_var_p, can_vec_perm_const_p): ...these two functions.
	(can_mult_highpart_p): Use can_vec_perm_const_p to test whether a
	particular selector is valid.
	* tree-ssa-forwprop.c (simplify_vector_constructor): Likewise.
	* tree-vect-data-refs.c (vect_grouped_store_supported): Likewise.
	(vect_grouped_load_supported): Likewise.
	(vect_shift_permute_load_chain): Likewise.
	* tree-vect-slp.c (vect_build_slp_tree_1): Likewise.
	(vect_transform_slp_perm_load): Likewise.
	* tree-vect-stmts.c (perm_mask_for_reverse): Likewise.
	(vectorizable_bswap): Likewise.
	(vect_gen_perm_mask_checked): Likewise.
	* fold-const.c (fold_ternary_loc): Likewise.  Don't take
	implementations of variable permutation vectors into account
	when deciding which selector to use.
	* tree-vect-loop.c (have_whole_vector_shift): Don't check whether
	vec_perm_const_optab is supported; instead use can_vec_perm_const_p
	with a false third argument.
	* tree-vect-generic.c (lower_vec_perm): Use can_vec_perm_const_p
	to test whether the constant selector is valid and can_vec_perm_var_p
	to test whether a variable selector is valid.

From-SVN: r256091

1 files changed, 19 insertions, 19 deletions

diff --git a/gcc/tree-vect-data-refs.c b/gcc/tree-vect-data-refs.c
index 014862a..bbbeef6 100644
--- a/gcc/tree-vect-data-refs.c
+++ b/gcc/tree-vect-data-refs.c
@@ -4600,11 +4600,11 @@ vect_grouped_store_supported (tree vectype, unsigned HOST_WIDE_INT count)
 		  if (3 * i + nelt2 < nelt)
 		    sel[3 * i + nelt2] = 0;
 		}
-	      if (!can_vec_perm_p (mode, false, &sel))
+	      if (!can_vec_perm_const_p (mode, sel))
 		{
 		  if (dump_enabled_p ())
 		    dump_printf (MSG_MISSED_OPTIMIZATION,
-				 "permutaion op not supported by target.\n");
+				 "permutation op not supported by target.\n");
 		  return false;
 		}
 
@@ -4617,11 +4617,11 @@ vect_grouped_store_supported (tree vectype, unsigned HOST_WIDE_INT count)
 		  if (3 * i + nelt2 < nelt)
 		    sel[3 * i + nelt2] = nelt + j2++;
 		}
-	      if (!can_vec_perm_p (mode, false, &sel))
+	      if (!can_vec_perm_const_p (mode, sel))
 		{
 		  if (dump_enabled_p ())
 		    dump_printf (MSG_MISSED_OPTIMIZATION,
-				 "permutaion op not supported by target.\n");
+				 "permutation op not supported by target.\n");
 		  return false;
 		}
 	    }
@@ -4637,11 +4637,11 @@ vect_grouped_store_supported (tree vectype, unsigned HOST_WIDE_INT count)
 	      sel[i * 2] = i;
 	      sel[i * 2 + 1] = i + nelt;
 	    }
-	  if (can_vec_perm_p (mode, false, &sel))
+	  if (can_vec_perm_const_p (mode, sel))
 	    {
 	      for (i = 0; i < nelt; i++)
 		sel[i] += nelt / 2;
-	      if (can_vec_perm_p (mode, false, &sel))
+	      if (can_vec_perm_const_p (mode, sel))
 		return true;
 	    }
 	}
@@ -5179,7 +5179,7 @@ vect_grouped_load_supported (tree vectype, bool single_element_p,
 		  sel[i] = 3 * i + k;
 		else
 		  sel[i] = 0;
-	      if (!can_vec_perm_p (mode, false, &sel))
+	      if (!can_vec_perm_const_p (mode, sel))
 		{
 		  if (dump_enabled_p ())
 		    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5192,7 +5192,7 @@ vect_grouped_load_supported (tree vectype, bool single_element_p,
 		  sel[i] = i;
 		else
 		  sel[i] = nelt + ((nelt + k) % 3) + 3 * (j++);
-	      if (!can_vec_perm_p (mode, false, &sel))
+	      if (!can_vec_perm_const_p (mode, sel))
 		{
 		  if (dump_enabled_p ())
 		    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5209,11 +5209,11 @@ vect_grouped_load_supported (tree vectype, bool single_element_p,
 	  gcc_assert (pow2p_hwi (count));
 	  for (i = 0; i < nelt; i++)
 	    sel[i] = i * 2;
-	  if (can_vec_perm_p (mode, false, &sel))
+	  if (can_vec_perm_const_p (mode, sel))
 	    {
 	      for (i = 0; i < nelt; i++)
 		sel[i] = i * 2 + 1;
-	      if (can_vec_perm_p (mode, false, &sel))
+	      if (can_vec_perm_const_p (mode, sel))
 		return true;
 	    }
         }
@@ -5540,7 +5540,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	sel[i] = i * 2;
       for (i = 0; i < nelt / 2; ++i)
 	sel[nelt / 2 + i] = i * 2 + 1;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5554,7 +5554,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	sel[i] = i * 2 + 1;
       for (i = 0; i < nelt / 2; ++i)
 	sel[nelt / 2 + i] = i * 2;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5568,7 +5568,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	 For vector length 8 it is {4 5 6 7 8 9 10 11}.  */
       for (i = 0; i < nelt; i++)
 	sel[i] = nelt / 2 + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5583,7 +5583,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	sel[i] = i;
       for (i = nelt / 2; i < nelt; i++)
 	sel[i] = nelt + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5646,7 +5646,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	  sel[i] = 3 * k + (l % 3);
 	  k++;
 	}
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5660,7 +5660,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	 For vector length 8 it is {6 7 8 9 10 11 12 13}.  */
       for (i = 0; i < nelt; i++)
 	sel[i] = 2 * (nelt / 3) + (nelt % 3) + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5673,7 +5673,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	 For vector length 8 it is {5 6 7 8 9 10 11 12}.  */
       for (i = 0; i < nelt; i++)
 	sel[i] = 2 * (nelt / 3) + 1 + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5686,7 +5686,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	 For vector length 8 it is {3 4 5 6 7 8 9 10}.  */
       for (i = 0; i < nelt; i++)
 	sel[i] = (nelt / 3) + (nelt % 3) / 2 + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
@@ -5699,7 +5699,7 @@ vect_shift_permute_load_chain (vec<tree> dr_chain,
 	 For vector length 8 it is {5 6 7 8 9 10 11 12}.  */
       for (i = 0; i < nelt; i++)
 	sel[i] = 2 * (nelt / 3) + (nelt % 3) / 2 + i;
-      if (!can_vec_perm_p (TYPE_MODE (vectype), false, &sel))
+      if (!can_vec_perm_const_p (TYPE_MODE (vectype), sel))
 	{
 	  if (dump_enabled_p ())
 	    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,