poly_int: vectorizable_reduction

This patch makes vectorizable_reduction cope with variable-length vectors.
We can handle the simple case of an inner loop reduction for which
the target has native support for the epilogue operation.  For now we
punt on other cases, but patches after the main SVE submission allow
SLP and double reductions too.

2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
	    Alan Hayward  <alan.hayward@arm.com>
	    David Sherwood  <david.sherwood@arm.com>

gcc/
	* tree.h (build_index_vector): Declare.
	* tree.c (build_index_vector): New function.
	* tree-vect-loop.c (get_initial_defs_for_reduction): Treat the number
	of units as polynomial, forcibly converting it to a constant if
	vectorizable_reduction has already enforced the condition.
	(vect_create_epilog_for_reduction): Likewise.  Use build_index_vector
	to create a {1,2,3,...} vector.
	(vectorizable_reduction): Treat the number of units as polynomial.
	Choose vectype_in based on the largest scalar element size rather
	than the smallest number of units.  Enforce the restrictions
	relied on above.

Co-Authored-By: Alan Hayward <alan.hayward@arm.com>
Co-Authored-By: David Sherwood <david.sherwood@arm.com>
From-SVN: r256133

diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index e42270c40195b3f149472774c5dcaa6b83dcfa8b..eda66257b4708fdece1ffb39e5c9345204be1410 100644 (file)
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,19 @@
+2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
+           Alan Hayward  <alan.hayward@arm.com>
+           David Sherwood  <david.sherwood@arm.com>
+
+       * tree.h (build_index_vector): Declare.
+       * tree.c (build_index_vector): New function.
+       * tree-vect-loop.c (get_initial_defs_for_reduction): Treat the number
+       of units as polynomial, forcibly converting it to a constant if
+       vectorizable_reduction has already enforced the condition.
+       (vect_create_epilog_for_reduction): Likewise.  Use build_index_vector
+       to create a {1,2,3,...} vector.
+       (vectorizable_reduction): Treat the number of units as polynomial.
+       Choose vectype_in based on the largest scalar element size rather
+       than the smallest number of units.  Enforce the restrictions
+       relied on above.
+
 2018-01-03  Richard Sandiford  <richard.sandiford@linaro.org>
            Alan Hayward  <alan.hayward@arm.com>
            David Sherwood  <david.sherwood@arm.com>

diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index 557522c2ee5c6349a1f86e907db5d401d17c896a..93e430c7a562f0884138039ec1e2b3abf8214719 100644 (file)
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -4150,6 +4150,8 @@ get_initial_defs_for_reduction (slp_tree slp_node,
 
   vector_type = STMT_VINFO_VECTYPE (stmt_vinfo);
   scalar_type = TREE_TYPE (vector_type);
+  /* vectorizable_reduction has already rejected SLP reductions on
+     variable-length vectors.  */
   nunits = TYPE_VECTOR_SUBPARTS (vector_type);
 
   gcc_assert (STMT_VINFO_DEF_TYPE (stmt_vinfo) == vect_reduction_def);
@@ -4537,8 +4539,7 @@ vect_create_epilog_for_reduction (vec<tree> vect_defs, gimple *stmt,
   if (STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info) == COND_REDUCTION)
     {
       tree indx_before_incr, indx_after_incr;
-      int nunits_out = TYPE_VECTOR_SUBPARTS (vectype);
-      int k;
+      poly_uint64 nunits_out = TYPE_VECTOR_SUBPARTS (vectype);
 
       gimple *vec_stmt = STMT_VINFO_VEC_STMT (stmt_info);
       gcc_assert (gimple_assign_rhs_code (vec_stmt) == VEC_COND_EXPR);
@@ -4554,10 +4555,7 @@ vect_create_epilog_for_reduction (vec<tree> vect_defs, gimple *stmt,
         vector size (STEP).  */
 
       /* Create a {1,2,3,...} vector.  */
-      tree_vector_builder vtemp (cr_index_vector_type, 1, 3);
-      for (k = 0; k < 3; ++k)
-       vtemp.quick_push (build_int_cst (cr_index_scalar_type, k + 1));
-      tree series_vect = vtemp.build ();
+      tree series_vect = build_index_vector (cr_index_vector_type, 1, 1);
 
       /* Create a vector of the step value.  */
       tree step = build_int_cst (cr_index_scalar_type, nunits_out);
@@ -4935,8 +4933,11 @@ vect_create_epilog_for_reduction (vec<tree> vect_defs, gimple *stmt,
       tree data_eltype = TREE_TYPE (TREE_TYPE (new_phi_result));
       tree idx_eltype = TREE_TYPE (TREE_TYPE (induction_index));
       unsigned HOST_WIDE_INT el_size = tree_to_uhwi (TYPE_SIZE (idx_eltype));
-      unsigned HOST_WIDE_INT v_size
-       = el_size * TYPE_VECTOR_SUBPARTS (TREE_TYPE (induction_index));
+      poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (TREE_TYPE (induction_index));
+      /* Enforced by vectorizable_reduction, which ensures we have target
+        support before allowing a conditional reduction on variable-length
+        vectors.  */
+      unsigned HOST_WIDE_INT v_size = el_size * nunits.to_constant ();
       tree idx_val = NULL_TREE, val = NULL_TREE;
       for (unsigned HOST_WIDE_INT off = 0; off < v_size; off += el_size)
        {
@@ -5055,6 +5056,9 @@ vect_create_epilog_for_reduction (vec<tree> vect_defs, gimple *stmt,
     {
       bool reduce_with_shift = have_whole_vector_shift (mode);
       int element_bitsize = tree_to_uhwi (bitsize);
+      /* Enforced by vectorizable_reduction, which disallows SLP reductions
+        for variable-length vectors and also requires direct target support
+        for loop reductions.  */
       int vec_size_in_bits = tree_to_uhwi (TYPE_SIZE (vectype));
       tree vec_temp;
 
@@ -5743,10 +5747,10 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
          if (k == 1
              && gimple_assign_rhs_code (reduc_stmt) == COND_EXPR)
            continue;
-         tem = get_vectype_for_scalar_type (TREE_TYPE (op));
-         if (! vectype_in
-             || TYPE_VECTOR_SUBPARTS (tem) < TYPE_VECTOR_SUBPARTS (vectype_in))
-           vectype_in = tem;
+         if (!vectype_in
+             || (GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype_in)))
+                 < GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (op)))))
+           vectype_in = get_vectype_for_scalar_type (TREE_TYPE (op));
          break;
        }
       gcc_assert (vectype_in);
@@ -5912,7 +5916,8 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
          /* To properly compute ncopies we are interested in the widest
             input type in case we're looking at a widening accumulation.  */
          if (!vectype_in
-             || TYPE_VECTOR_SUBPARTS (vectype_in) > TYPE_VECTOR_SUBPARTS (tem))
+             || (GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (vectype_in)))
+                 < GET_MODE_SIZE (SCALAR_TYPE_MODE (TREE_TYPE (tem)))))
            vectype_in = tem;
        }
 
@@ -6097,6 +6102,7 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
   gcc_assert (ncopies >= 1);
 
   vec_mode = TYPE_MODE (vectype_in);
+  poly_uint64 nunits_out = TYPE_VECTOR_SUBPARTS (vectype_out);
 
   if (code == COND_EXPR)
     {
@@ -6278,14 +6284,23 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
       int scalar_precision
        = GET_MODE_PRECISION (SCALAR_TYPE_MODE (scalar_type));
       cr_index_scalar_type = make_unsigned_type (scalar_precision);
-      cr_index_vector_type = build_vector_type
-       (cr_index_scalar_type, TYPE_VECTOR_SUBPARTS (vectype_out));
+      cr_index_vector_type = build_vector_type (cr_index_scalar_type,
+                                               nunits_out);
 
       if (direct_internal_fn_supported_p (IFN_REDUC_MAX, cr_index_vector_type,
                                          OPTIMIZE_FOR_SPEED))
        reduc_fn = IFN_REDUC_MAX;
     }
 
+  if (reduc_fn == IFN_LAST && !nunits_out.is_constant ())
+    {
+      if (dump_enabled_p ())
+       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                        "missing target support for reduction on"
+                        " variable-length vectors.\n");
+      return false;
+    }
+
   if ((double_reduc
        || STMT_VINFO_VEC_REDUCTION_TYPE (stmt_info) != TREE_CODE_REDUCTION)
       && ncopies > 1)
@@ -6297,6 +6312,27 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
       return false;
     }
 
+  if (double_reduc && !nunits_out.is_constant ())
+    {
+      /* The current double-reduction code creates the initial value
+        element-by-element.  */
+      if (dump_enabled_p ())
+       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                        "double reduction not supported for variable-length"
+                        " vectors.\n");
+      return false;
+    }
+
+  if (slp_node && !nunits_out.is_constant ())
+    {
+      /* The current SLP code creates the initial value element-by-element.  */
+      if (dump_enabled_p ())
+       dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+                        "SLP reduction not supported for variable-length"
+                        " vectors.\n");
+      return false;
+    }
+
   /* In case of widenning multiplication by a constant, we update the type
      of the constant to be the type of the other operand.  We check that the
      constant fits the type in the pattern recognition pass.  */

diff --git a/gcc/tree.c b/gcc/tree.c
index f13e2d8227dc8ef75cb6a71bf4bfc8f6aa161945..93c4654309d597c57c8817a3fcd7d92b8e4ef5d4 100644 (file)
--- a/gcc/tree.c
+++ b/gcc/tree.c
@@ -1930,6 +1930,29 @@ build_vec_series (tree type, tree base, tree step)
   return build2 (VEC_SERIES_EXPR, type, base, step);
 }
 
+/* Return a vector with the same number of units and number of bits
+   as VEC_TYPE, but in which the elements are a linear series of unsigned
+   integers { BASE, BASE + STEP, BASE + STEP * 2, ... }.  */
+
+tree
+build_index_vector (tree vec_type, poly_uint64 base, poly_uint64 step)
+{
+  tree index_vec_type = vec_type;
+  tree index_elt_type = TREE_TYPE (vec_type);
+  poly_uint64 nunits = TYPE_VECTOR_SUBPARTS (vec_type);
+  if (!INTEGRAL_TYPE_P (index_elt_type) || !TYPE_UNSIGNED (index_elt_type))
+    {
+      index_elt_type = build_nonstandard_integer_type
+       (GET_MODE_BITSIZE (SCALAR_TYPE_MODE (index_elt_type)), true);
+      index_vec_type = build_vector_type (index_elt_type, nunits);
+    }
+
+  tree_vector_builder v (index_vec_type, 1, 3);
+  for (unsigned int i = 0; i < 3; ++i)
+    v.quick_push (build_int_cstu (index_elt_type, base + i * step));
+  return v.build ();
+}
+
 /* Something has messed with the elements of CONSTRUCTOR C after it was built;
    calculate TREE_CONSTANT and TREE_SIDE_EFFECTS.  */
 

diff --git a/gcc/tree.h b/gcc/tree.h
index f523a0850ca48a1c404b9cdc07504ecb05bccaec..a45c2cd5aa681ce87fd23a6257a7bcd2484003dd 100644 (file)
--- a/gcc/tree.h
+++ b/gcc/tree.h
@@ -4062,6 +4062,7 @@ extern tree make_vector (unsigned, unsigned CXX_MEM_STAT_INFO);
 extern tree build_vector_from_ctor (tree, vec<constructor_elt, va_gc> *);
 extern tree build_vector_from_val (tree, tree);
 extern tree build_vec_series (tree, tree, tree);
+extern tree build_index_vector (tree, poly_uint64, poly_uint64);
 extern void recompute_constructor_flags (tree);
 extern void verify_constructor_flags (tree);
 extern tree build_constructor (tree, vec<constructor_elt, va_gc> *);