[PATCH] Tidy: remove reduc_xxx_optab migration code

[Alan Lawrence <alan dot lawrence at arm dot com>]

If/when mips-ps-3d.md is moved from reduc_* to reduc_*_scal optabs (patch here:
https://gcc.gnu.org/ml/gcc-patches/2016-01/msg00311.html ), there will be no
uses of the old reduc_* optabs remaining. This patch removes those optabs and
the migration path.

Bootstrapped + check-gcc + check-g++ on x86_64 and AArch64.

I'm not sure whether such a code tidy is acceptable for stage 3, please advise?

Thanks, Alan

gcc/ChangeLog:

	* doc/md.texi (reduc_smin_@var{m}, reduc_smax_@var{m},
	reduc_umin_@var{m}, reduc_umax_@var{m}, reduc_splus_@var{m},
	reduc_uplus_@var{m}): Remove.
	* expr.c (expand_expr_real_2): Remove expansion path for
	reduc_[us](min|max|plus) optabs.
	* optabs-tree.c (scalar_reduc_to_vector): Remove.
	* optabs-tree.h (scalar_reduc_to_vector): Remove.
	* optabs.def (reduc_smax_optab, reduc_smin_optab, reduc_splus_optab,
	reduc_umax_optab, reduc_umin_optab, reduc_uplus_optab): Remove.
	* tree-vect-loop.c (vectorizable_reduction): Remove test for
	reduc_[us](min|max|plus) optabs.
---
 gcc/doc/md.texi      | 27 ---------------------------
 gcc/expr.c           | 39 ++++++++++-----------------------------
 gcc/optabs-tree.c    | 20 --------------------
 gcc/optabs-tree.h    |  1 -
 gcc/optabs.def       |  7 -------
 gcc/tree-vect-loop.c | 12 ++++--------
 6 files changed, 14 insertions(+), 92 deletions(-)

diff --git a/gcc/doc/md.texi b/gcc/doc/md.texi
index faf3910..68321dc 100644
--- a/gcc/doc/md.texi
+++ b/gcc/doc/md.texi
@@ -5007,33 +5007,6 @@ raised and a quiet @code{NaN} is returned.
 All operands have mode @var{m}, which is a scalar or vector
 floating-point mode.  These patterns are not allowed to @code{FAIL}.
 
-@cindex @code{reduc_smin_@var{m}} instruction pattern
-@cindex @code{reduc_smax_@var{m}} instruction pattern
-@item @samp{reduc_smin_@var{m}}, @samp{reduc_smax_@var{m}}
-Find the signed minimum/maximum of the elements of a vector. The vector is
-operand 1, and the result is stored in the least significant bits of
-operand 0 (also a vector). The output and input vector should have the same
-modes. These are legacy optabs, and platforms should prefer to implement
-@samp{reduc_smin_scal_@var{m}} and @samp{reduc_smax_scal_@var{m}}.
-
-@cindex @code{reduc_umin_@var{m}} instruction pattern
-@cindex @code{reduc_umax_@var{m}} instruction pattern
-@item @samp{reduc_umin_@var{m}}, @samp{reduc_umax_@var{m}}
-Find the unsigned minimum/maximum of the elements of a vector. The vector is
-operand 1, and the result is stored in the least significant bits of
-operand 0 (also a vector). The output and input vector should have the same
-modes. These are legacy optabs, and platforms should prefer to implement
-@samp{reduc_umin_scal_@var{m}} and @samp{reduc_umax_scal_@var{m}}.
-
-@cindex @code{reduc_splus_@var{m}} instruction pattern
-@cindex @code{reduc_uplus_@var{m}} instruction pattern
-@item @samp{reduc_splus_@var{m}}, @samp{reduc_uplus_@var{m}}
-Compute the sum of the signed/unsigned elements of a vector. The vector is
-operand 1, and the result is stored in the least significant bits of operand 0
-(also a vector). The output and input vector should have the same modes.
-These are legacy optabs, and platforms should prefer to implement
-@samp{reduc_plus_scal_@var{m}}.
-
 @cindex @code{reduc_smin_scal_@var{m}} instruction pattern
 @cindex @code{reduc_smax_scal_@var{m}} instruction pattern
 @item @samp{reduc_smin_scal_@var{m}}, @samp{reduc_smax_scal_@var{m}}
diff --git a/gcc/expr.c b/gcc/expr.c
index 8973893..e1ed44d 100644
--- a/gcc/expr.c
+++ b/gcc/expr.c
@@ -9164,35 +9164,16 @@ expand_expr_real_2 (sepops ops, rtx target, machine_mode tmode,
         this_optab = optab_for_tree_code (code, type, optab_default);
         machine_mode vec_mode = TYPE_MODE (TREE_TYPE (treeop0));
 
-	if (optab_handler (this_optab, vec_mode) != CODE_FOR_nothing)
-	  {
-	    struct expand_operand ops[2];
-	    enum insn_code icode = optab_handler (this_optab, vec_mode);
-
-	    create_output_operand (&ops[0], target, mode);
-	    create_input_operand (&ops[1], op0, vec_mode);
-	    if (maybe_expand_insn (icode, 2, ops))
-	      {
-		target = ops[0].value;
-		if (GET_MODE (target) != mode)
-		  return gen_lowpart (tmode, target);
-		return target;
-	      }
-	  }
-	/* Fall back to optab with vector result, and then extract scalar.  */
-	this_optab = scalar_reduc_to_vector (this_optab, type);
-        temp = expand_unop (vec_mode, this_optab, op0, NULL_RTX, unsignedp);
-        gcc_assert (temp);
-        /* The tree code produces a scalar result, but (somewhat by convention)
-           the optab produces a vector with the result in element 0 if
-           little-endian, or element N-1 if big-endian.  So pull the scalar
-           result out of that element.  */
-        int index = BYTES_BIG_ENDIAN ? GET_MODE_NUNITS (vec_mode) - 1 : 0;
-	int bitsize = GET_MODE_UNIT_BITSIZE (vec_mode);
-        temp = extract_bit_field (temp, bitsize, bitsize * index, unsignedp,
-				  target, mode, mode, false);
-        gcc_assert (temp);
-        return temp;
+	struct expand_operand ops[2];
+	enum insn_code icode = optab_handler (this_optab, vec_mode);
+
+	create_output_operand (&ops[0], target, mode);
+	create_input_operand (&ops[1], op0, vec_mode);
+	expand_insn (icode, 2, ops);
+	target = ops[0].value;
+	if (GET_MODE (target) != mode)
+	  return gen_lowpart (tmode, target);
+	return target;
       }
 
     case VEC_UNPACK_HI_EXPR:
diff --git a/gcc/optabs-tree.c b/gcc/optabs-tree.c
index d9dd3fc..a229b97 100644
--- a/gcc/optabs-tree.c
+++ b/gcc/optabs-tree.c
@@ -246,26 +246,6 @@ optab_for_tree_code (enum tree_code code, const_tree type,
     }
 }
 
-/* Given optab UNOPTAB that reduces a vector to a scalar, find instead the old
-   optab that produces a vector with the reduction result in one element,
-   for a tree with type TYPE.  */
-
-optab
-scalar_reduc_to_vector (optab unoptab, const_tree type)
-{
-  switch (unoptab)
-    {
-    case reduc_plus_scal_optab:
-      return TYPE_UNSIGNED (type) ? reduc_uplus_optab : reduc_splus_optab;
-
-    case reduc_smin_scal_optab: return reduc_smin_optab;
-    case reduc_umin_scal_optab: return reduc_umin_optab;
-    case reduc_smax_scal_optab: return reduc_smax_optab;
-    case reduc_umax_scal_optab: return reduc_umax_optab;
-    default: return unknown_optab;
-    }
-}
-
 /* Function supportable_convert_operation
 
    Check whether an operation represented by the code CODE is a
diff --git a/gcc/optabs-tree.h b/gcc/optabs-tree.h
index 0727925..c3b9280 100644
--- a/gcc/optabs-tree.h
+++ b/gcc/optabs-tree.h
@@ -36,7 +36,6 @@ enum optab_subtype
    the second argument.  The third argument distinguishes between the types of
    vector shifts and rotates.  */
 optab optab_for_tree_code (enum tree_code, const_tree, enum optab_subtype);
-optab scalar_reduc_to_vector (optab, const_tree);
 bool supportable_convert_operation (enum tree_code, tree, tree, tree *,
 				    enum tree_code *);
 bool expand_vec_cmp_expr_p (tree, tree);
diff --git a/gcc/optabs.def b/gcc/optabs.def
index 4faedc6..c938b42 100644
--- a/gcc/optabs.def
+++ b/gcc/optabs.def
@@ -285,13 +285,6 @@ OPTAB_D (reduc_smin_scal_optab, "reduc_smin_scal_$a")
 OPTAB_D (reduc_plus_scal_optab, "reduc_plus_scal_$a")
 OPTAB_D (reduc_umax_scal_optab, "reduc_umax_scal_$a")
 OPTAB_D (reduc_umin_scal_optab, "reduc_umin_scal_$a")
-/* (Old) Vector reduction, returning a vector with the result in one lane.  */
-OPTAB_D (reduc_smax_optab, "reduc_smax_$a")
-OPTAB_D (reduc_smin_optab, "reduc_smin_$a")
-OPTAB_D (reduc_splus_optab, "reduc_splus_$a")
-OPTAB_D (reduc_umax_optab, "reduc_umax_$a")
-OPTAB_D (reduc_umin_optab, "reduc_umin_$a")
-OPTAB_D (reduc_uplus_optab, "reduc_uplus_$a")
 
 OPTAB_D (sdot_prod_optab, "sdot_prod$I$a")
 OPTAB_D (ssum_widen_optab, "widen_ssum$I$a3")
diff --git a/gcc/tree-vect-loop.c b/gcc/tree-vect-loop.c
index a82cf26..d658d9b 100644
--- a/gcc/tree-vect-loop.c
+++ b/gcc/tree-vect-loop.c
@@ -5743,15 +5743,11 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
 	    }
 	  else if (optab_handler (reduc_optab, vec_mode) == CODE_FOR_nothing)
 	    {
-	      optab = scalar_reduc_to_vector (reduc_optab, vectype_out);
-	      if (optab_handler (optab, vec_mode) == CODE_FOR_nothing)
-		{
-		  if (dump_enabled_p ())
-		    dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
-				     "reduc op not supported by target.\n");
+	      if (dump_enabled_p ())
+		dump_printf_loc (MSG_MISSED_OPTIMIZATION, vect_location,
+				 "reduc op not supported by target.\n");
 
-		  epilog_reduc_code = ERROR_MARK;
-		}
+	      epilog_reduc_code = ERROR_MARK;
 	    }
 
 	  /* When epilog_reduc_code is ERROR_MARK then a reduction will be
-- 
1.9.1