ifcvt/vect: Emit COND_OP for conditional scalar reduction.

As described in PR111401 we currently emit a COND and a PLUS expression
for conditional reductions.  This makes it difficult to combine both
into a masked reduction statement later.
This patch improves that by directly emitting a COND_ADD/COND_OP during
ifcvt and adjusting some vectorizer code to handle it.

It also makes neutral_op_for_reduction return -0 if HONOR_SIGNED_ZEROS
is true.

gcc/ChangeLog:

	PR middle-end/111401
	* internal-fn.cc (internal_fn_else_index): New function.
	* internal-fn.h (internal_fn_else_index): Define.
	* tree-if-conv.cc (convert_scalar_cond_reduction): Emit COND_OP
	if supported.
	(predicate_scalar_phi): Add whitespace.
	* tree-vect-loop.cc (fold_left_reduction_fn): Add IFN_COND_OP.
	(neutral_op_for_reduction): Return -0 for PLUS.
	(check_reduction_path): Don't count else operand in COND_OP.
	(vect_is_simple_reduction): Ditto.
	(vect_create_epilog_for_reduction): Fix whitespace.
	(vectorize_fold_left_reduction): Add COND_OP handling.
	(vectorizable_reduction): Don't count else operand in COND_OP.
	(vect_transform_reduction): Add COND_OP handling.
	* tree-vectorizer.h (neutral_op_for_reduction): Add default
	parameter.

gcc/testsuite/ChangeLog:

	* gcc.dg/vect/vect-cond-reduc-in-order-2-signed-zero.c: New test.
	* gcc.target/riscv/rvv/autovec/cond/pr111401.c: New test.
	* gcc.target/riscv/rvv/autovec/reduc/reduc_call-2.c: Adjust.
	* gcc.target/riscv/rvv/autovec/reduc/reduc_call-4.c: Ditto.

1 files changed, 34 insertions, 15 deletions

diff --git a/gcc/tree-if-conv.cc b/gcc/tree-if-conv.cc
index 16e06d8..a7a751b 100644
--- a/gcc/tree-if-conv.cc
+++ b/gcc/tree-if-conv.cc
@@ -1856,10 +1856,12 @@ convert_scalar_cond_reduction (gimple *reduc, gimple_stmt_iterator *gsi,
   gimple *new_assign;
   tree rhs;
   tree rhs1 = gimple_assign_rhs1 (reduc);
+  tree lhs = gimple_assign_lhs (reduc);
   tree tmp = make_temp_ssa_name (TREE_TYPE (rhs1), NULL, "_ifc_");
   tree c;
   enum tree_code reduction_op  = gimple_assign_rhs_code (reduc);
-  tree op_nochange = neutral_op_for_reduction (TREE_TYPE (rhs1), reduction_op, NULL);
+  tree op_nochange = neutral_op_for_reduction (TREE_TYPE (rhs1), reduction_op,
+					       NULL, false);
   gimple_seq stmts = NULL;
 
   if (dump_file && (dump_flags & TDF_DETAILS))
@@ -1868,19 +1870,36 @@ convert_scalar_cond_reduction (gimple *reduc, gimple_stmt_iterator *gsi,
       print_gimple_stmt (dump_file, reduc, 0, TDF_SLIM);
     }
 
-  /* Build cond expression using COND and constant operand
-     of reduction rhs.  */
-  c = fold_build_cond_expr (TREE_TYPE (rhs1),
-			    unshare_expr (cond),
-			    swap ? op_nochange : op1,
-			    swap ? op1 : op_nochange);
-
-  /* Create assignment stmt and insert it at GSI.  */
-  new_assign = gimple_build_assign (tmp, c);
-  gsi_insert_before (gsi, new_assign, GSI_SAME_STMT);
-  /* Build rhs for unconditional increment/decrement/logic_operation.  */
-  rhs = gimple_build (&stmts, reduction_op,
-		      TREE_TYPE (rhs1), op0, tmp);
+  /* If possible create a COND_OP instead of a COND_EXPR and an OP_EXPR.
+     The COND_OP will have a neutral_op else value.  */
+  internal_fn ifn;
+  ifn = get_conditional_internal_fn (reduction_op);
+  if (ifn != IFN_LAST
+      && vectorized_internal_fn_supported_p (ifn, TREE_TYPE (lhs))
+      && !swap)
+    {
+      gcall *cond_call = gimple_build_call_internal (ifn, 4,
+						     unshare_expr (cond),
+						     op0, op1, op0);
+      gsi_insert_before (gsi, cond_call, GSI_SAME_STMT);
+      gimple_call_set_lhs (cond_call, tmp);
+      rhs = tmp;
+    }
+  else
+    {
+      /* Build cond expression using COND and constant operand
+	 of reduction rhs.  */
+      c = fold_build_cond_expr (TREE_TYPE (rhs1),
+				unshare_expr (cond),
+				swap ? op_nochange : op1,
+				swap ? op1 : op_nochange);
+      /* Create assignment stmt and insert it at GSI.  */
+      new_assign = gimple_build_assign (tmp, c);
+      gsi_insert_before (gsi, new_assign, GSI_SAME_STMT);
+      /* Build rhs for unconditional increment/decrement/logic_operation.  */
+      rhs = gimple_build (&stmts, reduction_op,
+			  TREE_TYPE (rhs1), op0, tmp);
+    }
 
   if (has_nop)
     {
@@ -2292,7 +2311,7 @@ predicate_scalar_phi (gphi *phi, gimple_stmt_iterator *gsi)
 	{
 	  /* Convert reduction stmt into vectorizable form.  */
 	  rhs = convert_scalar_cond_reduction (reduc, gsi, cond, op0, op1,
-					       swap,has_nop, nop_reduc);
+					       swap, has_nop, nop_reduc);
 	  redundant_ssa_names.safe_push (std::make_pair (res, rhs));
 	}
       new_stmt = gimple_build_assign (res, rhs);