[09/46] Add vec_info::lookup_single_use

This patch adds a helper function for seeing whether there is a single
user of an SSA name, and whether that user has a stmt_vec_info.

2018-07-31  Richard Sandiford  <richard.sandiford@arm.com>

gcc/
	* tree-vectorizer.h (vec_info::lookup_single_use): Declare.
	* tree-vectorizer.c (vec_info::lookup_single_use): New function.
	* tree-vect-loop.c (vectorizable_reduction): Use it instead of
	a single_imm_use-based sequence.
	* tree-vect-stmts.c (supportable_widening_operation): Likewise.

From-SVN: r263124

1 files changed, 5 insertions, 8 deletions

diff --git a/gcc/tree-vect-stmts.c b/gcc/tree-vect-stmts.c
index 8f4b66d..f21599e 100644
--- a/gcc/tree-vect-stmts.c
+++ b/gcc/tree-vect-stmts.c
@@ -10310,14 +10310,11 @@ supportable_widening_operation (enum tree_code code, gimple *stmt,
              same operation.  One such an example is s += a * b, where elements
              in a and b cannot be reordered.  Here we check if the vector defined
              by STMT is only directly used in the reduction statement.  */
-          tree lhs = gimple_assign_lhs (stmt);
-          use_operand_p dummy;
-          gimple *use_stmt;
-          stmt_vec_info use_stmt_info = NULL;
-          if (single_imm_use (lhs, &dummy, &use_stmt)
-              && (use_stmt_info = vinfo_for_stmt (use_stmt))
-              && STMT_VINFO_DEF_TYPE (use_stmt_info) == vect_reduction_def)
-            return true;
+	  tree lhs = gimple_assign_lhs (stmt);
+	  stmt_vec_info use_stmt_info = loop_info->lookup_single_use (lhs);
+	  if (use_stmt_info
+	      && STMT_VINFO_DEF_TYPE (use_stmt_info) == vect_reduction_def)
+	    return true;
         }
       c1 = VEC_WIDEN_MULT_LO_EXPR;
       c2 = VEC_WIDEN_MULT_HI_EXPR;