re PR tree-optimization/69848 (poor vectorization of a loop from SPEC2006 464.h264ref)

	PR tree-optimization/69848
	* tree-vect-loop.c (vectorizable_reduction): Don't factor
	comparison expr out of VEC_COND_EXPR for COND_REDUCTION.

From-SVN: r236447

gcc/ChangeLog

+2016-05-19 Bin Cheng  <bin.cheng@arm.com>
+
+	PR tree-optimization/69848
+	* tree-vect-loop.c (vectorizable_reduction): Don't factor
+	comparison expr out of VEC_COND_EXPR for COND_REDUCTION.
+
 2016-05-19  Segher Boessenkool  <segher@kernel.crashing.org>
 
 	* function.c (thread_prologue_and_epilogue_insn): Move the

gcc/tree-vect-loop.c

@@ -6159,21 +6159,14 @@ vectorizable_reduction (gimple *stmt, gimple_stmt_iterator *gsi,
 	     Finally, we update the phi (NEW_PHI_TREE) to take the value of
 	     the new cond_expr (INDEX_COND_EXPR).  */
 
-	  /* Turn the condition from vec_stmt into an ssa name.  */
-	  gimple_stmt_iterator vec_stmt_gsi = gsi_for_stmt (*vec_stmt);
-	  tree ccompare = gimple_assign_rhs1 (*vec_stmt);
-	  tree ccompare_name = make_ssa_name (TREE_TYPE (ccompare));
-	  gimple *ccompare_stmt = gimple_build_assign (ccompare_name,
-						       ccompare);
-	  gsi_insert_before (&vec_stmt_gsi, ccompare_stmt, GSI_SAME_STMT);
-	  gimple_assign_set_rhs1 (*vec_stmt, ccompare_name);
-	  update_stmt (*vec_stmt);
+	  /* Duplicate the condition from vec_stmt.  */
+	  tree ccompare = unshare_expr (gimple_assign_rhs1 (*vec_stmt));
 
 	  /* Create a conditional, where the condition is taken from vec_stmt
-	     (CCOMPARE_NAME), then is the induction index (INDEX_BEFORE_INCR)
-	     and else is the phi (NEW_PHI_TREE).  */
+	     (CCOMPARE), then is the induction index (INDEX_BEFORE_INCR) and
+	     else is the phi (NEW_PHI_TREE).  */
 	  tree index_cond_expr = build3 (VEC_COND_EXPR, cr_index_vector_type,
-					 ccompare_name, indx_before_incr,
+					 ccompare, indx_before_incr,
 					 new_phi_tree);
 	  cond_name = make_ssa_name (cr_index_vector_type);
 	  gimple *index_condition = gimple_build_assign (cond_name,