ifcombine: factor out inner block viability test

Bail out early if the inner block has side effects or is otherwise not
eligible for ifcombine.

for  gcc/ChangeLog

	* tree-ssa-ifcombine.c (tree_ssa_ifcombine_bb_1): Factor out
	bb_no_side_effects_p tests...
	(tree_ssa_ifcombine_bb): ... here.

From-SVN: r229691

gcc/ChangeLog

 2015-11-02  Alexandre Oliva <aoliva@redhat.com>
 
+	* tree-ssa-ifcombine.c (tree_ssa_ifcombine_bb_1): Factor out
+	bb_no_side_effects_p tests...
+	(tree_ssa_ifcombine_bb): ... here.
+
 	PR tree-optimization/68083
 	* tree-ssa-ifcombine.c: Include tree-ssa.h.
 	(bb_no_side_effects_p): Test for undefined uses too.

gcc/tree-ssa-ifcombine.c

@@ -576,8 +576,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
      the inner cond_bb having no side-effects.  */
   if (phi_pred_bb != else_bb
       && recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &else_bb)
-      && same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb)
-      && bb_no_side_effects_p (inner_cond_bb))
+      && same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb))
     {
       /* We have
 	   <outer_cond_bb>
@@ -595,8 +594,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
   /* And a version where the outer condition is negated.  */
   if (phi_pred_bb != else_bb
       && recognize_if_then_else (outer_cond_bb, &else_bb, &inner_cond_bb)
-      && same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb)
-      && bb_no_side_effects_p (inner_cond_bb))
+      && same_phi_args_p (outer_cond_bb, phi_pred_bb, else_bb))
     {
       /* We have
 	   <outer_cond_bb>
@@ -617,8 +615,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
      having no side-effects.  */
   if (phi_pred_bb != then_bb
       && recognize_if_then_else (outer_cond_bb, &then_bb, &inner_cond_bb)
-      && same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb)
-      && bb_no_side_effects_p (inner_cond_bb))
+      && same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb))
     {
       /* We have
 	   <outer_cond_bb>
@@ -635,8 +632,7 @@ tree_ssa_ifcombine_bb_1 (basic_block inner_cond_bb, basic_block outer_cond_bb,
   /* And a version where the outer condition is negated.  */
   if (phi_pred_bb != then_bb
       && recognize_if_then_else (outer_cond_bb, &inner_cond_bb, &then_bb)
-      && same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb)
-      && bb_no_side_effects_p (inner_cond_bb))
+      && same_phi_args_p (outer_cond_bb, phi_pred_bb, then_bb))
     {
       /* We have
 	   <outer_cond_bb>
@@ -673,7 +669,8 @@ tree_ssa_ifcombine_bb (basic_block inner_cond_bb)
        if (a && b)
 	 ;
      This requires a single predecessor of the inner cond_bb.  */
-  if (single_pred_p (inner_cond_bb))
+  if (single_pred_p (inner_cond_bb)
+      && bb_no_side_effects_p (inner_cond_bb))
     {
       basic_block outer_cond_bb = single_pred (inner_cond_bb);