tree-scalar-evolution.c (follow_ssa_edge_in_condition_phi): Give up as soon as…

tree-scalar-evolution.c (follow_ssa_edge_in_condition_phi): Give up as soon as the evolution is known not computable.

	* tree-scalar-evolution.c (follow_ssa_edge_in_condition_phi):
	Give up as soon as the evolution is known not computable.

From-SVN: r90491

gcc/ChangeLog

+2004-11-11  Sebastian Pop  <pop@cri.ensmp.fr>
+
+	* tree-scalar-evolution.c (follow_ssa_edge_in_condition_phi): 
+	Give up as soon as the evolution is known not computable.
+
 2004-11-11  Nathan Sidwell  <nathan@codesourcery.com>
 
 	PR target/16457

gcc/tree-scalar-evolution.c

@@ -1398,6 +1398,11 @@ follow_ssa_edge_in_condition_phi (struct loop *loop,
 
   for (i = 1; i < PHI_NUM_ARGS (condition_phi); i++)
     {
+      /* Quickly give up when the evolution of one of the branches is
+	 not known.  */
+      if (*evolution_of_loop == chrec_dont_know)
+	return true;
+
       if (!follow_ssa_edge_in_condition_phi_branch (i, loop, condition_phi,
 						    halting_phi,
 						    &evolution_of_branch,