re PR tree-optimization/44124 (valgrind reports invalid read while compiling compile/pr34091.c)

2010-05-14  Richard Guenther  <rguenther@suse.de>

	PR tree-optimization/44124
	* tree-ssa-sccvn.c (vn_nary_may_trap): Fix invalid memory access.

From-SVN: r159390

gcc/ChangeLog

+2010-05-14  Richard Guenther  <rguenther@suse.de>
+
+	PR tree-optimization/44124
+	* tree-ssa-sccvn.c (vn_nary_may_trap): Fix invalid memory access.
+
 2010-05-14  Alan Modra  <amodra@gmail.com>
 
 	PR target/44075

gcc/tree-ssa-sccvn.c

@@ -3408,7 +3408,7 @@ bool
 vn_nary_may_trap (vn_nary_op_t nary)
 {
   tree type;
-  tree rhs2;
+  tree rhs2 = NULL_TREE;
   bool honor_nans = false;
   bool honor_snans = false;
   bool fp_operation = false;
@@ -3431,7 +3431,8 @@ vn_nary_may_trap (vn_nary_op_t nary)
 	       && TYPE_OVERFLOW_TRAPS (type))
 	honor_trapv = true;
     }
-  rhs2 = nary->op[1];
+  if (nary->length >= 2)
+    rhs2 = nary->op[1];
   ret = operation_could_trap_helper_p (nary->opcode, fp_operation,
 				       honor_trapv,
 				       honor_nans, honor_snans, rhs2,