avoid dangerous use of memcmp

[r19467]

ir/be/bearch_t.h

@@ -33,6 +33,7 @@
 #include "bemachine.h"
 #include "beirg.h"
 #include "beabi.h"
+#include "raw_bitset.h"
 
 /**
  * A register.
@@ -139,6 +140,32 @@ struct arch_register_req_t {
 	                                         (must_be_different) */
 };
 
+static INLINE int reg_reqs_equal(const arch_register_req_t *req1,
+                                 const arch_register_req_t *req2)
+{
+	if (req1 == req2)
+		return 1;
+
+	if (req1->type != req2->type
+			|| req1->cls != req2->cls
+			|| req1->other_same != req2->other_same
+			|| req1->other_different != req2->other_different)
+		return 0;
+
+	if (req1->limited != NULL) {
+		size_t n_regs;
+
+		if (req2->limited == NULL)
+			return 0;
+
+		n_regs = arch_register_class_n_regs(req1->cls);
+		if (!rbitset_equal(req1->limited, req2->limited, n_regs))
+			return 0;
+	}
+
+	return 1;
+}
+
 /**
  * An inverse operation returned by the backend
  */

ir/be/benode.c

@@ -167,8 +167,8 @@ static int _node_cmp_attr(const be_node_attr_t *a, const be_node_attr_t *b) {
 	len = ARR_LEN(a->reg_data);
 	for (i = 0; i < len; ++i) {
 		if (a->reg_data[i].reg != b->reg_data[i].reg ||
-				memcmp(&a->reg_data[i].in_req, &b->reg_data[i].in_req, sizeof(b->reg_data[i].in_req)) ||
-			    memcmp(&a->reg_data[i].req,    &b->reg_data[i].req,    sizeof(a->reg_data[i].req)))
+				!reg_reqs_equal(&a->reg_data[i].in_req, &b->reg_data[i].in_req) ||
+			    !reg_reqs_equal(&a->reg_data[i].req,    &b->reg_data[i].req))
 			return 1;
 	}