diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index ca8f544901e927758bafe4932c7b5d5cfee5d0d3..055fc374808d6ffee3e79b42e6340ac8644a969f 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,9 @@
+2004-08-17  Roger Sayle  <roger@eyesopen.com>
+
+	* regclass.c (init_reg_sets_1): Add ENABLE_CHECKING sanity tests to
+	ensure that call_used_regs is a superset of both fixed_regs and
+	call_really_used_regs.
+
 2004-08-17  Daniel Bornstein  <danfuzz@milk.com>
 
 	PR target/17019
diff --git a/gcc/regclass.c b/gcc/regclass.c
index 1f51af610c2f135f22113036bd683d6a4d9200c5..1304313d90d4240313b087d52e9d870ff82cb712 100644
--- a/gcc/regclass.c
+++ b/gcc/regclass.c
@@ -427,6 +427,17 @@ init_reg_sets_1 (void)
 
   for (i = 0; i < FIRST_PSEUDO_REGISTER; i++)
     {
+#ifdef ENABLE_CHECKING
+      /* call_used_regs must include fixed_regs.  */
+      if (fixed_regs[i] && !call_used_regs[i])
+	abort ();
+#ifdef CALL_REALLY_USED_REGISTERS
+      /* call_used_regs must include call_really_used_regs.  */
+      if (call_really_used_regs[i] && !call_used_regs[i])
+	abort ();
+#endif
+#endif
+
       if (fixed_regs[i])
 	SET_HARD_REG_BIT (fixed_reg_set, i);
       else