dylan: Ensure important object slots are guaranteed initialized

Slots that the compiler knows are aways initialized don't need to be
checked for %unbound when they are accessed, reducing overhead.

* sources/dylan/new-dispatch.dylan
  (<dispatch-state>): Add dummy initializations to slots that don't
   already have them (%ds-gf, %ds-parent, %ds-args, %ds-argnum-set,
   %ds-headed-methods).

* sources/dylan/condition.dylan
  (<handler>): Mark all slot init keywords as required.

Author: housel

sources/dylan/condition.dylan

@@ -8,10 +8,10 @@ Warranty:     Distributed WITHOUT WARRANTY OF ANY KIND
 //// HANDLERS
 
 define primary class <handler> (<object>)
-  constant slot handler-type, init-keyword: type:;
-  constant slot handler-function, init-keyword: function:;
-  constant slot handler-test, init-keyword: test:;
-  constant slot handler-init-arguments, init-keyword: init-arguments:;
+  constant slot handler-type, required-init-keyword: type:;
+  constant slot handler-function, required-init-keyword: function:;
+  constant slot handler-test, required-init-keyword: test:;
+  constant slot handler-init-arguments, required-init-keyword: init-arguments:;
 end class <handler>;
 
 define sealed domain make (singleton(<handler>));

sources/dylan/new-dispatch.dylan

@@ -1427,14 +1427,18 @@ end function;
 
 //// Handle-missed-dispatch
 
+// NB: Slot initializations are not respected when <dispatch-state>
+// instances are allocated using system-allocate-simple-instance, but
+// are included so that the compiler sees the slots as
+// guaranteed-initialized.
 
 define primary class <dispatch-state> (<object>)
-  slot %ds-gf :: <generic-function>;
-  slot %ds-parent :: <dispatch-starter>;
-  slot %ds-args :: <simple-object-vector>;
-  slot %ds-argnum-set :: <argnum-set>;
+  slot %ds-gf :: <generic-function> = sorted-applicable-methods;
+  slot %ds-parent :: <dispatch-starter> = sorted-applicable-methods;
+  slot %ds-args :: <simple-object-vector> = #[];
+  slot %ds-argnum-set :: <argnum-set> = #(0);
   slot %ds-args-to-check-first :: <list> = #();
-  slot %ds-headed-methods :: <pair>;
+  slot %ds-headed-methods :: <pair> = #(#f);
   slot %ds-cache = #f;
   slot %ds-result = #f;
   slot %ds-conditions = #();