+(defun expand-atomic-frob (name place diff)
+ (flet ((invalid-place ()
+ (error "Invalid first argument to ~S: ~S" name place)))
+ (unless (consp place)
+ (invalid-place))
+ (destructuring-bind (op &rest args) place
+ (case op
+ (aref
+ (when (cddr args)
+ (invalid-place))
+ #!+(or x86 x86-64 ppc)
+ (with-unique-names (array)
+ `(let ((,array (the (simple-array sb!ext:word (*)) ,(car args))))
+ (%array-atomic-incf/word
+ ,array
+ (%check-bound ,array (array-dimension ,array 0) ,(cadr args))
+ (logand #.(1- (ash 1 sb!vm:n-word-bits))
+ ,(ecase name
+ (atomic-incf
+ `(the sb!vm:signed-word ,diff))
+ (atomic-decf
+ `(- (the sb!vm:signed-word ,diff))))))))
+ #!-(or x86 x86-64 ppc)
+ (with-unique-names (array index old-value)
+ (let ((incremented-value
+ (ecase name
+ (atomic-incf
+ `(+ ,old-value (the sb!vm:signed-word ,diff)))
+ (atomic-decf
+ `(- ,old-value (the sb!vm:signed-word ,diff))))))
+ `(sb!sys:without-interrupts
+ (let* ((,array ,(car args))
+ (,index ,(cadr args))
+ (,old-value (aref ,array ,index)))
+ (setf (aref ,array ,index)
+ (logand #.(1- (ash 1 sb!vm:n-word-bits))
+ ,incremented-value))
+ ,old-value)))))
+ (t
+ (when (cdr args)
+ (invalid-place))
+ (let ((dd (info :function :structure-accessor op)))
+ (if dd
+ (let* ((structure (dd-name dd))
+ (slotd (find op (dd-slots dd) :key #'dsd-accessor-name))
+ (index (dsd-index slotd))
+ (type (dsd-type slotd)))
+ (declare (ignorable structure index))
+ (unless (and (eq 'sb!vm:word (dsd-raw-type slotd))
+ (type= (specifier-type type) (specifier-type 'sb!vm:word)))
+ (error "~S requires a slot of type (UNSIGNED-BYTE ~S), not ~S: ~S"
+ name sb!vm:n-word-bits type place))
+ (when (dsd-read-only slotd)
+ (error "Cannot use ~S with structure accessor for a read-only slot: ~S"
+ name place))
+ #!+(or x86 x86-64 ppc)
+ `(truly-the sb!vm:word
+ (%raw-instance-atomic-incf/word
+ (the ,structure ,@args) ,index
+ (logand #.(1- (ash 1 sb!vm:n-word-bits))
+ ,(ecase name
+ (atomic-incf
+ `(the sb!vm:signed-word ,diff))
+ (atomic-decf
+ `(- (the sb!vm:signed-word ,diff)))))))
+ ;; No threads outside x86 and x86-64 for now, so this is easy...
+ #!-(or x86 x86-64 ppc)
+ (with-unique-names (structure old)
+ `(sb!sys:without-interrupts
+ (let* ((,structure ,@args)
+ (,old (,op ,structure)))
+ (setf (,op ,structure)
+ (logand #.(1- (ash 1 sb!vm:n-word-bits))
+ ,(ecase name
+ (atomic-incf
+ `(+ ,old (the sb!vm:signed-word ,diff)))
+ (atomic-decf
+ `(- ,old (the sb!vm:signed-word ,diff))))))
+ ,old))))
+ (invalid-place))))))))
+