1.0.29.12: nicer DX capability conditionalization

[sbcl.git] / src / code / defboot.lisp

diff --git a/src/code/defboot.lisp b/src/code/defboot.lisp
index 2ad6f6f..13d0618 100644 (file)
--- a/src/code/defboot.lisp
+++ b/src/code/defboot.lisp
@@ -617,9 +617,7 @@ evaluated as a PROGN."
               (cons (list ,@(mapcar (lambda (x) `(cons ',(car x) ,(cadr x)))
                                     mapped-bindings))
                     *handler-clusters*)))
-         ;; KLUDGE: Only on platforms with DX FIXED-ALLOC. FIXME: Add a
-         ;; feature for that, so we can conditionalize on it neatly.
-         #!+(or hppa mips x86 x86-64)
+         #!+stack-allocatable-fixed-objects
          (declare (truly-dynamic-extent *handler-clusters*))
          (progn ,form)))))
 
@@ -662,7 +660,7 @@ specification."
                               (push `(,fun ,ll ,@body) local-funs)
                               (list tag type ll fun))))
                         cases)))
-          (with-unique-names (block var form-fun)
+          (with-unique-names (block cell form-fun)
             `(dx-flet ((,form-fun ()
                          #!-x86 ,form
                          ;; Need to catch FP errors here!
@@ -670,8 +668,14 @@ specification."
                        ,@(reverse local-funs))
                (declare (optimize (sb!c::check-tag-existence 0)))
                (block ,block
-                 (dx-let ((,var nil))
-                   (declare (ignorable ,var))
+                 ;; KLUDGE: We use a dx CONS cell instead of just assigning to
+                 ;; the variable directly, so that we can stack allocate
+                 ;; robustly: dx value cells don't work quite right, and it is
+                 ;; possible to construct user code that should loop
+                 ;; indefinitely, but instead eats up some stack each time
+                 ;; around.
+                 (dx-let ((,cell (cons :condition nil)))
+                   (declare (ignorable ,cell))
                    (tagbody
                       (%handler-bind
                        ,(mapcar (lambda (annotated-case)
@@ -680,7 +684,7 @@ specification."
                                     (list type
                                           `(lambda (temp)
                                              ,(if ll
-                                                  `(setf ,var temp)
+                                                  `(setf (cdr ,cell) temp)
                                                   '(declare (ignore temp)))
                                              (go ,tag)))))
                                 annotated-cases)
@@ -692,7 +696,7 @@ specification."
                              (list tag
                                    `(return-from ,block
                                       ,(if ll
-                                           `(,fun-name ,var)
+                                           `(,fun-name (cdr ,cell))
                                            `(,fun-name))))))
                          annotated-cases))))))))))
 \f