X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fknownfun.lisp;h=3b38e95a331d0f92e5f7b9b6c1685848c38c941a;hb=872175cd9cb5b4966a36d4bd92421cc407a0355b;hp=3d2ee4fbdeca79672ba2a14fc8059420e22baf96;hpb=a530bbe337109d898d5b4a001fc8f1afa3b5dc39;p=sbcl.git

diff --git a/src/compiler/knownfun.lisp b/src/compiler/knownfun.lisp
index 3d2ee4f..3b38e95 100644
--- a/src/compiler/knownfun.lisp
+++ b/src/compiler/knownfun.lisp
@@ -14,8 +14,7 @@
 
 (in-package "SB!C")
 
-(file-comment
-  "$Header$")
+(/show0 "knownfun.lisp 17")
 
 ;;; IR1 boolean function attributes
 ;;;
@@ -119,18 +118,18 @@
 
 ;;;; interfaces to defining macros
 
-;;; The TRANSFORM structure represents an IR1 transform.
-(defstruct transform
-  ;; The function-type which enables this transform.
+;;; an IR1 transform
+(defstruct (transform (:copier nil))
+  ;; the function-type which enables this transform
   (type (required-argument) :type ctype)
-  ;; The transformation function. Takes the Combination node and Returns a
+  ;; the transformation function. Takes the COMBINATION node and returns a
   ;; lambda, or throws out.
   (function (required-argument) :type function)
-  ;; String used in efficency notes.
+  ;; string used in efficency notes
   (note (required-argument) :type string)
-  ;; T if we should spew a failure note even if speed=brevity.
+  ;; T if we should emit a failure note even if SPEED=INHIBIT-WARNINGS.
   (important nil :type (member t nil))
-  ;; Usable for byte code, native code, or both.
+  ;; usable for byte code, native code, or both
   (when :native :type (member :byte :native :both)))
 
 (defprinter (transform) type note important when)
@@ -170,8 +169,22 @@
 	(info (make-function-info :attributes attributes
 				  :derive-type derive-type
 				  :optimizer optimizer))
-	(target-env (or *backend-info-environment* *info-environment*)))
+	(target-env *info-environment*))
     (dolist (name names)
+      (let ((old-function-info (info :function :info name)))
+	(when old-function-info
+	  ;; This is handled as an error because it's generally a bad
+	  ;; thing to blow away all the old optimization stuff. It's
+	  ;; also a potential source of sneaky bugs:
+	  ;;    DEFKNOWN FOO
+	  ;;    DEFTRANSFORM FOO
+	  ;;    DEFKNOWN FOO ; possibly hidden inside some macroexpansion
+	  ;;    ; Now the DEFTRANSFORM doesn't exist in the target Lisp.
+	  ;; However, it's continuable because it might be useful to do
+	  ;; it when testing new optimization stuff interactively.
+	  (cerror "Go ahead, overwrite it."
+		  "~@<overwriting old FUNCTION-INFO ~2I~_~S ~I~_for ~S~:>"
+		  old-function-info name)))
       (setf (info :function :type name target-env) ctype)
       (setf (info :function :where-from name target-env) :declared)
       (setf (info :function :kind name target-env) :function)
@@ -179,14 +192,18 @@
   names)
 
 ;;; Return the FUNCTION-INFO for NAME or die trying. Since this is
-;;; used by people who want to modify the info, and the info may be
+;;; used by callers who want to modify the info, and the info may be
 ;;; shared, we copy it. We don't have to copy the lists, since each
 ;;; function that has generators or transforms has already been
 ;;; through here.
 (declaim (ftype (function (t) function-info) function-info-or-lose))
 (defun function-info-or-lose (name)
-  (let ((*info-environment* (or *backend-info-environment*
-				*info-environment*)))
+  (let (;; FIXME: Do we need this rebinding here? It's a literal
+	;; translation of the old CMU CL rebinding to
+	;; (OR *BACKEND-INFO-ENVIRONMENT* *INFO-ENVIRONMENT*),
+	;; and it's not obvious whether the rebinding to itself is
+	;; needed that SBCL doesn't need *BACKEND-INFO-ENVIRONMENT*.
+	(*info-environment* *info-environment*))
     (let ((old (info :function :info name)))
       (unless old (error "~S is not a known function." name))
       (setf (info :function :info name) (copy-function-info old)))))
@@ -236,3 +253,5 @@
     (let ((cont (nth (1- n) (combination-args call))))
       (when (and cont (constant-continuation-p cont))
 	(specifier-type (continuation-value cont))))))
+
+(/show0 "knownfun.lisp end of file")