X-Git-Url: http://repo.macrolet.net/gitweb/?a=blobdiff_plain;f=src%2Fcompiler%2Fx86%2Fc-call.lisp;h=7eec4723a4838d0ed621ff8c3e5e9f552c570bd2;hb=08917ec0d00a781a1089922a5419b7f136cdf08f;hp=b202a240b3c2e41db977a554092ab89626a099f4;hpb=395c461b58f0cd484c21913c1e075593c206b5c1;p=sbcl.git

diff --git a/src/compiler/x86/c-call.lisp b/src/compiler/x86/c-call.lisp
index b202a24..7eec472 100644
--- a/src/compiler/x86/c-call.lisp
+++ b/src/compiler/x86/c-call.lisp
@@ -79,9 +79,10 @@
       (my-make-wired-tn ptype reg-sc (result-reg-offset num-results)))))
 
 (define-alien-type-method (integer :naturalize-gen) (type alien)
-  (if (and (alien-integer-type-signed type)
-           (<= (alien-type-bits type) 16))
-      `(sign-extend ,alien ,(alien-type-bits type))
+  (if (<= (alien-type-bits type) 16)
+      (if (alien-integer-type-signed type)
+          `(sign-extend ,alien ,(alien-type-bits type))
+          `(logand ,alien ,(1- (ash 1 (alien-type-bits type)))))
       alien))
 
 (define-alien-type-method (system-area-pointer :result-tn) (type state)
@@ -189,8 +190,10 @@
 
 ;;; The ABI is vague about how signed sub-word integer return values
 ;;; are handled, but since gcc versions >=4.3 no longer do sign
-;;; extension in the callee, we need to do it in the caller.
-(defknown sign-extend ((signed-byte 16) t) fixnum
+;;; extension in the callee, we need to do it in the caller.  FIXME:
+;;; If the value to be extended is known to already be of the target
+;;; type at compile time, we can (and should) elide the extension.
+(defknown sign-extend ((signed-byte 32) t) fixnum
     (foldable flushable movable))
 
 (define-vop (sign-extend)
@@ -200,7 +203,7 @@
   ;; have a matching word or byte register.
   (:args (val :scs (signed-reg) :target eax))
   (:temporary (:sc signed-reg :offset eax-offset :from :eval :to :result) eax)
-  (:arg-types fixnum (:constant fixnum))
+  (:arg-types signed-num (:constant fixnum))
   (:info size)
   (:results (res :scs (signed-reg)))
   (:result-types fixnum)
@@ -215,7 +218,7 @@
 
 #-sb-xc-host
 (defun sign-extend (x size)
-  (declare (type fixnum x))
+  (declare (type (signed-byte 32) x))
   (ecase size
     (8 (sign-extend x size))
     (16 (sign-extend x size))))