0.8.4.15:

[sbcl.git] / src / compiler / generic / vm-tran.lisp

diff --git a/src/compiler/generic/vm-tran.lisp b/src/compiler/generic/vm-tran.lisp
index f8e7bda..1d93eba 100644 (file)
--- a/src/compiler/generic/vm-tran.lisp
+++ b/src/compiler/generic/vm-tran.lisp
@@ -439,10 +439,32 @@
        (= (double-float-high-bits x) (double-float-high-bits y))))
 
 \f
-;;;; 32-bit operations
+;;;; modular functions
 (define-good-modular-fun logand)
 (define-good-modular-fun logior)
 ;;; FIXME: XOR? ANDC1, ANDC2?  -- CSR, 2003-09-16
+
+#!-alpha
+(progn
+  (defknown sb!vm::ash-left-mod32 (integer (integer 0)) (unsigned-byte 32)
+            (foldable flushable movable))
+  (define-modular-fun-optimizer ash ((integer count) :width width)
+    (when (and (<= width 32)
+               (constant-lvar-p count)  ; ?
+               (plusp (lvar-value count)))
+      (cut-to-width integer width)
+      'sb!vm::ash-left-mod32)))
+#!+alpha
+(progn
+  (defknown sb!vm::ash-left-mod64 (integer (integer 0)) (unsigned-byte 64)
+            (foldable flushable movable))
+  (define-modular-fun-optimizer ash ((integer count) :width width)
+    (when (and (<= width 64)
+               (constant-lvar-p count)  ; ?
+               (plusp (lvar-value count)))
+      (cut-to-width integer width)
+      'sb!vm::ash-left-mod64)))
+
 \f
 ;;; There are two different ways the multiplier can be recoded. The
 ;;; more obvious is to shift X by the correct amount for each bit set
@@ -456,13 +478,11 @@
   (declare (type (unsigned-byte 32) num))
   (let ((adds 0) (shifts 0)
        (result nil) first-one)
-    (labels ((tub32 (x) `(logand ,x #xffffffff)) ; uses modular arithmetic
-            (add (next-factor)
+    (labels ((add (next-factor)
               (setf result
-                    (tub32
-                     (if result
-                         (progn (incf adds) `(+ ,result ,(tub32 next-factor)))
-                         next-factor)))))
+                    (if result
+                         (progn (incf adds) `(+ ,result ,next-factor))
+                         next-factor))))
       (declare (inline add))
       (dotimes (bitpos 32)
        (if first-one
@@ -474,8 +494,8 @@
                       (progn
                         (incf adds)
                         (incf shifts 2)
-                        `(- ,(tub32 `(ash ,arg ,bitpos))
-                            ,(tub32 `(ash ,arg ,first-one))))))
+                        `(- (ash ,arg ,bitpos)
+                            (ash ,arg ,first-one)))))
              (setf first-one nil))
            (when (logbitp bitpos num)
              (setf first-one bitpos))))
@@ -485,8 +505,12 @@
              (t
               (incf shifts 2)
               (incf adds)
-              (add `(- ,(tub32 `(ash ,arg 31)) 
-                       ,(tub32 `(ash ,arg ,first-one))))))
+              (add `(- (ash ,arg 31)
+                       (ash ,arg ,first-one)))))
        (incf shifts)
        (add `(ash ,arg 31))))
-    (values result adds shifts)))
+    (values (if (plusp adds)
+                `(logand ,result #.(1- (ash 1 32))) ; using modular arithmetic
+                result)
+            adds
+            shifts)))