From: Christophe Rhodes <csr21@cam.ac.uk>
Date: Fri, 30 Jul 2004 10:45:30 +0000 (+0000)
Subject: 0.8.13.12:
X-Git-Url: http://repo.macrolet.net/gitweb/?a=commitdiff_plain;h=ad5cd2538240a4283cb4498b21ff7ab23adcde92;p=sbcl.git

0.8.13.12:
	Fix for division-of-integer-by-constant-zero bug
	... don't perform the 2^k transform for k = -1 (which when
		rounded to an integer gives zero...)
	... tests.
---

diff --git a/NEWS b/NEWS
index 4f52e72..0e37ace 100644
--- a/NEWS
+++ b/NEWS
@@ -8,6 +8,9 @@ changes in sbcl-0.8.14 relative to sbcl-0.8.13:
     (reported by Rick Taube)
   * bug fix: structures defined by WITH-ALIEN can be referred to
     within other definitions in the same WITH-ALIEN.
+  * bug fix: division operators (MOD, TRUNCATE and the like) with
+    constant zero divisors and integer dividends no longer generate
+    left shifts.
 
 changes in sbcl-0.8.13 relative to sbcl-0.8.12:
   * new feature: SB-PACKAGE-LOCKS. See the "Package Locks" section of
diff --git a/src/compiler/aliencomp.lisp b/src/compiler/aliencomp.lisp
index 56ff0f3..5ff9427 100644
--- a/src/compiler/aliencomp.lisp
+++ b/src/compiler/aliencomp.lisp
@@ -565,7 +565,7 @@
     (give-up-ir1-transform))
   (let* ((denominator (lvar-value denominator))
 	 (bits (1- (integer-length denominator))))
-    (unless (= (ash 1 bits) denominator)
+    (unless (and (> denominator 0) (= (ash 1 bits) denominator))
       (give-up-ir1-transform))
     (let ((alignment (count-low-order-zeros numerator)))
       (unless (>= alignment bits)
diff --git a/src/compiler/srctran.lisp b/src/compiler/srctran.lisp
index cbc59ca..e4084c3 100644
--- a/src/compiler/srctran.lisp
+++ b/src/compiler/srctran.lisp
@@ -2665,7 +2665,7 @@
   (let* ((y (lvar-value y))
 	 (y-abs (abs y))
 	 (len (1- (integer-length y-abs))))
-    (unless (= y-abs (ash 1 len))
+    (unless (and (> y-abs 0) (= y-abs (ash 1 len)))
       (give-up-ir1-transform))
     (if (minusp y)
 	`(- (ash x ,len))
@@ -2680,7 +2680,7 @@
 	 (let* ((y (lvar-value y))
 		(y-abs (abs y))
 		(len (1- (integer-length y-abs))))
-	   (unless (= y-abs (ash 1 len))
+	   (unless (and (> y-abs 0) (= y-abs (ash 1 len)))
 	     (give-up-ir1-transform))
 	   (let ((shift (- len))
 		 (mask (1- y-abs))
@@ -2706,7 +2706,7 @@
   (let* ((y (lvar-value y))
 	 (y-abs (abs y))
 	 (len (1- (integer-length y-abs))))
-    (unless (= y-abs (ash 1 len))
+    (unless (and (> y-abs 0) (= y-abs (ash 1 len)))
       (give-up-ir1-transform))
     (let ((mask (1- y-abs)))
       (if (minusp y)
@@ -2721,7 +2721,7 @@
   (let* ((y (lvar-value y))
 	 (y-abs (abs y))
 	 (len (1- (integer-length y-abs))))
-    (unless (= y-abs (ash 1 len))
+    (unless (and (> y-abs 0) (= y-abs (ash 1 len)))
       (give-up-ir1-transform))
     (let* ((shift (- len))
 	   (mask (1- y-abs)))
@@ -2743,7 +2743,7 @@
   (let* ((y (lvar-value y))
 	 (y-abs (abs y))
 	 (len (1- (integer-length y-abs))))
-    (unless (= y-abs (ash 1 len))
+    (unless (and (> y-abs 0) (= y-abs (ash 1 len)))
       (give-up-ir1-transform))
     (let ((mask (1- y-abs)))
       `(if (minusp x)
diff --git a/tests/arith.pure.lisp b/tests/arith.pure.lisp
index 8c47082..8d1d12b 100644
--- a/tests/arith.pure.lisp
+++ b/tests/arith.pure.lisp
@@ -206,3 +206,17 @@
 ;;; ASH of a negative bignum by a bignum count would erroneously
 ;;; return 0 prior to sbcl-0.8.4.4
 (assert (= (ash (1- most-negative-fixnum) (1- most-negative-fixnum)) -1))
+
+;;; Whoops.  Too much optimization in division operators for 0
+;;; divisor.
+(macrolet ((frob (name)
+	     `(let ((fn (compile nil '(lambda (x)
+				       (declare (optimize speed) (fixnum x))
+				       (,name x 0)))))
+	       (assert (raises-error? (funcall fn 1) division-by-zero)))))
+  (frob mod)
+  (frob truncate)
+  (frob rem)
+  (frob /)
+  (frob floor)
+  (frob ceiling))
diff --git a/version.lisp-expr b/version.lisp-expr
index 1836c0c..59b49f0 100644
--- a/version.lisp-expr
+++ b/version.lisp-expr
@@ -17,4 +17,4 @@
 ;;; checkins which aren't released. (And occasionally for internal
 ;;; versions, especially for internal versions off the main CVS
 ;;; branch, it gets hairier, e.g. "0.pre7.14.flaky4.13".)
-"0.8.13.11"
+"0.8.13.12"