repair multiply of (- (expt 2 30)) to itself

On a 64-bit platform, the test for "short" arguments to
avoid overflow was incorrect, because `(- (expt 2 30))`
counted as short.

original commit: 6d05b70e86987c0e7a07f221ba5def492300aaaf

LOG

@@ -1313,3 +1313,5 @@
     externs.h, system.h, expeditor.c, configure, Mf-*, Makefile.*nt,
     workarea, mat.ss, io.ms, io.stex, objects.stex, release_notes.stex,
     root-experr*, patch*
+- fix multiply of most negative fixnum to itself on 64-bit platforms
+    number.c, 5_3.ms

c/number.c

@@ -637,7 +637,7 @@ static ptr big_mul(tc, x, y, xl, yl, sign) ptr tc, x, y; iptr xl, yl; IBOOL sign
   return copy_normalize(&BIGIT(W(tc),0),xl+yl,sign);
 }
 
-#define SHORTMIN (most_negative_fixnum / (1 << (fixnum_bits / 2)))
+#define SHORTMIN ((most_negative_fixnum / (1 << (fixnum_bits / 2))) + 1)
 #define SHORTMAX (most_positive_fixnum / (1 << (fixnum_bits / 2)))
 #define SHORTRANGE(x) ((x) >= SHORTMIN && (x) <= SHORTMAX)
 

mats/5_3.ms

@@ -1628,6 +1628,14 @@
     (error? (* 'a 3 4))
     (error? (* 3 5 'a 4))
     (eqv? (* 1 2) 2)
+    (let loop ([n 0])
+      (or (= n 100)
+          (and
+           (eqv? (* (expt 2 n) (expt 2 n)) (expt 2 (* 2 n)))
+           (eqv? (* (- (expt 2 n)) (- (expt 2 n))) (expt 2 (* 2 n)))
+           (eqv? (* (- (expt 2 n)) (expt 2 n)) (- (expt 2 (* 2 n))))
+           (eqv? (* (expt 2 n) (- (expt 2 n))) (- (expt 2 (* 2 n))))
+           (loop (add1 n)))))
     (fl~= (* 1.0 2) 2.0)
     (fl~= (* 1 2.0) 2.0)
     (eqv? (* 3/5 2/5) 6/25)