[perl #825] [PATCH] Fix underflow error in fact_x_i

[via RT]

# New Ticket Created by  Tony Payne 
# Please include the string:  [perl #825]
# in the subject line of all future correspondence about this issue. 
# <URL: http://bugs6.perl.org/rt2/Ticket/Display.html?id=825 >



Conversion from a signed (int,float) to an unsigned int was causing
underflow.  Therefore, fact(-1) becomes fact(UINT_MAX), which is
absurdly large :-).  With this patch, it returns 0.  Tests are also
included.

++t



-- attachment  1 ------------------------------------------------------
url: http://bugs6.perl.org/rt2/attach/3880/3590/523641/fact.diff


Index: math.ops
===================================================================
RCS file: /cvs/public/parrot/math.ops,v
retrieving revision 1.1
diff -u -r1.1 math.ops
--- math.ops	17 Jun 2002 18:06:11 -0000	1.1
+++ math.ops	16 Jul 2002 22:03:46 -0000
@@ -122,8 +122,9 @@
 =cut
 
 inline op fact(out INT, in INT) {
-
-UINTVAL i = $2;
+/* Coercing a negative to a UINT can get pretty ugly
+ * in this situation. */
+INTVAL i = $2;
 UINTVAL q = 1;
   while(i>0) {
     q = q*i;
@@ -134,8 +135,9 @@
 }
 
 inline op fact(out NUM, in INT) {
-
-UINTVAL i = $2;
+/* Coercing a negative to a UINT can get pretty ugly
+ * in this situation. */
+INTVAL i = $2;
 UINTVAL q = 1;
   while(i>0) {
     q = q*i;
Index: t/op/integer.t
===================================================================
RCS file: /cvs/public/parrot/t/op/integer.t,v
retrieving revision 1.25
diff -u -r1.25 integer.t
--- t/op/integer.t	28 Jun 2002 18:50:40 -0000	1.25
+++ t/op/integer.t	16 Jul 2002 22:03:46 -0000
@@ -1,6 +1,6 @@
 #! perl -w
 
-use Parrot::Test tests => 33;
+use Parrot::Test tests => 35;
 
 output_is(<<CODE, <<OUTPUT, "set_i_ic");
 	# XXX: Need a test for writing outside the set of available
@@ -1044,6 +1044,52 @@
     end
 CODE
 12
+OUTPUT
+
+output_is(<<CODE, <<OUTPUT, "fact_i_i");
+    set I0, 3
+    set I1, 11
+    set I2, 0
+    set I3, -563
+    fact I5, I0
+    print I5
+    print "\\n"
+    fact I6, I1
+    print I6
+    print "\\n"
+    fact I7, I2
+    print I7
+    print "\\n"
+    fact I8, I3
+    print I8
+    print "\\n"
+    end
+CODE
+6
+39916800
+1
+1
+OUTPUT
+
+output_is(<<CODE, <<OUTPUT, "fact_i_ic");
+    fact I5, 3
+    print I5
+    print "\\n"
+    fact I6, 11
+    print I6
+    print "\\n"
+    fact I7, 0
+    print I7
+    print "\\n"
+    fact I8, -563
+    print I8
+    print "\\n"
+    end
+CODE
+6
+39916800
+1
+1
 OUTPUT
 
 1;
Index: t/op/number.t
===================================================================
RCS file: /cvs/public/parrot/t/op/number.t,v
retrieving revision 1.19
diff -u -r1.19 number.t
--- t/op/number.t	28 Jun 2002 18:50:40 -0000	1.19
+++ t/op/number.t	16 Jul 2002 22:03:46 -0000
@@ -1,6 +1,6 @@
 #! perl -w
 
-use Parrot::Test tests => 30;
+use Parrot::Test tests => 32;
 use Test::More;
 
 output_is(<<CODE, <<OUTPUT, "set_n_nc");
@@ -900,6 +900,52 @@
     end
 CODE
 12.000000
+OUTPUT
+
+output_is(<<CODE, <<OUTPUT, "fact_n_i");
+    set I0, 3
+    set I1, 11
+    set I2, 0
+    set I3, -563
+    fact N5, I0
+    print N5
+    print "\\n"
+    fact N6, I1
+    print N6
+    print "\\n"
+    fact N7, I2
+    print N7
+    print "\\n"
+    fact N8, I3
+    print N8
+    print "\\n"
+    end
+CODE
+6.000000
+39916800.000000
+1.000000
+1.000000
+OUTPUT
+
+output_is(<<CODE, <<OUTPUT, "fact_n_ic");
+    fact N5, 3
+    print N5
+    print "\\n"
+    fact N6, 11
+    print N6
+    print "\\n"
+    fact N7, 0
+    print N7
+    print "\\n"
+    fact N8, -563
+    print N8
+    print "\\n"
+    end
+CODE
+6.000000
+39916800.000000
+1.000000
+1.000000
 OUTPUT
 
 1;