>Number:         10065
>Category:       port-alpha
>Synopsis:       __divq(0x8000000000000000, 1) dies with SIGFPE
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    port-alpha-maintainer
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun May 07 16:25:00 PDT 2000
>Closed-Date:
>Last-Modified:
>Originator:     ITOH Yasufumi
>Release:        1.4X (April 28, 2000)
>Organization:
	
>Environment:
System: NetBSD libble.my.domain 1.4X NetBSD 1.4X (LIBBLE) #2: Mon May 1 01:01:21 JST 2000 itohy@libble.my.domain:/usr/src/sys/arch/alpha/compile/LIBBLE alpha


>Description:
	__divq(0x8000000000000000, 1) causes SIGFPE
	(note that __divq is not a normal function).

	This causes failure on "make test" of gforth-0.4.0.

>How-To-Repeat:
	Try following program.

	% cc divqtest.c
	% ./a.out
	Floating point exception (core dumped)
	%

	Any combinations of arg1 and arg2 (!= 0) other than
	0x8000000000000000 and 1 seem to work fine.

divqtest.c:
#include <stdio.h>

main()
{
	register long arg1 asm("$24") = 0x8000000000000000;
	register long arg2 asm("$25") = 1;
	register long result asm("$27");

	/*
	 * t10($24) / t11($25) -> t12($27)
	 * return addr is t9($23), not ra($26)
	 */
	asm("jsr $23,__divq" : "=r" (result) : "r" (arg1), "r" (arg2));

	printf("result %lx\n", result);

	return 0;
}

>Fix:
	Do not raise interger overflow exception.

diff -u lib/libc/arch/alpha/gen/divrem.m4.orig lib/libc/arch/alpha/gen/divrem.m4
--- lib/libc/arch/alpha/gen/divrem.m4.orig	Thu Oct 17 20:12:22 1996
+++ lib/libc/arch/alpha/gen/divrem.m4	Tue May  2 23:34:55 2000
@@ -171,7 +171,7 @@
 ifelse(S, `true',
 `
 	/* Check to see if we should negate it. */
-	subqv	zero, RESULT, T_0
+	subq	zero, RESULT, T_0
 	cmovlbs	NEG, T_0, RESULT
 ')
 
diff -u sys/lib/libkern/arch/alpha/divrem.m4.orig sys/lib/libkern/arch/alpha/divrem.m4
--- sys/lib/libkern/arch/alpha/divrem.m4.orig	Thu Oct 17 20:21:07 1996
+++ sys/lib/libkern/arch/alpha/divrem.m4	Tue May  2 23:34:55 2000
@@ -171,7 +171,7 @@
 ifelse(S, `true',
 `
 	/* Check to see if we should negate it. */
-	subqv	zero, RESULT, T_0
+	subq	zero, RESULT, T_0
 	cmovlbs	NEG, T_0, RESULT
 ')
 
>Release-Note:
>Audit-Trail:
>Unformatted: