From: Dirk Behme <dirk.behme@googlemail.com>
To: qemu-devel@nongnu.org
Subject: [Qemu-devel] [PATCH] Fix overflow conditions for MIPS add/subtract
Date: Mon, 01 May 2006 18:44:28 +0200 [thread overview]
Message-ID: <44563AEC.8070903@gmail.com> (raw)
[-- Attachment #1: Type: text/plain, Size: 165 bytes --]
Fix overflow conditions for MIPS add/subtract as proposed by
Daniel Jacobowitz.
http://lists.gnu.org/archive/html/qemu-devel/2006-04/msg00538.html
Regards
Dirk
[-- Attachment #2: qemu-mips-overflow.txt --]
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--- target-mips/op.c_orig 2006-04-30 09:40:46.000000000 +0200
+++ target-mips/op.c 2006-04-30 09:41:52.000000000 +0200
@@ -206,7 +206,7 @@ void op_addo (void)
tmp = T0;
T0 += T1;
- if (((tmp ^ T1 ^ (-1)) & (T0 ^ T1)) >> 31) {
+ if (~(T0 ^ T1) & (T0 ^ tmp) & 0x80000000) {
/* operands of same sign, result different sign */
CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW);
}
@@ -225,7 +225,7 @@ void op_subo (void)
tmp = T0;
T0 = (int32_t)T0 - (int32_t)T1;
- if (((tmp ^ T1) & (tmp ^ T0)) >> 31) {
+ if ((T0 ^ T1) & (T0 ^ tmp) & 0x80000000) {
/* operands of different sign, first operand and result different sign */
CALL_FROM_TB1(do_raise_exception_direct, EXCP_OVERFLOW);
}
next reply other threads:[~2006-05-01 16:44 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-01 16:44 Dirk Behme [this message]
2006-05-01 19:01 ` [Qemu-devel] [PATCH] Fix overflow conditions for MIPS add/subtract Fabrice Bellard
-- strict thread matches above, loose matches on Subject: below --
2006-05-01 18:42 Stefan Weil
2006-05-01 19:18 ` Daniel Jacobowitz
2006-05-01 21:40 ` Fabrice Bellard
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