From: Olivier Danet <odanet@caramail.com>
To: qemu-devel <qemu-devel@nongnu.org>,
Blue Swirl <blauwirbel@gmail.com>,
Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Subject: [Qemu-devel] [PATCH v2] sparc32 : Signed integer division overflow
Date: Wed, 19 Mar 2014 23:29:04 +0100 [thread overview]
Message-ID: <532A1A30.3040306@caramail.com> (raw)
The signed integer division -0x8000_0000_0000_0000 / -1 must be handled
separately to avoid an overflow on the QEMU host.
Signed-off-by: Olivier Danet <odanet@caramail.com>
---
target-sparc/helper.c | 13 ++++++++-----
1 file changed, 8 insertions(+), 5 deletions(-)
diff --git a/target-sparc/helper.c b/target-sparc/helper.c
index f3c7fbf..3822c48 100644
--- a/target-sparc/helper.c
+++ b/target-sparc/helper.c
@@ -122,12 +122,15 @@ static target_ulong helper_sdiv_common(CPUSPARCState *env, target_ulong a,
if (x1 == 0) {
cpu_restore_state(CPU(cpu), GETPC());
helper_raise_exception(env, TT_DIV_ZERO);
- }
-
- x0 = x0 / x1;
- if ((int32_t) x0 != x0) {
- x0 = x0 < 0 ? 0x80000000 : 0x7fffffff;
+ } else if (x1 == -1 && x0 == INT64_MIN) {
+ x0 = 0x7fffffff;
overflow = 1;
+ } else {
+ x0 = x0 / x1;
+ if ((int32_t) x0 != x0) {
+ x0 = x0 < 0 ? 0x80000000 : 0x7fffffff;
+ overflow = 1;
+ }
}
if (cc) {
--
1.8.1.5
next reply other threads:[~2014-03-19 22:27 UTC|newest]
Thread overview: 3+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-03-19 22:29 Olivier Danet [this message]
2014-03-20 15:54 ` [Qemu-devel] [PATCH v2] sparc32 : Signed integer division overflow Richard Henderson
2014-03-20 16:15 ` Richard Henderson
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