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[Bug middle-end/57859] New: -ftrapv does not trap on signed overflows for struct fields (32-bit mode)
- From: "su at cs dot ucdavis.edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: Tue, 09 Jul 2013 08:04:38 +0000
- Subject: [Bug middle-end/57859] New: -ftrapv does not trap on signed overflows for struct fields (32-bit mode)
- Auto-submitted: auto-generated
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57859
Bug ID: 57859
Summary: -ftrapv does not trap on signed overflows for struct
fields (32-bit mode)
Product: gcc
Version: 4.9.0
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
Assignee: unassigned at gcc dot gnu.org
Reporter: su at cs dot ucdavis.edu
The following code (which has a signed integer overflow) doesn't trap when
compiled at -O1 or above with -ftrapv on x86_64-linux. This applies to the
current gcc trunk, as well as gcc-4.6, gcc-4.7, and gcc-4.8.
$ gcc-trunk -v
gcc version 4.9.0 20130708 (experimental) [trunk revision 200751] (GCC)
$ gcc-trunk -m32 -O0 -ftrapv small.c
$ a.out
Aborted (core dumped)
$ gcc-trunk -m32 -O1 -ftrapv small.c
$ a.out
$ gcc-4.8 -m32 -O1 -ftrapv small.c
$ a.out
$ gcc-4.7 -m32 -O1 -ftrapv small.c
$ a.out
$ gcc-4.6 -m32 -O1 -ftrapv small.c
$ a.out
$
-------------------------------------------
struct S
{
int f;
};
int
main ()
{
struct S s;
for (s.f = 1; s.f > 0; ++s.f)
;
return 0;
}
-------------------------------------------
The following code does trap in 32-bit mode (but still not in 64-bit):
int
main ()
{
int i;
for (i = 1; i > 0; ++i)
;
return 0;
}