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* [Bug middle-end/54848] New: -ftrapv doesn't work when assigning to an integer with smaller size
@ 2012-10-07 16:13 mikulas at artax dot karlin.mff.cuni.cz
2012-10-08 10:44 ` [Bug middle-end/54848] " rguenth at gcc dot gnu.org
2024-05-20 0:24 ` bruno at clisp dot org
0 siblings, 2 replies; 3+ messages in thread
From: mikulas at artax dot karlin.mff.cuni.cz @ 2012-10-07 16:13 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54848
Bug #: 54848
Summary: -ftrapv doesn't work when assigning to an integer with
smaller size
Classification: Unclassified
Product: gcc
Version: 4.7.2
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: middle-end
AssignedTo: unassigned@gcc.gnu.org
ReportedBy: mikulas@artax.karlin.mff.cuni.cz
Host: i686-pc-linux-gnu
Target: i686-pc-linux-gnu
Build: i686-pc-linux-gnu
When adding, subtracting or multiplying two integers and assigning the result
to a variable with smaller size, trap on overflow doesn't happen.
See for example this program:
#include <stdio.h>
int main(void)
{
int a = 0x70000000;
int b = 0x50000000;
short c = a + b;
printf("%x\n", c);
return 0;
}
We compile the program without optimization and with -ftrapv, so that it should
crash because of integer overflow. But the program doesn't crash. If we replace
"short" with "int", an overflow crash happens correctly.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/54848] -ftrapv doesn't work when assigning to an integer with smaller size
2012-10-07 16:13 [Bug middle-end/54848] New: -ftrapv doesn't work when assigning to an integer with smaller size mikulas at artax dot karlin.mff.cuni.cz
@ 2012-10-08 10:44 ` rguenth at gcc dot gnu.org
2024-05-20 0:24 ` bruno at clisp dot org
1 sibling, 0 replies; 3+ messages in thread
From: rguenth at gcc dot gnu.org @ 2012-10-08 10:44 UTC (permalink / raw)
To: gcc-bugs
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54848
Richard Guenther <rguenth at gcc dot gnu.org> changed:
What |Removed |Added
----------------------------------------------------------------------------
Keywords| |wrong-code
Status|UNCONFIRMED |NEW
Last reconfirmed| |2012-10-08
Ever Confirmed|0 |1
--- Comment #1 from Richard Guenther <rguenth at gcc dot gnu.org> 2012-10-08 10:43:53 UTC ---
Confirmed. One of the many known issues with -ftrapv.
^ permalink raw reply [flat|nested] 3+ messages in thread
* [Bug middle-end/54848] -ftrapv doesn't work when assigning to an integer with smaller size
2012-10-07 16:13 [Bug middle-end/54848] New: -ftrapv doesn't work when assigning to an integer with smaller size mikulas at artax dot karlin.mff.cuni.cz
2012-10-08 10:44 ` [Bug middle-end/54848] " rguenth at gcc dot gnu.org
@ 2024-05-20 0:24 ` bruno at clisp dot org
1 sibling, 0 replies; 3+ messages in thread
From: bruno at clisp dot org @ 2024-05-20 0:24 UTC (permalink / raw)
To: gcc-bugs
https://gcc.gnu.org/bugzilla/show_bug.cgi?id=54848
Bruno Haible <bruno at clisp dot org> changed:
What |Removed |Added
----------------------------------------------------------------------------
CC| |bruno at clisp dot org
--- Comment #2 from Bruno Haible <bruno at clisp dot org> ---
Another test case:
==================== u.c =====================
int
main ()
{
unsigned short a = 0xeb64;
unsigned short b = 0xf1e2;
unsigned short c = a * b;
}
==============================================
$ gcc -ftrapv u.c
$ ./a.out; echo $?
0
Reproduced with gcc 14.1.0.
^ permalink raw reply [flat|nested] 3+ messages in thread
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2012-10-07 16:13 [Bug middle-end/54848] New: -ftrapv doesn't work when assigning to an integer with smaller size mikulas at artax dot karlin.mff.cuni.cz
2012-10-08 10:44 ` [Bug middle-end/54848] " rguenth at gcc dot gnu.org
2024-05-20 0:24 ` bruno at clisp dot org
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