See description and how to repeat below:
[EMAIL PROTECTED]:~> cat foo.c
#include <stdio.h>
int i;
void foo(long long l, void *buf)
{
float f= (float) l;
i= (long long) f != l;
*(float*) buf= f;
}
int main()
{
float f;
long long l= 1073741825;
foo(l, &f);
printf("%lld %d %f\n", l, i, f);
}
[EMAIL PROTECTED]:~> gcc foo.c; ./a.out
1073741825 1 1073741824.000000
[EMAIL PROTECTED]:~> gcc -O1 foo.c; ./a.out
1073741825 0 1073741824.000000
[EMAIL PROTECTED]:~> gcc -O3 foo.c; ./a.out
1073741825 0 1073741825.000000
[EMAIL PROTECTED]:~> gcc -O3 -ffloat-store foo.c; ./a.out
1073741825 1 1073741824.000000
[EMAIL PROTECTED]:~> gcc -v
Reading specs from /usr/local/lib/gcc/i686-pc-linux-gnu/3.4.3/specs
Configured with: ../gcc-3.4.3/configure --enable-threads=posix
--enable-language=c,c++ : (reconfigured) ../gcc-3.4.3/configure
--enable-threads=posix --enable-languages=c,c++ : (reconfigured)
../gcc-3.4.3/configure --enable-threads=posix --enable-languages=c,c++
Thread model: posix
gcc version 3.4.3
While I see no problem with cases 1 and 3, the case 2 (-O1) seems to be
broken: gcc fails to check that truncation happened, although it's there.
Environment:
System: Linux dragonfly 2.6.5-7.108-default #1 Wed Aug 25 13:34:40 UTC 2004
i686 i686 i386 GNU/Linux
Architecture: i686
host: i686-pc-linux-gnu
build: i686-pc-linux-gnu
target: i686-pc-linux-gnu
configured with: ../gcc-3.4.3/configure --enable-threads=posix
--enable-language=c,c++ : (reconfigured) ../gcc-3.4.3/configure
--enable-threads=posix --enable-languages=c,c++ : (reconfigured)
../gcc-3.4.3/configure --enable-threads=posix --enable-languages=c,c++
How-To-Repeat:
See the program given in description.
------- Additional Comments From konstantin at mysql dot com 2004-12-15 13:29
-------
Fix:
I know of no workaround.
--
Summary: check if float -> long store truncation happened fails
with -O1
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: konstantin at mysql dot com
CC: gcc-bugs at gcc dot gnu dot org
GCC build triplet: i686-pc-linux-gnu
GCC host triplet: i686-pc-linux-gnu
GCC target triplet: i686-pc-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=19011
