http://gcc.gnu.org/bugzilla/show_bug.cgi?id=55544
Bug #: 55544
Summary: invalid optimisation long long->double->long long
(with -m32)
Classification: Unclassified
Product: gcc
Version: unknown
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: c
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: joerg.rich...@pdv-fs.de
$ cat t.c
#include <stdio.h>
int main( int argc, char** argv )
{
long long v1;
sscanf( argv[1], "%lld", &v1 );
double d = (double)v1;
long long v2 = (long long)d;
printf( "v1=%lld d=%19.0f v2=%lld\n", v1, d, v2 );
return 0;
}
$ gcc -m32 -O -o t t.c
$ t 9223372036854774781
v1=9223372036854774781 d=9223372036854774784 v2=9223372036854774781
please note that v1 == v2. This is wrong
$ gcc -m32 -o t t.c
$ t 9223372036854774781
v1=9223372036854774781 d=9223372036854774784 v2=9223372036854774784
v2 == d. This is correct
-m64 (with or without optimisation) works too
