http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57131
Bug #: 57131
Summary: Wong register assignment?
Classification: Unclassified
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: rtl-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ishiura-compi...@ml.kwansei.ac.jp
This miscompile occurs only on 32bit x86 (i686) target of GCC 4.8.1
(prerelease).
(There is no problem with x86_64 target or GCC 4.7.3.)
A dubious option is "-foptimize-register-move."
$ cat error.c
int main (void)
{
volatile int x1 = 0;
volatile long long x2 = 0;
volatile int x3 = 0;
volatile int x4 = 1;
volatile int x5 = 1;
volatile long long x6 = 1;
long long t = ( ( x1 * ( x2 << x3 ) ) / (x4 * x5) ) + x6 ;
return (t == 1);
}
$ i686-pc-linux-gnu-gcc-4.8.1 error.c -O1 -fexpensive-optimizations
-foptimize-register-move
$ ./a.out
Floating point exception (core dumped)
-----
$ i686-pc-linux-gnu-gcc-4.8.1 -v
Using built-in specs.
COLLECT_GCC=i686-pc-linux-gnu-gcc-4.8.1
COLLECT_LTO_WRAPPER=/usr/local/i686-tools/gcc-4.8.1/libexec/gcc/i686-pc-linux-gnu/4.8.1/lto-wrapper
Target: i686-pc-linux-gnu
Configured with: /home/hassy-i686-linux/gcc/configure
--prefix=/usr/local/i686-tools/gcc-4.8.1/
--with-gmp=/usr/local/gmp-5.1.1/ --with-mpfr=/usr/local/mpfr-3.1.2/
--with-mpc=/usr/local/mpc-1.0.1/ --disable-multilib --disable-nls
--enable-languages=c
Thread model: posix
gcc version 4.8.1 20130428 (prerelease) (GCC)
