http://gcc.gnu.org/bugzilla/show_bug.cgi?id=57083
Bug #: 57083
Summary: Wrong constant folding
Classification: Unclassified
Product: gcc
Version: 4.8.1
Status: UNCONFIRMED
Severity: normal
Priority: P3
Component: tree-optimization
AssignedTo: unassig...@gcc.gnu.org
ReportedBy: ishiura-compi...@ml.kwansei.ac.jp
GCC 4.8.1 prerelease (x86_64 for both linux and darwin12) miscompiles
the following code with optimize option "-O1 -ftree-vrp."
$ cat error.c
/* UINT_MAX == 4294967295 */
short x = 1;
int y = 0;
int main (void)
{
unsigned t = ( 2147450881U - (unsigned) x ) << ( y == 0 );
if ( t != 4294901760U ) { __builtin_abort(); }
return 0;
}
$ x86_64-unknown-linux-gnu-gcc-4.8.1 error.c -O1 -ftree-vrp
$ ./a.out
Aborted (core dumped)
There was no problem with GCC 4.7.3.
-----
$ x86_64-unknown-linux-gnu-gcc-4.8.1 -v
Target: x86_64-unknown-linux-gnu
Configured with: /home/hassy/gcc/configure
--prefix=/usr/local/x86_64-tools/gcc-4.8.0/
--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 20130422 (prerelease) (GCC)
$ gcc-mp-4.8 -v
Using built-in specs.
COLLECT_GCC=gcc-mp-4.8
COLLECT_LTO_WRAPPER=/opt/local/libexec/gcc/x86_64-apple-darwin12/4.8.1/lto-wrapper
Target: x86_64-apple-darwin12
Configured with: ../gcc-4.8-20130411/configure --prefix=/opt/local
--build=x86_64-apple-darwin12
--enable-languages=c,c++,objc,obj-c++,lto,fortran,java
--libdir=/opt/local/lib/gcc48 --includedir=/opt/local/include/gcc48
--infodir=/opt/local/share/info --mandir=/opt/local/share/man
--datarootdir=/opt/local/share/gcc-4.8 --with-local-prefix=/opt/local
--with-system-zlib --disable-nls --program-suffix=-mp-4.8
--with-gxx-include-dir=/opt/local/include/gcc48/c++/ --with-gmp=/opt/local
--with-mpfr=/opt/local --with-mpc=/opt/local --with-ppl=/opt/local
--with-cloog=/opt/local --enable-cloog-backend=isl
--disable-cloog-version-check --enable-stage1-checking --disable-multilib
--enable-lto --enable-libstdcxx-time --with-as=/opt/local/bin/as
--with-ld=/opt/local/bin/ld --with-ar=/opt/local/bin/ar
--with-bugurl=https://trac.macports.org/newticket --with-pkgversion='MacPorts
gcc48 4.8-20130411_0'
Thread model: posix
gcc version 4.8.1 20130411 (prerelease) (MacPorts gcc48 4.8-20130411_0)
