http://gcc.gnu.org/bugzilla/show_bug.cgi?id=48717
Summary: likely integer wrong code bug Product: gcc Version: 4.7.0 Status: UNCONFIRMED Severity: normal Priority: P3 Component: c AssignedTo: unassig...@gcc.gnu.org ReportedBy: reg...@cs.utah.edu [regehr@gamow tmp012]$ current-gcc -O1 small.c -o small [regehr@gamow tmp012]$ ./small 65535 [regehr@gamow tmp012]$ current-gcc -O2 small.c -o small [regehr@gamow tmp012]$ ./small -1 [regehr@gamow tmp012]$ current-gcc -v Using built-in specs. COLLECT_GCC=current-gcc COLLECT_LTO_WRAPPER=/uusoc/exports/scratch/regehr/z/compiler-install/gcc-r172845-install/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.7.0/lto-wrapper Target: x86_64-unknown-linux-gnu Configured with: ../configure --with-libelf=/usr/local --enable-lto --prefix=/home/regehr/z/compiler-install/gcc-r172845-install --program-prefix=r172845- --enable-languages=c,c++ Thread model: posix gcc version 4.7.0 20110421 (experimental) (GCC) [regehr@gamow tmp012]$ cat small.c unsigned short safe_52 (unsigned short ui1, unsigned short ui2) { return ui1 + ui2; } extern int printf (const char *, ...); int g_7 = 1; int g_8; void func_1 (void) { g_7 = safe_52 (~g_8, g_8); } int main (void) { func_1 (); printf ("%d\n", g_7); return 0; }