When this function is compiled with -O, it works. When it's compiled without -O, it reports error "error: can't find a register in class `GENERAL_REGS' while reloading `asm'".
I think that syntactic corectness of language shouldn't depend on optimization flags --- it should either report error in both cases or always succeed. void f(char *p) { asm volatile (""::"m"(p[0]),"m"(p[0]),"m"(p[0]),"m"(p[0]),"m"(p[0]),"m"(p[0]),"m"(p[0]),"m"(p[0])); } -- Summary: Complilation success depends on optimization being used Product: gcc Version: 3.4.3 Status: UNCONFIRMED Severity: minor Priority: P3 Component: c AssignedTo: unassigned at gcc dot gnu dot org ReportedBy: mikulas at artax dot karlin dot mff dot cuni dot cz 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=20645