__jmp_buf
__CTASSERT(_SIZEOF_SC + _JB_G4 == offsetof(struct __jmp_buf,regs.g4));
__CTASSERT(_SIZEOF_SC + _JB_G7 == offsetof(struct __jmp_buf,regs.g7));
__CTASSERT(sizeof(jmp_buf) >= sizeof(struct __jmp_buf));
struct __jmp_buf *context = (void *)env;