On 27 October 2015 at 14:24, <[email protected]> wrote: > From: Marc-André Lureau <[email protected]> > > When running vhost-user-test with clang compiled qemu with > --extra-cflags=-fsanitize=undefined, the following error is printed: > > qemu/target-i386/translate.c:2435:26: runtime error: left shift of negative > value -8 > > According to c99, this is undefined behaviour. (see also > http://stackoverflow.com/questions/22883790/left-shift-of-negative-values) > > I guess the intended code is to subtract (8 << s->dflag), thus adding > parentheses seems to be enough. > > Signed-off-by: Marc-André Lureau <[email protected]> > --- > target-i386/translate.c | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/target-i386/translate.c b/target-i386/translate.c > index 764b1e4..862f8e0 100644 > --- a/target-i386/translate.c > +++ b/target-i386/translate.c > @@ -2432,7 +2432,7 @@ static void gen_pusha(DisasContext *s) > { > int i; > gen_op_movl_A0_reg(R_ESP); > - gen_op_addl_A0_im(-8 << s->dflag); > + gen_op_addl_A0_im(-(8 << s->dflag)); > if (!s->ss32) > tcg_gen_ext16u_tl(cpu_A0, cpu_A0); > tcg_gen_mov_tl(cpu_T[1], cpu_A0);
Looks like Eduardo already had a patch on list for this: http://patchwork.ozlabs.org/patch/524590/ thanks -- PMM
