On Wed, Nov 02, 2016 at 11:10:53AM +0100, Jakub Jelinek wrote:
> On Wed, Nov 02, 2016 at 10:59:26AM +0100, Jakub Jelinek wrote:
> > > Which is gimplified as:
> > >
> > > int * ptr;
> > >
> > > switch (argc) <default: <D.2575>, case 1: <D.2573>>
> > > {
> > > int a;
> > >
> > > try
> > > {
> > > ASAN_MARK (2, &a, 4);
> > > <D.2573>:
> > > goto <D.2574>;
> > > <D.2575>:
> > > ptr = &a;
> > > goto <D.2574>;
> > > }
> > > finally
> > > {
> > > ASAN_MARK (1, &a, 4);
> > > }
>
> > Shouldn't there be also ASAN_MARK on the implicit gotos from the switch
> > statement? Otherwise, consider this being done in a loop, after the first
> > iteration you ASAN_MARK (1, &a, 4) (i.e. poison), then you iterate say with
> > args 1 and have in case 1: a = 0;, won't that trigger runtime error?
>
> Wonder if for the variables declared inside of switch body, because we don't
> care about uses before scope, it wouldn't be more efficient to arrange for
> int *p, *q, *r;
> switch (x)
> {
> int a;
> case 1:
> p = &a;
> a = 5;
> break;
> int b;
> case 2:
> int c;
> q = &b;
> r = &c;
> b = 3;
> c = 4;
> break;
> }
> to effectively ASAN_MARK (2, &a, 4); ASAN_MARK (2, &b, 4); ASAN_MARK (2, &c,
> 4);
> before the GIMPLE_SWITCH, instead of unpoisoning them on every case label
> where they might be in scope. Though, of course, at least until lower pass
> that is quite ugly, because it would refer to "not yet declared" variables.
> Perhaps we'd need to move the ASAN_MARK and GIMPLE_SWITCH (but of course not
> the expression evaluation of the switch control expression) inside of the
> switches' GIMPLE_BIND.
So is there anything I should do wrt -Wswitch-unreachable?
Marek
