On Thu, Sep 01, 2016 at 08:59:57AM +0200, Richard Biener wrote:
> > Bootstrapped/regtested on x86_64-linux and i686-linux, ok for trunk?
>
> Hmm, maybe simply do
>
> if (gimple_call_builtin_p (g, BUILT_IN_ASAN_AFTER_DYNAMIC_INIT))
> {
> gimple *def = SSA_NAME_DEF_STMT (gimple_vuse (g));
> if (gimple_call_builtin_p (def, BUILT_IN_ASAN_BEFORE_DYNAMIC_INIT))
> ... remove both ...
>
> intervening non-memory-def stmts do not really matter, do they? If
> loads matter then checking for the single-vdef-use of
> BUILT_IN_ASAN_BEFORE_DYNAMIC_INIT to be BUILT_IN_ASAN_AFTER_DYNAMIC_INIT
> would also work.
Loads matter too. What I've been worried about is that some optimizations
would turn the original
__asan_before_dynamic_init ("foobar");
...
__asan_after_dynamic_init ();
into:
__asan_before_dynamic_init ("foobar");
...
if (...)
{
...
__asan_after_dynamic_init ();
return;
}
...
__asan_after_dynamic_init ();
or something similar and then if removing both on seeing after and its vuse
before, we'd then keep around the other after call.
Maybe instead of removing both I could just remember both, if it ever finds
more than one of each kind of calls, punt, and otherwise remove at the end
of the stmt walk?
> Otherwise looks ok but I wonder why libasan needs to assert this ..
It a tiny bit simplifies the code, and of course, a perfect compiler would
never emit those if there isn't anything to protect, it is just that it is
hard on the compiler side to guarantee it always.
// PR sanitizer/77396
// { dg-do run }
// { dg-additional-options "-O2" }
// { dg-set-target-env-var ASAN_OPTIONS "check_initialization_order=true" }
struct S { S () { asm volatile ("" : : : "memory"); } };
static S c;
int
main ()
{
return 0;
}
is what still fails even with the patch.
Jakub
