On Tue, 21 Nov 2023, Alexander Monakov wrote:
> I am concerned that if GCC ever learns to leave out the following access
> to 'this->foo', leaving tmp uninitialized, we will end up with:
>
> this->foo = 42;
Sorry, this store will be DSE'd out, of course, but my question stands.
Alexander
> *this = { CLOBBER };
> __valgrind_make_mem_undefined(this, sizeof *this);
> int tmp(D);
> return tmp(D); // uninitialized
>
> and Valgrind will not report anything since the invalid load is optimized out.
>
> With early instrumentation such optimization is not going to happen, since the
> builtin may modify *this.
>
> Is my concern reasonable?
>
> Thanks.
> Alexander
