On 09/16/2014 10:56 AM, Jakub Jelinek wrote:
vptr-5.C is one Jason mailed me yesterday, clang++ doesn't instrument this
and g++ right now doesn't either, build_static_cast_1 certainly isn't called
in that case, and I must say I have no idea what should be checked there,
where etc.
What needs to be checked is conversion (in this case implicit) to a
virtual base; if the vptr doesn't point to a vtable that has the
appropriate vbase offset, we should complain.
virtual base conversions are implemented in build_base_path under if
(virtual_access).
vptr-6.C shows where the this optimization is performed and where it isn't
(clang++ has 10 instrumentations in T::h and 1 in S::l, g++ has fewer than
that, but not 0 in T::h (1 in S::l is right and needed I think)).
I agree that 0 is enough for T::h and 1 for S::l.
I hope all of f[1-6] is invalid, I really don't see how we could instrument
member accesses otherwise (we'd need to limit to not taking address of it);
NULL pointer shouldn't point at a valid object.
I don't see anything in the standard saying that these are undefined,
only that trying to access the (non-)object pointed to is undefined. It
would be undefined if a conversion to virtual base were involved, i.e.
struct V: virtual R { };
// undefined if p doesn't point to a V because of the conversion to
// virtual base R
int* f7 (V* p) { return &p->r; }
These conditions were loosened in C++11 by DRs 597 and 1531; before that
it was reasonable to regard f[1-6] as undefined, and perhaps clang is
using the earlier interpretation.
+ TREE_SIDE_EFFECTS (cond) = 1;
...
+ TREE_SIDE_EFFECTS (hash) = 1;
Why do you need to set TREE_SIDE_EFFECTS on these?
+ if (current_function_decl == NULL_TREE
+ || lookup_attribute ("no_sanitize_undefined",
+ DECL_ATTRIBUTES (current_function_decl)))
+ return NULL_TREE;
When would this be called outside a function? If for namespace-scope
variable initializers, I'd think we do want instrumentation.
+ /* T t; t.foo (); doesn't need instrumentation, if the type is known. */
+ if (is_addr
+ && TREE_CODE (op) == ADDR_EXPR
+ && DECL_P (TREE_OPERAND (op, 0))
+ && same_type_p (type,
+ TYPE_MAIN_VARIANT (TREE_TYPE (TREE_OPERAND (op, 0)))))
+ return NULL_TREE;
You might want to use resolves_to_fixed_type_p in the optimizations.
Jason
