On 11/02/2016 10:40 AM, Richard Biener wrote:
> On Tue, Nov 1, 2016 at 4:12 PM, Jakub Jelinek <[email protected]> wrote:
>> On Tue, Nov 01, 2016 at 03:53:46PM +0100, Martin Liška wrote:
>>> @@ -1504,7 +1505,7 @@ non_rewritable_lvalue_p (tree lhs)
>>>
>>> static void
>>> maybe_optimize_var (tree var, bitmap addresses_taken, bitmap not_reg_needs,
>>> - bitmap suitable_for_renaming)
>>> + bitmap suitable_for_renaming, bitmap
>>> marked_nonaddressable)
>>> {
>>> /* Global Variables, result decls cannot be changed. */
>>> if (is_global_var (var)
>>> @@ -1522,6 +1523,7 @@ maybe_optimize_var (tree var, bitmap addresses_taken,
>>> bitmap not_reg_needs,
>>> || !bitmap_bit_p (not_reg_needs, DECL_UID (var))))
>>> {
>>> TREE_ADDRESSABLE (var) = 0;
>>> + bitmap_set_bit (marked_nonaddressable, DECL_UID (var));
>>
>> Why do you need the marked_nonaddressable bitmap?
>>
>>> if (is_gimple_reg (var))
>>> bitmap_set_bit (suitable_for_renaming, DECL_UID (var));
>>> if (dump_file)
>>> @@ -1550,20 +1552,43 @@ maybe_optimize_var (tree var, bitmap
>>> addresses_taken, bitmap not_reg_needs,
>>> }
>>> }
>>>
>>> -/* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables. */
>>> +/* Return true when STMT is ASAN mark where second argument is an address
>>> + of a local variable. */
>>>
>>> -void
>>> -execute_update_addresses_taken (void)
>>> +static bool
>>> +is_asan_mark_p (gimple *stmt)
>>> +{
>>> + if (!gimple_call_internal_p (stmt, IFN_ASAN_MARK))
>>> + return false;
>>> +
>>> + tree addr = get_base_address (gimple_call_arg (stmt, 1));
>>> + if (TREE_CODE (addr) == ADDR_EXPR
>>> + && TREE_CODE (TREE_OPERAND (addr, 0)) == VAR_DECL)
>>
>> Just check here if dropping TREE_ADDRESSABLE from the VAR (use VAR_P btw)
>> would turn it into is_gimple_reg), and don't return true if not.
>>
>>> + return true;
>>> +
>>> + return false;
>>> +}
>>> +
>>> +/* Compute TREE_ADDRESSABLE and DECL_GIMPLE_REG_P for local variables.
>>> + If SANITIZE_ASAN_MARK is set to true, sanitize also ASAN_MARK
>>> built-ins. */
>>> +
>>> +
>>> +static void
>>> +execute_update_addresses_taken (bool sanitize_asan_mark = false)
>>
>> I wonder if the sanitize_asan_mark wouldn't better be some PROP_* property
>> set during the asan pass and kept on until end of compilation of that
>> function. That means even if a var only addressable because of ASAN_MARK is
>> discovered after this pass we'd still be able to rewrite it into SSA.
>
> Note that being TREE_ADDRESSABLE also has effects on alias analysis
> (didn't follow the patches to see whether you handle ASAN_MARK specially
> in points-to analysis and/or alias analysis).
Currently all manipulation with shadow memory is done via a pointer type
which has created a separate aliasing set:
static void
asan_init_shadow_ptr_types (void)
{
asan_shadow_set = new_alias_set ();
tree types[3] = { signed_char_type_node, short_integer_type_node,
integer_type_node };
for (unsigned i = 0; i < 3; i++)
{
shadow_ptr_types[i] = build_distinct_type_copy (types[i]);
TYPE_ALIAS_SET (shadow_ptr_types[i]) = asan_shadow_set;
shadow_ptr_types[i] = build_pointer_type (shadow_ptr_types[i]);
}
...
Martin
>
> Generally in update-address-taken you can handle ASAN_MARK similar to
> MEM_REF (and drop it in the rewrite phase?).
>
> As said, I didnt look at the patches and just came by here seeing
> tree-ssa.c pieces...
>
> Richard.
>
>> Jakub
