On 9 July 2019 15:37:30 CEST, Richard Biener <rguent...@suse.de> wrote:
>On Tue, 9 Jul 2019, Jan Hubicka wrote:
>
>> Hi,
>> this is updated variant I am testing.
>> It documents better how function works and streamlines the checks.
>>
>> OK assuming it passes the tests?
>>
>> Honza
>>
>> Index: tree-ssa-alias.c
>> ===================================================================
>> --- tree-ssa-alias.c (revision 273193)
>> +++ tree-ssa-alias.c (working copy)
>> @@ -1128,6 +1128,91 @@ aliasing_component_refs_p (tree ref1,
>> return false;
>> }
>>
>> +/* FIELD1 and FIELD2 are two fields of component refs. We assume
>> + that bases of both component refs are
>> + (*) are either equivalent or they point to different objects.
>
>are either equivalent(*) or not overlapping
>
>> + We do not assume that FIELD1 and FIELD2 are of same type.
>
>that the containers of FIELD1 and FIELD2 are of the same type?
>
>> +
>> + Return 0 if FIELD1 and FIELD2 satisfy (*).
>> + This is the case when their offsets are the same.
>
>Hmm, so when the offsets are the same then the bases are equivalent?
>I think you want to say
>
> Return 0 if in case the component refs satisfy (*) we
> know FIELD1 and FIELD2 are overlapping exactly.
>
>> + Return 1 if FIELD1 and FIELD2 are non-overlapping.
>> +
>> + Return -1 otherwise.
>> +
>> + Main difference between 0 and -1 is to let
>> + nonoverlapping_component_refs_since_match_p discover the
>semnatically
>
>semantically
>
>otherwise looks good now.
>
>Thanks,
>Richard.
>
>> + equivalent part of the access path.
>> +
>> + Note that this function is used even with -fno-strict-aliasing
>> + and makes use of no TBAA assumptions. */
>> +
>> +static int
>> +nonoverlapping_component_refs_p_1 (const_tree field1, const_tree
>field2)
>> +{
>> + /* If both fields are of the same type, we could save hard work of
>> + comparing offsets. */
>> + tree type1 = DECL_CONTEXT (field1);
>> + tree type2 = DECL_CONTEXT (field2);
>> +
>> + if (DECL_BIT_FIELD_REPRESENTATIVE (field1))
>> + field1 = DECL_BIT_FIELD_REPRESENTATIVE (field1);
>> + if (DECL_BIT_FIELD_REPRESENTATIVE (field2))
>> + field2 = DECL_BIT_FIELD_REPRESENTATIVE (field1);
Typo: s/field1/field2/
>> +
>> + /* ??? Bitfields can overlap at RTL level so punt on them.
>> + FIXME: RTL expansion should be fixed by adjusting the access
>path
>> + when producing MEM_ATTRs for MEMs which are wider than
>> + the bitfields similarly as done in set_mem_attrs_minus_bitpos.
>*/
>> + if (DECL_BIT_FIELD (field1) && DECL_BIT_FIELD (field2))
>> + return -1;
That's a pity.
thanks,
