Re: PING^1: [PATCH] Add TYPE_EMPTY_RECORD for C++ empty class

["H.J. Lu" <hjl.tools@gmail.com>]

On Wed, Mar 16, 2016 at 10:02 AM, H.J. Lu <hjl.tools@gmail.com> wrote:
> On Wed, Mar 16, 2016 at 9:58 AM, Jason Merrill <jason@redhat.com> wrote:
>> On 03/16/2016 08:38 AM, H.J. Lu wrote:
>>>
>>> FAIL: g++.dg/abi/pr60336-1.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx9true_type
>>> FAIL: g++.dg/abi/pr60336-5.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx9true_type
>>> FAIL: g++.dg/abi/pr60336-6.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx9true_type
>>> FAIL: g++.dg/abi/pr60336-7.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx9true_type
>>> FAIL: g++.dg/abi/pr60336-9.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx9true_type
>>> FAIL: g++.dg/abi/pr68355.C   scan-assembler jmp[\t
>>> ]+[^$]*?_Z3xxx17integral_constantIbLb1EE
>>
>>
>> These pass for me on x86_64, but I do see calls with -m32.
>>
>>> They are expected since get_ref_base_and_extent needs to be
>>> changed to set bitsize to 0 for empty types so that when
>>> ref_maybe_used_by_call_p_1 calls get_ref_base_and_extent to
>>> get 0 as the maximum size on empty type.  Otherwise, find_tail_calls
>>> won't perform tail call optimization for functions with empty type
>>> parameters.
>>
>>
>> That isn't why the optimization isn't happening in pr68355 with -m32; the
>> .optimized dump has
>>
>>   xxx (D.2289); [tail call]
>>
>> Rather, the failure seems to happen in load_register_parameter, at
>>
>>>               /* Check for overlap with already clobbered argument area,
>>>                  providing that this has non-zero size.  */
>>>               if (is_sibcall
>>>                   && (size == 0
>>>                       || mem_overlaps_already_clobbered_arg_p
>>>                                            (XEXP (args[i].value, 0),
>>> size)))
>>>                 *sibcall_failure = 1;
>>
>>
>> The code seems to contradict the comment, and seems to have been broken by
>> r162402.  Applying this additional patch fixes those tests.
>>
>
> I am running the full test now.

On x86-64, I got

export/gnu/import/git/sources/gcc/gcc/testsuite/gcc.dg/ubsan/object-size-9.c:11:13:
runtime error: load of address 0x000000600ffa with insufficient space
for an object of type 'char'
0x000000600ffa: note: pointer points here
<memory cannot be printed>
PASS: gcc.dg/ubsan/object-size-9.c   -O2  execution test
FAIL: gcc.dg/ubsan/object-size-9.c   -O2  output pattern test
Output was:


-- 
H.J.