On Thu, Jan 28, 2016 at 2:06 AM, Ilya Enkovich <enkovich....@gmail.com> wrote:
> 2016-01-28 9:00 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>> On Wed, Jan 27, 2016 at 8:36 AM, H.J. Lu <hjl.to...@gmail.com> wrote:
>>> On Wed, Jan 27, 2016 at 8:29 AM, Ilya Enkovich <enkovich....@gmail.com>
>>> wrote:
>>>> 2016-01-27 19:18 GMT+03:00 H.J. Lu <hjl.to...@gmail.com>:
>>>>> On Wed, Jan 27, 2016 at 8:11 AM, Ilya Enkovich <enkovich....@gmail.com>
>>>>> wrote:
>>>>>> On 27 Jan 16:44, Jakub Jelinek wrote:
>>>>>>> On Wed, Jan 27, 2016 at 06:34:41PM +0300, Ilya Enkovich wrote:
>>>>>>> > @@ -5453,6 +5443,11 @@ ix86_option_override_internal (bool
>>>>>>> > main_args_p,
>>>>>>> > opts->x_target_flags |= MASK_VZEROUPPER;
>>>>>>> > if (!(opts_set->x_target_flags & MASK_STV))
>>>>>>> > opts->x_target_flags |= MASK_STV;
>>>>>>> > + /* Disable STV if -mpreferred-stack-boundary={2,3} - the needed
>>>>>>>
>>>>>>> The comment doesn't match the code, you disable STV only for
>>>>>>> -mpreferred-stack-boundary=2.
>>>>>>
>>>>>> Thanks, here is an updated version.
>>>>>>
>>>>>> Ilya
>>>>>> --
>>>>>> gcc/
>>>>>>
>>>>>> 2016-01-27 Jakub Jelinek <ja...@redhat.com>
>>>>>> Ilya Enkovich <enkovich....@gmail.com>
>>>>>>
>>>>>> PR target/69454
>>>>>> * config/i386/i386.c (convert_scalars_to_vector): Remove
>>>>>> stack alignment fixes.
>>>>>> (ix86_option_override_internal): Disable TARGET_STV if stack
>>>>>> is not properly aligned.
>>>>>>
>>>>>> gcc/testsuite/
>>>>>>
>>>>>> 2016-01-27 Ilya Enkovich <enkovich....@gmail.com>
>>>>>>
>>>>>> PR target/69454
>>>>>> * gcc.target/i386/pr69454-1.c: New test.
>>>>>> * gcc.target/i386/pr69454-2.c: New test.
>>>>>>
>>>>>>
>>>>>> diff --git a/gcc/config/i386/i386.c b/gcc/config/i386/i386.c
>>>>>> index 34b57a4..9fb8db8 100644
>>>>>> --- a/gcc/config/i386/i386.c
>>>>>> +++ b/gcc/config/i386/i386.c
>>>>>> @@ -3588,16 +3588,6 @@ convert_scalars_to_vector ()
>>>>>> bitmap_obstack_release (NULL);
>>>>>> df_process_deferred_rescans ();
>>>>>>
>>>>>> - /* Conversion means we may have 128bit register spills/fills
>>>>>> - which require aligned stack. */
>>>>>> - if (converted_insns)
>>>>>> - {
>>>>>> - if (crtl->stack_alignment_needed < 128)
>>>>>> - crtl->stack_alignment_needed = 128;
>>>>>> - if (crtl->stack_alignment_estimated < 128)
>>>>>> - crtl->stack_alignment_estimated = 128;
>>>>>> - }
>>>>>> -
>>>>>> return 0;
>>>>>> }
>>>>>>
>>>>>> @@ -5453,6 +5443,11 @@ ix86_option_override_internal (bool main_args_p,
>>>>>> opts->x_target_flags |= MASK_VZEROUPPER;
>>>>>> if (!(opts_set->x_target_flags & MASK_STV))
>>>>>> opts->x_target_flags |= MASK_STV;
>>>>>> + /* Disable STV if -mpreferred-stack-boundary=2 - the needed
>>>>>> + stack realignment will be extra cost the pass doesn't take into
>>>>>> + account and the pass can't realign the stack. */
>>>>>> + if (ix86_preferred_stack_boundary < 64)
>>>>>> + opts->x_target_flags &= ~MASK_STV;
>>
>> This won't work for 32-bit incoming stack boundary and 64-bit preferred
>> stack boundary. In this case, STV won't be off. When LRA needs 64-bit
>> aligned stack slot, stack must be realigned. But for leaf function, we may
>> not realign stack if ix86_minimum_alignment returns 32 for DImode. You
>> must either add assert (!TARGET_STV) before returning 32 for DImode or
>> return 64 for DImode if STV is on in ix86_minimum_alignment.
>
> TARGET_STV doesn't mean STV pass will run. We can check alignment in STV
> pass gate and this assert would be wrong. If we decide STV to be dependent on
> stack alignment then we shouldn't make alignment be dependent on STV. I can
> add
> assert into convert_scalars_to_vector to check
> crtl->stack_alignment_estimated >= 64
> by that moment.
>
The bottom line is ix86_minimum_alignment must return the correct
number for DImode or you can just turn off STV. My suggestion is
to use my patch.
--
H.J.
