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.
>>>> if (!ix86_tune_features[X86_TUNE_AVX256_UNALIGNED_LOAD_OPTIMAL]
>>>> && !(opts_set->x_target_flags & MASK_AVX256_SPLIT_UNALIGNED_LOAD))
>>>> opts->x_target_flags |= MASK_AVX256_SPLIT_UNALIGNED_LOAD;
>>>
>>> MINIMUM_ALIGNMENT keeps track stack alignment. It is OK
>>> to disable STV for -mpreferred-stack-boundary=2. But you should
>>> also update ix86_minimum_alignment to make sure that STV is
>>> disabled before returning 32 for DImode.
>>
>> If -mpreferred-stack-boundary=2 then STV is disabled, if STV is enabled then
>> -mpreferred-stack-boundary>=3 and this condition in
>> ix86_minimum_alignment works:
>>
>> if (TARGET_64BIT || align != 64 || ix86_preferred_stack_boundary >= 64)
>> return align;
>>
>
> No, you shouldn't make assumptions in ix86_minimum_alignment. You
> should check explicitly that STV is disabled in ix86_minimum_alignment.
>
>
> --
> H.J.
--
H.J.
