From: Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>
To: Jani Nikula <jani.nikula@linux.intel.com>,
Joonas Lahtinen <joonas.lahtinen@linux.intel.com>,
Tvrtko Ursulin <tursulin@ursulin.net>,
Intel-gfx@lists.freedesktop.org
Subject: Re: [PATCH] drm/i915: More reasonable memcpy unroll in i915_gem_swizzle_page
Date: Tue, 20 Dec 2016 09:48:18 +0000 [thread overview]
Message-ID: <ddcd4d91-7f9e-6adc-61b7-984c261c4df8@linux.intel.com> (raw)
In-Reply-To: <87pokomcon.fsf@intel.com>
On 19/12/2016 10:32, Jani Nikula wrote:
> On Mon, 19 Dec 2016, Joonas Lahtinen <joonas.lahtinen@linux.intel.com> wrote:
>> On ma, 2016-12-19 at 09:19 +0000, Tvrtko Ursulin wrote:
>>> +++ b/drivers/gpu/drm/i915/i915_gem_fence_reg.c
>>> @@ -631,9 +631,9 @@ i915_gem_swizzle_page(struct page *page)
>>> vaddr = kmap(page);
>>>
>>> for (i = 0; i < PAGE_SIZE; i += 128) {
>>> - memcpy(temp, &vaddr[i], 64);
>>> + memcpy(&temp[0], &vaddr[i], 64);
>>> memcpy(&vaddr[i], &vaddr[i + 64], 64);
>>> - memcpy(&vaddr[i + 64], temp, 64);
>>> + memcpy(&vaddr[i + 64], &temp[0], 64);
>>
>> This reeks of GCC bug badly. So I would not apply as next time the bug
>> could be into the another direction.
>
> Agreed. Please file a bug over at https://gcc.gnu.org/bugs/
Bug filed: https://gcc.gnu.org/bugzilla/show_bug.cgi?id=78869
Potentially useful code generation explorer picked up from #gcc:
https://godbolt.org/g/XNioHs
Regards,
Tvrtko
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prev parent reply other threads:[~2016-12-20 9:48 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-19 9:19 [PATCH] drm/i915: More reasonable memcpy unroll in i915_gem_swizzle_page Tvrtko Ursulin
2016-12-19 9:46 ` ✗ Fi.CI.BAT: warning for " Patchwork
2016-12-19 9:47 ` [PATCH] " Joonas Lahtinen
2016-12-19 10:32 ` Jani Nikula
2016-12-20 9:48 ` Tvrtko Ursulin [this message]
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