From mboxrd@z Thu Jan 1 00:00:00 1970 From: bugzilla-daemon@freedesktop.org Subject: [Bug 97988] [radeonsi] playing back videos with VDPAU exhibits deinterlacing/anti-aliasing issues not visible with VA-API Date: Sat, 01 Oct 2016 18:41:03 +0000 Message-ID: References: Mime-Version: 1.0 Content-Type: multipart/mixed; boundary="===============0962322608==" Return-path: Received: from culpepper.freedesktop.org (culpepper.freedesktop.org [131.252.210.165]) by gabe.freedesktop.org (Postfix) with ESMTP id C36D76E130 for ; Sat, 1 Oct 2016 18:41:02 +0000 (UTC) In-Reply-To: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dri-devel-bounces@lists.freedesktop.org Sender: "dri-devel" To: dri-devel@lists.freedesktop.org List-Id: dri-devel@lists.freedesktop.org --===============0962322608== Content-Type: multipart/alternative; boundary="14753472620.FbC9C.22853"; charset="UTF-8" --14753472620.FbC9C.22853 Date: Sat, 1 Oct 2016 18:41:02 +0000 MIME-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://bugs.freedesktop.org/ Auto-Submitted: auto-generated https://bugs.freedesktop.org/show_bug.cgi?id=3D97988 --- Comment #11 from Marek Ol=C5=A1=C3=A1k --- Thanks Grigori. GLSL: color =3D fract(gl_FragCoord.y / 2) < 0.5 ? texture(texture0, texcoord0) : texture(texture1, texcoord0); texture0 and texture1 are SMEM loads. LLVM (SimplifyCFG) transforms it to: color =3D texture(fract(gl_FragCoord.y / 2) < 0.5 ? texture0 : texture1, texcoord0); That's a nice transformation. You don't have to use 2 SMEM loads, you can j= ust use one SMEM load depending on the result of the condition. The problem is gl_FragCoord.y is a VGPR and texture0/1 are SGPRs, therefore flat VMEM loads are used to load the descriptors. However, image_sample requires descriptors in SGPRs, so v_readfirstlane is used. That effectively uses the result of the condition from the first active lane, discarding the results from all other lanes. The result would be exactly the same if the compiler did: v_readfirstlane s0, gl_FragCoord.y; The test case seems pretty trivial I wonder how many other apps are affecte= d. --=20 You are receiving this mail because: You are the assignee for the bug.= --14753472620.FbC9C.22853 Date: Sat, 1 Oct 2016 18:41:02 +0000 MIME-Version: 1.0 Content-Type: text/html; charset="UTF-8" Content-Transfer-Encoding: quoted-printable X-Bugzilla-URL: http://bugs.freedesktop.org/ Auto-Submitted: auto-generated

Commen= t # 11 on bug 97988<= /a> from Marek Ol=C5=A1=C3=A1k 
Thanks Grigori.

GLSL:
  color =3D fract(gl_FragCoord.y / 2) < 0.5 ?
             texture(texture0, texcoord0) :
             texture(texture1, texcoord0);

texture0 and texture1 are SMEM loads.

LLVM (SimplifyCFG) transforms it to:
  color =3D texture(fract(gl_FragCoord.y / 2) < 0.5 ? texture0 : texture=
1,
                  texcoord0);

That's a nice transformation. You don't have to use 2 SMEM loads, you can j=
ust
use one SMEM load depending on the result of the condition.

The problem is gl_FragCoord.y is a VGPR and texture0/1 are SGPRs, therefore
flat VMEM loads are used to load the descriptors. However, image_sample
requires descriptors in SGPRs, so v_readfirstlane is used. That effectively
uses the result of the condition from the first active lane, discarding the
results from all other lanes. The result would be exactly the same if the
compiler did: v_readfirstlane s0, gl_FragCoord.y;

The test case seems pretty trivial I wonder how many other apps are affecte=
d.

You are receiving this mail because:
  • You are the assignee for the bug.
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