<html> <head> <base href="https://bugs.freedesktop.org/"> </head> <body> <div> <a class="bz_bug_link bz_status_CLOSED bz_closed" title="CLOSED FIXED - Dual-Core CPU E5500 / G45: RetroArch with reicast core results in corrupted graphics" href="https://bugs.freedesktop.org/show_bug.cgi?id=107212#c41">Comment # 41</a> on <a class="bz_bug_link bz_status_CLOSED bz_closed" title="CLOSED FIXED - Dual-Core CPU E5500 / G45: RetroArch with reicast core results in corrupted graphics" href="https://bugs.freedesktop.org/show_bug.cgi?id=107212">bug 107212</a> from <a class="email" href="mailto:diego.viola@gmail.com" title="Diego Viola <diego.viola@gmail.com>"> Diego Viola</a> <pre>commit 08a5c395abdafd0d7556060596f78c238b4a989f Author: Kenneth Graunke <<a href="mailto:kenneth@whitecape.org">kenneth@whitecape.org</a>> Date: Thu Aug 2 15:02:18 2018 -0700 intel: Fix SIMD16 unaligned payload GRF reads on Gen4-5. When the SIMD16 Gen4-5 fragment shader payload contains source depth (g2-3), destination stencil (g4), and destination depth (g5-6), the single register of stencil makes the destination depth unaligned. We were generating this instruction in the RT write payload setup: mov(16) m14<1>F g5<8,8,1>F { align1 compr }; which is illegal, instructions with a source region spanning more than one register need to be aligned to even registers. This is because the hardware implicitly does (nr | 1) instead of (nr + 1) when splitting the compressed instruction into two mov(8)'s. I believe this would cause the hardware to load g5 twice, replicating subspan 0-1's destination depth to subspan 2-3. This showed up as 2x2 artifact blocks in both TIS-100 and Reicast. Normally, we rely on the register allocator to even-align our virtual GRFs. But we don't control the payload, so we need to lower SIMD widths to make it work. To fix this, we teach lower_simd_width about the restriction, and then call it again after lower_load_payload (which is what generates the offending MOV). Fixes: 8aee87fe4cce0a883867df3546db0e0a36908086 (i965: Use SIMD16 instead of SIMD8 on Gen4 when possible.) Bugzilla: <a class="bz_bug_link bz_status_CLOSED bz_closed" title="CLOSED FIXED - Dual-Core CPU E5500 / G45: RetroArch with reicast core results in corrupted graphics" href="show_bug.cgi?id=107212">https://bugs.freedesktop.org/show_bug.cgi?id=107212</a> Bugzilla: <a class="bz_bug_link bz_status_RESOLVED bz_closed" title="RESOLVED FIXED - [G965] Some objects in Neverwinter Nights Linux version not displayed correctly" href="show_bug.cgi?id=13728">https://bugs.freedesktop.org/show_bug.cgi?id=13728</a> Reviewed-by: Jason Ekstrand <<a href="mailto:jason@jlekstrand.net">jason@jlekstrand.net</a>> Tested-by: Diego Viola <<a href="mailto:diego.viola@gmail.com">diego.viola@gmail.com</a>></pre> </div> <hr> You are receiving this mail because: <ul> <li>You are the QA Contact for the bug.</li> </ul> </body> </html>