Created attachment 97371 [details] t.shader_test The fragment shader runs in scalar mode, so to do vec4 comparisons we generate multiple compares and join them together using and or ors, depending on the comparison. INTEL_DEBUG=fs,no16 bin/shader_runner t.shader_test -auto generates: cmp.e.f0(8) g3<1>D g2.3<0,1,0>F g2.7<0,1,0>F cmp.e.f0(8) g4<1>D g2.2<0,1,0>F g2.6<0,1,0>F cmp.e.f0(8) g5<1>D g2.1<0,1,0>F g2.5<0,1,0>F cmp.e.f0(8) g6<1>D g2<0,1,0>F g2.4<0,1,0>F and(8) g7<1>D g5<8,8,1>D g6<8,8,1>D and(8) g8<1>D g4<8,8,1>D g7<8,8,1>D and(8) g9<1>D g3<8,8,1>D g8<8,8,1>D and.ne.f0(8) null g9<8,8,1>D 1D ... (+f0) sel ... We could have just predicated all but the first cmp instruction and skipped the and instructions completely: cmp.e.f0(8) g3<1>D g2.3<0,1,0>F g2.7<0,1,0>F (+f0) cmp.e.f0(8) g4<1>D g2.2<0,1,0>F g2.6<0,1,0>F (+f0) cmp.e.f0(8) g5<1>D g2.1<0,1,0>F g2.5<0,1,0>F (+f0) cmp.e.f0(8) g6<1>D g2<0,1,0>F g2.4<0,1,0>F ... (+f0) sel ... I think a similar thing can be done for !=, where the join operation is or.
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