Hello, I've been looking at removing some of the optimization passes ahead of nouveau's codegen, and noticed a huge increase in instructions for some shaders. Upon further investigation, I think there's an error in the renumbering pass, which causes a bunch of values to be overwritten and thus dead (which nouveau then dutifully eliminates).
Here's a TGSI sequence without renumbering: 94: MUL TEMP[56].xyz, TEMP[34].xxxx, TEMP[55].xyzz 95: MOV TEMP[32].yzw, TEMP[56].yxyz 96: FSGE TEMP[57].x, TEMP[48].xxxx, IMM[3].zzzz 97: UIF TEMP[57].xxxx :0 98: MOV TEMP[58].xyz, TEMP[56].xyzx 99: ELSE :0 100: MOV TEMP[58].xyz, IMM[3].zzzz 101: ENDIF 102: MOV TEMP[59].xyz, TEMP[58].xyzx 103: MOV TEMP[32].xyz, TEMP[58].xyzx And here's the same sequence with merging and renumbering enabled: 94: MUL TEMP[5].xyz, TEMP[7].xxxx, TEMP[5].xyzz 95: MOV TEMP[5].yzw, TEMP[5].yxyz 96: FSGE TEMP[7].x, TEMP[13].xxxx, IMM[3].zzzz 97: UIF TEMP[7].xxxx :0 98: MOV TEMP[5].xyz, TEMP[5].xyzx 99: ELSE :0 100: MOV TEMP[5].xyz, IMM[3].zzzz 101: ENDIF 102: MOV TEMP[16].xyz, TEMP[5].xyzx 103: MOV TEMP[5].xyz, TEMP[5].xyzx Note that the IF selects between TEMP[56].xyz and some immediate, where TEMP[56].xyz is the output of the MUL at label 94. However in the merged/renumbered version, it immediately overwrites TEMP[5].yzw with TEMP[5].xyz. If things had been adjusted to then use TEMP[5].yzw instead of .xyz, then it would make sense, but it doesn't seem like such an adjustment was made. Mainly my question is... does my analysis appear to be correct? I guess it should avoid merges (or renumbers?) when it does a MOV with a non-identity swizzle? Thanks, -ilia P.S. FTR, this particular shader is from "Dungeon Defenders", but it's hardly the only example. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
