Hello all,
Hardware; Radeon 6850HD, Mesa: mesa 17.0.1 and git (sha 531887), llvm: 4.0.0 Playing a bit around with the Unreal Editor I was confronted with the same error message reported in #99349, i.e. "Failed to build shader (translation from TGSI). After some digging though the code I found that the TGSI code [1] of the offending shader reserves 151 temporaries so that the available 128 GPRs are already allocated right from the start, and when the operation "MUL TEMP[11], CONST[26], CONST[23]" is translated to byte code, both constants are read from the cfile region, because tgsi_split_constant could not move one constant to a proper GPR. As one can see in the TGSI dump [1], the shader does not really use 151 temporaries, only 40 are actually also addresses as source, to all the other temps values are just written once (assuming the the TGSI notation is OP DEST, SRC0, SRC1 ...). My questions are now: Does the GSLS-TGSI stage of the compilation do any optimizations? Specifically, should the unused temporaries be eliminated in that step and that I get this TGSI-dump is actually a bug in this compilation stage? (In the Gallium3D wikipedia article [2] it is written that there is a TGSI optimization stage.) As far as I understand there is a optimization pass done after the TGSI translation, but because of the nature of the problem the shader is rejected before. Would it make sense to implement a patch that would work around this problem by reserving some GORs to move constants to (and the temporary that is now ctx.temp_reg), and then test the number of allocated registers only after the byte code optimization? I partially implemented something like this [3] when I tried to find the source of the bug, so I could clean that up and propose a patch, so far the graphical output is clobbered though. many thank, Gert [1] https://bugs.freedesktop.org/attachment.cgi?id=131567 (12kb, xz compressed) [2] https://en.wikipedia.org/wiki/Gallium3D#Tungsten_Graphics_Shader_In frastructure [3] https://github.com/gerddie/mesa _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org https://lists.freedesktop.org/mailman/listinfo/mesa-dev
