On Mon, Mar 16, 2015 at 9:21 PM, Jason Ekstrand <ja...@jlekstrand.net> wrote: > Because of the way that NIR does conditionals, we get them in any old SSA > value. The actual boolean value used in the select or if is x != 0. > Previously, we handled this by emitting a mov.nz to move the value to the > flag register. However, this almost always adds at least one if not two > instructions because we have to go through the VGRF when we could be > comparing directly to the flag and then using the flag. > > With this commit, we simply re-emit the instruction that produces the value > when we can. By doing so, we can use the flag directly and we trust in CSE > to clean up for us if it can. > > Shader-db results: > > total instructions in shared programs: 4164120 -> 4110511 (-1.29%) > instructions in affected programs: 2397042 -> 2343433 (-2.24%) > helped: 13167 > HURT: 31 > GAINED: 4 > LOST: 4 > ---
A small change to the cmod_propagation branch accomplishes most of this -- total instructions in shared programs: 7850607 -> 7793875 (-0.72%) instructions in affected programs: 2425140 -> 2368408 (-2.34%) helped: 13502 HURT: 0 GAINED: 1 LOST: 5 We always emit the MOV.NZ with a D-typed destination, which cmod_propagate won't combine with a CMP with an F-typed destination. I don't think we ever emit MOV.NZ without NIR, so no changes without it. Let me play with this some more. _______________________________________________ mesa-dev mailing list mesa-dev@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/mesa-dev
