an) On Mon, Nov 12, 2018 at 12:37 AM Jason Ekstrand <[email protected]> wrote: > > On November 11, 2018 16:36:16 Karol Herbst <[email protected]> wrote: > > > On Sun, Nov 11, 2018 at 10:48 PM Jason Ekstrand <[email protected]> > > wrote: > >> > >> On Sun, Nov 11, 2018 at 3:35 PM Plamena Manolova > >> <[email protected]> wrote: > >>> > >>> > >>> Lowering shader variables which depend on the local work group > >>> size being available in nir_lower_system_values is only possible > >>> if the local work group size isn't variable, otherwise this should > >>> be handled by the native driver (if it supports > >>> ARB_compute_variable_group_size). > >>> > >>> > >>> Signed-off-by: Plamena Manolova <[email protected]> > >>> --- > >>> src/compiler/nir/nir_lower_system_values.c | 22 ++++++++++++++++++++++ > >>> 1 file changed, 22 insertions(+) > >>> > >>> > >>> diff --git a/src/compiler/nir/nir_lower_system_values.c > >>> b/src/compiler/nir/nir_lower_system_values.c > >>> index bde7eb1180..6fdf9f9c51 100644 > >>> --- a/src/compiler/nir/nir_lower_system_values.c > >>> +++ b/src/compiler/nir/nir_lower_system_values.c > >>> @@ -77,6 +77,15 @@ convert_block(nir_block *block, nir_builder *b) > >>> * "The value of gl_GlobalInvocationID is equal to > >>> * gl_WorkGroupID * gl_WorkGroupSize + gl_LocalInvocationID" > >>> */ > >>> + > >>> + /* > >>> + * If the local work group size is variable we can't lower the > >>> global > >>> + * invocation id here. > >> > >> > >> Why not? > >> > >>> > >>> > >>> + */ > >>> + if (b->shader->info.cs.local_size_variable) { > >> > >> > >> I didn't realize we'd added a bit for this. At one point in time, Karol > >> had patches which had it keyed off of the size being zero. Having a > >> separate bit is probably fine, it just surpised me. > > > > > > yeah.. I guess I choose that, because I had nothing better. But I > > guess having the size being 0 is good enough as long as we sure it is > > 0 in relevant cases. > > It's fine. I just thought we'd chosen a different convention bit there's > nothing wrong with it. I was just surprised. That's all. > > > > >>> > >>> > >>> + break; > >>> + } > >>> + > >>> nir_ssa_def *group_size = build_local_group_size(b); > >>> nir_ssa_def *group_id = nir_load_work_group_id(b); > >>> nir_ssa_def *local_id = nir_load_local_invocation_id(b); > >>> @@ -115,6 +124,11 @@ convert_block(nir_block *block, nir_builder *b) > >>> } > >>> > >>> > >>> case SYSTEM_VALUE_LOCAL_GROUP_SIZE: { > >>> + /* If the local work group size is variable we can't lower it > >>> here */ > >>> + if (b->shader->info.cs.local_size_variable) { > >>> + break; > >>> + } > >>> + > >>> sysval = build_local_group_size(b); > >>> break; > >>> } > >>> @@ -189,6 +203,14 @@ convert_block(nir_block *block, nir_builder *b) > >>> break; > >>> > >>> > >>> case SYSTEM_VALUE_GLOBAL_GROUP_SIZE: { > >>> + /* > >>> + * If the local work group size is variable we can't lower the > >>> global > >>> + * group size here. > >>> + */ > >>> + if (b->shader->info.cs.local_size_variable) { > >>> + break; > >>> + } > >> > >> > >> Why can't we lower the global size? It seems like we would want the below > >> multiplication regardless of whether the local size is constant. > > > > well I am not sure about ARB_compute_variable_group_size, but at least > > in CL you know nothing about it at compile time as you specify > > everything when you enqueue the kernel. Could be that the number of > > work_groups is fixed with ARB_compute_variable_group_size though > > Why can't you multiply two non-constant things together? Maybe the driver > can do something now efficient but it's not clear to me that this isn't > what we want. >
oh, you meant it that way. Mhh, I actually wrote the patch adding build_local_group_size to handle that inside that function (lower to constants if known, intrinsics otherwise) as we need the local_size for three different system values. I have a patch for that for CL, but the patch itself is a bit hacky right now (as in, it doesn't handle it inside build_local_group_size). And I think that patch misses handling for SYSTEM_VALUE_GLOBAL_GROUP_SIZE anyhow. For CL we even want to add a global_invocation_id_offset system value and add it when handling SYSTEM_VALUE_GLOBAL_INVOCATION_ID, but that we can ignore for now. Anyhow, I think it would make sense to move the check into build_local_group_sized and either return a constant value or an intrinsic loading the value from the driver. I just remember vaguely that I think somebody brought that up months ago and there was a good reason not to do that for every driver? > > > >>> > >>> > >>> + > >>> nir_ssa_def *group_size = build_local_group_size(b); > >>> nir_ssa_def *num_work_groups = nir_load_num_work_groups(b); > >>> sysval = nir_imul(b, group_size, num_work_groups); > >>> -- > >>> 2.11.0 > >>> > >>> > >>> _______________________________________________ > >>> mesa-dev mailing list > >>> [email protected] > >>> https://lists.freedesktop.org/mailman/listinfo/mesa-dev > > > _______________________________________________ mesa-dev mailing list [email protected] https://lists.freedesktop.org/mailman/listinfo/mesa-dev
