[Mesa-dev] [PATCH 4/4] nir: add ARB_shader_ballot and ARB_shader_group_vote instructions

[Connor Abbott]

I pushed a v2 at
https://cgit.freedesktop.org/~cwabbott0/mesa/log/?h=nir-divergence-v2.
I'm not sure if I like this version better, though. I'll have to think
about it. In the meantime, feel free to take a look.

On Mon, Jun 5, 2017 at 2:43 PM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> On Mon, Jun 5, 2017 at 1:50 PM, Connor Abbott <cwabbott0 at gmail.com> wrote:
>>
>> On Mon, Jun 5, 2017 at 1:37 PM, Jason Ekstrand <jason at jlekstrand.net>
>> wrote:
>> > I'm not sure how I feel about having these as ALU operations.  ALU
>> > operations are generally pure functions (with the exception derivative)
>> > that
>> > can be re-ordered at will.  I don't really like breaking that.  In fact,
>> > I'd
>> > almost be inclined to make derivatives intrinsics and just special-case
>> > them
>> > in constant folding.  Thoughts?
>>
>> I wasn't too sure about this either. It is a little weird to make
>> these ALU instructions. I followed the rule here that if something can
>> be constant-folded, it should be an ALU instruction, but I guess you
>> can argue that it's just a coincidence that these can be
>> constant-folded anyways.
>
>
> Yeah.  As subgroup ops get more complicated, I think a log of the subgroup
> operations can be constant-folded after a fashion but the rules get weird
> fast.
>
>>
>> I guess the main downside is that it would be
>> impossible to make nir_algebraic patterns with these, although I can't
>> think of too many simple pattern-matching type things you'd want to do
>> on these instructions anyways.
>
>
> Yeah.  My gut also tells me that shaders which are "advanced" enough to use
> subgroup features probably don't need (or it can't be done) the massive
> reductions we do for D3D9-generated shaders.
>
>>
>> Maybe something like not(any(not(foo)))
>> -> all(foo) and vice-versa?
>>
>> >
>> > On Mon, Jun 5, 2017 at 12:22 PM, Connor Abbott <cwabbott0 at gmail.com>
>> > wrote:
>> >>
>> >> Signed-off-by: Connor Abbott <cwabbott0 at gmail.com>
>> >> ---
>> >>  src/compiler/nir/nir_intrinsics.h | 14 ++++++++++++++
>> >>  src/compiler/nir/nir_opcodes.py   | 18 ++++++++++++++++--
>> >>  2 files changed, 30 insertions(+), 2 deletions(-)
>> >>
>> >> diff --git a/src/compiler/nir/nir_intrinsics.h
>> >> b/src/compiler/nir/nir_intrinsics.h
>> >> index 21e7d90..157df7f 100644
>> >> --- a/src/compiler/nir/nir_intrinsics.h
>> >> +++ b/src/compiler/nir/nir_intrinsics.h
>> >> @@ -330,6 +330,20 @@ SYSTEM_VALUE(channel_num, 1, 0, xx, xx, xx)
>> >>  SYSTEM_VALUE(alpha_ref_float, 1, 0, xx, xx, xx)
>> >>  SYSTEM_VALUE(layer_id, 1, 0, xx, xx, xx)
>> >>  SYSTEM_VALUE(view_index, 1, 0, xx, xx, xx)
>> >> +SYSTEM_VALUE(subgroup_invocation, 1, 0, xx, xx, xx)
>> >> +
>> >> +
>> >> +/* ARB_shader_ballot instructions */
>> >> +
>> >> +SYSTEM_VALUE(subgroup_eq_mask, 1, 0, xx, xx, xx)
>> >> +SYSTEM_VALUE(subgroup_ge_mask, 1, 0, xx, xx, xx)
>> >> +SYSTEM_VALUE(subgroup_gt_mask, 1, 0, xx, xx, xx)
>> >> +SYSTEM_VALUE(subgroup_le_mask, 1, 0, xx, xx, xx)
>> >> +SYSTEM_VALUE(subgroup_lt_mask, 1, 0, xx, xx, xx)
>> >> +
>> >> +INTRINSIC(ballot, 1, ARR(0), true, 0, 0, 0, xx, xx, xx,
>> >> +          NIR_INTRINSIC_CAN_ELIMINATE | NIR_INTRINSIC_CAN_REORDER |
>> >> +          NIR_INTRINSIC_CROSS_THREAD)
>> >>
>> >>  /* Blend constant color values.  Float values are clamped. */
>> >>  SYSTEM_VALUE(blend_const_color_r_float, 1, 0, xx, xx, xx)
>> >> diff --git a/src/compiler/nir/nir_opcodes.py
>> >> b/src/compiler/nir/nir_opcodes.py
>> >> index be3ab6d..05a80b2 100644
>> >> --- a/src/compiler/nir/nir_opcodes.py
>> >> +++ b/src/compiler/nir/nir_opcodes.py
>> >> @@ -120,8 +120,10 @@ def opcode(name, output_size, output_type,
>> >> input_sizes, input_types,
>> >>                            input_types, convergent, cross_thread,
>> >>                            algebraic_properties, const_expr)
>> >>
>> >> -def unop_convert(name, out_type, in_type, const_expr):
>> >> -   opcode(name, 0, out_type, [0], [in_type], "", const_expr)
>> >> +def unop_convert(name, out_type, in_type, const_expr,
>> >> cross_thread=False,
>> >> +                 convergent=False):
>> >> +   opcode(name, 0, out_type, [0], [in_type], "", const_expr,
>> >> convergent,
>> >> +          cross_thread)
>> >>
>> >>  def unop(name, ty, const_expr, convergent=False, cross_thread=False):
>> >>     opcode(name, 0, ty, [0], [ty], "", const_expr, convergent,
>> >> cross_thread)
>> >> @@ -355,6 +357,18 @@ for i in xrange(1, 5):
>> >>     for j in xrange(1, 5):
>> >>        unop_horiz("fnoise{0}_{1}".format(i, j), i, tfloat, j, tfloat,
>> >> "0.0f")
>> >>
>> >> +# ARB_shader_ballot instructions
>> >> +
>> >> +opcode("read_invocation", 0, tuint, [0, 1], [tuint, tuint32], "",
>> >> "src0",
>> >> +        cross_thread=True)
>> >> +unop("read_first_invocation", tuint, "src0", cross_thread=True)
>> >> +
>> >> +# ARB_shader_group_vote instructions
>> >> +
>> >> +unop("any_invocations", tbool, "src0", cross_thread=True)
>> >> +unop("all_invocations", tbool, "src0", cross_thread=True)
>> >> +unop("all_invocations_equal", tbool, "true", cross_thread=True)
>> >> +
>> >>  def binop_convert(name, out_type, in_type, alg_props, const_expr):
>> >>     opcode(name, 0, out_type, [0, 0], [in_type, in_type], alg_props,
>> >> const_expr)
>> >>
>> >> --
>> >> 2.9.3
>> >>
>> >> _______________________________________________
>> >> mesa-dev mailing list
>> >> mesa-dev at lists.freedesktop.org
>> >> https://lists.freedesktop.org/mailman/listinfo/mesa-dev
>> >
>> >
>
>