[Mesa-dev] [PATCH] nir: Add an IO scalarizing pass using the intrinsic's first_component.
Timothy Arceri
timothy.arceri at collabora.com
Sun Aug 7 10:51:25 UTC 2016
On Sat, 2016-08-06 at 10:15 +1000, Timothy Arceri wrote:
> On Fri, 2016-08-05 at 16:27 -0700, Eric Anholt wrote:
> > vc4 wants to have per-scalar IO load/stores so that dead code
> > elimination
> > can happen on a more granular basis,
Out of interest what is it exactly that you are doing in the backend?
I was looking at brw_do_vector_splitting() and it seems to me that
moving that out of the Intel backend and making it also work on
varyings could be benefical to all drivers as we could extend it to
work across stages which would hopefully also improve varying packing.
Currently it says:
"This skips vectors in uniforms and varyings, which need to be
accessible as vectors for their access by the GL."
But that really only applies to vs inputs and the outward facing stages
of SSOs.
> > which it has been doing in the
> > backend using a multiplication by 4 of the intrinsic's
> > driver_location.
> > We can represent it properly in the NIR using the first_component
> > field,
> > though.
> > ---
> >
> > Next part of the vc4 GTN series. I can't do uniforms because they
> > don't have a first-component field.
> >
> > NIR developers -- is this the right usage of the first-component
> > field? Also, do I need to be splitting up the variable
> > declarations
> > if I do this? There's a check during shader printing that the
> > fractional component of the variable matches the component field of
> > the intrinsic, even if the intrinsics's component value would lie
> > within the vector variable.
>
> This is just because the field was intended to be used with the
> ARB_enhanced_layouts component packing rules, so currently there
> should
> be no way for a component value to lie within the vector variable.
>
> Your use of the component field seems fine to me.
>
> >
> > src/compiler/Makefile.sources | 1 +
> > src/compiler/nir/nir.h | 1 +
> > src/compiler/nir/nir_lower_io_to_scalar.c | 129
> > ++++++++++++++++++++++++++++++
> > 3 files changed, 131 insertions(+)
> > create mode 100644 src/compiler/nir/nir_lower_io_to_scalar.c
> >
> > diff --git a/src/compiler/Makefile.sources
> > b/src/compiler/Makefile.sources
> > index 0ff9b23e4c38..04016d32db56 100644
> > --- a/src/compiler/Makefile.sources
> > +++ b/src/compiler/Makefile.sources
> > @@ -201,6 +201,7 @@ NIR_FILES = \
> > nir/nir_lower_indirect_derefs.c \
> > nir/nir_lower_io.c \
> > nir/nir_lower_io_to_temporaries.c \
> > + nir/nir_lower_io_to_scalar.c \
> > nir/nir_lower_io_types.c \
> > nir/nir_lower_passthrough_edgeflags.c \
> > nir/nir_lower_phis_to_scalar.c \
> > diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> > index 9ce5be2176d9..379a5f8e022e 100644
> > --- a/src/compiler/nir/nir.h
> > +++ b/src/compiler/nir/nir.h
> > @@ -2398,6 +2398,7 @@ void nir_lower_alu_to_scalar(nir_shader
> > *shader);
> > void nir_lower_load_const_to_scalar(nir_shader *shader);
> >
> > void nir_lower_phis_to_scalar(nir_shader *shader);
> > +void nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode
> > mask);
> >
> > void nir_lower_samplers(nir_shader *shader,
> > const struct gl_shader_program
> > *shader_program);
> > diff --git a/src/compiler/nir/nir_lower_io_to_scalar.c
> > b/src/compiler/nir/nir_lower_io_to_scalar.c
> > new file mode 100644
> > index 000000000000..f2345d58acfc
> > --- /dev/null
> > +++ b/src/compiler/nir/nir_lower_io_to_scalar.c
> > @@ -0,0 +1,129 @@
> > +/*
> > + * Copyright © 2016 Broadcom
> > + *
> > + * Permission is hereby granted, free of charge, to any person
> > obtaining a
> > + * copy of this software and associated documentation files (the
> > "Software"),
> > + * to deal in the Software without restriction, including without
> > limitation
> > + * the rights to use, copy, modify, merge, publish, distribute,
> > sublicense,
> > + * and/or sell copies of the Software, and to permit persons to
> > whom
> > the
> > + * Software is furnished to do so, subject to the following
> > conditions:
> > + *
> > + * The above copyright notice and this permission notice
> > (including
> > the next
> > + * paragraph) shall be included in all copies or substantial
> > portions of the
> > + * Software.
> > + *
> > + * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
> > EXPRESS OR
> > + * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
> > MERCHANTABILITY,
> > + * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO
> > EVENT SHALL
> > + * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM,
> > DAMAGES
> > OR OTHER
> > + * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
> > ARISING
> > + * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
> > OTHER DEALINGS
> > + * IN THE SOFTWARE.
> > + */
> > +
> > +#include "nir.h"
> > +#include "nir_builder.h"
> > +
> > +/** @file nir_lower_io_to_scalar.c
> > + *
> > + * Replaces nir_load_input/nir_store_output operations with
> > num_components !=
> > + * 1 with individual per-channel operations.
> > + */
> > +
> > +static void
> > +lower_load_input_to_scalar(nir_builder *b, nir_intrinsic_instr
> > *intr)
> > +{
> > + b->cursor = nir_before_instr(&intr->instr);
> > +
> > + assert(intr->dest.is_ssa);
> > +
> > + nir_ssa_def *loads[4];
> > +
> > + for (unsigned i = 0; i < intr->num_components; i++) {
> > + nir_intrinsic_instr *chan_intr =
> > + nir_intrinsic_instr_create(b->shader, intr->intrinsic);
> > + nir_ssa_dest_init(&chan_intr->instr, &chan_intr->dest,
> > + 1, intr->dest.ssa.bit_size, NULL);
> > + chan_intr->num_components = 1;
> > +
> > + nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
> > + nir_intrinsic_set_component(chan_intr,
> > nir_intrinsic_component(intr) + i);
> > + /* offset */
> > + chan_intr->src[0] = intr->src[0];
> > +
> > + nir_builder_instr_insert(b, &chan_intr->instr);
> > +
> > + loads[i] = &chan_intr->dest.ssa;
> > + }
> > +
> > + nir_ssa_def_rewrite_uses(&intr->dest.ssa,
> > + nir_src_for_ssa(nir_vec(b, loads,
> > + intr-
> > > num_components)));
> > + nir_instr_remove(&intr->instr);
> > +}
> > +
> > +static void
> > +lower_store_output_to_scalar(nir_builder *b, nir_intrinsic_instr
> > *intr)
> > +{
> > + b->cursor = nir_before_instr(&intr->instr);
> > +
> > + nir_ssa_def *value = nir_ssa_for_src(b, intr->src[0], intr-
> > > num_components);
> > +
> > + for (unsigned i = 0; i < intr->num_components; i++) {
> > + if (!(nir_intrinsic_write_mask(intr) & (1 << i)))
> > + continue;
> > +
> > + nir_intrinsic_instr *chan_intr =
> > + nir_intrinsic_instr_create(b->shader, intr->intrinsic);
> > + chan_intr->num_components = 1;
> > +
> > + nir_intrinsic_set_base(chan_intr, nir_intrinsic_base(intr));
> > + nir_intrinsic_set_write_mask(chan_intr, 0x1);
> > + nir_intrinsic_set_component(chan_intr,
> > nir_intrinsic_component(intr) + i);
> > +
> > + /* value */
> > + chan_intr->src[0] = nir_src_for_ssa(nir_channel(b, value,
> > i));
> > + /* offset */
> > + chan_intr->src[1] = intr->src[1];
> > +
> > + nir_builder_instr_insert(b, &chan_intr->instr);
> > + }
> > +
> > + nir_instr_remove(&intr->instr);
> > +}
> > +
> > +void
> > +nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask)
> > +{
> > + nir_foreach_function(function, shader) {
> > + if (function->impl) {
> > + nir_builder b;
> > + nir_builder_init(&b, function->impl);
> > +
> > + nir_foreach_block(block, function->impl) {
> > + nir_foreach_instr_safe(instr, block) {
> > + if (instr->type != nir_instr_type_intrinsic)
> > + continue;
> > +
> > + nir_intrinsic_instr *intr =
> > nir_instr_as_intrinsic(instr);
> > +
> > + if (intr->num_components == 1)
> > + continue;
> > +
> > + switch (intr->intrinsic) {
> > + case nir_intrinsic_load_input:
> > + if (mask & nir_var_shader_in)
> > + lower_load_input_to_scalar(&b, intr);
> > + break;
> > + case nir_intrinsic_store_output:
> > + if (mask & nir_var_shader_out)
> > + lower_store_output_to_scalar(&b, intr);
> > + break;
> > + default:
> > + break;
> > + }
> > + }
> > + }
> > + }
> > + }
> > +}
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