[Mesa-dev] [PATCH 01/11] intel/compiler: lower 16-bit integer extended math instructions
Jason Ekstrand
jason at jlekstrand.net
Tue Apr 24 13:56:26 UTC 2018
It may be useful to just use nir_algebraic for this. We already do for
trig workarounds. It's more painful from a build-system perspective but,
in general, the fewer hand-rolled algebraic lowering passes we have, the
better.
On Wed, Apr 11, 2018 at 12:20 AM, Iago Toral Quiroga <itoral at igalia.com>
wrote:
> The hardware doesn't support 16-bit integer types, so we need to implement
> these using 32-bit integer instructions and then convert the result back
> to 16-bit.
> ---
> src/intel/Makefile.sources | 1 +
> src/intel/compiler/brw_nir.c | 2 +
> src/intel/compiler/brw_nir.h | 2 +
> src/intel/compiler/brw_nir_lower_16bit_int_math.c | 108
> ++++++++++++++++++++++
> src/intel/compiler/meson.build | 1 +
> 5 files changed, 114 insertions(+)
> create mode 100644 src/intel/compiler/brw_nir_lower_16bit_int_math.c
>
> diff --git a/src/intel/Makefile.sources b/src/intel/Makefile.sources
> index 91c71a8dfaf..2cd76961ea4 100644
> --- a/src/intel/Makefile.sources
> +++ b/src/intel/Makefile.sources
> @@ -79,6 +79,7 @@ COMPILER_FILES = \
> compiler/brw_nir_analyze_boolean_resolves.c \
> compiler/brw_nir_analyze_ubo_ranges.c \
> compiler/brw_nir_attribute_workarounds.c \
> + compiler/brw_nir_lower_16bit_int_math.c \
> compiler/brw_nir_lower_cs_intrinsics.c \
> compiler/brw_nir_opt_peephole_ffma.c \
> compiler/brw_nir_tcs_workarounds.c \
> diff --git a/src/intel/compiler/brw_nir.c b/src/intel/compiler/brw_nir.c
> index 69ab162f888..2e5754076ed 100644
> --- a/src/intel/compiler/brw_nir.c
> +++ b/src/intel/compiler/brw_nir.c
> @@ -638,6 +638,8 @@ brw_preprocess_nir(const struct brw_compiler
> *compiler, nir_shader *nir)
> nir_lower_isign64 |
> nir_lower_divmod64);
>
> + brw_nir_lower_16bit_int_math(nir);
> +
> nir = brw_nir_optimize(nir, compiler, is_scalar);
>
> if (is_scalar) {
> diff --git a/src/intel/compiler/brw_nir.h b/src/intel/compiler/brw_nir.h
> index 03f52da08e5..6ba1a8bc654 100644
> --- a/src/intel/compiler/brw_nir.h
> +++ b/src/intel/compiler/brw_nir.h
> @@ -152,6 +152,8 @@ void brw_nir_analyze_ubo_ranges(const struct
> brw_compiler *compiler,
>
> bool brw_nir_opt_peephole_ffma(nir_shader *shader);
>
> +bool brw_nir_lower_16bit_int_math(nir_shader *shader);
> +
> nir_shader *brw_nir_optimize(nir_shader *nir,
> const struct brw_compiler *compiler,
> bool is_scalar);
> diff --git a/src/intel/compiler/brw_nir_lower_16bit_int_math.c
> b/src/intel/compiler/brw_nir_lower_16bit_int_math.c
> new file mode 100644
> index 00000000000..6876309a822
> --- /dev/null
> +++ b/src/intel/compiler/brw_nir_lower_16bit_int_math.c
> @@ -0,0 +1,108 @@
> +/*
> + * Copyright © 2018 Intel Corporation
> + *
> + * 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 "brw_nir.h"
> +#include "nir_builder.h"
> +
> +/**
> + * Intel hardware doesn't support 16-bit integer Math instructions so this
> + * pass implements them in 32-bit and then converts the result back to
> 16-bit.
> + */
> +static void
> +lower_math_instr(nir_builder *bld, nir_alu_instr *alu, bool is_signed)
> +{
> + const nir_op op = alu->op;
> +
> + bld->cursor = nir_before_instr(&alu->instr);
> +
> + nir_ssa_def *srcs_32[4] = { NULL, NULL, NULL, NULL };
> + const uint32_t num_inputs = nir_op_infos[op].num_inputs;
> + for (uint32_t i = 0; i < num_inputs; i++) {
> + nir_ssa_def *src = nir_ssa_for_alu_src(bld, alu, i);
> + srcs_32[i] = is_signed ? nir_i2i32(bld, src) : nir_u2u32(bld, src);
> + }
> +
> + nir_ssa_def *dst_32 =
> + nir_build_alu(bld, op, srcs_32[0], srcs_32[1], srcs_32[2],
> srcs_32[3]);
> +
> + nir_ssa_def *dst_16 =
> + is_signed ? nir_i2i16(bld, dst_32) : nir_u2u16(bld, dst_32);
> +
> + nir_ssa_def_rewrite_uses(&alu->dest.dest.ssa,
> nir_src_for_ssa(dst_16));
> +}
> +
> +static bool
> +lower_instr(nir_builder *bld, nir_alu_instr *alu)
> +{
> + assert(alu->dest.dest.is_ssa);
> + if (alu->dest.dest.ssa.bit_size != 16)
> + return false;
> +
> + bool is_signed = false;
> + switch (alu->op) {
> + case nir_op_idiv:
> + case nir_op_imod:
> + is_signed = true;
>
You can get is_signed from nit_op_infos
> + /* Fallthrough */
> + case nir_op_udiv:
> + case nir_op_umod:
> + case nir_op_irem:
>
How is irem unsigned?
> + lower_math_instr(bld, alu, is_signed);
> + return true;
> + default:
> + return false;
> + }
> +}
> +
> +static bool
> +lower_impl(nir_function_impl *impl)
> +{
> + nir_builder b;
> + nir_builder_init(&b, impl);
> + bool progress = false;
> +
> + nir_foreach_block(block, impl) {
> + nir_foreach_instr_safe(instr, block) {
> + if (instr->type == nir_instr_type_alu)
> + progress |= lower_instr(&b, nir_instr_as_alu(instr));
> + }
> + }
> +
> + nir_metadata_preserve(impl, nir_metadata_block_index |
> + nir_metadata_dominance);
> +
> + return progress;
> +}
> +
> +bool
> +brw_nir_lower_16bit_int_math(nir_shader *shader)
> +{
> + bool progress = false;
> +
> + nir_foreach_function(function, shader) {
> + if (function->impl)
> + progress |= lower_impl(function->impl);
> + }
> +
> + return progress;
> +}
> diff --git a/src/intel/compiler/meson.build b/src/intel/compiler/meson.
> build
> index 72b7a6796cb..d80fcd6e31b 100644
> --- a/src/intel/compiler/meson.build
> +++ b/src/intel/compiler/meson.build
> @@ -76,6 +76,7 @@ libintel_compiler_files = files(
> 'brw_nir_analyze_boolean_resolves.c',
> 'brw_nir_analyze_ubo_ranges.c',
> 'brw_nir_attribute_workarounds.c',
> + 'brw_nir_lower_16bit_int_math.c',
> 'brw_nir_lower_cs_intrinsics.c',
> 'brw_nir_opt_peephole_ffma.c',
> 'brw_nir_tcs_workarounds.c',
> --
> 2.14.1
>
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> mesa-dev at lists.freedesktop.org
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>
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