[Mesa-dev] [PATCH] nir: Add nir_lower_alu_scalar.

Jason Ekstrand jason at jlekstrand.net
Thu Jan 22 16:33:41 PST 2015


Also, Could we rename this to nir_lower_alu_to_scalar?  That's more
descriptive.
--Jason

On Thu, Jan 22, 2015 at 4:27 PM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

>
>
> On Thu, Jan 22, 2015 at 2:52 PM, Eric Anholt <eric at anholt.net> wrote:
>
>> This is the equivalent of brw_fs_channel_expressions.cpp, which I wanted
>> for vc4.
>>
>> v2: Use the nir_src_for_ssa() helper, and another instance of
>>     nir_alu_src_copy().
>> v3: Drop the non-SSA support.  All intended callers will have SSA-only ALU
>>     ops.
>> v4: Use insert_before, drop stale bcsel/fcsel comment, drop now-unused
>>     unsupported() function, drop lower_context struct.
>> ---
>>
>> This can also be found on my nir-scalarize-2 branch.
>>
>> src/glsl/Makefile.sources           |   1 +
>>  src/glsl/nir/nir.h                  |   1 +
>>  src/glsl/nir/nir_lower_alu_scalar.c | 182
>> ++++++++++++++++++++++++++++++++++++
>>  3 files changed, 184 insertions(+)
>>  create mode 100644 src/glsl/nir/nir_lower_alu_scalar.c
>>
>> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
>> index 6237627..9cd1a6a 100644
>> --- a/src/glsl/Makefile.sources
>> +++ b/src/glsl/Makefile.sources
>> @@ -24,6 +24,7 @@ NIR_FILES = \
>>         $(GLSL_SRCDIR)/nir/nir_intrinsics.c \
>>         $(GLSL_SRCDIR)/nir/nir_intrinsics.h \
>>         $(GLSL_SRCDIR)/nir/nir_live_variables.c \
>> +       $(GLSL_SRCDIR)/nir/nir_lower_alu_scalar.c \
>>         $(GLSL_SRCDIR)/nir/nir_lower_atomics.c \
>>         $(GLSL_SRCDIR)/nir/nir_lower_global_vars_to_local.c \
>>         $(GLSL_SRCDIR)/nir/nir_lower_locals_to_regs.c \
>> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
>> index 0dbe000..aa0927a 100644
>> --- a/src/glsl/nir/nir.h
>> +++ b/src/glsl/nir/nir.h
>> @@ -1520,6 +1520,7 @@ void nir_lower_vars_to_ssa(nir_shader *shader);
>>  void nir_remove_dead_variables(nir_shader *shader);
>>
>>  void nir_lower_vec_to_movs(nir_shader *shader);
>> +void nir_lower_ops_scalar(nir_shader *shader);
>>
>>  void nir_lower_samplers(nir_shader *shader,
>>                          struct gl_shader_program *shader_program,
>> diff --git a/src/glsl/nir/nir_lower_alu_scalar.c
>> b/src/glsl/nir/nir_lower_alu_scalar.c
>> new file mode 100644
>> index 0000000..64552be
>> --- /dev/null
>> +++ b/src/glsl/nir/nir_lower_alu_scalar.c
>> @@ -0,0 +1,182 @@
>> +/*
>> + * Copyright © 2014-2015 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"
>> +
>> +/** @file nir_lower_alu_scalar.c
>> + *
>> + * Replaces nir_alu_instr operations with more than one channel used in
>> the
>> + * arguments with individual per-channel operations.
>> + */
>> +
>> +static void
>> +nir_alu_ssa_dest_init(nir_alu_instr *instr, unsigned num_components)
>> +{
>> +   nir_ssa_dest_init(&instr->instr, &instr->dest.dest, num_components,
>> NULL);
>> +   instr->dest.write_mask = (1 << num_components) - 1;
>> +}
>> +
>> +static void
>> +lower_reduction(nir_alu_instr *instr, nir_op chan_op, nir_op merge_op,
>> +                void *mem_ctx)
>> +{
>> +   unsigned num_components = nir_op_infos[instr->op].input_sizes[0];
>> +
>> +   nir_ssa_def *last = NULL;
>> +   for (unsigned i = 0; i < num_components; i++) {
>> +      nir_alu_instr *chan = nir_alu_instr_create(mem_ctx, chan_op);
>> +      nir_alu_ssa_dest_init(chan, 1);
>> +      nir_alu_src_copy(&chan->src[0], &instr->src[0], mem_ctx);
>> +      chan->src[0].swizzle[0] = chan->src[0].swizzle[i];
>> +      if (nir_op_infos[chan_op].num_inputs > 1) {
>> +         assert(nir_op_infos[chan_op].num_inputs == 2);
>> +         nir_alu_src_copy(&chan->src[1], &instr->src[1], mem_ctx);
>> +         chan->src[1].swizzle[0] = chan->src[1].swizzle[i];
>> +      }
>> +
>> +      nir_instr_insert_before(&instr->instr, &chan->instr);
>> +
>> +      if (i == 0) {
>> +         last = &chan->dest.dest.ssa;
>> +      } else {
>> +         nir_alu_instr *merge = nir_alu_instr_create(mem_ctx, merge_op);
>> +         nir_alu_ssa_dest_init(merge, 1);
>> +         merge->dest.write_mask = 1;
>> +         merge->src[0].src = nir_src_for_ssa(last);
>> +         merge->src[1].src = nir_src_for_ssa(&chan->dest.dest.ssa);
>> +         nir_instr_insert_before(&instr->instr, &merge->instr);
>> +         last = &merge->dest.dest.ssa;
>> +      }
>> +   }
>> +
>> +   assert(instr->dest.write_mask == 1);
>> +   nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa, nir_src_for_ssa(last),
>> +                            mem_ctx);
>> +   nir_instr_remove(&instr->instr);
>> +}
>> +
>> +static void
>> +lower_alu_instr_scalar(nir_alu_instr *instr, void *mem_ctx)
>> +{
>> +   unsigned num_src = nir_op_infos[instr->op].num_inputs;
>> +   unsigned i, chan;
>> +
>> +   assert(instr->dest.dest.is_ssa);
>> +   assert(instr->dest.write_mask != 0);
>> +
>> +#define LOWER_REDUCTION(name, chan, merge) \
>> +   case name##2: \
>> +   case name##3: \
>> +   case name##4: \
>> +      lower_reduction(instr, chan, merge, mem_ctx); \
>> +      break;
>> +
>> +   switch (instr->op) {
>> +   case nir_op_vec4:
>> +   case nir_op_vec3:
>> +   case nir_op_vec2:
>> +      /* We don't need to scalarize these ops, they're the ones
>> generated to
>> +       * group up outputs into a value that can be SSAed.
>> +       */
>> +      return;
>> +
>> +      LOWER_REDUCTION(nir_op_fdot, nir_op_fmul, nir_op_fadd);
>> +      LOWER_REDUCTION(nir_op_ball_fequal, nir_op_feq, nir_op_iand);
>> +      LOWER_REDUCTION(nir_op_ball_iequal, nir_op_ieq, nir_op_iand);
>> +      LOWER_REDUCTION(nir_op_bany_fnequal, nir_op_fne, nir_op_ior);
>> +      LOWER_REDUCTION(nir_op_bany_inequal, nir_op_ine, nir_op_ior);
>> +      LOWER_REDUCTION(nir_op_fall_equal, nir_op_seq, nir_op_fand);
>> +      LOWER_REDUCTION(nir_op_fany_nequal, nir_op_sne, nir_op_for);
>> +      LOWER_REDUCTION(nir_op_ball, nir_op_imov, nir_op_iand);
>> +      LOWER_REDUCTION(nir_op_bany, nir_op_imov, nir_op_ior);
>> +      LOWER_REDUCTION(nir_op_fall, nir_op_fmov, nir_op_fand);
>> +      LOWER_REDUCTION(nir_op_fany, nir_op_fmov, nir_op_for);
>> +
>> +   default:
>> +      break;
>> +   }
>> +
>> +   if (instr->dest.dest.ssa.num_components == 1)
>> +      return;
>> +
>> +   unsigned num_components = instr->dest.dest.ssa.num_components;
>> +   static const nir_op nir_op_map[] = {nir_op_vec2, nir_op_vec3,
>> nir_op_vec4};
>> +   nir_alu_instr *vec_instr =
>> +      nir_alu_instr_create(mem_ctx, nir_op_map[num_components - 2]);
>> +   nir_alu_ssa_dest_init(vec_instr, num_components);
>> +
>> +   for (chan = 0; chan < 4; chan++) {
>> +      if (!(instr->dest.write_mask & (1 << chan)))
>> +         continue;
>> +
>> +      nir_alu_instr *lower = nir_alu_instr_create(mem_ctx, instr->op);
>> +      for (i = 0; i < num_src; i++) {
>> +         unsigned src_chan = (nir_op_infos[instr->op].input_sizes[i] ==
>> 1 ?
>> +                              0 : chan);
>>
>
> If we're going to do input_sizes == 1 rather than input_sizes != 0, can we
> at least put in an assert?  While I can't really immagine a vectorized
> instruction with an explicit vec2 source, it is possible in the IR.  If we
> ever add one, this is going to be a really annoying bug to find.
>
> Other than that,
> Reviewed-by: Jason Ekstrand <jason.ekstrand at iastate.edu>
>
>
>> +
>> +         nir_alu_src_copy(&lower->src[i], &instr->src[i], mem_ctx);
>> +         for (int j = 0; j < 4; j++)
>> +            lower->src[i].swizzle[j] = instr->src[i].swizzle[src_chan];
>> +      }
>> +
>> +      nir_alu_ssa_dest_init(lower, 1);
>> +      lower->dest.saturate = instr->dest.saturate;
>> +      vec_instr->src[chan].src = nir_src_for_ssa(&lower->dest.dest.ssa);
>> +
>> +      nir_instr_insert_before(&instr->instr, &lower->instr);
>> +   }
>> +
>> +   nir_instr_insert_before(&instr->instr, &vec_instr->instr);
>> +
>> +   nir_ssa_def_rewrite_uses(&instr->dest.dest.ssa,
>> +                            nir_src_for_ssa(&vec_instr->dest.dest.ssa),
>> +                            mem_ctx);
>> +
>> +   nir_instr_remove(&instr->instr);
>> +}
>> +
>> +static bool
>> +lower_ops_scalar_block(nir_block *block, void *data)
>> +{
>> +   nir_foreach_instr_safe(block, instr) {
>> +      if (instr->type == nir_instr_type_alu)
>> +         lower_alu_instr_scalar((nir_alu_instr *)instr, data);
>> +   }
>> +
>> +   return true;
>> +}
>> +
>> +static void
>> +nir_lower_ops_scalar_impl(nir_function_impl *impl)
>> +{
>> +   nir_foreach_block(impl, lower_ops_scalar_block, ralloc_parent(impl));
>> +}
>> +
>> +void
>> +nir_lower_ops_scalar(nir_shader *shader)
>> +{
>> +   nir_foreach_overload(shader, overload) {
>> +      if (overload->impl)
>> +         nir_lower_ops_scalar_impl(overload->impl);
>> +   }
>> +}
>> --
>> 2.1.3
>>
>> _______________________________________________
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>> mesa-dev at lists.freedesktop.org
>> http://lists.freedesktop.org/mailman/listinfo/mesa-dev
>>
>
>
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