[Mesa-dev] [PATCH v4 006/129] nir: Add helpers for working with deref instructions

Bas Nieuwenhuizen bas at basnieuwenhuizen.nl
Fri Jun 1 13:03:36 UTC 2018


On Fri, Jun 1, 2018 at 7:01 AM, Jason Ekstrand <jason at jlekstrand.net> wrote:
> This commit adds a pass for lowering deref instructions to deref chains
> as well as some smaller helpers to ease the transition.
>
> Reviewed-by: Caio Marcelo de Oliveira Filho <caio.oliveira at intel.com>
> ---
>  src/compiler/Makefile.sources  |   1 +
>  src/compiler/nir/meson.build   |   1 +
>  src/compiler/nir/nir.h         |  33 +++++
>  src/compiler/nir/nir_builder.h |  23 ++++
>  src/compiler/nir/nir_deref.c   | 301 +++++++++++++++++++++++++++++++++++++++++
>  5 files changed, 359 insertions(+)
>  create mode 100644 src/compiler/nir/nir_deref.c
>
> diff --git a/src/compiler/Makefile.sources b/src/compiler/Makefile.sources
> index 3daa2c5..ee30046 100644
> --- a/src/compiler/Makefile.sources
> +++ b/src/compiler/Makefile.sources
> @@ -201,6 +201,7 @@ NIR_FILES = \
>         nir/nir_control_flow.c \
>         nir/nir_control_flow.h \
>         nir/nir_control_flow_private.h \
> +       nir/nir_deref.c \
>         nir/nir_dominance.c \
>         nir/nir_format_convert.h \
>         nir/nir_from_ssa.c \
> diff --git a/src/compiler/nir/meson.build b/src/compiler/nir/meson.build
> index 3fec363..6c80c36 100644
> --- a/src/compiler/nir/meson.build
> +++ b/src/compiler/nir/meson.build
> @@ -92,6 +92,7 @@ files_libnir = files(
>    'nir_control_flow.c',
>    'nir_control_flow.h',
>    'nir_control_flow_private.h',
> +  'nir_deref.c',
>    'nir_dominance.c',
>    'nir_format_convert.h',
>    'nir_from_ssa.c',
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 4f359f1..8b826d8 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -1003,6 +1003,27 @@ nir_src_as_deref(nir_src src)
>     return nir_instr_as_deref(src.ssa->parent_instr);
>  }
>
> +static inline nir_deref_instr *
> +nir_deref_instr_parent(const nir_deref_instr *instr)
> +{
> +   if (instr->deref_type == nir_deref_type_var)
> +      return NULL;
> +   else
> +      return nir_src_as_deref(instr->parent);
> +}
> +
> +static inline nir_variable *
> +nir_deref_instr_get_variable(const nir_deref_instr *instr)
> +{
> +   while (instr->deref_type != nir_deref_type_var)
> +      instr = nir_deref_instr_parent(instr);

I think we need to handle casts here, for which the type can be !=
nir_deref_type_var, but the next iteration can have instr = NULL. Can
be fixed with


 static inline nir_variable *
 nir_deref_instr_get_variable(const nir_deref_instr *instr)
 {
-   while (instr->deref_type != nir_deref_type_var)
+   while (instr && instr->deref_type != nir_deref_type_var)
       instr = nir_deref_instr_parent(instr);

-   return instr->var;
+   return instr ? instr->var : NULL;
 }


(Unless we want it to not look past casts, then we need to add &&
instr->deref_type != nir_deref_type_cast to the while condition)

> +
> +   return instr->var;
> +}
> +
> +nir_deref_var *
> +nir_deref_instr_to_deref(nir_deref_instr *instr, void *mem_ctx);
> +
>  typedef struct {
>     nir_instr instr;
>
> @@ -2598,6 +2619,18 @@ bool nir_inline_functions(nir_shader *shader);
>
>  bool nir_propagate_invariant(nir_shader *shader);
>
> +enum nir_lower_deref_flags {
> +   nir_lower_load_store_derefs =       (1 << 0),
> +   nir_lower_texture_derefs =          (1 << 1),
> +   nir_lower_interp_derefs =           (1 << 2),
> +   nir_lower_atomic_counter_derefs =   (1 << 3),
> +   nir_lower_atomic_derefs =           (1 << 4),
> +   nir_lower_image_derefs =            (1 << 5),
> +};
> +
> +bool nir_lower_deref_instrs(nir_shader *shader,
> +                            enum nir_lower_deref_flags flags);
> +
>  void nir_lower_var_copy_instr(nir_intrinsic_instr *copy, nir_shader *shader);
>  bool nir_lower_var_copies(nir_shader *shader);
>
> diff --git a/src/compiler/nir/nir_builder.h b/src/compiler/nir/nir_builder.h
> index a667372..42fe285 100644
> --- a/src/compiler/nir/nir_builder.h
> +++ b/src/compiler/nir/nir_builder.h
> @@ -644,6 +644,29 @@ nir_build_deref_cast(nir_builder *build, nir_ssa_def *parent,
>     return deref;
>  }
>
> +static inline nir_deref_instr *
> +nir_build_deref_for_chain(nir_builder *b, nir_deref_var *deref_var)
> +{
> +   nir_deref_instr *tail = nir_build_deref_var(b, deref_var->var);
> +   for (nir_deref *d = deref_var->deref.child; d; d = d->child) {
> +      if (d->deref_type == nir_deref_type_array) {
> +         nir_deref_array *a = nir_deref_as_array(d);
> +         assert(a->deref_array_type != nir_deref_array_type_wildcard);
> +
> +         nir_ssa_def *index = nir_imm_int(b, a->base_offset);
> +         if (a->deref_array_type == nir_deref_array_type_indirect)
> +            index = nir_iadd(b, index, nir_ssa_for_src(b, a->indirect, 1));
> +
> +         tail = nir_build_deref_array(b, tail, index);
> +      } else {
> +         nir_deref_struct *s = nir_deref_as_struct(d);
> +         tail = nir_build_deref_struct(b, tail, s->index);
> +      }
> +   }
> +
> +   return tail;
> +}
> +
>  static inline nir_ssa_def *
>  nir_load_reg(nir_builder *build, nir_register *reg)
>  {
> diff --git a/src/compiler/nir/nir_deref.c b/src/compiler/nir/nir_deref.c
> new file mode 100644
> index 0000000..87a8192
> --- /dev/null
> +++ b/src/compiler/nir/nir_deref.c
> @@ -0,0 +1,301 @@
> +/*
> + * 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 "nir.h"
> +#include "nir_builder.h"
> +
> +nir_deref_var *
> +nir_deref_instr_to_deref(nir_deref_instr *instr, void *mem_ctx)
> +{
> +   nir_deref *deref = NULL;
> +
> +   while (instr->deref_type != nir_deref_type_var) {
> +      nir_deref *nderef;
> +      switch (instr->deref_type) {
> +      case nir_deref_type_array:
> +      case nir_deref_type_array_wildcard: {
> +         nir_deref_array *deref_arr = nir_deref_array_create(mem_ctx);
> +         if (instr->deref_type == nir_deref_type_array) {
> +            nir_const_value *const_index =
> +               nir_src_as_const_value(instr->arr.index);
> +            if (const_index) {
> +               deref_arr->deref_array_type = nir_deref_array_type_direct;
> +               deref_arr->base_offset = const_index->u32[0];
> +            } else {
> +               deref_arr->deref_array_type = nir_deref_array_type_indirect;
> +               deref_arr->base_offset = 0;
> +               nir_src_copy(&deref_arr->indirect, &instr->arr.index, mem_ctx);
> +            }
> +         } else {
> +            deref_arr->deref_array_type = nir_deref_array_type_wildcard;
> +         }
> +         nderef = &deref_arr->deref;
> +         break;
> +      }
> +
> +      case nir_deref_type_struct:
> +         nderef = &nir_deref_struct_create(mem_ctx, instr->strct.index)->deref;
> +         break;
> +
> +      default:
> +         unreachable("Invalid deref instruction type");
> +      }
> +
> +      nderef->child = deref;
> +      ralloc_steal(nderef, deref);
> +      nderef->type = instr->type;
> +
> +      deref = nderef;
> +      assert(instr->parent.is_ssa);
> +      instr = nir_src_as_deref(instr->parent);
> +   }
> +
> +   assert(instr->deref_type == nir_deref_type_var);
> +   nir_deref_var *deref_var = nir_deref_var_create(mem_ctx, instr->var);
> +   deref_var->deref.child = deref;
> +   ralloc_steal(deref_var, deref);
> +
> +   return deref_var;
> +}
> +
> +static nir_deref_var *
> +nir_deref_src_to_deref(nir_src src, void *mem_ctx)
> +{
> +   return nir_deref_instr_to_deref(nir_src_as_deref(src), mem_ctx);
> +}
> +
> +static bool
> +nir_lower_deref_instrs_tex(nir_tex_instr *tex)
> +{
> +   bool progress = false;
> +
> +   /* Remove the instruction before we modify it.  This way we won't mess up
> +    * use-def chains when we move sources around.
> +    */
> +   nir_cursor cursor = nir_instr_remove(&tex->instr);
> +
> +   unsigned new_num_srcs = 0;
> +   for (unsigned i = 0; i < tex->num_srcs; i++) {
> +      if (tex->src[i].src_type == nir_tex_src_texture_deref) {
> +         tex->texture = nir_deref_src_to_deref(tex->src[i].src, tex);
> +         progress = true;
> +         continue;
> +      } else if (tex->src[i].src_type == nir_tex_src_sampler_deref) {
> +         tex->sampler = nir_deref_src_to_deref(tex->src[i].src, tex);
> +         progress = true;
> +         continue;
> +      }
> +
> +      /* Compact the sources down to remove the deref sources */
> +      assert(new_num_srcs <= i);
> +      tex->src[new_num_srcs++] = tex->src[i];
> +   }
> +   tex->num_srcs = new_num_srcs;
> +
> +   nir_instr_insert(cursor, &tex->instr);
> +
> +   return progress;
> +}
> +
> +static bool
> +nir_lower_deref_instrs_intrin(nir_intrinsic_instr *intrin,
> +                              enum nir_lower_deref_flags flags)
> +{
> +   nir_intrinsic_op deref_op = intrin->intrinsic;
> +   nir_intrinsic_op var_op;
> +
> +   switch (deref_op) {
> +#define CASE(a) \
> +   case nir_intrinsic_##a##_deref: \
> +      if (!(flags & nir_lower_load_store_derefs)) \
> +         return false; \
> +      var_op = nir_intrinsic_##a##_var; \
> +      break;
> +   CASE(load)
> +   CASE(store)
> +   CASE(copy)
> +#undef CASE
> +
> +#define CASE(a) \
> +   case nir_intrinsic_interp_deref_##a: \
> +      if (!(flags & nir_lower_interp_derefs)) \
> +         return false; \
> +      var_op = nir_intrinsic_interp_var_##a; \
> +      break;
> +   CASE(at_centroid)
> +   CASE(at_sample)
> +   CASE(at_offset)
> +#undef CASE
> +
> +#define CASE(a) \
> +   case nir_intrinsic_atomic_counter_##a##_deref: \
> +      if (!(flags & nir_lower_atomic_counter_derefs)) \
> +         return false; \
> +      var_op = nir_intrinsic_atomic_counter_##a##_var; \
> +      break;
> +   CASE(inc)
> +   CASE(dec)
> +   CASE(read)
> +   CASE(add)
> +   CASE(min)
> +   CASE(max)
> +   CASE(and)
> +   CASE(or)
> +   CASE(xor)
> +   CASE(exchange)
> +   CASE(comp_swap)
> +#undef CASE
> +
> +#define CASE(a) \
> +   case nir_intrinsic_deref_atomic_##a: \
> +      if (!(flags & nir_lower_atomic_derefs)) \
> +         return false; \
> +      var_op = nir_intrinsic_var_atomic_##a; \
> +      break;
> +   CASE(add)
> +   CASE(imin)
> +   CASE(umin)
> +   CASE(imax)
> +   CASE(umax)
> +   CASE(and)
> +   CASE(or)
> +   CASE(xor)
> +   CASE(exchange)
> +   CASE(comp_swap)
> +#undef CASE
> +
> +#define CASE(a) \
> +   case nir_intrinsic_image_deref_##a: \
> +      if (!(flags & nir_lower_image_derefs)) \
> +         return false; \
> +      var_op = nir_intrinsic_image_var_##a; \
> +      break;
> +   CASE(load)
> +   CASE(store)
> +   CASE(atomic_add)
> +   CASE(atomic_min)
> +   CASE(atomic_max)
> +   CASE(atomic_and)
> +   CASE(atomic_or)
> +   CASE(atomic_xor)
> +   CASE(atomic_exchange)
> +   CASE(atomic_comp_swap)
> +   CASE(size)
> +   CASE(samples)
> +#undef CASE
> +
> +   default:
> +      return false;
> +   }
> +
> +   /* Remove the instruction before we modify it.  This way we won't mess up
> +    * use-def chains when we move sources around.
> +    */
> +   nir_cursor cursor = nir_instr_remove(&intrin->instr);
> +
> +   unsigned num_derefs = nir_intrinsic_infos[var_op].num_variables;
> +   assert(nir_intrinsic_infos[var_op].num_srcs + num_derefs ==
> +          nir_intrinsic_infos[deref_op].num_srcs);
> +
> +   /* Move deref sources to variables */
> +   for (unsigned i = 0; i < num_derefs; i++)
> +      intrin->variables[i] = nir_deref_src_to_deref(intrin->src[i], intrin);
> +
> +   /* Shift all the other sources down */
> +   for (unsigned i = 0; i < nir_intrinsic_infos[var_op].num_srcs; i++)
> +      nir_src_copy(&intrin->src[i], &intrin->src[i + num_derefs], intrin);
> +
> +   /* Rewrite the extra sources to NIR_SRC_INIT just in case */
> +   for (unsigned i = 0; i < num_derefs; i++)
> +      intrin->src[nir_intrinsic_infos[var_op].num_srcs + i] = NIR_SRC_INIT;
> +
> +   /* It's safe to just stomp the intrinsic to var intrinsic since every
> +    * intrinsic has room for some variables and the number of sources only
> +    * shrinks.
> +    */
> +   intrin->intrinsic = var_op;
> +
> +   nir_instr_insert(cursor, &intrin->instr);
> +
> +   return true;
> +}
> +
> +static bool
> +nir_lower_deref_instrs_impl(nir_function_impl *impl,
> +                            enum nir_lower_deref_flags flags)
> +{
> +   bool progress = false;
> +
> +   /* Walk the instructions in reverse order so that we can safely clean up
> +    * the deref instructions after we clean up their uses.
> +    */
> +   nir_foreach_block_reverse(block, impl) {
> +      nir_foreach_instr_reverse_safe(instr, block) {
> +         switch (instr->type) {
> +         case nir_instr_type_deref:
> +            if (list_empty(&nir_instr_as_deref(instr)->dest.ssa.uses)) {
> +               nir_instr_remove(instr);
> +               progress = true;
> +            }
> +            break;
> +
> +         case nir_instr_type_tex:
> +            if (flags & nir_lower_texture_derefs)
> +               progress |= nir_lower_deref_instrs_tex(nir_instr_as_tex(instr));
> +            break;
> +
> +         case nir_instr_type_intrinsic:
> +            progress |=
> +               nir_lower_deref_instrs_intrin(nir_instr_as_intrinsic(instr),
> +                                             flags);
> +            break;
> +
> +         default:
> +            break; /* Nothing to do */
> +         }
> +      }
> +   }
> +
> +   if (progress) {
> +      nir_metadata_preserve(impl, nir_metadata_block_index |
> +                                  nir_metadata_dominance);
> +   }
> +
> +   return progress;
> +}
> +
> +bool
> +nir_lower_deref_instrs(nir_shader *shader,
> +                       enum nir_lower_deref_flags flags)
> +{
> +   bool progress = false;
> +
> +   nir_foreach_function(function, shader) {
> +      if (!function->impl)
> +         continue;
> +
> +      progress |= nir_lower_deref_instrs_impl(function->impl, flags);
> +   }
> +
> +   return progress;
> +}
> --
> 2.5.0.400.gff86faf
>
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