[Mesa-dev] [PATCH 1/8] nir: Add a pass for lowering away constant initializers

[Iago Toral]

On Wed, 2016-07-20 at 15:28 -0700, Jason Ekstrand wrote:
> Signed-off-by: Jason Ekstrand <jason at jlekstrand.net>
> ---
>  src/compiler/Makefile.sources                      |   1 +
>  src/compiler/nir/nir.h                             |   2 +
>  src/compiler/nir/nir_lower_constant_initializers.c | 102
> +++++++++++++++++++++
>  3 files changed, 105 insertions(+)
>  create mode 100644
> src/compiler/nir/nir_lower_constant_initializers.c
> 
> diff --git a/src/compiler/Makefile.sources
> b/src/compiler/Makefile.sources
> index 0ff9b23..127b62e 100644
> --- a/src/compiler/Makefile.sources
> +++ b/src/compiler/Makefile.sources
> @@ -190,6 +190,7 @@ NIR_FILES = \
>  	nir/nir_lower_bitmap.c \
>  	nir/nir_lower_clamp_color_outputs.c \
>  	nir/nir_lower_clip.c \
> +	nir/nir_lower_constant_initializers.c \
>  	nir/nir_lower_double_ops.c \
>  	nir/nir_lower_double_packing.c \
>  	nir/nir_lower_drawpixels.c \
> diff --git a/src/compiler/nir/nir.h b/src/compiler/nir/nir.h
> index 54598a2..99c2fc0 100644
> --- a/src/compiler/nir/nir.h
> +++ b/src/compiler/nir/nir.h
> @@ -2330,6 +2330,8 @@ void nir_lower_io_types(nir_shader *shader);
>  void nir_lower_vars_to_ssa(nir_shader *shader);
>  
>  bool nir_remove_dead_variables(nir_shader *shader, nir_variable_mode
> modes);
> +bool nir_lower_constant_initializers(nir_shader *shader,
> +                                     nir_variable_mode modes);
>  
>  void nir_move_vec_src_uses_to_dest(nir_shader *shader);
>  bool nir_lower_vec_to_movs(nir_shader *shader);
> diff --git a/src/compiler/nir/nir_lower_constant_initializers.c
> b/src/compiler/nir/nir_lower_constant_initializers.c
> new file mode 100644
> index 0000000..d0935e9
> --- /dev/null
> +++ b/src/compiler/nir/nir_lower_constant_initializers.c
> @@ -0,0 +1,102 @@
> +/*
> + * Copyright © 2016 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"
> +
> +static bool
> +deref_apply_constant_initializer(nir_deref_var *deref, void *state)
> +{
> +   struct nir_builder *b = state;
> +
> +   nir_load_const_instr *initializer =
> +      nir_deref_get_const_initializer_load(b->shader, deref);
> +   nir_builder_instr_insert(b, &initializer->instr);
> +
> +   nir_store_deref_var(b, deref, &initializer->def, 0xf);
> +
> +   return true;
> +}
> +
> +static bool
> +lower_const_initializer(struct nir_builder *b, struct exec_list
> *var_list)
> +{
> +   bool progress = false;
> +
> +   b->cursor = nir_before_cf_list(&b->impl->body);
> +
> +   nir_foreach_variable(var, var_list) {
> +      if (!var->constant_initializer)
> +         continue;
> +
> +      progress = true;
> +
> +      nir_deref_var deref;
> +      deref.deref.deref_type = nir_deref_type_var,
> +      deref.deref.child = NULL;
> +      deref.deref.type = var->type,
> +      deref.var = var;
> +
> +      nir_deref_foreach_leaf(&deref,
> deref_apply_constant_initializer, b);
> +
> +      var->constant_initializer = NULL;
> +   }
> +
> +   return progress;
> +}
> +
> +bool
> +nir_lower_constant_initializers(nir_shader *shader,
> nir_variable_mode modes)
> +{
> +   bool progress = false;
> +
> +   nir_builder builder;
> +   if (modes & ~nir_var_local)
> +      nir_builder_init(&builder, nir_shader_get_entrypoint(shader)-
> >impl);
> +
> +   if (modes & nir_var_shader_out)
> +      progress |= lower_const_initializer(&builder, &shader-
> >outputs);
> +
> +   if (modes & nir_var_global)
> +      progress |= lower_const_initializer(&builder, &shader-
> >globals);
> +
> +   if (modes & nir_var_system_value)
> +      progress |= lower_const_initializer(&builder, &shader-
> >system_values);
> +
> +   if (modes & nir_var_local) {
> +      nir_foreach_function(function, shader) {
> +         if (!function->impl)
> +            continue;
> +
> +         nir_builder_init(&builder, function->impl);
> +         if (lower_const_initializer(&builder, &function->impl-
> >locals)) {
> +            nir_metadata_preserve(function->impl,
> nir_metadata_block_index |
> +                                                  nir_metadata_domin
> ance |
> +                                                  nir_metadata_live_
> ssa_defs);

why don't we need to call nir_metadata_preserve if we make progress
with non-local variables? Assuming there is a reason for that this
looks good to me.

Iago

> +            progress = true;
> +         }
> +      }
> +   }
> +
> +   return progress;
> +}