[Mesa-dev] [PATCH 094/133] nir: Add a pass to lower global variables to local variables

[Connor Abbott]

On Tue, Dec 16, 2014 at 1:11 AM, Jason Ekstrand <jason at jlekstrand.net>
wrote:

> ---
>  src/glsl/Makefile.sources                     |   1 +
>  src/glsl/nir/nir.h                            |   2 +
>  src/glsl/nir/nir_lower_global_vars_to_local.c | 107
> ++++++++++++++++++++++++++
>  3 files changed, 110 insertions(+)
>  create mode 100644 src/glsl/nir/nir_lower_global_vars_to_local.c
>
> diff --git a/src/glsl/Makefile.sources b/src/glsl/Makefile.sources
> index 53c3e98..3f5c0bd 100644
> --- a/src/glsl/Makefile.sources
> +++ b/src/glsl/Makefile.sources
> @@ -22,6 +22,7 @@ NIR_FILES = \
>         $(GLSL_SRCDIR)/nir/nir_intrinsics.h \
>         $(GLSL_SRCDIR)/nir/nir_live_variables.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 \
>         $(GLSL_SRCDIR)/nir/nir_lower_io.c \
>         $(GLSL_SRCDIR)/nir/nir_lower_samplers.cpp \
> diff --git a/src/glsl/nir/nir.h b/src/glsl/nir/nir.h
> index ec9ce07..30146d6 100644
> --- a/src/glsl/nir/nir.h
> +++ b/src/glsl/nir/nir.h
> @@ -1358,6 +1358,8 @@ void nir_dump_cfg(nir_shader *shader, FILE *fp);
>
>  void nir_split_var_copies(nir_shader *shader);
>
> +void nir_lower_global_vars_to_local(nir_shader *shader);
> +
>  void nir_lower_locals_to_regs(nir_shader *shader);
>
>  void nir_lower_io(nir_shader *shader);
> diff --git a/src/glsl/nir/nir_lower_global_vars_to_local.c
> b/src/glsl/nir/nir_lower_global_vars_to_local.c
> new file mode 100644
> index 0000000..ec23a0a
> --- /dev/null
> +++ b/src/glsl/nir/nir_lower_global_vars_to_local.c
> @@ -0,0 +1,107 @@
> +/*
> + * Copyright © 2014 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.
> + *
> + * Authors:
> + *    Jason Ekstrand (jason at jlekstrand.net)
> + *
> + */
> +
> +/*
> + * This lowering pass detects when a global variable is only being used by
> + * one function and makes it local to that function
> + */
> +
> +#include "nir.h"
> +
> +struct global_to_local_state {
> +   nir_function_impl *impl;
> +   /* A hash table keyed on variable pointers that stores the unique
> +    * nir_function_impl that uses the given variable.  If a variable is
> +    * used in multiple functions, the data for the given key will be NULL.
> +    */
> +   struct hash_table *var_func_table;
> +};
> +
> +static bool
> +mark_global_var_uses_block(nir_block *block, void *void_state)
> +{
> +   struct global_to_local_state *state = void_state;
> +
> +   nir_foreach_instr(block, instr) {
> +      if (instr->type != nir_instr_type_intrinsic)
> +         continue;
> +
> +      nir_intrinsic_instr *intrin = nir_instr_as_intrinsic(instr);
> +      unsigned num_vars =
> nir_intrinsic_infos[intrin->intrinsic].num_variables;
> +
> +      for (unsigned i = 0; i < num_vars; i++) {
> +         nir_variable *var = intrin->variables[i]->var;
> +         if (var->data.mode != nir_var_global)
> +            continue;
> +
> +         uint32_t hash = _mesa_hash_pointer(var);
> +         struct hash_entry *entry =
> +            _mesa_hash_table_search(state->var_func_table, hash, var);
> +
> +         if (entry) {
> +            if (entry->data != state->impl)
> +               entry->data = NULL;
> +         }
> +
> +         _mesa_hash_table_insert(state->var_func_table, hash, var,
> state->impl);
>

I think you should be doing:

if (entry) {
   ...
} else {
   _mesa_hash_table_insert(state->var_func_table, hash, var, state->impl);
}


> +      }
> +   }
> +
> +   return true;
> +}
> +
> +void
> +nir_lower_global_vars_to_local(nir_shader *shader)
> +{
> +   struct global_to_local_state state;
> +
> +   state.var_func_table = _mesa_hash_table_create(NULL,
> +
> _mesa_key_pointer_equal);
> +
> +   nir_foreach_overload(shader, overload) {
> +      if (overload->impl) {
> +         state.impl = overload->impl;
> +         nir_foreach_block(overload->impl, mark_global_var_uses_block,
> &state);
> +      }
> +   }
> +
> +   struct hash_entry *entry;
> +   hash_table_foreach(state.var_func_table, entry) {
> +      nir_variable *var = (void *)entry->key;
> +      nir_function_impl *impl = entry->data;
> +
> +      assert(var->data.mode == nir_var_global);
> +
> +      if (impl != NULL) {
> +         exec_node_remove(&var->node);
> +         var->data.mode = nir_var_local;
> +         exec_list_push_tail(&impl->locals, &var->node);
> +      }
> +   }
> +
> +   _mesa_hash_table_destroy(state.var_func_table, NULL);
> +}
> --
> 2.2.0
>
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