[Mesa-dev] [PATCH 11/16] nir/lower-io: split out some helper fxns

[Jason Ekstrand]

I don't know that I like the lower-io prefix.  Maybe nir/io-to-temp?
Doesn't really matter

On Sat, Mar 26, 2016 at 2:02 PM, Rob Clark <robdclark at gmail.com> wrote:

> From: Rob Clark <robclark at freedesktop.org>
>
> Prep work to reduce the noise in the next patch.
>
> Signed-off-by: Rob Clark <robclark at freedesktop.org>
> ---
>  src/compiler/nir/nir_lower_io_to_temporaries.c | 95
> +++++++++++++++-----------
>  1 file changed, 57 insertions(+), 38 deletions(-)
>
> diff --git a/src/compiler/nir/nir_lower_io_to_temporaries.c
> b/src/compiler/nir/nir_lower_io_to_temporaries.c
> index 0db436b..8e9df99 100644
> --- a/src/compiler/nir/nir_lower_io_to_temporaries.c
> +++ b/src/compiler/nir/nir_lower_io_to_temporaries.c
> @@ -35,25 +35,30 @@ struct lower_io_state {
>  };
>
>  static void
> -emit_output_copies(nir_cursor cursor, struct lower_io_state *state)
> +emit_copies(nir_cursor cursor, nir_shader *shader, struct exec_list
> *new_vars,
> +          struct exec_list *old_vars)
>  {
> -   assert(exec_list_length(&state->shader->outputs) ==
> -          exec_list_length(&state->old_outputs));
> +   assert(exec_list_length(new_vars) == exec_list_length(old_vars));
>
> -   foreach_two_lists(out_node, &state->shader->outputs,
> -                     temp_node, &state->old_outputs) {
> -      nir_variable *output = exec_node_data(nir_variable, out_node, node);
> -      nir_variable *temp = exec_node_data(nir_variable, temp_node, node);
> +   foreach_two_lists(new_node, new_vars, old_node, old_vars) {
> +      nir_variable *newv = exec_node_data(nir_variable, new_node, node);
> +      nir_variable *temp = exec_node_data(nir_variable, old_node, node);
>
>        nir_intrinsic_instr *copy =
> -         nir_intrinsic_instr_create(state->shader,
> nir_intrinsic_copy_var);
> -      copy->variables[0] = nir_deref_var_create(copy, output);
> +         nir_intrinsic_instr_create(shader, nir_intrinsic_copy_var);
> +      copy->variables[0] = nir_deref_var_create(copy, newv);
>        copy->variables[1] = nir_deref_var_create(copy, temp);
>
>        nir_instr_insert(cursor, &copy->instr);
>     }
>  }
>
> +static void
> +emit_output_copies(nir_cursor cursor, struct lower_io_state *state)
> +{
> +   emit_copies(cursor, state->shader, &state->shader->outputs,
> &state->old_outputs);
> +}
> +
>  static bool
>  emit_output_copies_block(nir_block *block, void *state)
>  {
> @@ -69,6 +74,47 @@ emit_output_copies_block(nir_block *block, void *state)
>     return true;
>  }
>
> +static void
> +emit_output_copies_impl(nir_function_impl *impl, struct lower_io_state
> *state)
>

In light of the change to make lower_io_to_temporaries take a nir_function,
this will have to be reworked a bit.  Perhaps we want an
emit_gs_output_copies and emit_output_copies?  The GS version would walk
the entire shader and the non-GS version would take a function impl and
just put the copies at the end of it.

In any case, I like the direction this is going.


> +{
> +   if (state->shader->stage == MESA_SHADER_GEOMETRY) {
> +      /* For geometry shaders, we have to emit the output copies right
> +       * before each EmitVertex call.
> +       */
> +      nir_foreach_block(impl, emit_output_copies_block, state);
> +   } else if (strcmp(impl->function->name, "main") == 0) {
> +      /* For all other shader types, we need to do the copies right before
> +       * the jumps to the end block.
> +       */
> +      struct set_entry *block_entry;
> +      set_foreach(impl->end_block->predecessors, block_entry) {
> +         struct nir_block *block = (void *)block_entry->key;
> +         emit_output_copies(nir_after_block_before_jump(block), state);
> +      }
> +   }
> +}
> +
> +static nir_variable *
> +create_shadow_temp(struct lower_io_state *state, nir_variable *var)
> +{
> +   nir_variable *nvar = ralloc(state->shader, nir_variable);
> +   memcpy(nvar, var, sizeof *nvar);
> +
> +   /* The original is now the temporary */
> +   nir_variable *temp = var;
> +
> +   /* Reparent the name to the new variable */
> +   ralloc_steal(nvar, nvar->name);
> +
> +   /* Give the output a new name with @out-temp appended */
> +   const char *mode = "out";
> +   temp->name = ralloc_asprintf(var, "%s@%s-temp", mode, nvar->name);
> +   temp->data.mode = nir_var_global;
> +   temp->constant_initializer = NULL;
> +
> +   return nvar;
> +}
> +
>  void
>  nir_lower_io_to_temporaries(nir_shader *shader)
>  {
> @@ -84,20 +130,7 @@ nir_lower_io_to_temporaries(nir_shader *shader)
>      * make a new variable for the actual output.
>      */
>     nir_foreach_variable(var, &state.old_outputs) {
> -      nir_variable *output = ralloc(shader, nir_variable);
> -      memcpy(output, var, sizeof *output);
> -
> -      /* The orignal is now the temporary */
> -      nir_variable *temp = var;
> -
> -      /* Reparent the name to the new variable */
> -      ralloc_steal(output, output->name);
> -
> -      /* Give the output a new name with @out-temp appended */
> -      temp->name = ralloc_asprintf(var, "%s at out-temp", output->name);
> -      temp->data.mode = nir_var_global;
> -      temp->constant_initializer = NULL;
> -
> +      nir_variable *output = create_shadow_temp(&state, var);
>        exec_list_push_tail(&shader->outputs, &output->node);
>     }
>
> @@ -105,21 +138,7 @@ nir_lower_io_to_temporaries(nir_shader *shader)
>        if (function->impl == NULL)
>           continue;
>
> -      if (shader->stage == MESA_SHADER_GEOMETRY) {
> -         /* For geometry shaders, we have to emit the output copies right
> -          * before each EmitVertex call.
> -          */
> -         nir_foreach_block(function->impl, emit_output_copies_block,
> &state);
> -      } else if (strcmp(function->name, "main") == 0) {
> -         /* For all other shader types, we need to do the copies right
> before
> -          * the jumps to the end block.
> -          */
> -         struct set_entry *block_entry;
> -         set_foreach(function->impl->end_block->predecessors,
> block_entry) {
> -            struct nir_block *block = (void *)block_entry->key;
> -            emit_output_copies(nir_after_block_before_jump(block),
> &state);
> -         }
> -      }
> +      emit_output_copies_impl(function->impl, &state);
>
>        nir_metadata_preserve(function->impl, nir_metadata_block_index |
>                                              nir_metadata_dominance);
> --
> 2.5.5
>
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