[Mesa-dev] [PATCH 06/11] nir: rework force_unroll_array_access()

[Thomas Helland]

Den tir. 20. nov. 2018 kl. 09:15 skrev Timothy Arceri <tarceri at itsqueeze.com>:
>
> Here we rework force_unroll_array_access() so that we can reused
> the induction variable detection in a following patch.
> ---
>  src/compiler/nir/nir_loop_analyze.c | 49 ++++++++++++++++++++---------
>  1 file changed, 35 insertions(+), 14 deletions(-)
>
> diff --git a/src/compiler/nir/nir_loop_analyze.c b/src/compiler/nir/nir_loop_analyze.c
> index 700d1fe552..a103a22afd 100644
> --- a/src/compiler/nir/nir_loop_analyze.c
> +++ b/src/compiler/nir/nir_loop_analyze.c
> @@ -350,6 +350,38 @@ find_loop_terminators(loop_info_state *state)
>     return success;
>  }
>
> +/* This function looks for an array access within a loop that use an induction
> + * variable for the array index. If found it returns the size of the array,
> + * otherwise 0 is returned.
> + */
> +static unsigned
> +find_array_access_via_induction(loop_info_state *state,
> +                                nir_deref_instr *deref,
> +                                nir_loop_variable **array_index_out)

Maybe make a small comment about the last parameter?
I guess it's quite obvious, but I'd rather have too much
handholding than too little =)

> +{
> +   for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
> +      if (d->deref_type != nir_deref_type_array)
> +         continue;
> +
> +      assert(d->arr.index.is_ssa);
> +      nir_loop_variable *array_index = get_loop_var(d->arr.index.ssa, state);
> +
> +      if (array_index->type != basic_induction)
> +         continue;
> +
> +      if (array_index_out)
> +         *array_index_out = array_index;
> +
> +      nir_deref_instr *parent = nir_deref_instr_parent(d);
> +      assert(glsl_type_is_array(parent->type) ||
> +             glsl_type_is_matrix(parent->type));

Maybe use glsl_type_is_array_or_matrix() ?
With (or without) that this patchs looks good and is:

Reviewed-by: Thomas Helland <thomashelland90 at gmail.com>

> +
> +      return glsl_get_length(parent->type);
> +   }
> +
> +   return 0;
> +}
> +
>  static int32_t
>  get_iteration(nir_op cond_op, nir_const_value *initial, nir_const_value *step,
>                nir_const_value *limit)
> @@ -626,20 +658,9 @@ find_trip_count(loop_info_state *state)
>  static bool
>  force_unroll_array_access(loop_info_state *state, nir_deref_instr *deref)
>  {
> -   for (nir_deref_instr *d = deref; d; d = nir_deref_instr_parent(d)) {
> -      if (d->deref_type != nir_deref_type_array)
> -         continue;
> -
> -      assert(d->arr.index.is_ssa);
> -      nir_loop_variable *array_index = get_loop_var(d->arr.index.ssa, state);
> -
> -      if (array_index->type != basic_induction)
> -         continue;
> -
> -      nir_deref_instr *parent = nir_deref_instr_parent(d);
> -      assert(glsl_type_is_array(parent->type) ||
> -             glsl_type_is_matrix(parent->type));
> -      if (glsl_get_length(parent->type) == state->loop->info->max_trip_count)
> +   unsigned array_size = find_array_access_via_induction(state, deref, NULL);
> +   if (array_size) {
> +      if (array_size == state->loop->info->max_trip_count)
>           return true;
>
>        if (deref->mode & state->indirect_mask)
> --
> 2.19.1
>
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