[Mesa-dev] [PATCH] compiler/glsl: Fix uniform location counting.

Ilia Mirkin imirkin at alum.mit.edu
Thu Feb 11 16:39:14 UTC 2016


On Thu, Feb 11, 2016 at 11:31 AM, Plamena Manolova
<plamena.manolova at intel.com> wrote:
> This patch moves the calculation of current uniforms to
> link_uniforms, which makes use of UniformRemapTable which
> stores all the reserved uniform locations.
>
> Location assignment for implicit uniforms now tries to use
> any gaps left in the table after the location assignment
> for explicit uniforms. This gives us more space to store more
> uniforms.
>
> Patch is based on earlier patch with following changes/additions:
>
>    1: Move the counting of explicit locations to
>       check_explicit_uniform_locations and then pass
>       the number to link_assign_uniform_locations.
>    2: Count the number of empty slots in UniformRemapTable
>       and store them in a list_head.
>    3: Try to find an empty slot for implicit locations from
>       the list, if that fails resize UniformRemapTable.
>
> Fixes following CTS tests:
>    ES31-CTS.explicit_uniform_location.uniform-loc-mix-with-implicit-max
>    ES31-CTS.explicit_uniform_location.uniform-loc-mix-with-implicit-max-array
>
> Signed-off-by: Tapani Pälli <tapani.palli at intel.com>
> Signed-off-by: Plamena Manolova <plamena.manolova at intel.com>
> Bugzilla: https://bugs.freedesktop.org/show_bug.cgi?id=93696
> ---
>  src/compiler/glsl/link_uniforms.cpp | 79 ++++++++++++++++++++++++++++++++-----
>  src/compiler/glsl/linker.cpp        | 78 +++++++++++++++++++++++++-----------
>  src/compiler/glsl/linker.h          | 17 +++++++-
>  src/mesa/main/mtypes.h              |  8 ++++
>  4 files changed, 147 insertions(+), 35 deletions(-)
>
> diff --git a/src/compiler/glsl/link_uniforms.cpp b/src/compiler/glsl/link_uniforms.cpp
> index 7072c16..8192c21 100644
> --- a/src/compiler/glsl/link_uniforms.cpp
> +++ b/src/compiler/glsl/link_uniforms.cpp
> @@ -1038,9 +1038,36 @@ assign_hidden_uniform_slot_id(const char *name, unsigned hidden_id,
>     uniform_size->map->put(hidden_uniform_start + hidden_id, name);
>  }
>
> +/**
> + * Search through the list of empty blocks to find one that fits the current
> + * uniform.
> + */
> +static int
> +find_empty_block(struct gl_shader_program *prog,
> +                 struct gl_uniform_storage *uniform)
> +{
> +   const unsigned entries = MAX2(1, uniform->array_elements);
> +
> +   list_for_each_entry_safe(struct empty_uniform_block, block,
> +                            &prog->EmptyUniformLocations, link) {
> +      /* Found a block with enough slots to fit the uniform */
> +      if (block->slots == entries) {

I haven't fully absorbed this patch, but if you have a bunch of holes
of 2 slots and then you try to allocate something needing 1 slot, then
you'll never decide you have a free block right? I think this needs to
be

block->slots >= entries

and then

if (block->slots > entries) {
  block->slots -= entries;
  block->start += entries;
} else {
  list_del(&block->link);
  ralloc_free(block);
}

Or am I misunderstanding something? This sort of greedy approach
doesn't guarantee optimal packing, you could do something much fancier
involving dynamic programming, but that hardly seems necessary.

> +         unsigned start = block->start;
> +         list_del(&block->link);
> +         ralloc_free(block);
> +
> +         return start;
> +      }
> +   }
> +
> +   return -1;
> +}
> +
>  void
>  link_assign_uniform_locations(struct gl_shader_program *prog,
> -                              unsigned int boolean_true)
> +                              unsigned int boolean_true,
> +                              unsigned int num_explicit_uniform_locs,
> +                              unsigned int max_uniform_locs)
>  {
>     ralloc_free(prog->UniformStorage);
>     prog->UniformStorage = NULL;
> @@ -1131,6 +1158,9 @@ link_assign_uniform_locations(struct gl_shader_program *prog,
>
>     parcel_out_uniform_storage parcel(prog, prog->UniformHash, uniforms, data);
>
> +   unsigned total_entries = num_explicit_uniform_locs;
> +   unsigned empty_locs = prog->NumUniformRemapTable - num_explicit_uniform_locs;
> +
>     for (unsigned i = 0; i < MESA_SHADER_STAGES; i++) {
>        if (prog->_LinkedShaders[i] == NULL)
>          continue;
> @@ -1194,21 +1224,43 @@ link_assign_uniform_locations(struct gl_shader_program *prog,
>        /* how many new entries for this uniform? */
>        const unsigned entries = MAX2(1, uniforms[i].array_elements);
>
> -      /* resize remap table to fit new entries */
> -      prog->UniformRemapTable =
> -         reralloc(prog,
> -                  prog->UniformRemapTable,
> -                  gl_uniform_storage *,
> -                  prog->NumUniformRemapTable + entries);
> +      /* Find UniformRemapTable for empty blocks where we can fit this uniform. */
> +      int chosen_location = -1;
> +
> +      if (empty_locs)
> +         chosen_location = find_empty_block(prog, &uniforms[i]);
> +
> +      if (chosen_location != -1) {
> +         empty_locs -= entries;
> +      } else {
> +         chosen_location = prog->NumUniformRemapTable;
> +
> +         /* Add new entries to the total amount of entries. */
> +         total_entries += entries;
> +
> +         /* resize remap table to fit new entries */
> +         prog->UniformRemapTable =
> +            reralloc(prog,
> +                     prog->UniformRemapTable,
> +                     gl_uniform_storage *,
> +                     prog->NumUniformRemapTable + entries);
> +         prog->NumUniformRemapTable += entries;
> +      }
>
>        /* set pointers for this uniform */
>        for (unsigned j = 0; j < entries; j++)
> -         prog->UniformRemapTable[prog->NumUniformRemapTable+j] = &uniforms[i];
> +         prog->UniformRemapTable[chosen_location + j] = &uniforms[i];
>
>        /* set the base location in remap table for the uniform */
> -      uniforms[i].remap_location = prog->NumUniformRemapTable;
> +      uniforms[i].remap_location = chosen_location;
> +   }
>
> -      prog->NumUniformRemapTable += entries;
> +   /* Verify that total amount of entries for explicit and implicit locations
> +    * is less than MAX_UNIFORM_LOCATIONS.
> +    */
> +   if (total_entries >= max_uniform_locs) {
> +      linker_error(prog, "count of uniform locations >= MAX_UNIFORM_LOCATIONS"
> +                   "(%u >= %u)", total_entries, max_uniform_locs);
>     }
>
>     /* Reserve all the explicit locations of the active subroutine uniforms. */
> @@ -1284,5 +1336,12 @@ link_assign_uniform_locations(struct gl_shader_program *prog,
>
>     link_set_uniform_initializers(prog, boolean_true);
>
> +   list_for_each_entry_safe(struct empty_uniform_block, block,
> +                            &prog->EmptyUniformLocations, link) {
> +      ralloc_free(block);
> +   }
> +
> +   list_inithead(&prog->EmptyUniformLocations);
> +
>     return;
>  }
> diff --git a/src/compiler/glsl/linker.cpp b/src/compiler/glsl/linker.cpp
> index bad1c17..cbbb6f1 100644
> --- a/src/compiler/glsl/linker.cpp
> +++ b/src/compiler/glsl/linker.cpp
> @@ -3008,12 +3008,13 @@ check_image_resources(struct gl_context *ctx, struct gl_shader_program *prog)
>   * for a variable, checks for overlaps between other uniforms using explicit
>   * locations.
>   */
> -static bool
> +static int
>  reserve_explicit_locations(struct gl_shader_program *prog,
>                             string_to_uint_map *map, ir_variable *var)
>  {
>     unsigned slots = var->type->uniform_locations();
>     unsigned max_loc = var->data.location + slots - 1;
> +   unsigned return_value = slots;
>
>     /* Resize remap table if locations do not fit in the current one. */
>     if (max_loc + 1 > prog->NumUniformRemapTable) {
> @@ -3024,7 +3025,7 @@ reserve_explicit_locations(struct gl_shader_program *prog,
>
>        if (!prog->UniformRemapTable) {
>           linker_error(prog, "Out of memory during linking.\n");
> -         return false;
> +         return -1;
>        }
>
>        /* Initialize allocated space. */
> @@ -3042,8 +3043,10 @@ reserve_explicit_locations(struct gl_shader_program *prog,
>
>           /* Possibly same uniform from a different stage, this is ok. */
>           unsigned hash_loc;
> -         if (map->get(hash_loc, var->name) && hash_loc == loc - i)
> -               continue;
> +         if (map->get(hash_loc, var->name) && hash_loc == loc - i) {
> +            return_value = 0;
> +            continue;
> +         }
>
>           /* ARB_explicit_uniform_location specification states:
>            *
> @@ -3055,7 +3058,7 @@ reserve_explicit_locations(struct gl_shader_program *prog,
>                        "location qualifier for uniform %s overlaps "
>                        "previously used location\n",
>                        var->name);
> -         return false;
> +         return -1;
>        }
>
>        /* Initialize location as inactive before optimization
> @@ -3067,7 +3070,7 @@ reserve_explicit_locations(struct gl_shader_program *prog,
>     /* Note, base location used for arrays. */
>     map->put(var->data.location, var->name);
>
> -   return true;
> +   return return_value;
>  }
>
>  static bool
> @@ -3128,12 +3131,12 @@ reserve_subroutine_explicit_locations(struct gl_shader_program *prog,
>   * any optimizations happen to handle also inactive uniforms and
>   * inactive array elements that may get trimmed away.
>   */
> -static void
> +static int
>  check_explicit_uniform_locations(struct gl_context *ctx,
>                                   struct gl_shader_program *prog)
>  {
>     if (!ctx->Extensions.ARB_explicit_uniform_location)
> -      return;
> +      return -1;
>
>     /* This map is used to detect if overlapping explicit locations
>      * occur with the same uniform (from different stage) or a different one.
> @@ -3142,7 +3145,7 @@ check_explicit_uniform_locations(struct gl_context *ctx,
>
>     if (!uniform_map) {
>        linker_error(prog, "Out of memory during linking.\n");
> -      return;
> +      return -1;
>     }
>
>     unsigned entries_total = 0;
> @@ -3157,31 +3160,55 @@ check_explicit_uniform_locations(struct gl_context *ctx,
>           if (!var || var->data.mode != ir_var_uniform)
>              continue;
>
> -         entries_total += var->type->uniform_locations();
> -
>           if (var->data.explicit_location) {
> -            bool ret;
> +            bool ret = false;
>              if (var->type->without_array()->is_subroutine())
>                 ret = reserve_subroutine_explicit_locations(prog, sh, var);
> -            else
> -               ret = reserve_explicit_locations(prog, uniform_map, var);
> +            else {
> +               int slots = reserve_explicit_locations(prog, uniform_map,
> +                                                      var);
> +               if (slots != -1) {
> +                  ret = true;
> +                  entries_total += slots;
> +               }
> +            }
>              if (!ret) {
>                 delete uniform_map;
> -               return;
> +               return -1;
>              }
>           }
>        }
>     }
>
> -   /* Verify that total amount of entries for explicit and implicit locations
> -    * is less than MAX_UNIFORM_LOCATIONS.
> -    */
> -   if (entries_total >= ctx->Const.MaxUserAssignableUniformLocations) {
> -      linker_error(prog, "count of uniform locations >= MAX_UNIFORM_LOCATIONS"
> -                   "(%u >= %u)", entries_total,
> -                   ctx->Const.MaxUserAssignableUniformLocations);
> +   if (entries_total > 0)
> +      entries_total -= 1;
> +
> +   list_inithead(&prog->EmptyUniformLocations);
> +
> +   struct empty_uniform_block *current_block = NULL;
> +   unsigned prev_location = -1;
> +
> +   for (unsigned i = 0; i < prog->NumUniformRemapTable; i++) {
> +      /* We found empty space in UniformRemapTable. */
> +      if (prog->UniformRemapTable[i] == NULL) {
> +         /* We've found the beginning of new continous block of empty slots */
> +         if ((i == 0) || !current_block || (i != prev_location + 1)) {
> +            current_block = ralloc(NULL, struct empty_uniform_block);
> +            current_block->start = i;
> +            current_block->slots = 1;
> +            list_addtail(&current_block->link, &prog->EmptyUniformLocations);
> +            prev_location = i;
> +            continue;
> +         }
> +
> +         /* The current block continues, so we simply increment its slots */
> +         current_block->slots++;
> +         prev_location = i;
> +      }
>     }
> +
>     delete uniform_map;
> +   return entries_total;
>  }
>
>  static bool
> @@ -4129,6 +4156,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
>
>     tfeedback_decl *tfeedback_decls = NULL;
>     unsigned num_tfeedback_decls = prog->TransformFeedback.NumVarying;
> +   unsigned int num_explicit_uniform_locs = 0;
>
>     void *mem_ctx = ralloc_context(NULL); // temporary linker context
>
> @@ -4310,7 +4338,7 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
>        last = i;
>     }
>
> -   check_explicit_uniform_locations(ctx, prog);
> +   num_explicit_uniform_locs = check_explicit_uniform_locations(ctx, prog);
>     link_assign_subroutine_types(prog);
>
>     if (!prog->LinkStatus)
> @@ -4541,7 +4569,9 @@ link_shaders(struct gl_context *ctx, struct gl_shader_program *prog)
>        goto done;
>
>     update_array_sizes(prog);
> -   link_assign_uniform_locations(prog, ctx->Const.UniformBooleanTrue);
> +   link_assign_uniform_locations(prog, ctx->Const.UniformBooleanTrue,
> +                                 num_explicit_uniform_locs,
> +                                 ctx->Const.MaxUserAssignableUniformLocations);
>     link_assign_atomic_counter_resources(ctx, prog);
>     store_fragdepth_layout(prog);
>
> diff --git a/src/compiler/glsl/linker.h b/src/compiler/glsl/linker.h
> index c80be1c..9f1fa3e 100644
> --- a/src/compiler/glsl/linker.h
> +++ b/src/compiler/glsl/linker.h
> @@ -35,7 +35,9 @@ link_invalidate_variable_locations(exec_list *ir);
>
>  extern void
>  link_assign_uniform_locations(struct gl_shader_program *prog,
> -                              unsigned int boolean_true);
> +                              unsigned int boolean_true,
> +                              unsigned int num_explicit_uniform_locs,
> +                              unsigned int max_uniform_locs);
>
>  extern void
>  link_set_uniform_initializers(struct gl_shader_program *prog,
> @@ -202,4 +204,17 @@ linker_error(gl_shader_program *prog, const char *fmt, ...);
>  void
>  linker_warning(gl_shader_program *prog, const char *fmt, ...);
>
> +/**
> + * Sometimes there are empty slots left over in UniformRemapTable after we
> + * allocate slots to explicit locations. This struct represents a single
> + * continouous block of empty slots in UniformRemapTable.
> + */
> +struct empty_uniform_block {
> +   struct list_head link;
> +   /* The start location of the block */
> +   unsigned start;
> +   /* The number of slots in the block */
> +   unsigned slots;
> +};
> +
>  #endif /* GLSL_LINKER_H */
> diff --git a/src/mesa/main/mtypes.h b/src/mesa/main/mtypes.h
> index e987177..fcc9017 100644
> --- a/src/mesa/main/mtypes.h
> +++ b/src/mesa/main/mtypes.h
> @@ -44,6 +44,7 @@
>  #include "math/m_matrix.h"     /* GLmatrix */
>  #include "compiler/shader_enums.h"
>  #include "main/formats.h"       /* MESA_FORMAT_COUNT */
> +#include "util/list.h"
>
>
>  #ifdef __cplusplus
> @@ -2764,6 +2765,13 @@ struct gl_shader_program
>     struct gl_uniform_storage **UniformRemapTable;
>
>     /**
> +    * Sometimes there are empty slots left over in UniformRemapTable after we
> +    * allocate slots to explicit locations. This list stores the blocks of
> +    * continuous empty slots inside UniformRemapTable.
> +    */
> +   struct list_head EmptyUniformLocations;
> +
> +   /**
>      * Size of the gl_ClipDistance array that is output from the last pipeline
>      * stage before the fragment shader.
>      */
> --
> 2.4.3
>
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