nir/linker: Add gl_nir_link_uniforms()

This function will be the entry point for linking the uniforms from
the nir_shader objects associated with the gl_linked_shaders of a
program.

This patch includes initial support for linking uniforms from NIR
shaders. It is tailored for the ARB_gl_spirv needs, and it is far from
complete, but it should handle most cases of uniforms, array
uniforms, structs, samplers and images.

There are some FIXMEs related to specific features that will be
implemented in following patches, like atomic counters, UBOs and
SSBOs.

Also, note that ARB_gl_spirv makes mandatory explicit location for
normal uniforms, so this code only handles uniforms with explicit
location. But there are cases, like uniform atomic counters, that
doesn't have a location from the OpenGL point of view (they have a
binding), but that Mesa assign internally a location. That will be
handled on following patches.

A nir_linker.h file is also added. More NIR-linking related API will
be added in subsequent patches and those will include stuff from Mesa,
so reusing nir.h didn't seem a good idea.

v2: move from compiler/nir to compiler/glsl (Timothy Arceri)
v3: sets var->driver.location if the uniform was found from a previous
    stage (Neil Roberts).

Signed-off-by: Eduardo Lima <[email protected]>
Signed-off-by: Neil Roberts <[email protected]
Signed-off-by: Alejandro Piñeiro <[email protected]>

Reviewed-by: Timothy Arceri <[email protected]>

3 files changed, 504 insertions, 0 deletions

diff --git a/src/compiler/glsl/gl_nir_link_uniforms.c b/src/compiler/glsl/gl_nir_link_uniforms.c
new file mode 100644
index 00000000000..d3a39577177
--- /dev/null
+++ b/src/compiler/glsl/gl_nir_link_uniforms.c
@@ -0,0 +1,461 @@
+/*
+ * Copyright © 2018 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 "gl_nir_linker.h"
+#include "compiler/glsl/ir_uniform.h" /* for gl_uniform_storage */
+#include "linker_util.h"
+#include "main/context.h"
+#include "main/mtypes.h"
+
+/* This file do the common link for GLSL uniforms, using NIR, instead of IR as
+ * the counter-part glsl/link_uniforms.cpp
+ *
+ * Also note that this is tailored for ARB_gl_spirv needs and particularities
+ * (like need to work/link without name available, explicit location for
+ * normal uniforms as mandatory, and so on).
+ */
+
+static void
+nir_setup_uniform_remap_tables(struct gl_context *ctx,
+                               struct gl_shader_program *prog)
+{
+   prog->UniformRemapTable = rzalloc_array(prog,
+                                           struct gl_uniform_storage *,
+                                           prog->NumUniformRemapTable);
+   union gl_constant_value *data =
+      rzalloc_array(prog->data,
+                    union gl_constant_value, prog->data->NumUniformDataSlots);
+   if (!prog->UniformRemapTable || !data) {
+      linker_error(prog, "Out of memory during linking.\n");
+      return;
+   }
+   prog->data->UniformDataSlots = data;
+
+   unsigned data_pos = 0;
+
+   /* Reserve all the explicit locations of the active uniforms. */
+   for (unsigned i = 0; i < prog->data->NumUniformStorage; i++) {
+      struct gl_uniform_storage *uniform = &prog->data->UniformStorage[i];
+
+      /* How many new entries for this uniform? */
+      const unsigned entries = MAX2(1, uniform->array_elements);
+      unsigned num_slots = glsl_get_component_slots(uniform->type);
+
+      uniform->storage = &data[data_pos];
+
+      /* Set remap table entries point to correct gl_uniform_storage. */
+      for (unsigned j = 0; j < entries; j++) {
+         unsigned element_loc = uniform->remap_location + j;
+         prog->UniformRemapTable[element_loc] = uniform;
+
+         data_pos += num_slots;
+      }
+   }
+}
+
+static struct gl_uniform_storage *
+find_previous_uniform_storage(struct gl_shader_program *prog,
+                              int location)
+{
+   /* This would only work for uniform with explicit location, as all the
+    * uniforms without location (ie: atomic counters) would have a initial
+    * location equal to -1. We early return in that case.
+    */
+   if (location == -1)
+      return NULL;
+
+   for (unsigned i = 0; i < prog->data->NumUniformStorage; i++)
+      if (prog->data->UniformStorage[i].remap_location == location)
+         return &prog->data->UniformStorage[i];
+
+   return NULL;
+}
+
+/* Used to build a tree representing the glsl_type so that we can have a place
+ * to store the next index for opaque types. Array types are expanded so that
+ * they have a single child which is used for all elements of the array.
+ * Struct types have a child for each member. The tree is walked while
+ * processing a uniform so that we can recognise when an opaque type is
+ * encountered a second time in order to reuse the same range of indices that
+ * was reserved the first time. That way the sampler indices can be arranged
+ * so that members of an array are placed sequentially even if the array is an
+ * array of structs containing other opaque members.
+ */
+struct type_tree_entry {
+   /* For opaque types, this will be the next index to use. If we haven’t
+    * encountered this member yet, it will be UINT_MAX.
+    */
+   unsigned next_index;
+   unsigned array_size;
+   struct type_tree_entry *parent;
+   struct type_tree_entry *next_sibling;
+   struct type_tree_entry *children;
+};
+
+struct nir_link_uniforms_state {
+   /* per-whole program */
+   unsigned num_hidden_uniforms;
+   unsigned num_values;
+   unsigned max_uniform_location;
+   unsigned next_sampler_index;
+   unsigned next_image_index;
+
+   /* per-shader stage */
+   unsigned num_shader_samplers;
+   unsigned num_shader_images;
+   unsigned num_shader_uniform_components;
+   unsigned shader_samplers_used;
+   unsigned shader_shadow_samplers;
+
+   nir_variable *current_var;
+
+   struct type_tree_entry *current_type;
+};
+
+static struct type_tree_entry *
+build_type_tree_for_type(const struct glsl_type *type)
+{
+   struct type_tree_entry *entry = malloc(sizeof *entry);
+
+   entry->array_size = 1;
+   entry->next_index = UINT_MAX;
+   entry->children = NULL;
+   entry->next_sibling = NULL;
+   entry->parent = NULL;
+
+   if (glsl_type_is_array(type)) {
+      entry->array_size = glsl_get_length(type);
+      entry->children = build_type_tree_for_type(glsl_get_array_element(type));
+      entry->children->parent = entry;
+   } else if (glsl_type_is_struct(type)) {
+      struct type_tree_entry *last = NULL;
+
+      for (unsigned i = 0; i < glsl_get_length(type); i++) {
+         const struct glsl_type *field_type = glsl_get_struct_field(type, i);
+         struct type_tree_entry *field_entry =
+            build_type_tree_for_type(field_type);
+
+         if (last == NULL)
+            entry->children = field_entry;
+         else
+            last->next_sibling = field_entry;
+
+         field_entry->parent = entry;
+
+         last = field_entry;
+      }
+   }
+
+   return entry;
+}
+
+static void
+free_type_tree(struct type_tree_entry *entry)
+{
+   struct type_tree_entry *p, *next;
+
+   for (p = entry->children; p; p = next) {
+      next = p->next_sibling;
+      free_type_tree(p);
+   }
+
+   free(entry);
+}
+
+static unsigned
+get_next_index(struct nir_link_uniforms_state *state,
+               const struct gl_uniform_storage *uniform,
+               unsigned *next_index)
+{
+   /* If we’ve already calculated an index for this member then we can just
+    * offset from there.
+    */
+   if (state->current_type->next_index == UINT_MAX) {
+      /* Otherwise we need to reserve enough indices for all of the arrays
+       * enclosing this member.
+       */
+
+      unsigned array_size = 1;
+
+      for (const struct type_tree_entry *p = state->current_type;
+           p;
+           p = p->parent) {
+         array_size *= p->array_size;
+      }
+
+      state->current_type->next_index = *next_index;
+      *next_index += array_size;
+   }
+
+   unsigned index = state->current_type->next_index;
+
+   state->current_type->next_index += MAX2(1, uniform->array_elements);
+
+   return index;
+}
+
+
+/**
+ * Creates the neccessary entries in UniformStorage for the uniform. Returns
+ * the number of locations used or -1 on failure.
+ */
+static int
+nir_link_uniform(struct gl_context *ctx,
+                 struct gl_shader_program *prog,
+                 struct gl_program *stage_program,
+                 gl_shader_stage stage,
+                 const struct glsl_type *type,
+                 int location,
+                 struct nir_link_uniforms_state *state)
+{
+   struct gl_uniform_storage *uniform = NULL;
+
+   /* gl_uniform_storage can cope with one level of array, so if the type is a
+    * composite type or an array where each element occupies more than one
+    * location than we need to recursively process it.
+    */
+   if (glsl_type_is_struct(type) ||
+       (glsl_type_is_array(type) &&
+        (glsl_type_is_array(glsl_get_array_element(type)) ||
+         glsl_type_is_struct(glsl_get_array_element(type))))) {
+      int location_count = 0;
+      struct type_tree_entry *old_type = state->current_type;
+
+      state->current_type = old_type->children;
+
+      for (unsigned i = 0; i < glsl_get_length(type); i++) {
+         const struct glsl_type *field_type;
+
+         if (glsl_type_is_struct(type))
+            field_type = glsl_get_struct_field(type, i);
+         else
+            field_type = glsl_get_array_element(type);
+
+         int entries = nir_link_uniform(ctx, prog, stage_program, stage,
+                                        field_type, location,
+                                        state);
+         if (entries == -1)
+            return -1;
+
+         if (location != -1)
+            location += entries;
+         location_count += entries;
+
+         if (glsl_type_is_struct(type))
+            state->current_type = state->current_type->next_sibling;
+      }
+
+      state->current_type = old_type;
+
+      return location_count;
+   } else {
+      /* Create a new uniform storage entry */
+      prog->data->UniformStorage =
+         reralloc(prog->data,
+                  prog->data->UniformStorage,
+                  struct gl_uniform_storage,
+                  prog->data->NumUniformStorage + 1);
+      if (!prog->data->UniformStorage) {
+         linker_error(prog, "Out of memory during linking.\n");
+         return -1;
+      }
+
+      uniform = &prog->data->UniformStorage[prog->data->NumUniformStorage];
+      prog->data->NumUniformStorage++;
+
+      /* Initialize its members */
+      memset(uniform, 0x00, sizeof(struct gl_uniform_storage));
+      /* ARB_gl_spirv: names are considered optional debug info, so the linker
+       * needs to work without them, and returning them is optional. For
+       * simplicity we ignore names.
+       */
+      uniform->name = NULL;
+
+      const struct glsl_type *type_no_array = glsl_without_array(type);
+      if (glsl_type_is_array(type)) {
+         uniform->type = type_no_array;
+         uniform->array_elements = glsl_get_length(type);
+      } else {
+         uniform->type = type;
+         uniform->array_elements = 0;
+      }
+      uniform->active_shader_mask |= 1 << stage;
+
+      /* Uniform has an explicit location */
+      uniform->remap_location = location;
+
+      /* @FIXME: the initialization of the following will be done as we
+       * implement support for their specific features, like SSBO, atomics,
+       * etc.
+       */
+      uniform->block_index = -1;
+      uniform->offset = -1;
+      uniform->matrix_stride = -1;
+      uniform->array_stride = -1;
+      uniform->row_major = false;
+      uniform->hidden = false;
+      uniform->builtin = false;
+      uniform->is_shader_storage = false;
+      uniform->atomic_buffer_index = -1;
+      uniform->top_level_array_size = 0;
+      uniform->top_level_array_stride = 0;
+      uniform->is_bindless = false;
+
+      /* The following are not for features not supported by ARB_gl_spirv */
+      uniform->num_compatible_subroutines = 0;
+
+      unsigned entries = MAX2(1, uniform->array_elements);
+
+      if (glsl_type_is_sampler(type_no_array)) {
+         int sampler_index =
+            get_next_index(state, uniform, &state->next_sampler_index);
+
+         state->num_shader_samplers++;
+
+         uniform->opaque[stage].active = true;
+         uniform->opaque[stage].index = sampler_index;
+
+         const unsigned shadow = glsl_sampler_type_is_shadow(type_no_array);
+
+         for (unsigned i = sampler_index;
+              i < MIN2(state->next_sampler_index, MAX_SAMPLERS);
+              i++) {
+            stage_program->sh.SamplerTargets[i] =
+               glsl_get_sampler_target(type_no_array);
+            state->shader_samplers_used |= 1U << i;
+            state->shader_shadow_samplers |= shadow << i;
+         }
+      } else if (glsl_type_is_image(type_no_array)) {
+         /* @FIXME: image_index should match that of the same image
+          * uniform in other shaders. This means we need to match image
+          * uniforms by location (GLSL does it by variable name, but we
+          * want to avoid that).
+          */
+         int image_index = state->next_image_index;
+         state->next_image_index += entries;
+
+         state->num_shader_images++;
+
+         uniform->opaque[stage].active = true;
+         uniform->opaque[stage].index = image_index;
+
+         /* Set image access qualifiers */
+         const GLenum access =
+            (state->current_var->data.image.read_only ? GL_READ_ONLY :
+             state->current_var->data.image.write_only ? GL_WRITE_ONLY :
+             GL_READ_WRITE);
+         for (unsigned i = image_index;
+              i < MIN2(state->next_image_index, MAX_IMAGE_UNIFORMS);
+              i++) {
+            stage_program->sh.ImageAccess[i] = access;
+         }
+      }
+
+      unsigned values = glsl_get_component_slots(type);
+      state->num_shader_uniform_components += values;
+      state->num_values += values;
+
+      if (state->max_uniform_location < uniform->remap_location + entries)
+         state->max_uniform_location = uniform->remap_location + entries;
+
+      return MAX2(uniform->array_elements, 1);
+   }
+}
+
+bool
+gl_nir_link_uniforms(struct gl_context *ctx,
+                     struct gl_shader_program *prog)
+{
+   /* First free up any previous UniformStorage items */
+   ralloc_free(prog->data->UniformStorage);
+   prog->data->UniformStorage = NULL;
+   prog->data->NumUniformStorage = 0;
+
+   /* Iterate through all linked shaders */
+   struct nir_link_uniforms_state state = {0,};
+
+   for (unsigned shader_type = 0; shader_type < MESA_SHADER_STAGES; shader_type++) {
+      struct gl_linked_shader *sh = prog->_LinkedShaders[shader_type];
+      if (!sh)
+         continue;
+
+      nir_shader *nir = sh->Program->nir;
+      assert(nir);
+
+      state.num_shader_samplers = 0;
+      state.num_shader_images = 0;
+      state.num_shader_uniform_components = 0;
+      state.shader_samplers_used = 0;
+      state.shader_shadow_samplers = 0;
+
+      nir_foreach_variable(var, &nir->uniforms) {
+         struct gl_uniform_storage *uniform = NULL;
+
+         /* Check if the uniform has been processed already for
+          * other stage. If so, validate they are compatible and update
+          * the active stage mask.
+          */
+         uniform = find_previous_uniform_storage(prog, var->data.location);
+         if (uniform) {
+            uniform->active_shader_mask |= 1 << shader_type;
+            var->data.location = uniform - prog->data->UniformStorage;
+
+            continue;
+         }
+
+         int location = var->data.location;
+         /* From now on the variable’s location will be its uniform index */
+         var->data.location = prog->data->NumUniformStorage;
+
+         state.current_var = var;
+
+         struct type_tree_entry *type_tree =
+            build_type_tree_for_type(var->type);
+         state.current_type = type_tree;
+
+         int res = nir_link_uniform(ctx, prog, sh->Program, shader_type, var->type,
+                                    location, &state);
+
+         free_type_tree(type_tree);
+
+         if (res == -1)
+            return false;
+      }
+
+      sh->Program->SamplersUsed = state.shader_samplers_used;
+      sh->shadow_samplers = state.shader_shadow_samplers;
+      sh->Program->info.num_textures = state.num_shader_samplers;
+      sh->Program->info.num_images = state.num_shader_images;
+      sh->num_uniform_components = state.num_shader_uniform_components;
+      sh->num_combined_uniform_components = sh->num_uniform_components;
+   }
+
+   prog->data->NumHiddenUniforms = state.num_hidden_uniforms;
+   prog->NumUniformRemapTable = state.max_uniform_location;
+   prog->data->NumUniformDataSlots = state.num_values;
+
+   nir_setup_uniform_remap_tables(ctx, prog);
+
+   return true;
+}
diff --git a/src/compiler/glsl/gl_nir_linker.h b/src/compiler/glsl/gl_nir_linker.h
new file mode 100644
index 00000000000..31e8fe1a201
--- /dev/null
+++ b/src/compiler/glsl/gl_nir_linker.h
@@ -0,0 +1,41 @@
+/*
+ * Copyright © 2017 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.
+ */
+
+#ifndef GL_NIR_LINKER_H
+#define GL_NIR_LINKER_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+struct gl_context;
+struct gl_shader_program;
+
+bool gl_nir_link_uniforms(struct gl_context *ctx,
+                          struct gl_shader_program *prog);
+
+#ifdef __cplusplus
+} /* extern "C" */
+#endif
+
+#endif /* GL_NIR_LINKER_H */
diff --git a/src/compiler/glsl/meson.build b/src/compiler/glsl/meson.build
index 686a5a4ac0b..a42c68b5eeb 100644
--- a/src/compiler/glsl/meson.build
+++ b/src/compiler/glsl/meson.build
@@ -69,6 +69,8 @@ files_libglsl = files(
   'gl_nir_lower_atomics.c',
   'gl_nir_lower_samplers.c',
   'gl_nir_lower_samplers_as_deref.c',
+  'gl_nir_link_uniforms.c',
+  'gl_nir_linker.h',
   'gl_nir.h',
   'glsl_parser_extras.cpp',
   'glsl_parser_extras.h',