nir: add nir_lower_samplers_as_deref pass

This pass is a replacement for the nir_lower_samplers pass, which has the
advantage of keeping sampler references as derefs. This allows a unified
treatment of texture instructions and image intrinsics in the backend.

src/compiler/Makefile.sources

@@ -233,6 +233,7 @@ NIR_FILES = \
 	nir/nir_lower_regs_to_ssa.c \
 	nir/nir_lower_returns.c \
 	nir/nir_lower_samplers.c \
+	nir/nir_lower_samplers_as_deref.c \
 	nir/nir_lower_system_values.c \
 	nir/nir_lower_tex.c \
 	nir/nir_lower_to_source_mods.c \

src/compiler/nir/nir.h

@@ -2442,6 +2442,8 @@ void nir_lower_io_to_scalar(nir_shader *shader, nir_variable_mode mask);
 
 bool nir_lower_samplers(nir_shader *shader,
                         const struct gl_shader_program *shader_program);
+bool nir_lower_samplers_as_deref(nir_shader *shader,
+                                 const struct gl_shader_program *shader_program);
 
 bool nir_lower_system_values(nir_shader *shader);
 

src/compiler/nir/nir_lower_samplers_as_deref.c

@@ -0,0 +1,243 @@
+/*
+ * Copyright (C) 2005-2007  Brian Paul   All Rights Reserved.
+ * Copyright (C) 2008  VMware, Inc.   All Rights Reserved.
+ * Copyright © 2014 Intel Corporation
+ * Copyright © 2017 Advanced Micro Devices, Inc.
+ *
+ * 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.
+ */
+
+/**
+ * \file
+ *
+ * Lower sampler and image references of (non-bindless) uniforms by removing
+ * struct dereferences, and synthesizing new uniform variables without structs
+ * if required.
+ *
+ * This will allow backends to have a simple, uniform treatment of bindless and
+ * non-bindless samplers and images.
+ *
+ * Example:
+ *
+ *   struct S {
+ *      sampler2D tex[2];
+ *      sampler2D other;
+ *   };
+ *   uniform S s[2];
+ *
+ *   tmp = texture(s[n].tex[m], coord);
+ *
+ * Becomes:
+ *
+ *   decl_var uniform INTERP_MODE_NONE sampler2D[2][2] lower@s.tex (...)
+ *
+ *   vec1 32 ssa_idx = $(2 * n + m)
+ *   vec4 32 ssa_out = tex ssa_coord (coord), lower@s.tex[n][m] (texture), lower@s.tex[n][m] (sampler)
+ *
+ * and lower@s.tex has var->data.binding set to the base index as defined by
+ * the opaque uniform mapping.
+ */
+
+#include "nir.h"
+#include "nir_builder.h"
+#include "compiler/glsl/ir_uniform.h"
+
+#include "main/compiler.h"
+#include "main/mtypes.h"
+#include "program/prog_parameter.h"
+#include "program/program.h"
+
+struct lower_samplers_as_deref_state {
+   nir_shader *shader;
+   const struct gl_shader_program *shader_program;
+   struct hash_table *remap_table;
+};
+
+static void
+remove_struct_derefs(nir_deref *tail,
+                     struct lower_samplers_as_deref_state *state,
+                     nir_builder *b, char **path, unsigned *location)
+{
+   if (!tail->child)
+      return;
+
+   switch (tail->child->deref_type) {
+   case nir_deref_type_array: {
+      unsigned length = glsl_get_length(tail->type);
+
+      remove_struct_derefs(tail->child, state, b, path, location);
+
+      tail->type = glsl_get_array_instance(tail->child->type, length);
+      break;
+   }
+
+   case nir_deref_type_struct: {
+      nir_deref_struct *deref_struct = nir_deref_as_struct(tail->child);
+
+      *location += glsl_get_record_location_offset(tail->type, deref_struct->index);
+      ralloc_asprintf_append(path, ".%s",
+                             glsl_get_struct_elem_name(tail->type, deref_struct->index));
+
+      remove_struct_derefs(tail->child, state, b, path, location);
+
+      /* Drop the struct deref and re-parent. */
+      ralloc_steal(tail, tail->child->child);
+      tail->type = tail->child->type;
+      tail->child = tail->child->child;
+      break;
+   }
+
+   default:
+      unreachable("Invalid deref type");
+      break;
+   }
+}
+
+static void
+lower_deref(nir_deref_var *deref,
+            struct lower_samplers_as_deref_state *state,
+            nir_builder *b)
+{
+   nir_variable *var = deref->var;
+   gl_shader_stage stage = state->shader->stage;
+   unsigned location = var->data.location;
+   unsigned binding;
+   const struct glsl_type *orig_type = deref->deref.type;
+   char *path;
+
+   assert(var->data.mode == nir_var_uniform);
+
+   path = ralloc_asprintf(state->remap_table, "lower@%s", var->name);
+   remove_struct_derefs(&deref->deref, state, b, &path, &location);
+
+   assert(location < state->shader_program->data->NumUniformStorage &&
+          state->shader_program->data->UniformStorage[location].opaque[stage].active);
+
+   binding = state->shader_program->data->UniformStorage[location].opaque[stage].index;
+
+   if (orig_type == deref->deref.type) {
+      /* Fast path: We did not encounter any struct derefs. */
+      var->data.binding = binding;
+      return;
+   }
+
+   uint32_t hash = _mesa_key_hash_string(path);
+   struct hash_entry *h =
+      _mesa_hash_table_search_pre_hashed(state->remap_table, hash, path);
+
+   if (h) {
+      var = (nir_variable *)h->data;
+   } else {
+      var = nir_variable_create(state->shader, nir_var_uniform, deref->deref.type, path);
+      var->data.binding = binding;
+      _mesa_hash_table_insert_pre_hashed(state->remap_table, hash, path, var);
+   }
+
+   deref->var = var;
+}
+
+static bool
+lower_sampler(nir_tex_instr *instr, struct lower_samplers_as_deref_state *state,
+              nir_builder *b)
+{
+   /* In GLSL, we only fill out the texture field.  The sampler is inferred */
+   assert(instr->texture != NULL);
+   assert(instr->sampler == NULL);
+
+   b->cursor = nir_before_instr(&instr->instr);
+   lower_deref(instr->texture, state, b);
+
+   if (instr->op != nir_texop_txf_ms &&
+       instr->op != nir_texop_txf_ms_mcs &&
+       instr->op != nir_texop_samples_identical) {
+      nir_instr_rewrite_deref(&instr->instr, &instr->sampler,
+                              nir_deref_var_clone(instr->texture, instr));
+   } else {
+      assert(!instr->sampler);
+   }
+
+   return true;
+}
+
+static bool
+lower_intrinsic(nir_intrinsic_instr *instr,
+                struct lower_samplers_as_deref_state *state,
+                nir_builder *b)
+{
+   if (instr->intrinsic == nir_intrinsic_image_load ||
+       instr->intrinsic == nir_intrinsic_image_store ||
+       instr->intrinsic == nir_intrinsic_image_atomic_add ||
+       instr->intrinsic == nir_intrinsic_image_atomic_min ||
+       instr->intrinsic == nir_intrinsic_image_atomic_max ||
+       instr->intrinsic == nir_intrinsic_image_atomic_and ||
+       instr->intrinsic == nir_intrinsic_image_atomic_or ||
+       instr->intrinsic == nir_intrinsic_image_atomic_xor ||
+       instr->intrinsic == nir_intrinsic_image_atomic_exchange ||
+       instr->intrinsic == nir_intrinsic_image_atomic_comp_swap ||
+       instr->intrinsic == nir_intrinsic_image_size) {
+      b->cursor = nir_before_instr(&instr->instr);
+      lower_deref(instr->variables[0], state, b);
+      return true;
+   }
+
+   return false;
+}
+
+static bool
+lower_impl(nir_function_impl *impl, struct lower_samplers_as_deref_state *state)
+{
+   nir_builder b;
+   nir_builder_init(&b, impl);
+   bool progress = false;
+
+   nir_foreach_block(block, impl) {
+      nir_foreach_instr(instr, block) {
+         if (instr->type == nir_instr_type_tex)
+            progress |= lower_sampler(nir_instr_as_tex(instr), state, &b);
+         else if (instr->type == nir_instr_type_intrinsic)
+            progress |= lower_intrinsic(nir_instr_as_intrinsic(instr), state, &b);
+      }
+   }
+
+   return progress;
+}
+
+bool
+nir_lower_samplers_as_deref(nir_shader *shader,
+                            const struct gl_shader_program *shader_program)
+{
+   bool progress = false;
+   struct lower_samplers_as_deref_state state;
+
+   state.shader = shader;
+   state.shader_program = shader_program;
+   state.remap_table = _mesa_hash_table_create(NULL, _mesa_key_hash_string,
+                                               _mesa_key_string_equal);
+
+   nir_foreach_function(function, shader) {
+      if (function->impl)
+         progress |= lower_impl(function->impl, &state);
+   }
+
+   /* keys are freed automatically by ralloc */
+   _mesa_hash_table_destroy(state.remap_table, NULL);
+
+   return progress;
+}

src/compiler/nir_types.cpp

@@ -48,6 +48,13 @@ glsl_without_array(const glsl_type *type)
    return type->without_array();
 }
 
+const glsl_type *
+glsl_get_array_instance(const glsl_type *type,
+                        unsigned array_size)
+{
+   return glsl_type::get_array_instance(type, array_size);
+}
+
 const glsl_type *
 glsl_get_struct_field(const glsl_type *type, unsigned index)
 {

src/compiler/nir_types.h

@@ -48,6 +48,8 @@ const struct glsl_type *glsl_get_struct_field(const struct glsl_type *type,
 
 const struct glsl_type *glsl_get_array_element(const struct glsl_type *type);
 const struct glsl_type *glsl_without_array(const struct glsl_type *type);
+const struct glsl_type *glsl_get_array_instance(const struct glsl_type *type,
+                                                unsigned array_size);
 
 const struct glsl_type *glsl_get_column_type(const struct glsl_type *type);