/*
 * Copyright (C) 2005-2007  Brian Paul   All Rights Reserved.
 * Copyright (C) 2008  VMware, Inc.   All Rights Reserved.
 * Copyright © 2014 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 "nir_builder.h"
#include "compiler/glsl/ir_uniform.h"

#include "main/compiler.h"
#include "main/mtypes.h"

/* Calculate the sampler index based on array indicies and also
 * calculate the base uniform location for struct members.
 */
static void
calc_sampler_offsets(nir_deref *tail, nir_tex_instr *instr,
                     unsigned *array_elements, nir_ssa_def **indirect,
                     nir_builder *b, unsigned *location)
{
   if (tail->child == NULL)
      return;

   switch (tail->child->deref_type) {
   case nir_deref_type_array: {
      nir_deref_array *deref_array = nir_deref_as_array(tail->child);

      assert(deref_array->deref_array_type != nir_deref_array_type_wildcard);

      calc_sampler_offsets(tail->child, instr, array_elements,
                           indirect, b, location);
      instr->texture_index += deref_array->base_offset * *array_elements;

      if (deref_array->deref_array_type == nir_deref_array_type_indirect) {
         nir_ssa_def *mul =
            nir_imul(b, nir_imm_int(b, *array_elements),
                     nir_ssa_for_src(b, deref_array->indirect, 1));

         nir_instr_rewrite_src(&instr->instr, &deref_array->indirect,
                               NIR_SRC_INIT);

         if (*indirect) {
            *indirect = nir_iadd(b, *indirect, mul);
         } else {
            *indirect = mul;
         }
      }

      *array_elements *= glsl_get_length(tail->type);
       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);
      calc_sampler_offsets(tail->child, instr, array_elements,
                           indirect, b, location);
      break;
   }

   default:
      unreachable("Invalid deref type");
      break;
   }
}

static bool
lower_sampler(nir_tex_instr *instr, const struct gl_shader_program *shader_program,
              gl_shader_stage stage, nir_builder *b)
{
   if (instr->texture == NULL)
      return false;

   /* In GLSL, we only fill out the texture field.  The sampler is inferred */
   assert(instr->sampler == NULL);

   instr->texture_index = 0;
   unsigned location = instr->texture->var->data.location;
   unsigned array_elements = 1;
   nir_ssa_def *indirect = NULL;

   b->cursor = nir_before_instr(&instr->instr);
   calc_sampler_offsets(&instr->texture->deref, instr, &array_elements,
                        &indirect, b, &location);

   if (indirect) {
      assert(array_elements >= 1);
      indirect = nir_umin(b, indirect, nir_imm_int(b, array_elements - 1));

      nir_tex_instr_add_src(instr, nir_tex_src_texture_offset,
                            nir_src_for_ssa(indirect));
      nir_tex_instr_add_src(instr, nir_tex_src_sampler_offset,
                            nir_src_for_ssa(indirect));

      instr->texture_array_size = array_elements;
   }

   assert(location < shader_program->data->NumUniformStorage &&
          shader_program->data->UniformStorage[location].opaque[stage].active);

   instr->texture_index +=
      shader_program->data->UniformStorage[location].opaque[stage].index;

   instr->sampler_index = instr->texture_index;

   instr->texture = NULL;

   return true;
}

static bool
lower_impl(nir_function_impl *impl, const struct gl_shader_program *shader_program,
           gl_shader_stage stage)
{
   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),
                                      shader_program, stage, &b);
      }
   }

   return progress;
}

bool
nir_lower_samplers(nir_shader *shader,
                   const struct gl_shader_program *shader_program)
{
   bool progress = false;

   nir_foreach_function(function, shader) {
      if (function->impl)
         progress |= lower_impl(function->impl, shader_program,
                                shader->info.stage);
   }

   return progress;
}