/*
 * Copyright © 2017 Ilia Mirkin
 *
 * 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 "compiler/nir/nir_builder.h"
#include "ir3_nir.h"

/* A4XX has a broken GATHER4 operation. It performs the texture swizzle on the
 * gather results, rather than before. As a result, it must be emulated with
 * direct texture calls.
 */

static nir_ssa_def *
ir3_nir_lower_tg4_to_tex_instr(nir_builder *b, nir_instr *instr, void *data)
{
   nir_tex_instr *tg4 = nir_instr_as_tex(instr);
   static const int offsets[3][2] = {{0, 1}, {1, 1}, {1, 0}};

   nir_ssa_def *results[4];
   int offset_index = nir_tex_instr_src_index(tg4, nir_tex_src_offset);
   for (int i = 0; i < 4; i++) {
      int num_srcs = tg4->num_srcs + 1 /* lod */;
      if (offset_index < 0 && i < 3)
         num_srcs++;

      nir_tex_instr *tex = nir_tex_instr_create(b->shader, num_srcs);
      tex->op = nir_texop_txl;
      tex->sampler_dim = tg4->sampler_dim;
      tex->coord_components = tg4->coord_components;
      tex->is_array = tg4->is_array;
      tex->is_shadow = tg4->is_shadow;
      tex->is_new_style_shadow = tg4->is_new_style_shadow;
      tex->texture_index = tg4->texture_index;
      tex->sampler_index = tg4->sampler_index;
      tex->dest_type = tg4->dest_type;

      for (int j = 0; j < tg4->num_srcs; j++) {
         nir_src_copy(&tex->src[j].src, &tg4->src[j].src);
         tex->src[j].src_type = tg4->src[j].src_type;
      }
      if (i != 3) {
         nir_ssa_def *offset = nir_vec2(b, nir_imm_int(b, offsets[i][0]),
                                        nir_imm_int(b, offsets[i][1]));
         if (offset_index < 0) {
            tex->src[tg4->num_srcs].src = nir_src_for_ssa(offset);
            tex->src[tg4->num_srcs].src_type = nir_tex_src_offset;
         } else {
            assert(nir_tex_instr_src_size(tex, offset_index) == 2);
            nir_ssa_def *orig =
               nir_ssa_for_src(b, tex->src[offset_index].src, 2);
            tex->src[offset_index].src =
               nir_src_for_ssa(nir_iadd(b, orig, offset));
         }
      }
      tex->src[num_srcs - 1].src = nir_src_for_ssa(nir_imm_float(b, 0));
      tex->src[num_srcs - 1].src_type = nir_tex_src_lod;

      nir_ssa_dest_init(&tex->instr, &tex->dest, nir_tex_instr_dest_size(tex),
                        32, NULL);
      nir_builder_instr_insert(b, &tex->instr);

      results[i] = nir_channel(b, &tex->dest.ssa, tg4->component);
   }

   return nir_vec(b, results, 4);
}

static bool
ir3_nir_lower_tg4_to_tex_filter(const nir_instr *instr, const void *data)
{
   return (instr->type == nir_instr_type_tex &&
           nir_instr_as_tex(instr)->op == nir_texop_tg4);
}

bool
ir3_nir_lower_tg4_to_tex(nir_shader *shader)
{
   return nir_shader_lower_instructions(shader, ir3_nir_lower_tg4_to_tex_filter,
                                        ir3_nir_lower_tg4_to_tex_instr, NULL);
}