text: /*
   * Copyright © 2015 Broadcom
   *
   * 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 "vc4_qir.h"
  #include "compiler/nir/nir_builder.h"
  #include "util/u_format.h"
  
  /**
   * Walks the NIR generated by TGSI-to-NIR or GLSL-to-NIR to lower its io
   * intrinsics into something amenable to the VC4 architecture.
   *
   * Currently, it splits VS inputs and uniforms into scalars, drops any
   * non-position outputs in coordinate shaders, and fixes up the addressing on
   * indirect uniform loads.  FS input and VS output scalarization is handled by
   * nir_lower_io_to_scalar().
   */
  
  static void
  replace_intrinsic_with_vec(nir_builder *b, nir_intrinsic_instr *intr,
                             nir_ssa_def **comps)
  {
  
          /* Batch things back together into a vector.  This will get split by
           * the later ALU scalarization pass.
           */
          nir_ssa_def *vec = nir_vec(b, comps, intr->num_components);
  
          /* Replace the old intrinsic with a reference to our reconstructed
           * vector.
           */
          nir_ssa_def_rewrite_uses(&intr->dest.ssa, nir_src_for_ssa(vec));
          nir_instr_remove(&intr->instr);
  }
  
  static nir_ssa_def *
  vc4_nir_unpack_8i(nir_builder *b, nir_ssa_def *src, unsigned chan)
  {
          return nir_ubitfield_extract(b,
                                       src,
                                       nir_imm_int(b, 8 * chan),
                                       nir_imm_int(b, 8));
  }
  
  /** Returns the 16 bit field as a sign-extended 32-bit value. */
  static nir_ssa_def *
  vc4_nir_unpack_16i(nir_builder *b, nir_ssa_def *src, unsigned chan)
  {
          return nir_ibitfield_extract(b,
                                       src,
                                       nir_imm_int(b, 16 * chan),
                                       nir_imm_int(b, 16));
  }
  
  /** Returns the 16 bit field as an unsigned 32 bit value. */
  static nir_ssa_def *
  vc4_nir_unpack_16u(nir_builder *b, nir_ssa_def *src, unsigned chan)
  {
          if (chan == 0) {
                  return nir_iand(b, src, nir_imm_int(b, 0xffff));
          } else {
                  return nir_ushr(b, src, nir_imm_int(b, 16));
          }
  }
  
  static nir_ssa_def *
  vc4_nir_unpack_8f(nir_builder *b, nir_ssa_def *src, unsigned chan)
  {
          return nir_channel(b, nir_unpack_unorm_4x8(b, src), chan);
  }
  
  static nir_ssa_def *
  vc4_nir_get_vattr_channel_vpm(struct vc4_compile *c,
                                nir_builder *b,
                                nir_ssa_def **vpm_reads,
                                uint8_t swiz,
                                const struct util_format_description *desc)
  {
          const struct util_format_channel_description *chan =
                  &desc->channel[swiz];
          nir_ssa_def *temp;
  
          if (swiz > PIPE_SWIZZLE_W) {
                  return vc4_nir_get_swizzled_channel(b, vpm_reads, swiz);
          } else if (chan->size == 32 && chan->type == UTIL_FORMAT_TYPE_FLOAT) {
                  return vc4_nir_get_swizzled_channel(b, vpm_reads, swiz);
          } else if (chan->size == 32 && chan->type == UTIL_FORMAT_TYPE_SIGNED) {
                  if (chan->normalized) {
                          return nir_fmul(b,
                                          nir_i2f32(b, vpm_reads[swiz]),
                                          nir_imm_float(b,
                                                        1.0 / 0x7fffffff));
                  } else {
                          return nir_i2f32(b, vpm_reads[swiz]);
                  }
          } else if (chan->size == 8 &&
                     (chan->type == UTIL_FORMAT_TYPE_UNSIGNED ||
                      chan->type == UTIL_FORMAT_TYPE_SIGNED)) {
                  nir_ssa_def *vpm = vpm_reads[0];
                  if (chan->type == UTIL_FORMAT_TYPE_SIGNED) {
                          temp = nir_ixor(b, vpm, nir_imm_int(b, 0x80808080));
                          if (chan->normalized) {
                                  return nir_fsub(b, nir_fmul(b,
                                                              vc4_nir_unpack_8f(b, temp, swiz),
                                                              nir_imm_float(b, 2.0)),
                                                  nir_imm_float(b, 1.0));
                          } else {
                                  return nir_fadd(b,
                                                  nir_i2f32(b,
                                                            vc4_nir_unpack_8i(b, temp,
                                                                              swiz)),
                                                  nir_imm_float(b, -128.0));
                          }
                  } else {
                          if (chan->normalized) {
                                  return vc4_nir_unpack_8f(b, vpm, swiz);
                          } else {
                                  return nir_i2f32(b, vc4_nir_unpack_8i(b, vpm, swiz));
                          }
                  }
          } else if (chan->size == 16 &&
                     (chan->type == UTIL_FORMAT_TYPE_UNSIGNED ||
                      chan->type == UTIL_FORMAT_TYPE_SIGNED)) {
                  nir_ssa_def *vpm = vpm_reads[swiz / 2];
  
                  /* Note that UNPACK_16F eats a half float, not ints, so we use
                   * UNPACK_16_I for all of these.
                   */
                  if (chan->type == UTIL_FORMAT_TYPE_SIGNED) {
                          temp = nir_i2f32(b, vc4_nir_unpack_16i(b, vpm, swiz & 1));
                          if (chan->normalized) {
                                  return nir_fmul(b, temp,
                                                  nir_imm_float(b, 1/32768.0f));
                          } else {
                                  return temp;
                          }
                  } else {
                          temp = nir_i2f32(b, vc4_nir_unpack_16u(b, vpm, swiz & 1));
                          if (chan->normalized) {
                                  return nir_fmul(b, temp,
                                                  nir_imm_float(b, 1 / 65535.0));
                          } else {
                                  return temp;
                          }
                  }
          } else {
                  return NULL;
          }
  }
  
  static void
  vc4_nir_lower_vertex_attr(struct vc4_compile *c, nir_builder *b,
                            nir_intrinsic_instr *intr)
  {
          b->cursor = nir_before_instr(&intr->instr);
  
          int attr = nir_intrinsic_base(intr);
          enum pipe_format format = c->vs_key->attr_formats[attr];
          uint32_t attr_size = util_format_get_blocksize(format);
  
          /* We only accept direct outputs and TGSI only ever gives them to us
           * with an offset value of 0.
           */
          assert(nir_src_as_const_value(intr->src[0]) &&
                 nir_src_as_const_value(intr->src[0])->u32[0] == 0);
  
          /* Generate dword loads for the VPM values (Since these intrinsics may
           * be reordered, the actual reads will be generated at the top of the
           * shader by ntq_setup_inputs().
           */
          nir_ssa_def *vpm_reads[4];
          for (int i = 0; i < align(attr_size, 4) / 4; i++) {
                  nir_intrinsic_instr *intr_comp =
                          nir_intrinsic_instr_create(c->s,
                                                     nir_intrinsic_load_input);
                  intr_comp->num_components = 1;
                  nir_intrinsic_set_base(intr_comp, nir_intrinsic_base(intr));
                  nir_intrinsic_set_component(intr_comp, i);
                  intr_comp->src[0] = nir_src_for_ssa(nir_imm_int(b, 0));
                  nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
                  nir_builder_instr_insert(b, &intr_comp->instr);
  
                  vpm_reads[i] = &intr_comp->dest.ssa;
          }
  
          bool format_warned = false;
          const struct util_format_description *desc =
                  util_format_description(format);
  
          nir_ssa_def *dests[4];
          for (int i = 0; i < intr->num_components; i++) {
                  uint8_t swiz = desc->swizzle[i];
                  dests[i] = vc4_nir_get_vattr_channel_vpm(c, b, vpm_reads, swiz,
                                                           desc);
  
                  if (!dests[i]) {
                          if (!format_warned) {
                                  fprintf(stderr,
                                          "vtx element %d unsupported type: %s\n",
                                          attr, util_format_name(format));
                                  format_warned = true;
                          }
                          dests[i] = nir_imm_float(b, 0.0);
                  }
          }
  
          replace_intrinsic_with_vec(b, intr, dests);
  }
  
  static bool
  is_point_sprite(struct vc4_compile *c, nir_variable *var)
  {
          if (var->data.location < VARYING_SLOT_VAR0 ||
              var->data.location > VARYING_SLOT_VAR31)
                  return false;
  
          return (c->fs_key->point_sprite_mask &
                  (1 << (var->data.location - VARYING_SLOT_VAR0)));
  }
  
  static void
  vc4_nir_lower_fs_input(struct vc4_compile *c, nir_builder *b,
                         nir_intrinsic_instr *intr)
  {
          b->cursor = nir_after_instr(&intr->instr);
  
          if (nir_intrinsic_base(intr) >= VC4_NIR_TLB_COLOR_READ_INPUT &&
              nir_intrinsic_base(intr) < (VC4_NIR_TLB_COLOR_READ_INPUT +
                                          VC4_MAX_SAMPLES)) {
                  /* This doesn't need any lowering. */
                  return;
          }
  
          nir_variable *input_var = NULL;
          nir_foreach_variable(var, &c->s->inputs) {
                  if (var->data.driver_location == nir_intrinsic_base(intr)) {
                          input_var = var;
                          break;
                  }
          }
          assert(input_var);
  
          int comp = nir_intrinsic_component(intr);
  
          /* Lower away point coordinates, and fix up PNTC. */
          if (is_point_sprite(c, input_var) ||
              input_var->data.location == VARYING_SLOT_PNTC) {
                  assert(intr->num_components == 1);
  
                  nir_ssa_def *result = &intr->dest.ssa;
  
                  switch (comp) {
                  case 0:
                  case 1:
                          /* If we're not rendering points, we need to set a
                           * defined value for the input that would come from
                           * PNTC.
                           */
                          if (!c->fs_key->is_points)
                                  result = nir_imm_float(b, 0.0);
                          break;
                  case 2:
                          result = nir_imm_float(b, 0.0);
                          break;
                  case 3:
                          result = nir_imm_float(b, 1.0);
                          break;
                  }
  
                  if (c->fs_key->point_coord_upper_left && comp == 1)
                          result = nir_fsub(b, nir_imm_float(b, 1.0), result);
  
                  if (result != &intr->dest.ssa) {
                          nir_ssa_def_rewrite_uses_after(&intr->dest.ssa,
                                                         nir_src_for_ssa(result),
                                                         result->parent_instr);
                  }
          }
  }
  
  static void
  vc4_nir_lower_output(struct vc4_compile *c, nir_builder *b,
                       nir_intrinsic_instr *intr)
  {
          nir_variable *output_var = NULL;
          nir_foreach_variable(var, &c->s->outputs) {
                  if (var->data.driver_location == nir_intrinsic_base(intr)) {
                          output_var = var;
                          break;
                  }
          }
          assert(output_var);
  
          if (c->stage == QSTAGE_COORD &&
              output_var->data.location != VARYING_SLOT_POS &&
              output_var->data.location != VARYING_SLOT_PSIZ) {
                  nir_instr_remove(&intr->instr);
                  return;
          }
  }
  
  static void
  vc4_nir_lower_uniform(struct vc4_compile *c, nir_builder *b,
                        nir_intrinsic_instr *intr)
  {
          b->cursor = nir_before_instr(&intr->instr);
  
          /* Generate scalar loads equivalent to the original vector. */
          nir_ssa_def *dests[4];
          for (unsigned i = 0; i < intr->num_components; i++) {
                  nir_intrinsic_instr *intr_comp =
                          nir_intrinsic_instr_create(c->s, intr->intrinsic);
                  intr_comp->num_components = 1;
                  nir_ssa_dest_init(&intr_comp->instr, &intr_comp->dest, 1, 32, NULL);
  
                  /* Convert the uniform offset to bytes.  If it happens
                   * to be a constant, constant-folding will clean up
                   * the shift for us.
                   */
                  nir_intrinsic_set_base(intr_comp,
                                         nir_intrinsic_base(intr) * 16 +
                                         i * 4);
  
                  intr_comp->src[0] =
                          nir_src_for_ssa(nir_ishl(b, intr->src[0].ssa,
                                                   nir_imm_int(b, 4)));
  
                  dests[i] = &intr_comp->dest.ssa;
  
                  nir_builder_instr_insert(b, &intr_comp->instr);
          }
  
          replace_intrinsic_with_vec(b, intr, dests);
  }
  
  static void
  vc4_nir_lower_io_instr(struct vc4_compile *c, nir_builder *b,
                         struct nir_instr *instr)
  {
          if (instr->type != nir_instr_type_intrinsic)
                  return;
          nir_intrinsic_instr *intr = nir_instr_as_intrinsic(instr);
  
          switch (intr->intrinsic) {
          case nir_intrinsic_load_input:
                  if (c->stage == QSTAGE_FRAG)
                          vc4_nir_lower_fs_input(c, b, intr);
                  else
                          vc4_nir_lower_vertex_attr(c, b, intr);
                  break;
  
          case nir_intrinsic_store_output:
                  vc4_nir_lower_output(c, b, intr);
                  break;
  
          case nir_intrinsic_load_uniform:
                  vc4_nir_lower_uniform(c, b, intr);
                  break;
  
          case nir_intrinsic_load_user_clip_plane:
          default:
                  break;
          }
  }
  
  static bool
  vc4_nir_lower_io_impl(struct vc4_compile *c, nir_function_impl *impl)
  {
          nir_builder b;
          nir_builder_init(&b, impl);
  
          nir_foreach_block(block, impl) {
                  nir_foreach_instr_safe(instr, block)
                          vc4_nir_lower_io_instr(c, &b, instr);
          }
  
          nir_metadata_preserve(impl, nir_metadata_block_index |
                                nir_metadata_dominance);
  
          return true;
  }
  
  void
  vc4_nir_lower_io(nir_shader *s, struct vc4_compile *c)
  {
          nir_foreach_function(function, s) {
                  if (function->impl)
                          vc4_nir_lower_io_impl(c, function->impl);
          }
  }
  