mesa/src/amd/compiler/aco_instruction_selection_setup.cpp

/*
 * Copyright © 2018 Valve 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 "aco_instruction_selection.h"

#include "common/ac_nir.h"
#include "common/sid.h"

#include "nir_control_flow.h"

#include <vector>

namespace aco {

namespace {

bool
is_loop_header_block(nir_block* block)
{
   return block->cf_node.parent->type == nir_cf_node_loop &&
          block == nir_loop_first_block(nir_cf_node_as_loop(block->cf_node.parent));
}

/* similar to nir_block_is_unreachable(), but does not require dominance information */
bool
is_block_reachable(nir_function_impl* impl, nir_block* known_reachable, nir_block* block)
{
   if (block == nir_start_block(impl) || block == known_reachable)
      return true;

   /* skip loop back-edges */
   if (is_loop_header_block(block)) {
      nir_loop* loop = nir_cf_node_as_loop(block->cf_node.parent);
      nir_block* preheader = nir_block_cf_tree_prev(nir_loop_first_block(loop));
      return is_block_reachable(impl, known_reachable, preheader);
   }

   set_foreach (block->predecessors, entry) {
      if (is_block_reachable(impl, known_reachable, (nir_block*)entry->key))
         return true;
   }

   return false;
}

/* Check whether the given SSA def is only used by cross-lane instructions. */
bool
only_used_by_cross_lane_instrs(nir_def* ssa, bool follow_phis = true)
{
   nir_foreach_use (src, ssa) {
      switch (src->parent_instr->type) {
      case nir_instr_type_alu: {
         nir_alu_instr* alu = nir_instr_as_alu(src->parent_instr);
         if (alu->op != nir_op_unpack_64_2x32_split_x && alu->op != nir_op_unpack_64_2x32_split_y)
            return false;
         if (!only_used_by_cross_lane_instrs(&alu->def, follow_phis))
            return false;

         continue;
      }
      case nir_instr_type_intrinsic: {
         nir_intrinsic_instr* intrin = nir_instr_as_intrinsic(src->parent_instr);
         if (intrin->intrinsic != nir_intrinsic_read_invocation &&
             intrin->intrinsic != nir_intrinsic_read_first_invocation &&
             intrin->intrinsic != nir_intrinsic_lane_permute_16_amd)
            return false;

         continue;
      }
      case nir_instr_type_phi: {
         /* Don't follow more than 1 phis, this avoids infinite loops. */
         if (!follow_phis)
            return false;

         nir_phi_instr* phi = nir_instr_as_phi(src->parent_instr);
         if (!only_used_by_cross_lane_instrs(&phi->def, false))
            return false;

         continue;
      }
      default: return false;
      }
   }

   return true;
}

/* If one side of a divergent IF ends in a branch and the other doesn't, we
 * might have to emit the contents of the side without the branch at the merge
 * block instead. This is so that we can use any SGPR live-out of the side
 * without the branch without creating a linear phi in the invert or merge block. */
bool
sanitize_if(nir_function_impl* impl, nir_if* nif)
{
   // TODO: skip this if the condition is uniform and there are no divergent breaks/continues?

   nir_block* then_block = nir_if_last_then_block(nif);
   nir_block* else_block = nir_if_last_else_block(nif);
   bool then_jump = nir_block_ends_in_jump(then_block) ||
                    !is_block_reachable(impl, nir_if_first_then_block(nif), then_block);
   bool else_jump = nir_block_ends_in_jump(else_block) ||
                    !is_block_reachable(impl, nir_if_first_else_block(nif), else_block);
   if (then_jump == else_jump)
      return false;

   /* If the continue from block is empty then return as there is nothing to
    * move.
    */
   if (nir_cf_list_is_empty_block(else_jump ? &nif->then_list : &nif->else_list))
      return false;

   /* Even though this if statement has a jump on one side, we may still have
    * phis afterwards.  Single-source phis can be produced by loop unrolling
    * or dead control-flow passes and are perfectly legal.  Run a quick phi
    * removal on the block after the if to clean up any such phis.
    */
   nir_opt_remove_phis_block(nir_cf_node_as_block(nir_cf_node_next(&nif->cf_node)));

   /* Finally, move the continue from branch after the if-statement. */
   nir_block* last_continue_from_blk = else_jump ? then_block : else_block;
   nir_block* first_continue_from_blk =
      else_jump ? nir_if_first_then_block(nif) : nir_if_first_else_block(nif);

   nir_cf_list tmp;
   nir_cf_extract(&tmp, nir_before_block(first_continue_from_blk),
                  nir_after_block(last_continue_from_blk));
   nir_cf_reinsert(&tmp, nir_after_cf_node(&nif->cf_node));

   return true;
}

bool
sanitize_cf_list(nir_function_impl* impl, struct exec_list* cf_list)
{
   bool progress = false;
   foreach_list_typed (nir_cf_node, cf_node, node, cf_list) {
      switch (cf_node->type) {
      case nir_cf_node_block: break;
      case nir_cf_node_if: {
         nir_if* nif = nir_cf_node_as_if(cf_node);
         progress |= sanitize_cf_list(impl, &nif->then_list);
         progress |= sanitize_cf_list(impl, &nif->else_list);
         progress |= sanitize_if(impl, nif);
         break;
      }
      case nir_cf_node_loop: {
         nir_loop* loop = nir_cf_node_as_loop(cf_node);
         assert(!nir_loop_has_continue_construct(loop));
         progress |= sanitize_cf_list(impl, &loop->body);
         break;
      }
      case nir_cf_node_function: unreachable("Invalid cf type");
      }
   }

   return progress;
}

void
apply_nuw_to_ssa(isel_context* ctx, nir_def* ssa)
{
   nir_scalar scalar;
   scalar.def = ssa;
   scalar.comp = 0;

   if (!nir_scalar_is_alu(scalar) || nir_scalar_alu_op(scalar) != nir_op_iadd)
      return;

   nir_alu_instr* add = nir_instr_as_alu(ssa->parent_instr);

   if (add->no_unsigned_wrap)
      return;

   nir_scalar src0 = nir_scalar_chase_alu_src(scalar, 0);
   nir_scalar src1 = nir_scalar_chase_alu_src(scalar, 1);

   if (nir_scalar_is_const(src0)) {
      nir_scalar tmp = src0;
      src0 = src1;
      src1 = tmp;
   }

   uint32_t src1_ub = nir_unsigned_upper_bound(ctx->shader, ctx->range_ht, src1, &ctx->ub_config);
   add->no_unsigned_wrap =
      !nir_addition_might_overflow(ctx->shader, ctx->range_ht, src0, src1_ub, &ctx->ub_config);
}

void
apply_nuw_to_offsets(isel_context* ctx, nir_function_impl* impl)
{
   nir_foreach_block (block, impl) {
      nir_foreach_instr (instr, block) {
         if (instr->type != nir_instr_type_intrinsic)
            continue;
         nir_intrinsic_instr* intrin = nir_instr_as_intrinsic(instr);

         switch (intrin->intrinsic) {
         case nir_intrinsic_load_constant:
         case nir_intrinsic_load_uniform:
         case nir_intrinsic_load_push_constant:
            if (!nir_src_is_divergent(intrin->src[0]))
               apply_nuw_to_ssa(ctx, intrin->src[0].ssa);
            break;
         case nir_intrinsic_load_ubo:
         case nir_intrinsic_load_ssbo:
            if (!nir_src_is_divergent(intrin->src[1]))
               apply_nuw_to_ssa(ctx, intrin->src[1].ssa);
            break;
         case nir_intrinsic_store_ssbo:
            if (!nir_src_is_divergent(intrin->src[2]))
               apply_nuw_to_ssa(ctx, intrin->src[2].ssa);
            break;
         case nir_intrinsic_load_scratch: apply_nuw_to_ssa(ctx, intrin->src[0].ssa); break;
         case nir_intrinsic_store_scratch:
         case nir_intrinsic_load_smem_amd: apply_nuw_to_ssa(ctx, intrin->src[1].ssa); break;
         default: break;
         }
      }
   }
}

RegClass
get_reg_class(isel_context* ctx, RegType type, unsigned components, unsigned bitsize)
{
   if (bitsize == 1)
      return RegClass(RegType::sgpr, ctx->program->lane_mask.size() * components);
   else
      return RegClass::get(type, components * bitsize / 8u);
}

void
setup_tcs_info(isel_context* ctx, nir_shader* nir, nir_shader* vs)
{
   ctx->tcs_in_out_eq = ctx->program->info.vs.tcs_in_out_eq;
   ctx->tcs_temp_only_inputs = ctx->program->info.vs.tcs_temp_only_input_mask;
}

void
setup_lds_size(isel_context* ctx, nir_shader* nir)
{
   /* TCS and GFX9 GS are special cases, already in units of the allocation granule. */
   if (ctx->stage.has(SWStage::TCS))
      ctx->program->config->lds_size = ctx->program->info.tcs.num_lds_blocks;
   else if (ctx->stage == vertex_geometry_gs || ctx->stage == tess_eval_geometry_gs)
      ctx->program->config->lds_size = ctx->program->info.gfx9_gs_ring_lds_size;
   else
      ctx->program->config->lds_size =
         DIV_ROUND_UP(nir->info.shared_size, ctx->program->dev.lds_encoding_granule);

   /* Make sure we fit the available LDS space. */
   assert((ctx->program->config->lds_size * ctx->program->dev.lds_encoding_granule) <=
          ctx->program->dev.lds_limit);
}

void
setup_nir(isel_context* ctx, nir_shader* nir)
{
   nir_convert_to_lcssa(nir, true, false);
   nir_lower_phis_to_scalar(nir, true);

   nir_function_impl* func = nir_shader_get_entrypoint(nir);
   nir_index_ssa_defs(func);
}

} /* end namespace */

void
init_context(isel_context* ctx, nir_shader* shader)
{
   nir_function_impl* impl = nir_shader_get_entrypoint(shader);
   ctx->shader = shader;

   /* Init NIR range analysis. */
   ctx->range_ht = _mesa_pointer_hash_table_create(NULL);
   ctx->ub_config.min_subgroup_size = 64;
   ctx->ub_config.max_subgroup_size = 64;
   if (ctx->shader->info.stage == MESA_SHADER_COMPUTE && ctx->program->info.cs.subgroup_size) {
      ctx->ub_config.min_subgroup_size = ctx->program->info.cs.subgroup_size;
      ctx->ub_config.max_subgroup_size = ctx->program->info.cs.subgroup_size;
   }
   ctx->ub_config.max_workgroup_invocations = 2048;
   ctx->ub_config.max_workgroup_count[0] = 65535;
   ctx->ub_config.max_workgroup_count[1] = 65535;
   ctx->ub_config.max_workgroup_count[2] = 65535;
   ctx->ub_config.max_workgroup_size[0] = 2048;
   ctx->ub_config.max_workgroup_size[1] = 2048;
   ctx->ub_config.max_workgroup_size[2] = 2048;

   nir_divergence_analysis(shader);
   if (nir_opt_uniform_atomics(shader) && nir_lower_int64(shader))
      nir_divergence_analysis(shader);

   apply_nuw_to_offsets(ctx, impl);

   /* sanitize control flow */
   sanitize_cf_list(impl, &impl->body);
   nir_metadata_preserve(impl, nir_metadata_none);

   /* we'll need these for isel */
   nir_metadata_require(impl, nir_metadata_block_index);

   if (ctx->options->dump_preoptir) {
      fprintf(stderr, "NIR shader before instruction selection:\n");
      nir_print_shader(shader, stderr);
   }

   ctx->first_temp_id = ctx->program->peekAllocationId();
   ctx->program->allocateRange(impl->ssa_alloc);
   RegClass* regclasses = ctx->program->temp_rc.data() + ctx->first_temp_id;

   std::unique_ptr<unsigned[]> nir_to_aco{new unsigned[impl->num_blocks]()};

   /* TODO: make this recursive to improve compile times */
   bool done = false;
   while (!done) {
      done = true;
      nir_foreach_block (block, impl) {
         nir_foreach_instr (instr, block) {
            switch (instr->type) {
            case nir_instr_type_alu: {
               nir_alu_instr* alu_instr = nir_instr_as_alu(instr);
               RegType type = alu_instr->def.divergent ? RegType::vgpr : RegType::sgpr;
               switch (alu_instr->op) {
               case nir_op_fmul:
               case nir_op_fmulz:
               case nir_op_fadd:
               case nir_op_fsub:
               case nir_op_ffma:
               case nir_op_ffmaz:
               case nir_op_fmax:
               case nir_op_fmin:
               case nir_op_fneg:
               case nir_op_fabs:
               case nir_op_fsat:
               case nir_op_fsign:
               case nir_op_frcp:
               case nir_op_frsq:
               case nir_op_fsqrt:
               case nir_op_fexp2:
               case nir_op_flog2:
               case nir_op_ffract:
               case nir_op_ffloor:
               case nir_op_fceil:
               case nir_op_ftrunc:
               case nir_op_fround_even:
               case nir_op_fsin_amd:
               case nir_op_fcos_amd:
               case nir_op_f2f16:
               case nir_op_f2f16_rtz:
               case nir_op_f2f16_rtne:
               case nir_op_f2f32:
               case nir_op_f2f64:
               case nir_op_u2f16:
               case nir_op_u2f32:
               case nir_op_u2f64:
               case nir_op_i2f16:
               case nir_op_i2f32:
               case nir_op_i2f64:
               case nir_op_pack_half_2x16_rtz_split:
               case nir_op_pack_half_2x16_split:
               case nir_op_pack_unorm_2x16:
               case nir_op_pack_snorm_2x16:
               case nir_op_pack_uint_2x16:
               case nir_op_pack_sint_2x16:
               case nir_op_unpack_half_2x16_split_x:
               case nir_op_unpack_half_2x16_split_y:
               case nir_op_fddx:
               case nir_op_fddy:
               case nir_op_fddx_fine:
               case nir_op_fddy_fine:
               case nir_op_fddx_coarse:
               case nir_op_fddy_coarse:
               case nir_op_fquantize2f16:
               case nir_op_ldexp:
               case nir_op_frexp_sig:
               case nir_op_frexp_exp:
               case nir_op_cube_amd:
               case nir_op_sad_u8x4:
               case nir_op_udot_4x8_uadd:
               case nir_op_sdot_4x8_iadd:
               case nir_op_sudot_4x8_iadd:
               case nir_op_udot_4x8_uadd_sat:
               case nir_op_sdot_4x8_iadd_sat:
               case nir_op_sudot_4x8_iadd_sat:
               case nir_op_udot_2x16_uadd:
               case nir_op_sdot_2x16_iadd:
               case nir_op_udot_2x16_uadd_sat:
               case nir_op_sdot_2x16_iadd_sat: type = RegType::vgpr; break;
               case nir_op_f2i16:
               case nir_op_f2u16:
               case nir_op_f2i32:
               case nir_op_f2u32:
               case nir_op_b2i8:
               case nir_op_b2i16:
               case nir_op_b2i32:
               case nir_op_b2b32:
               case nir_op_b2f16:
               case nir_op_b2f32:
               case nir_op_mov: break;
               case nir_op_iabs:
               case nir_op_iadd:
               case nir_op_iadd_sat:
               case nir_op_uadd_sat:
               case nir_op_isub:
               case nir_op_isub_sat:
               case nir_op_usub_sat:
               case nir_op_imul:
               case nir_op_imin:
               case nir_op_imax:
               case nir_op_umin:
               case nir_op_umax:
               case nir_op_ishl:
               case nir_op_ishr:
               case nir_op_ushr:
                  /* packed 16bit instructions have to be VGPR */
                  type = alu_instr->def.num_components == 2 ? RegType::vgpr : type;
                  FALLTHROUGH;
               default:
                  for (unsigned i = 0; i < nir_op_infos[alu_instr->op].num_inputs; i++) {
                     if (regclasses[alu_instr->src[i].src.ssa->index].type() == RegType::vgpr)
                        type = RegType::vgpr;
                  }
                  break;
               }

               RegClass rc =
                  get_reg_class(ctx, type, alu_instr->def.num_components, alu_instr->def.bit_size);
               regclasses[alu_instr->def.index] = rc;
               break;
            }
            case nir_instr_type_load_const: {
               unsigned num_components = nir_instr_as_load_const(instr)->def.num_components;
               unsigned bit_size = nir_instr_as_load_const(instr)->def.bit_size;
               RegClass rc = get_reg_class(ctx, RegType::sgpr, num_components, bit_size);
               regclasses[nir_instr_as_load_const(instr)->def.index] = rc;
               break;
            }
            case nir_instr_type_intrinsic: {
               nir_intrinsic_instr* intrinsic = nir_instr_as_intrinsic(instr);
               if (!nir_intrinsic_infos[intrinsic->intrinsic].has_dest)
                  break;
               if (intrinsic->intrinsic == nir_intrinsic_strict_wqm_coord_amd) {
                  regclasses[intrinsic->def.index] =
                     RegClass::get(RegType::vgpr, intrinsic->def.num_components * 4 +
                                                     nir_intrinsic_base(intrinsic))
                        .as_linear();
                  break;
               }
               RegType type = RegType::sgpr;
               switch (intrinsic->intrinsic) {
               case nir_intrinsic_load_push_constant:
               case nir_intrinsic_load_workgroup_id:
               case nir_intrinsic_load_num_workgroups:
               case nir_intrinsic_load_ray_launch_size:
               case nir_intrinsic_load_ray_launch_size_addr_amd:
               case nir_intrinsic_load_sbt_base_amd:
               case nir_intrinsic_load_subgroup_id:
               case nir_intrinsic_load_num_subgroups:
               case nir_intrinsic_load_first_vertex:
               case nir_intrinsic_load_base_instance:
               case nir_intrinsic_vote_all:
               case nir_intrinsic_vote_any:
               case nir_intrinsic_read_first_invocation:
               case nir_intrinsic_read_invocation:
               case nir_intrinsic_first_invocation:
               case nir_intrinsic_ballot:
               case nir_intrinsic_bindless_image_samples:
               case nir_intrinsic_load_force_vrs_rates_amd:
               case nir_intrinsic_load_scalar_arg_amd:
               case nir_intrinsic_load_lds_ngg_scratch_base_amd:
               case nir_intrinsic_load_lds_ngg_gs_out_vertex_base_amd:
               case nir_intrinsic_load_smem_amd: type = RegType::sgpr; break;
               case nir_intrinsic_load_sample_id:
               case nir_intrinsic_load_input:
               case nir_intrinsic_load_output:
               case nir_intrinsic_load_input_vertex:
               case nir_intrinsic_load_per_vertex_input:
               case nir_intrinsic_load_per_vertex_output:
               case nir_intrinsic_load_vertex_id_zero_base:
               case nir_intrinsic_load_barycentric_sample:
               case nir_intrinsic_load_barycentric_pixel:
               case nir_intrinsic_load_barycentric_model:
               case nir_intrinsic_load_barycentric_centroid:
               case nir_intrinsic_load_barycentric_at_offset:
               case nir_intrinsic_load_interpolated_input:
               case nir_intrinsic_load_frag_coord:
               case nir_intrinsic_load_frag_shading_rate:
               case nir_intrinsic_load_sample_pos:
               case nir_intrinsic_load_local_invocation_id:
               case nir_intrinsic_load_local_invocation_index:
               case nir_intrinsic_load_subgroup_invocation:
               case nir_intrinsic_load_ray_launch_id:
               case nir_intrinsic_load_tess_coord:
               case nir_intrinsic_write_invocation_amd:
               case nir_intrinsic_mbcnt_amd:
               case nir_intrinsic_lane_permute_16_amd:
               case nir_intrinsic_load_instance_id:
               case nir_intrinsic_ssbo_atomic:
               case nir_intrinsic_ssbo_atomic_swap:
               case nir_intrinsic_global_atomic_amd:
               case nir_intrinsic_global_atomic_swap_amd:
               case nir_intrinsic_bindless_image_atomic:
               case nir_intrinsic_bindless_image_atomic_swap:
               case nir_intrinsic_bindless_image_size:
               case nir_intrinsic_shared_atomic:
               case nir_intrinsic_shared_atomic_swap:
               case nir_intrinsic_load_scratch:
               case nir_intrinsic_load_invocation_id:
               case nir_intrinsic_load_primitive_id:
               case nir_intrinsic_load_typed_buffer_amd:
               case nir_intrinsic_load_buffer_amd:
               case nir_intrinsic_load_initial_edgeflags_amd:
               case nir_intrinsic_gds_atomic_add_amd:
               case nir_intrinsic_bvh64_intersect_ray_amd:
               case nir_intrinsic_load_vector_arg_amd:
               case nir_intrinsic_load_rt_dynamic_callable_stack_base_amd:
               case nir_intrinsic_ordered_xfb_counter_add_amd: type = RegType::vgpr; break;
               case nir_intrinsic_load_shared:
               case nir_intrinsic_load_shared2_amd:
                  /* When the result of these loads is only used by cross-lane instructions,
                   * it is beneficial to use a VGPR destination. This is because this allows
                   * to put the s_waitcnt further down, which decreases latency.
                   */
                  if (only_used_by_cross_lane_instrs(&intrinsic->def)) {
                     type = RegType::vgpr;
                     break;
                  }
                  FALLTHROUGH;
               case nir_intrinsic_shuffle:
               case nir_intrinsic_quad_broadcast:
               case nir_intrinsic_quad_swap_horizontal:
               case nir_intrinsic_quad_swap_vertical:
               case nir_intrinsic_quad_swap_diagonal:
               case nir_intrinsic_quad_swizzle_amd:
               case nir_intrinsic_masked_swizzle_amd:
               case nir_intrinsic_inclusive_scan:
               case nir_intrinsic_exclusive_scan:
               case nir_intrinsic_reduce:
               case nir_intrinsic_load_ubo:
               case nir_intrinsic_load_ssbo:
               case nir_intrinsic_load_global_amd:
                  type = intrinsic->def.divergent ? RegType::vgpr : RegType::sgpr;
                  break;
               case nir_intrinsic_load_view_index:
                  type = ctx->stage == fragment_fs ? RegType::vgpr : RegType::sgpr;
                  break;
               default:
                  for (unsigned i = 0; i < nir_intrinsic_infos[intrinsic->intrinsic].num_srcs;
                       i++) {
                     if (regclasses[intrinsic->src[i].ssa->index].type() == RegType::vgpr)
                        type = RegType::vgpr;
                  }
                  break;
               }
               RegClass rc =
                  get_reg_class(ctx, type, intrinsic->def.num_components, intrinsic->def.bit_size);
               regclasses[intrinsic->def.index] = rc;
               break;
            }
            case nir_instr_type_tex: {
               nir_tex_instr* tex = nir_instr_as_tex(instr);
               RegType type = tex->def.divergent ? RegType::vgpr : RegType::sgpr;

               if (tex->op == nir_texop_texture_samples) {
                  assert(!tex->def.divergent);
               }

               RegClass rc = get_reg_class(ctx, type, tex->def.num_components, tex->def.bit_size);
               regclasses[tex->def.index] = rc;
               break;
            }
            case nir_instr_type_ssa_undef: {
               unsigned num_components = nir_instr_as_ssa_undef(instr)->def.num_components;
               unsigned bit_size = nir_instr_as_ssa_undef(instr)->def.bit_size;
               RegClass rc = get_reg_class(ctx, RegType::sgpr, num_components, bit_size);
               regclasses[nir_instr_as_ssa_undef(instr)->def.index] = rc;
               break;
            }
            case nir_instr_type_phi: {
               nir_phi_instr* phi = nir_instr_as_phi(instr);
               RegType type = RegType::sgpr;
               unsigned num_components = phi->def.num_components;
               assert((phi->def.bit_size != 1 || num_components == 1) &&
                      "Multiple components not supported on boolean phis.");

               if (phi->def.divergent) {
                  type = RegType::vgpr;
               } else {
                  nir_foreach_phi_src (src, phi) {
                     if (regclasses[src->src.ssa->index].type() == RegType::vgpr)
                        type = RegType::vgpr;
                  }
               }

               RegClass rc = get_reg_class(ctx, type, num_components, phi->def.bit_size);
               if (rc != regclasses[phi->def.index])
                  done = false;
               regclasses[phi->def.index] = rc;
               break;
            }
            default: break;
            }
         }
      }
   }

   ctx->program->config->spi_ps_input_ena = ctx->program->info.ps.spi_ps_input;
   ctx->program->config->spi_ps_input_addr = ctx->program->info.ps.spi_ps_input;

   ctx->cf_info.nir_to_aco = std::move(nir_to_aco);

   /* align and copy constant data */
   while (ctx->program->constant_data.size() % 4u)
      ctx->program->constant_data.push_back(0);
   ctx->constant_data_offset = ctx->program->constant_data.size();
   ctx->program->constant_data.insert(ctx->program->constant_data.end(),
                                      (uint8_t*)shader->constant_data,
                                      (uint8_t*)shader->constant_data + shader->constant_data_size);
}

void
cleanup_context(isel_context* ctx)
{
   _mesa_hash_table_destroy(ctx->range_ht, NULL);
}

isel_context
setup_isel_context(Program* program, unsigned shader_count, struct nir_shader* const* shaders,
                   ac_shader_config* config, const struct aco_compiler_options* options,
                   const struct aco_shader_info* info, const struct ac_shader_args* args,
                   bool is_ps_epilog, bool is_tcs_epilog)
{
   SWStage sw_stage = SWStage::None;
   for (unsigned i = 0; i < shader_count; i++) {
      switch (shaders[i]->info.stage) {
      case MESA_SHADER_VERTEX: sw_stage = sw_stage | SWStage::VS; break;
      case MESA_SHADER_TESS_CTRL: sw_stage = sw_stage | SWStage::TCS; break;
      case MESA_SHADER_TESS_EVAL: sw_stage = sw_stage | SWStage::TES; break;
      case MESA_SHADER_GEOMETRY: sw_stage = sw_stage | SWStage::GS; break;
      case MESA_SHADER_FRAGMENT: sw_stage = sw_stage | SWStage::FS; break;
      case MESA_SHADER_KERNEL:
      case MESA_SHADER_COMPUTE: sw_stage = sw_stage | SWStage::CS; break;
      case MESA_SHADER_TASK: sw_stage = sw_stage | SWStage::TS; break;
      case MESA_SHADER_MESH: sw_stage = sw_stage | SWStage::MS; break;
      case MESA_SHADER_RAYGEN:
      case MESA_SHADER_CLOSEST_HIT:
      case MESA_SHADER_MISS:
      case MESA_SHADER_CALLABLE:
      case MESA_SHADER_INTERSECTION:
      case MESA_SHADER_ANY_HIT: sw_stage = SWStage::RT; break;
      default: unreachable("Shader stage not implemented");
      }
   }

   if (is_ps_epilog) {
      assert(shader_count == 0 && !shaders);
      sw_stage = SWStage::FS;
   }

   if (is_tcs_epilog) {
      assert(shader_count == 0 && !shaders);
      sw_stage = SWStage::TCS;
   }

   init_program(program, Stage{info->hw_stage, sw_stage}, info, options->gfx_level, options->family,
                options->wgp_mode, config);

   isel_context ctx = {};
   ctx.program = program;
   ctx.args = args;
   ctx.options = options;
   ctx.stage = program->stage;

   program->workgroup_size = program->info.workgroup_size;
   assert(program->workgroup_size);

   /* Mesh shading only works on GFX10.3+. */
   ASSERTED bool mesh_shading = ctx.stage.has(SWStage::TS) || ctx.stage.has(SWStage::MS);
   assert(!mesh_shading || ctx.program->gfx_level >= GFX10_3);

   if (ctx.stage == tess_control_hs && !is_tcs_epilog)
      setup_tcs_info(&ctx, shaders[0], NULL);
   else if (ctx.stage == vertex_tess_control_hs)
      setup_tcs_info(&ctx, shaders[1], shaders[0]);

   calc_min_waves(program);

   unsigned scratch_size = 0;
   for (unsigned i = 0; i < shader_count; i++) {
      nir_shader* nir = shaders[i];
      setup_nir(&ctx, nir);
      setup_lds_size(&ctx, nir);
   }

   for (unsigned i = 0; i < shader_count; i++)
      scratch_size = std::max(scratch_size, shaders[i]->scratch_size);

   ctx.program->config->scratch_bytes_per_wave = scratch_size * ctx.program->wave_size;

   unsigned nir_num_blocks = 0;
   for (unsigned i = 0; i < shader_count; i++)
      nir_num_blocks += nir_shader_get_entrypoint(shaders[i])->num_blocks;
   ctx.program->blocks.reserve(nir_num_blocks * 2);
   ctx.block = ctx.program->create_and_insert_block();
   ctx.block->kind = block_kind_top_level;

   return ctx;
}

} // namespace aco