/*
 * Copyright (c) 2017 Lima Project
 *
 * 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, sub license,
 * 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 NON-INFRINGEMENT. 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 <string.h>

#include "util/hash_table.h"
#include "util/ralloc.h"
#include "util/bitscan.h"
#include "compiler/nir/nir.h"
#include "pipe/p_state.h"


#include "ppir.h"

static void *ppir_node_create_ssa(ppir_block *block, ppir_op op, nir_ssa_def *ssa)
{
   ppir_node *node = ppir_node_create(block, op, ssa->index, 0);
   if (!node)
      return NULL;

   ppir_dest *dest = ppir_node_get_dest(node);
   dest->type = ppir_target_ssa;
   dest->ssa.num_components = ssa->num_components;
   dest->write_mask = u_bit_consecutive(0, ssa->num_components);

   if (node->type == ppir_node_type_load ||
       node->type == ppir_node_type_store)
      dest->ssa.is_head = true;

   return node;
}

static void *ppir_node_create_reg(ppir_block *block, ppir_op op,
                                  nir_register *reg, unsigned mask)
{
   ppir_node *node = ppir_node_create(block, op, reg->index, mask);
   if (!node)
      return NULL;

   ppir_dest *dest = ppir_node_get_dest(node);

   list_for_each_entry(ppir_reg, r, &block->comp->reg_list, list) {
      if (r->index == reg->index) {
         dest->reg = r;
         break;
      }
   }

   dest->type = ppir_target_register;
   dest->write_mask = mask;

   if (node->type == ppir_node_type_load ||
       node->type == ppir_node_type_store)
      dest->reg->is_head = true;

   return node;
}

static void *ppir_node_create_dest(ppir_block *block, ppir_op op,
                                   nir_dest *dest, unsigned mask)
{
   unsigned index = -1;

   if (dest) {
      if (dest->is_ssa)
         return ppir_node_create_ssa(block, op, &dest->ssa);
      else
         return ppir_node_create_reg(block, op, dest->reg.reg, mask);
   }

   return ppir_node_create(block, op, index, 0);
}

static void ppir_node_add_src(ppir_compiler *comp, ppir_node *node,
                              ppir_src *ps, nir_src *ns, unsigned mask)
{
   ppir_node *child = NULL;

   if (ns->is_ssa) {
      child = comp->var_nodes[ns->ssa->index];
      /* Clone consts for each successor */
      switch (child->op) {
      case ppir_op_const:
         child = ppir_node_clone(node->block, child);
         break;
      case ppir_op_load_varying: {
         bool is_load_coords = false;
         if (node->op == ppir_op_load_texture) {
            nir_tex_src *nts = (nir_tex_src *)ns;
            if (nts->src_type == nir_tex_src_coord)
               is_load_coords = true;
         }

         if (!is_load_coords) {
            /* Clone varying loads for each block */
            if (child->block != node->block) {
               ppir_node *new = ppir_node_clone(node->block, child);
               /* If we clone it for every block and there is no user of
                * the original load left, delete the original one. */
               ppir_delete_if_orphan(node->block, child);
               child = new;
               comp->var_nodes[ns->ssa->index] = child;
            }
            break;
         }
         /* At least one successor is load_texture, promote it to load_coords
          * to ensure that is has exactly one successor */
         child->op = ppir_op_load_coords;
      }
         /* Fallthrough */
      case ppir_op_load_uniform:
      case ppir_op_load_coords:
      case ppir_op_load_coords_reg:
         /* Clone uniform and texture coord loads for each block.
          * Also ensure that each load has a single successor.
          * Let's do a fetch each time and hope for a cache hit instead
          * of increasing reg pressure.
          */
         if (child->block != node->block || !ppir_node_is_root(child)) {
            child = ppir_node_clone(node->block, child);
            comp->var_nodes[ns->ssa->index] = child;
         }
         break;
      default:
         break;
      }

      if (child->op != ppir_op_undef)
         ppir_node_add_dep(node, child, ppir_dep_src);
   }
   else {
      nir_register *reg = ns->reg.reg;
      while (mask) {
         int swizzle = ps->swizzle[u_bit_scan(&mask)];
         child = comp->var_nodes[(reg->index << 2) + comp->reg_base + swizzle];
         /* Reg is read before it was written, create a dummy node for it */
         if (!child) {
            child = ppir_node_create_reg(node->block, ppir_op_dummy, reg,
               u_bit_consecutive(0, 4));
            comp->var_nodes[(reg->index << 2) + comp->reg_base + swizzle] = child;
         }
         /* Don't add dummies or recursive deps for ops like r1 = r1 + ssa1 */
         if (child && node != child && child->op != ppir_op_dummy)
            ppir_node_add_dep(node, child, ppir_dep_src);
      }
   }

   ppir_node_target_assign(ps, child);
}

static int nir_to_ppir_opcodes[nir_num_opcodes] = {
   /* not supported */
   [0 ... nir_last_opcode] = -1,

   [nir_op_mov] = ppir_op_mov,
   [nir_op_fmul] = ppir_op_mul,
   [nir_op_fabs] = ppir_op_abs,
   [nir_op_fneg] = ppir_op_neg,
   [nir_op_fadd] = ppir_op_add,
   [nir_op_fsum3] = ppir_op_sum3,
   [nir_op_fsum4] = ppir_op_sum4,
   [nir_op_frsq] = ppir_op_rsqrt,
   [nir_op_flog2] = ppir_op_log2,
   [nir_op_fexp2] = ppir_op_exp2,
   [nir_op_fsqrt] = ppir_op_sqrt,
   [nir_op_fsin] = ppir_op_sin,
   [nir_op_fcos] = ppir_op_cos,
   [nir_op_fmax] = ppir_op_max,
   [nir_op_fmin] = ppir_op_min,
   [nir_op_frcp] = ppir_op_rcp,
   [nir_op_ffloor] = ppir_op_floor,
   [nir_op_fceil] = ppir_op_ceil,
   [nir_op_ffract] = ppir_op_fract,
   [nir_op_sge] = ppir_op_ge,
   [nir_op_slt] = ppir_op_lt,
   [nir_op_seq] = ppir_op_eq,
   [nir_op_sne] = ppir_op_ne,
   [nir_op_fcsel] = ppir_op_select,
   [nir_op_inot] = ppir_op_not,
   [nir_op_ftrunc] = ppir_op_trunc,
   [nir_op_fsat] = ppir_op_sat,
   [nir_op_fddx] = ppir_op_ddx,
   [nir_op_fddy] = ppir_op_ddy,
};

static ppir_node *ppir_emit_alu(ppir_block *block, nir_instr *ni)
{
   nir_alu_instr *instr = nir_instr_as_alu(ni);
   int op = nir_to_ppir_opcodes[instr->op];

   if (op < 0) {
      ppir_error("unsupported nir_op: %s\n", nir_op_infos[instr->op].name);
      return NULL;
   }

   ppir_alu_node *node = ppir_node_create_dest(block, op, &instr->dest.dest,
                                               instr->dest.write_mask);
   if (!node)
      return NULL;

   ppir_dest *pd = &node->dest;
   nir_alu_dest *nd = &instr->dest;
   if (nd->saturate)
      pd->modifier = ppir_outmod_clamp_fraction;

   unsigned src_mask;
   switch (op) {
   case ppir_op_sum3:
      src_mask = 0b0111;
      break;
   case ppir_op_sum4:
      src_mask = 0b1111;
      break;
   default:
      src_mask = pd->write_mask;
      break;
   }

   unsigned num_child = nir_op_infos[instr->op].num_inputs;
   node->num_src = num_child;

   for (int i = 0; i < num_child; i++) {
      nir_alu_src *ns = instr->src + i;
      ppir_src *ps = node->src + i;
      memcpy(ps->swizzle, ns->swizzle, sizeof(ps->swizzle));
      ppir_node_add_src(block->comp, &node->node, ps, &ns->src, src_mask);

      ps->absolute = ns->abs;
      ps->negate = ns->negate;
   }

   return &node->node;
}

static ppir_block *ppir_block_create(ppir_compiler *comp);

static bool ppir_emit_discard_block(ppir_compiler *comp)
{
   ppir_block *block = ppir_block_create(comp);
   ppir_discard_node *discard;
   if (!block)
      return false;

   comp->discard_block = block;
   block->comp  = comp;

   discard = ppir_node_create(block, ppir_op_discard, -1, 0);
   if (discard)
      list_addtail(&discard->node.list, &block->node_list);
   else
      return false;

   return true;
}

static ppir_node *ppir_emit_discard_if(ppir_block *block, nir_instr *ni)
{
   nir_intrinsic_instr *instr = nir_instr_as_intrinsic(ni);
   ppir_node *node;
   ppir_compiler *comp = block->comp;
   ppir_branch_node *branch;

   if (!comp->discard_block && !ppir_emit_discard_block(comp))
      return NULL;

   node = ppir_node_create(block, ppir_op_branch, -1, 0);
   if (!node)
      return NULL;
   branch = ppir_node_to_branch(node);

   /* second src and condition will be updated during lowering */
   ppir_node_add_src(block->comp, node, &branch->src[0],
                     &instr->src[0], u_bit_consecutive(0, instr->num_components));
   branch->num_src = 1;
   branch->target = comp->discard_block;

   return node;
}

static ppir_node *ppir_emit_discard(ppir_block *block, nir_instr *ni)
{
   ppir_node *node = ppir_node_create(block, ppir_op_discard, -1, 0);

   return node;
}

static ppir_node *ppir_emit_intrinsic(ppir_block *block, nir_instr *ni)
{
   nir_intrinsic_instr *instr = nir_instr_as_intrinsic(ni);
   unsigned mask = 0;
   ppir_load_node *lnode;
   ppir_alu_node *alu_node;

   switch (instr->intrinsic) {
   case nir_intrinsic_load_input:
      if (!instr->dest.is_ssa)
         mask = u_bit_consecutive(0, instr->num_components);

      lnode = ppir_node_create_dest(block, ppir_op_load_varying, &instr->dest, mask);
      if (!lnode)
         return NULL;

      lnode->num_components = instr->num_components;
      lnode->index = nir_intrinsic_base(instr) * 4 + nir_intrinsic_component(instr);
      if (nir_src_is_const(instr->src[0]))
         lnode->index += (uint32_t)(nir_src_as_float(instr->src[0]) * 4);
      else {
         lnode->num_src = 1;
         ppir_node_add_src(block->comp, &lnode->node, &lnode->src, instr->src, 1);
      }
      return &lnode->node;

   case nir_intrinsic_load_frag_coord:
   case nir_intrinsic_load_point_coord:
   case nir_intrinsic_load_front_face:
      if (!instr->dest.is_ssa)
         mask = u_bit_consecutive(0, instr->num_components);

      ppir_op op;
      switch (instr->intrinsic) {
      case nir_intrinsic_load_frag_coord:
         op = ppir_op_load_fragcoord;
         break;
      case nir_intrinsic_load_point_coord:
         op = ppir_op_load_pointcoord;
         break;
      case nir_intrinsic_load_front_face:
         op = ppir_op_load_frontface;
         break;
      default:
         assert(0);
         break;
      }

      lnode = ppir_node_create_dest(block, op, &instr->dest, mask);
      if (!lnode)
         return NULL;

      lnode->num_components = instr->num_components;
      return &lnode->node;

   case nir_intrinsic_load_uniform:
      if (!instr->dest.is_ssa)
         mask = u_bit_consecutive(0, instr->num_components);

      lnode = ppir_node_create_dest(block, ppir_op_load_uniform, &instr->dest, mask);
      if (!lnode)
         return NULL;

      lnode->num_components = instr->num_components;
      lnode->index = nir_intrinsic_base(instr);
      if (nir_src_is_const(instr->src[0]))
         lnode->index += (uint32_t)nir_src_as_float(instr->src[0]);
      else {
         lnode->num_src = 1;
         ppir_node_add_src(block->comp, &lnode->node, &lnode->src, instr->src, 1);
      }

      return &lnode->node;

   case nir_intrinsic_store_output: {
      alu_node = ppir_node_create_dest(block, ppir_op_store_color, NULL, 0);
      if (!alu_node)
         return NULL;

      ppir_dest *dest = ppir_node_get_dest(&alu_node->node);
      dest->type = ppir_target_ssa;
      dest->ssa.num_components = instr->num_components;
      dest->ssa.index = 0;
      dest->write_mask = u_bit_consecutive(0, instr->num_components);

      alu_node->num_src = 1;

      for (int i = 0; i < instr->num_components; i++)
         alu_node->src[0].swizzle[i] = i;

      ppir_node_add_src(block->comp, &alu_node->node, alu_node->src, instr->src,
                        u_bit_consecutive(0, instr->num_components));

      return &alu_node->node;
   }

   case nir_intrinsic_discard:
      return ppir_emit_discard(block, ni);

   case nir_intrinsic_discard_if:
      return ppir_emit_discard_if(block, ni);

   default:
      ppir_error("unsupported nir_intrinsic_instr %s\n",
                 nir_intrinsic_infos[instr->intrinsic].name);
      return NULL;
   }
}

static ppir_node *ppir_emit_load_const(ppir_block *block, nir_instr *ni)
{
   nir_load_const_instr *instr = nir_instr_as_load_const(ni);
   ppir_const_node *node = ppir_node_create_ssa(block, ppir_op_const, &instr->def);
   if (!node)
      return NULL;

   assert(instr->def.bit_size == 32);

   for (int i = 0; i < instr->def.num_components; i++)
      node->constant.value[i].i = instr->value[i].i32;
   node->constant.num = instr->def.num_components;

   return &node->node;
}

static ppir_node *ppir_emit_ssa_undef(ppir_block *block, nir_instr *ni)
{
   nir_ssa_undef_instr *undef = nir_instr_as_ssa_undef(ni);
   ppir_node *node = ppir_node_create_ssa(block, ppir_op_undef, &undef->def);
   if (!node)
      return NULL;
   ppir_alu_node *alu = ppir_node_to_alu(node);

   ppir_dest *dest = &alu->dest;
   dest->ssa.undef = true;

   return node;
}

static ppir_node *ppir_emit_tex(ppir_block *block, nir_instr *ni)
{
   nir_tex_instr *instr = nir_instr_as_tex(ni);
   ppir_load_texture_node *node;

   switch (instr->op) {
   case nir_texop_tex:
   case nir_texop_txb:
   case nir_texop_txl:
      break;
   default:
      ppir_error("unsupported texop %d\n", instr->op);
      return NULL;
   }

   unsigned mask = 0;
   if (!instr->dest.is_ssa)
      mask = u_bit_consecutive(0, nir_tex_instr_dest_size(instr));

   node = ppir_node_create_dest(block, ppir_op_load_texture, &instr->dest, mask);
   if (!node)
      return NULL;

   node->sampler = instr->texture_index;

   switch (instr->sampler_dim) {
   case GLSL_SAMPLER_DIM_2D:
   case GLSL_SAMPLER_DIM_CUBE:
   case GLSL_SAMPLER_DIM_RECT:
   case GLSL_SAMPLER_DIM_EXTERNAL:
      break;
   default:
      ppir_error("unsupported sampler dim: %d\n", instr->sampler_dim);
      return NULL;
   }

   node->sampler_dim = instr->sampler_dim;

   for (int i = 0; i < instr->coord_components; i++)
         node->src[0].swizzle[i] = i;

   for (int i = 0; i < instr->num_srcs; i++) {
      switch (instr->src[i].src_type) {
      case nir_tex_src_coord:
         ppir_node_add_src(block->comp, &node->node, &node->src[0], &instr->src[i].src,
                           u_bit_consecutive(0, instr->coord_components));
         node->num_src++;
         break;
      case nir_tex_src_bias:
      case nir_tex_src_lod:
         node->lod_bias_en = true;
         node->explicit_lod = (instr->src[i].src_type == nir_tex_src_lod);
         ppir_node_add_src(block->comp, &node->node, &node->src[1], &instr->src[i].src, 1);
         node->num_src++;
         break;
      default:
         ppir_error("unsupported texture source type\n");
         return NULL;
      }
   }

   return &node->node;
}

static ppir_block *ppir_get_block(ppir_compiler *comp, nir_block *nblock)
{
   ppir_block *block = _mesa_hash_table_u64_search(comp->blocks, (uint64_t)nblock);

   return block;
}

static ppir_node *ppir_emit_jump(ppir_block *block, nir_instr *ni)
{
   ppir_node *node;
   ppir_compiler *comp = block->comp;
   ppir_branch_node *branch;
   ppir_block *jump_block;
   nir_jump_instr *jump = nir_instr_as_jump(ni);

   switch (jump->type) {
   case nir_jump_break: {
      assert(comp->current_block->successors[0]);
      assert(!comp->current_block->successors[1]);
      jump_block = comp->current_block->successors[0];
   }
   break;
   case nir_jump_continue:
      jump_block = comp->loop_cont_block;
   break;
   default:
      ppir_error("nir_jump_instr not support\n");
      return NULL;
   }

   assert(jump_block != NULL);

   node = ppir_node_create(block, ppir_op_branch, -1, 0);
   if (!node)
      return NULL;
   branch = ppir_node_to_branch(node);

   /* Unconditional */
   branch->num_src = 0;
   branch->target = jump_block;

   return node;
}

static ppir_node *(*ppir_emit_instr[nir_instr_type_phi])(ppir_block *, nir_instr *) = {
   [nir_instr_type_alu]        = ppir_emit_alu,
   [nir_instr_type_intrinsic]  = ppir_emit_intrinsic,
   [nir_instr_type_load_const] = ppir_emit_load_const,
   [nir_instr_type_ssa_undef]  = ppir_emit_ssa_undef,
   [nir_instr_type_tex]        = ppir_emit_tex,
   [nir_instr_type_jump]       = ppir_emit_jump,
};

static ppir_block *ppir_block_create(ppir_compiler *comp)
{
   ppir_block *block = rzalloc(comp, ppir_block);
   if (!block)
      return NULL;

   list_inithead(&block->node_list);
   list_inithead(&block->instr_list);

   block->comp = comp;

   return block;
}

static bool ppir_emit_block(ppir_compiler *comp, nir_block *nblock)
{
   ppir_block *block = ppir_get_block(comp, nblock);

   comp->current_block = block;

   list_addtail(&block->list, &comp->block_list);

   nir_foreach_instr(instr, nblock) {
      assert(instr->type < nir_instr_type_phi);
      ppir_node *node = ppir_emit_instr[instr->type](block, instr);
      if (!node)
         return false;

      list_addtail(&node->list, &block->node_list);
   }

   return true;
}

static bool ppir_emit_cf_list(ppir_compiler *comp, struct exec_list *list);

static bool ppir_emit_if(ppir_compiler *comp, nir_if *if_stmt)
{
   ppir_node *node;
   ppir_branch_node *else_branch, *after_branch;
   nir_block *nir_else_block = nir_if_first_else_block(if_stmt);
   bool empty_else_block =
      (nir_else_block == nir_if_last_else_block(if_stmt) &&
      exec_list_is_empty(&nir_else_block->instr_list));
   ppir_block *block = comp->current_block;

   node = ppir_node_create(block, ppir_op_branch, -1, 0);
   if (!node)
      return false;
   else_branch = ppir_node_to_branch(node);
   ppir_node_add_src(block->comp, node, &else_branch->src[0],
                     &if_stmt->condition, 1);
   else_branch->num_src = 1;
   /* Negate condition to minimize branching. We're generating following:
    * current_block: { ...; if (!statement) branch else_block; }
    * then_block: { ...; branch after_block; }
    * else_block: { ... }
    * after_block: { ... }
    *
    * or if else list is empty:
    * block: { if (!statement) branch else_block; }
    * then_block: { ... }
    * else_block: after_block: { ... }
    */
   else_branch->negate = true;
   list_addtail(&else_branch->node.list, &block->node_list);

   ppir_emit_cf_list(comp, &if_stmt->then_list);
   if (empty_else_block) {
      nir_block *nblock = nir_if_last_else_block(if_stmt);
      assert(nblock->successors[0]);
      assert(!nblock->successors[1]);
      else_branch->target = ppir_get_block(comp, nblock->successors[0]);
      /* Add empty else block to the list */
      list_addtail(&block->successors[1]->list, &comp->block_list);
      return true;
   }

   else_branch->target = ppir_get_block(comp, nir_if_first_else_block(if_stmt));

   nir_block *last_then_block = nir_if_last_then_block(if_stmt);
   assert(last_then_block->successors[0]);
   assert(!last_then_block->successors[1]);
   block = ppir_get_block(comp, last_then_block);
   node = ppir_node_create(block, ppir_op_branch, -1, 0);
   if (!node)
      return false;
   after_branch = ppir_node_to_branch(node);
   /* Unconditional */
   after_branch->num_src = 0;
   after_branch->target = ppir_get_block(comp, last_then_block->successors[0]);
   /* Target should be after_block, will fixup later */
   list_addtail(&after_branch->node.list, &block->node_list);

   ppir_emit_cf_list(comp, &if_stmt->else_list);

   return true;
}

static bool ppir_emit_loop(ppir_compiler *comp, nir_loop *nloop)
{
   ppir_block *save_loop_cont_block = comp->loop_cont_block;
   ppir_block *block;
   ppir_branch_node *loop_branch;
   nir_block *loop_last_block;
   ppir_node *node;

   comp->loop_cont_block = ppir_get_block(comp, nir_loop_first_block(nloop));

   ppir_emit_cf_list(comp, &nloop->body);

   loop_last_block = nir_loop_last_block(nloop);
   block = ppir_get_block(comp, loop_last_block);
   node = ppir_node_create(block, ppir_op_branch, -1, 0);
   if (!node)
      return false;
   loop_branch = ppir_node_to_branch(node);
   /* Unconditional */
   loop_branch->num_src = 0;
   loop_branch->target = comp->loop_cont_block;
   list_addtail(&loop_branch->node.list, &block->node_list);

   comp->loop_cont_block = save_loop_cont_block;

   comp->num_loops++;

   return true;
}

static bool ppir_emit_function(ppir_compiler *comp, nir_function_impl *nfunc)
{
   ppir_error("function nir_cf_node not support\n");
   return false;
}

static bool ppir_emit_cf_list(ppir_compiler *comp, struct exec_list *list)
{
   foreach_list_typed(nir_cf_node, node, node, list) {
      bool ret;

      switch (node->type) {
      case nir_cf_node_block:
         ret = ppir_emit_block(comp, nir_cf_node_as_block(node));
         break;
      case nir_cf_node_if:
         ret = ppir_emit_if(comp, nir_cf_node_as_if(node));
         break;
      case nir_cf_node_loop:
         ret = ppir_emit_loop(comp, nir_cf_node_as_loop(node));
         break;
      case nir_cf_node_function:
         ret = ppir_emit_function(comp, nir_cf_node_as_function(node));
         break;
      default:
         ppir_error("unknown NIR node type %d\n", node->type);
         return false;
      }

      if (!ret)
         return false;
   }

   return true;
}

static ppir_compiler *ppir_compiler_create(void *prog, unsigned num_reg, unsigned num_ssa)
{
   ppir_compiler *comp = rzalloc_size(
      prog, sizeof(*comp) + ((num_reg << 2) + num_ssa) * sizeof(ppir_node *));
   if (!comp)
      return NULL;

   list_inithead(&comp->block_list);
   list_inithead(&comp->reg_list);
   comp->blocks = _mesa_hash_table_u64_create(prog);

   comp->var_nodes = (ppir_node **)(comp + 1);
   comp->reg_base = num_ssa;
   comp->prog = prog;
   return comp;
}

static void ppir_add_ordering_deps(ppir_compiler *comp)
{
   /* Some intrinsics do not have explicit dependencies and thus depend
    * on instructions order. Consider discard_if and store_ouput as
    * example. If we don't add fake dependency of discard_if to store_output
    * scheduler may put store_output first and since store_output terminates
    * shader on Utgard PP, rest of it will never be executed.
    * Add fake dependencies for discard/branch/store to preserve
    * instruction order.
    *
    * TODO: scheduler should schedule discard_if as early as possible otherwise
    * we may end up with suboptimal code for cases like this:
    *
    * s3 = s1 < s2
    * discard_if s3
    * s4 = s1 + s2
    * store s4
    *
    * In this case store depends on discard_if and s4, but since dependencies can
    * be scheduled in any order it can result in code like this:
    *
    * instr1: s3 = s1 < s3
    * instr2: s4 = s1 + s2
    * instr3: discard_if s3
    * instr4: store s4
    */
   list_for_each_entry(ppir_block, block, &comp->block_list, list) {
      ppir_node *prev_node = NULL;
      list_for_each_entry_rev(ppir_node, node, &block->node_list, list) {
         if (prev_node && ppir_node_is_root(node) && node->op != ppir_op_const) {
            ppir_node_add_dep(prev_node, node, ppir_dep_sequence);
         }
         if (node->op == ppir_op_discard ||
             node->op == ppir_op_store_color ||
             node->op == ppir_op_store_temp ||
             node->op == ppir_op_branch) {
            prev_node = node;
         }
      }
   }
}

static void ppir_print_shader_db(struct nir_shader *nir, ppir_compiler *comp,
                                 struct pipe_debug_callback *debug)
{
   const struct shader_info *info = &nir->info;
   char *shaderdb;
   int ret = asprintf(&shaderdb,
                      "%s shader: %d inst, %d loops, %d:%d spills:fills\n",
                      gl_shader_stage_name(info->stage),
                      comp->cur_instr_index,
                      comp->num_loops,
                      comp->num_spills,
                      comp->num_fills);
   assert(ret >= 0);

   if (lima_debug & LIMA_DEBUG_SHADERDB)
      fprintf(stderr, "SHADER-DB: %s\n", shaderdb);

   pipe_debug_message(debug, SHADER_INFO, "%s", shaderdb);
   free(shaderdb);
}

static void ppir_add_write_after_read_deps(ppir_compiler *comp)
{
   list_for_each_entry(ppir_block, block, &comp->block_list, list) {
      list_for_each_entry(ppir_reg, reg, &comp->reg_list, list) {
         ppir_node *write = NULL;
         list_for_each_entry_rev(ppir_node, node, &block->node_list, list) {
            for (int i = 0; i < ppir_node_get_src_num(node); i++) {
               ppir_src *src = ppir_node_get_src(node, i);
               if (src && src->type == ppir_target_register &&
                   src->reg == reg &&
                   write) {
                  ppir_debug("Adding dep %d for write %d\n", node->index, write->index);
                  ppir_node_add_dep(write, node, ppir_dep_write_after_read);
               }
            }
            ppir_dest *dest = ppir_node_get_dest(node);
            if (dest && dest->type == ppir_target_register &&
                dest->reg == reg)
               write = node;
         }
      }
   }
}

bool ppir_compile_nir(struct lima_fs_shader_state *prog, struct nir_shader *nir,
                      struct ra_regs *ra,
                      struct pipe_debug_callback *debug)
{
   nir_function_impl *func = nir_shader_get_entrypoint(nir);
   ppir_compiler *comp = ppir_compiler_create(prog, func->reg_alloc, func->ssa_alloc);
   if (!comp)
      return false;

   comp->ra = ra;

   /* 1st pass: create ppir blocks */
   nir_foreach_function(function, nir) {
      if (!function->impl)
         continue;

      nir_foreach_block(nblock, function->impl) {
         ppir_block *block = ppir_block_create(comp);
         if (!block)
            return false;
         block->index = nblock->index;
         _mesa_hash_table_u64_insert(comp->blocks, (uint64_t)nblock, block);
      }
   }

   /* 2nd pass: populate successors */
   nir_foreach_function(function, nir) {
      if (!function->impl)
         continue;

      nir_foreach_block(nblock, function->impl) {
         ppir_block *block = ppir_get_block(comp, nblock);
         assert(block);

         for (int i = 0; i < 2; i++) {
            if (nblock->successors[i])
               block->successors[i] = ppir_get_block(comp, nblock->successors[i]);
         }
      }
   }

   /* Validate outputs, we support only gl_FragColor */
   nir_foreach_variable(var, &nir->outputs) {
      switch (var->data.location) {
      case FRAG_RESULT_COLOR:
      case FRAG_RESULT_DATA0:
         break;
      default:
         ppir_error("unsupported output type\n");
         goto err_out0;
         break;
      }
   }

   foreach_list_typed(nir_register, reg, node, &func->registers) {
      ppir_reg *r = rzalloc(comp, ppir_reg);
      if (!r)
         return false;

      r->index = reg->index;
      r->num_components = reg->num_components;
      r->is_head = false;
      list_addtail(&r->list, &comp->reg_list);
   }

   if (!ppir_emit_cf_list(comp, &func->body))
      goto err_out0;

   /* If we have discard block add it to the very end */
   if (comp->discard_block)
      list_addtail(&comp->discard_block->list, &comp->block_list);

   ppir_node_print_prog(comp);

   if (!ppir_lower_prog(comp))
      goto err_out0;

   ppir_add_ordering_deps(comp);
   ppir_add_write_after_read_deps(comp);

   ppir_node_print_prog(comp);

   if (!ppir_node_to_instr(comp))
      goto err_out0;

   if (!ppir_schedule_prog(comp))
      goto err_out0;

   if (!ppir_regalloc_prog(comp))
      goto err_out0;

   if (!ppir_codegen_prog(comp))
      goto err_out0;

   ppir_print_shader_db(nir, comp, debug);

   _mesa_hash_table_u64_destroy(comp->blocks, NULL);
   ralloc_free(comp);
   return true;

err_out0:
   _mesa_hash_table_u64_destroy(comp->blocks, NULL);
   ralloc_free(comp);
   return false;
}

