/*
 * 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 "ppir.h"


static bool create_new_instr(ppir_block *block, ppir_node *node)
{
   ppir_instr *instr = ppir_instr_create(block);
   if (unlikely(!instr))
      return false;

   if (!ppir_instr_insert_node(instr, node))
      return false;

   return true;
}

/*
 * If a node has a pipeline dest, schedule it in the same instruction as its
 * successor.
 * Since it has a pipeline dest, it must have only one successor and since we
 * schedule nodes backwards, its successor must have already been scheduled.
 */
static bool ppir_do_node_to_instr_pipeline(ppir_block *block, ppir_node *node)
{
   ppir_dest *dest = ppir_node_get_dest(node);

   if (!dest || dest->type != ppir_target_pipeline)
      return false;

   assert(ppir_node_has_single_succ(node));
   ppir_node *succ = ppir_node_first_succ(node);
   assert(succ);
   assert(succ->instr);

   if (!ppir_instr_insert_node(succ->instr, node))
      return false;

   return true;
}

static bool ppir_do_one_node_to_instr(ppir_block *block, ppir_node *node, ppir_node **next)
{
   switch (node->type) {
   case ppir_node_type_alu:
   {
      /* merge pred mul and succ add in the same instr can save a reg
       * by using pipeline reg ^vmul/^fmul */
      ppir_alu_node *alu = ppir_node_to_alu(node);
      if (alu->dest.type == ppir_target_ssa &&
          ppir_node_has_single_succ(node)) {
         ppir_node *succ = ppir_node_first_succ(node);
         if (succ->instr_pos == PPIR_INSTR_SLOT_ALU_VEC_ADD) {
            node->instr_pos = PPIR_INSTR_SLOT_ALU_VEC_MUL;
            ppir_instr_insert_mul_node(succ, node);
         }
         else if (succ->instr_pos == PPIR_INSTR_SLOT_ALU_SCL_ADD &&
                  alu->dest.ssa.num_components == 1) {
            node->instr_pos = PPIR_INSTR_SLOT_ALU_SCL_MUL;
            ppir_instr_insert_mul_node(succ, node);
         }
      }

      /* can't inserted to any existing instr, create one */
      if (!node->instr && !create_new_instr(block, node))
         return false;

      if (node->op == ppir_op_store_color)
         node->instr->is_end = true;

      break;
   }
   case ppir_node_type_load:
   case ppir_node_type_load_texture:
   {
      if (!create_new_instr(block, node))
         return false;

      /* load varying output can be a register, it doesn't need a mov */
      switch (node->op) {
      case ppir_op_load_varying:
      case ppir_op_load_coords:
      case ppir_op_load_fragcoord:
      case ppir_op_load_pointcoord:
      case ppir_op_load_frontface:
         return true;
      default:
         break;
      }

      /* Load cannot be pipelined, likely slot is already taken. Create a mov */
      assert(ppir_node_has_single_succ(node));
      ppir_dest *dest = ppir_node_get_dest(node);
      assert(dest->type == ppir_target_pipeline);
      ppir_pipeline pipeline_reg = dest->pipeline;

      /* Turn dest back to SSA, so we can update predecessors */
      ppir_node *succ = ppir_node_first_succ(node);
      ppir_src *succ_src = ppir_node_get_src_for_pred(succ, node);
      dest->type = ppir_target_ssa;
      dest->ssa.index = -1;
      ppir_node_target_assign(succ_src, node);

      ppir_node *move = ppir_node_insert_mov(node);
      if (unlikely(!move))
         return false;

      ppir_src *mov_src = ppir_node_get_src(move, 0);
      mov_src->type = dest->type = ppir_target_pipeline;
      mov_src->pipeline = dest->pipeline = pipeline_reg;

      ppir_debug("node_to_instr create move %d for load %d\n",
                 move->index, node->index);

      if (!ppir_instr_insert_node(node->instr, move))
         return false;

      break;
   }
   case ppir_node_type_const:
      /* Const nodes are supposed to go through do_node_to_instr_pipeline() */
      assert(false);
      break;
   case ppir_node_type_store:
   {
      if (node->op == ppir_op_store_temp) {
         if (!create_new_instr(block, node))
            return false;
         break;
      }
   }
   case ppir_node_type_discard:
      if (!create_new_instr(block, node))
         return false;
      node->instr->is_end = true;
      break;
   case ppir_node_type_branch:
      if (!create_new_instr(block, node))
         return false;
      break;
   default:
      return false;
   }

   return true;
}

static bool ppir_do_node_to_instr(ppir_block *block, ppir_node *node)
{
   ppir_node *next = node;

   /* first try pipeline sched, if that didn't succeed try normal scheduling */
   if (!ppir_do_node_to_instr_pipeline(block, node))
      if (!ppir_do_one_node_to_instr(block, node, &next))
         return false;

   /* next may have been updated in ppir_do_one_node_to_instr */
   node = next;

   /* we have to make sure the dep not be destroyed (due to
    * succ change) in ppir_do_node_to_instr, otherwise we can't
    * do recursion like this */
   ppir_node_foreach_pred(node, dep) {
      ppir_node *pred = dep->pred;
      bool ready = true;

      /* pred may already be processed by the previous pred
       * (this pred may be both node and previous pred's child) */
      if (pred->instr)
         continue;

      /* insert pred only when all its successors have been inserted */
      ppir_node_foreach_succ(pred, dep) {
         ppir_node *succ = dep->succ;
         if (!succ->instr) {
            ready = false;
            break;
         }
      }

      if (ready) {
         if (!ppir_do_node_to_instr(block, pred))
            return false;
      }
   }

   return true;
}

static bool ppir_create_instr_from_node(ppir_compiler *comp)
{
   list_for_each_entry(ppir_block, block, &comp->block_list, list) {
      list_for_each_entry(ppir_node, node, &block->node_list, list) {
         if (ppir_node_is_root(node)) {
            if (!ppir_do_node_to_instr(block, node))
               return false;
         }
      }
   }

   return true;
}

static void ppir_build_instr_dependency(ppir_compiler *comp)
{
   list_for_each_entry(ppir_block, block, &comp->block_list, list) {
      list_for_each_entry(ppir_instr, instr, &block->instr_list, list) {
         for (int i = 0; i < PPIR_INSTR_SLOT_NUM; i++) {
            ppir_node *node = instr->slots[i];
            if (node) {
               ppir_node_foreach_pred(node, dep) {
                  ppir_node *pred = dep->pred;
                  if (pred->instr && pred->instr != instr)
                     ppir_instr_add_dep(instr, pred->instr);
               }
            }
         }
      }
   }
}

bool ppir_node_to_instr(ppir_compiler *comp)
{
   if (!ppir_create_instr_from_node(comp))
      return false;
   ppir_instr_print_list(comp);

   ppir_build_instr_dependency(comp);
   ppir_instr_print_dep(comp);

   return true;
}