#include "codegen/allocation.h"
#include "codegen/liveness.h"
#include "codegen/layout.h"
#include "codegen/loop_info.h"
#include "ir/basic_block.h"
#include "ir/type.h"
#include "ir/value.h"
#include "ir/function.h"
#include "ir/instructions.h"

namespace tdl{
namespace codegen{

unsigned allocation::get_num_bytes(ir::value *x) const {
  ir::type *ty = x->get_type();
  unsigned num_elements = ty->get_tile_num_elements();
  if(has_double_buffer(x))
    num_elements *= 2;
  return num_elements * ty->get_scalar_ty()->get_size_in_bits();
}


void allocation::run(ir::function &fn){
  using std::max;
  using std::min;
  typedef std::multimap<unsigned, segment> triples_map_type;

  // Fill double buffering info
  for(ir::basic_block *block: fn.blocks())
  for(ir::instruction *v: block->get_inst_list())
    // If requires shared memory
    if(layout_->get_num_shared_views(v) &&
       loop_info_->get_loop_for(block))
      double_buffer_.insert(v);

  std::vector<ir::value *> I;
  for(auto x: liveness_->intervals())
    I.push_back(x.first);
  std::vector<ir::value *> J = I;

  triples_map_type H;
  H.insert({0, segment{0, 100}});

  std::vector<ir::value *> V;
  std::map<ir::value *, unsigned> starts;
  while(!J.empty()){
    auto h_it = H.begin();
    unsigned w = h_it->first;
    segment xh = h_it->second;
    H.erase(h_it);
    auto j_it = std::find_if(J.begin(), J.end(), [&](ir::value *JJ){
      segment xj = liveness_->get_interval(JJ);
      bool res = xj.intersect(xh);
      for(auto val: H)
        res = res && !val.second.intersect(xj);
      return res;
    });
    if(j_it != J.end()){
      unsigned size = get_num_bytes(*j_it);
      segment xj = liveness_->get_interval(*j_it);
      starts[*j_it] = w;
      H.insert({w + size, segment{max(xh.start, xj.start), min(xh.end, xj.end)}});
      if(xh.start < xj.start)
        H.insert({w, segment{xh.start, xj.end}});
      if(xj.end < xh.end)
        H.insert({w, segment{xj.start, xh.end}});
      V.push_back(*j_it);
      J.erase(j_it);
    }
  }


  // Build interference graph
  std::map<ir::value*, std::set<ir::value *>> interferences;
  for(ir::value *x: V)
  for(ir::value *y: V){
    if(x == y)
      continue;
    unsigned X0 = starts[x], Y0 = starts[y];
    unsigned NX = get_num_bytes(x);
    unsigned NY = get_num_bytes(y);
    segment XS = {X0, X0 + NX};
    segment YS = {Y0, Y0 + NY};
    if(liveness_->get_interval(x).intersect(liveness_->get_interval(y))
        && XS.intersect(YS))
      interferences[x].insert(y);
  }

  // Initialize colors
  std::map<ir::value *, int> colors;
  for(ir::value *X: V)
    colors[X] = (X==V[0])?0:-1;

  // First-fit coloring
  std::vector<bool> available(V.size());
  for(ir::value *x: V){
    // Non-neighboring colors are available
    std::fill(available.begin(), available.end(), true);
    for(ir::value *Y: interferences[x]){
      int color = colors[Y];
      if(color >= 0)
        available[color] = false;
    }
    // Assigns first available color
    auto It = std::find(available.begin(), available.end(), true);
    colors[x] = std::distance(available.begin(), It);
  }

  // Finalize allocation
  for(ir::value *x: V){
    unsigned Adj = 0;
    for(ir::value *y: interferences[x])
      Adj = std::max(Adj, starts[y] + get_num_bytes(y));
    offsets_[x] = starts[x] + colors[x] * Adj;
    if(auto *phi = dynamic_cast<ir::phi_node*>(x))
    for(ir::value *px: phi->ops()){
      if(offsets_.find(px) == offsets_.end())
        offsets_[px] = offsets_[x];
    }
  }

  // Save maximum size of induced memory space
  allocated_size_ = 0;
  for(auto &x: offsets_)
    allocated_size_ = std::max<size_t>(allocated_size_, x.second + get_num_bytes(x.first));
}

}
}