Merge remote-tracking branch 'upstream/facebook_opengo_nets' into next_lizzie

Author: Ka-zam

src/Network.cpp

@@ -88,6 +88,7 @@ static std::array<float, 256> ip1_val_b;
 
 static std::array<float, 256> ip2_val_w;
 static std::array<float, 1> ip2_val_b;
+static bool value_head_not_stm;
 
 // Symmetry helper
 static std::array<std::array<int, BOARD_SQUARES>, 8> symmetry_nn_idx_table;
@@ -194,8 +195,12 @@ std::vector<float> Network::zeropad_U(const std::vector<float>& U,
 std::pair<int, int> Network::load_v1_network(std::istream& wtfile) {
     // Count size of the network
     myprintf("Detecting residual layers...");
-    // We are version 1
-    myprintf("v%d...", 1);
+    // We are version 1 or 2
+    if (value_head_not_stm) {
+        myprintf("v%d...", 2);
+    } else {
+        myprintf("v%d...", 1);
+    }
     // First line was the version number
     auto linecount = size_t{1};
     auto channels = 0;
@@ -325,11 +330,18 @@ std::pair<int, int> Network::load_network_file(const std::string& filename) {
         auto iss = std::stringstream{line};
         // First line is the file format version id
         iss >> format_version;
-        if (iss.fail() || format_version != FORMAT_VERSION) {
+        if (iss.fail() || (format_version != 1 && format_version != 2)) {
             myprintf("Weights file is the wrong version.\n");
             return {0, 0};
         } else {
-            assert(format_version == FORMAT_VERSION);
+            // Version 2 networks are identical to v1, except
+            // that they return the score for black instead of
+            // the player to move. This is used by ELF Open Go.
+            if (format_version == 2) {
+                value_head_not_stm = true;
+            } else {
+                value_head_not_stm = false;
+            }
             return load_v1_network(buffer);
         }
     }
@@ -886,6 +898,13 @@ Network::Netresult Network::get_scored_moves(
         result = get_scored_moves_internal(planes, rand_sym);
     }
 
+    // v2 format (ELF Open Go) returns black value, not stm
+    if (value_head_not_stm) {
+        if (state->board.get_to_move() == FastBoard::WHITE) {
+            result.winrate = 1.0f - result.winrate;
+        }
+    }
+
     // Insert result into cache.
     NNCache::get_NNCache().insert(state->board.get_hash(), result);
 

src/Network.h

@@ -59,7 +59,6 @@ class Network {
                                       const int symmetry = -1,
                                       const bool skip_cache = false);
     // File format version
-    static constexpr auto FORMAT_VERSION = 1;
     static constexpr auto INPUT_MOVES = 8;
     static constexpr auto INPUT_CHANNELS = 2 * INPUT_MOVES + 2;
     static constexpr auto OUTPUTS_POLICY = 2;

training/elf/elf_convert.py

@@ -39,7 +39,8 @@ def write_block(f, b):
         print(key, state[key].shape)
 
 with open('elf_converted_weights.txt', 'w') as f:
-    f.write('1\n')
+    # version 2 means value head is for black, not for side to move
+    f.write('2\n')
     b = convert_block(state, 'init_conv')
 
     # Permutate input planes