Replace VTR_LOG with async-signal-safe writes in signal handler

and save block locs after each SA temprature update when signal
handler enabled.

Author: haydar-c

vpr/src/base/vpr_signal_handler.cpp

@@ -29,6 +29,10 @@
 void vpr_signal_handler(int signal);
 void checkpoint();
 
+static inline void safe_write(const char* msg) {
+    (void)!write(STDERR_FILENO, msg, strlen(msg));
+}
+
 #ifdef VPR_USE_SIGACTION
 
 void vpr_install_signal_handler() {
@@ -44,14 +48,14 @@ void vpr_install_signal_handler() {
 
 void vpr_signal_handler(int signal) {
     if (signal == SIGINT) {
-        VTR_LOG("Recieved SIGINT: Attempting to checkpoint then exit...\n");
+        safe_write("Received SIGINT: Attempting to checkpoint then exit...\n");
         checkpoint();
         std::quick_exit(INTERRUPTED_EXIT_CODE);
     } else if (signal == SIGHUP) {
-        VTR_LOG("Recieved SIGHUP: Attempting to checkpoint...\n");
+        safe_write("Received SIGHUP: Attempting to checkpoint...\n");
         checkpoint();
     } else if (signal == SIGTERM) {
-        VTR_LOG("Recieved SIGTERM: Attempting to checkpoint then exit...\n");
+        safe_write("Received SIGTERM: Attempting to checkpoint then exit...\n");
         checkpoint();
         std::quick_exit(INTERRUPTED_EXIT_CODE);
     }
@@ -74,14 +78,12 @@ void checkpoint() {
     //Dump the current placement and routing state
     vtr::ScopedStartFinishTimer timer("Checkpointing");
 
-    std::string placer_checkpoint_file = "placer_checkpoint.place";
-    VTR_LOG("Attempting to checkpoint current placement to file: %s\n", placer_checkpoint_file.c_str());
-    print_place(nullptr, nullptr, placer_checkpoint_file.c_str(), g_vpr_ctx.placement().block_locs());
+    safe_write("Attempting to checkpoint current placement to file: placer_checkpoint.place\n");
+    print_place(nullptr, nullptr, "placer_checkpoint.place", g_vpr_ctx.placement().block_locs());
 
     bool is_flat = g_vpr_ctx.routing().is_flat;
     const Netlist<>& router_net_list = is_flat ? (const Netlist<>&)g_vpr_ctx.atom().netlist() : (const Netlist<>&)g_vpr_ctx.clustering().clb_nlist;
 
-    std::string router_checkpoint_file = "router_checkpoint.route";
-    VTR_LOG("Attempting to checkpoint current routing to file: %s\n", router_checkpoint_file.c_str());
-    print_route(router_net_list, nullptr, router_checkpoint_file.c_str(), is_flat);
+    safe_write("Attempting to checkpoint current routing to file: router_checkpoint.route\n");
+    print_route(router_net_list, nullptr, "router_checkpoint.route", is_flat);
 }

vpr/src/place/annealer.cpp

@@ -898,6 +898,11 @@ void PlacementAnnealer::placement_inner_loop() {
         }
     }
 
+#ifdef VPR_USE_SIGACTION
+    // Save the block locations after each inner loop for checkpointing.
+    g_vpr_ctx.mutable_placement().mutable_block_locs() = placer_state_.block_locs();
+#endif
+
     // Calculate the success_rate and std_dev of the costs.
     placer_stats_.calc_iteration_stats(costs_, annealing_state_.move_lim);