From 3eecccc6f7f8c36994e9227adfc8ab1067ea287f Mon Sep 17 00:00:00 2001
From: Eddie Hung <e.hung@imperial.ac.uk>
Date: Sat, 21 Jul 2018 01:59:16 -0700
Subject: [PATCH] Avoid hysteresis preventing placer from stopping

---
 common/placer1.cc | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/common/placer1.cc b/common/placer1.cc
index 74a11040..be20c072 100644
--- a/common/placer1.cc
+++ b/common/placer1.cc
@@ -145,6 +145,7 @@ class SAPlacer
         }
 
         int n_no_progress = 0;
+        wirelen_t min_metric = curr_metric;
         double avg_metric = curr_metric;
         temp = 10000;
 
@@ -169,6 +170,12 @@ class SAPlacer
                         try_swap_position(cell, try_bel);
                 }
             }
+
+            if (curr_metric < min_metric) {
+                min_metric = curr_metric;
+                improved = true;
+            }
+
             // Heuristic to improve placement on the 8k
             if (improved)
                 n_no_progress = 0;
@@ -222,6 +229,9 @@ class SAPlacer
                 ctx->shuffle(autoplaced);
                 assign_budget(ctx);
             }
+            else {
+                update_budget(ctx);
+            }
 
             // Recalculate total metric entirely to avoid rounding errors
             // accumulating over time
@@ -365,8 +375,8 @@ class SAPlacer
         // SA acceptance criterea
         if (delta < 0 || (temp > 1e-6 && (ctx->rng() / float(0x3fffffff)) <= std::exp(-delta / temp))) {
             n_accept++;
-            if (delta < 2)
-                improved = true;
+            //if (delta < 2)
+            //    improved = true;
         } else {
             if (other != IdString())
                 ctx->unbindBel(oldBel);