From fa8a2777659aa8c229b451ff494b5b639d73ec14 Mon Sep 17 00:00:00 2001
From: aletempiac <alessandro.tempia@gmail.com>
Date: Thu, 29 Feb 2024 17:16:49 +0100
Subject: [PATCH] Changing search space exploration of ACD to search for better
 implementation and prune unnecessary computations based on theoretical
 properties

---
 src/map/if/acd/ac_decomposition.hpp | 18 +++++++++++++-----
 src/map/if/acd/ac_wrapper.cpp       |  2 +-
 2 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/src/map/if/acd/ac_decomposition.hpp b/src/map/if/acd/ac_decomposition.hpp
index 7cd6d9613..d573da2cd 100644
--- a/src/map/if/acd/ac_decomposition.hpp
+++ b/src/map/if/acd/ac_decomposition.hpp
@@ -58,7 +58,7 @@ struct ac_decomposition_params
   bool support_reducing_only{ true };
 
   /*! \brief Use the first feasible decomposition found. */
-  bool use_first{ true };
+  bool use_first{ false };
 
   /*! \brief If decomposition with delay profile fails, try without. */
   bool try_no_late_arrival{ false };
@@ -116,6 +116,10 @@ public:
     {
       ps.max_free_set_vars = num_vars - ps.lut_size;
     }
+    if ( late_arriving > ps.max_free_set_vars )
+    {
+      ps.max_free_set_vars = late_arriving;
+    }
 
     /* return a high cost if too many late arriving variables */
     if ( late_arriving > ps.lut_size - 1 || late_arriving > ps.max_free_set_vars )
@@ -227,11 +231,13 @@ private:
         best_cost = multiplicity + additional_cost;
         best_free_set = i;
 
-        if ( ps.use_first )
+        if ( !ps.use_first )
         {
-          break;
+          continue;
         }
       }
+
+      break;
     }
 
     if ( best_multiplicity == UINT32_MAX && ( !ps.try_no_late_arrival || late_arriving == 0 ) )
@@ -263,11 +269,13 @@ private:
           best_cost = multiplicity + additional_cost;
           best_free_set = i;
 
-          if ( ps.use_first )
+          if ( !ps.use_first )
           {
-            break;
+            continue;
           }
         }
+
+        break;
       }
     }
 
diff --git a/src/map/if/acd/ac_wrapper.cpp b/src/map/if/acd/ac_wrapper.cpp
index 7786f0e72..7551335f8 100644
--- a/src/map/if/acd/ac_wrapper.cpp
+++ b/src/map/if/acd/ac_wrapper.cpp
@@ -46,7 +46,7 @@ int acd_evaluate( word * pTruth, unsigned nVars, int lutSize, unsigned *pdelay,
     }
 
     *pdelay = acd.get_profile();
-    *cost = 2;
+    *cost = st.num_luts;
 
     return val;
   }