From f0040c7b9a9a60510f16f32903d8d1b23f8e2f0b Mon Sep 17 00:00:00 2001
From: Geza Lore <gezalore@gmail.com>
Date: Mon, 15 Aug 2022 20:33:20 +0100
Subject: [PATCH] Remove reliance on pointer comparison in MT scheduling

The critical path propagation used to rely on a pointer comparison to
break equal scoring critical path updates. Use the corresponding mtask
ids instead, which is deterministic across invocations.
---
 src/V3Partition.cpp | 16 ++++++++++------
 1 file changed, 10 insertions(+), 6 deletions(-)

diff --git a/src/V3Partition.cpp b/src/V3Partition.cpp
index 5e8cd4d01..f6dd5c05a 100644
--- a/src/V3Partition.cpp
+++ b/src/V3Partition.cpp
@@ -161,7 +161,7 @@ static void partCheckCachedScoreVsActual(uint32_t cached, uint32_t actual) {
 //  * Client calls PartPropagateCp::go(). Internally, this iteratively
 //    propagates the new CPs wayward through the graph.
 //
-template <class T_CostAccessor>
+template <class T_CostAccessor, class T_VtxCmp = std::less<V3GraphVertex*>>
 class PartPropagateCp final : GraphAlg<> {
 private:
     // MEMBERS
@@ -171,7 +171,7 @@ private:
     T_CostAccessor* const m_accessp;  // Access cost and CPs on V3GraphVertex's.
     //                        // confirm we only process each vertex once.
     const bool m_slowAsserts;  // Enable nontrivial asserts
-    SortByValueMap<V3GraphVertex*, uint32_t> m_pending;  // Pending rescores
+    SortByValueMap<V3GraphVertex*, uint32_t, T_VtxCmp> m_pending;  // Pending rescores
 
 public:
     // CONSTRUCTORS
@@ -361,6 +361,10 @@ public:
         bool operator()(const LogicMTask* ap, const LogicMTask* bp) const {
             return ap->id() < bp->id();
         }
+        bool operator()(const V3GraphVertex* ap, const V3GraphVertex* bp) const {
+            return operator()(static_cast<const LogicMTask*>(ap),
+                              static_cast<const LogicMTask*>(bp));
+        }
     };
 
     // This adaptor class allows the PartPropagateCp class to be somewhat
@@ -1380,10 +1384,10 @@ private:
                                 << donorNewCpFwd.propagateCp << endl);
 
         LogicMTask::CpCostAccessor cpAccess;
-        PartPropagateCp<LogicMTask::CpCostAccessor> forwardPropagator(m_mtasksp, GraphWay::FORWARD,
-                                                                      &cpAccess, m_slowAsserts);
-        PartPropagateCp<LogicMTask::CpCostAccessor> reversePropagator(m_mtasksp, GraphWay::REVERSE,
-                                                                      &cpAccess, m_slowAsserts);
+        PartPropagateCp<LogicMTask::CpCostAccessor, LogicMTask::CmpLogicMTask> forwardPropagator(
+            m_mtasksp, GraphWay::FORWARD, &cpAccess, m_slowAsserts);
+        PartPropagateCp<LogicMTask::CpCostAccessor, LogicMTask::CmpLogicMTask> reversePropagator(
+            m_mtasksp, GraphWay::REVERSE, &cpAccess, m_slowAsserts);
 
         recipientp->setCritPathCost(GraphWay::FORWARD, recipientNewCpFwd.cp);
         if (recipientNewCpFwd.propagate) {