Fix undefined behavior flagged by UBSAN

[alexxy/gromacs.git] / src / gromacs / nbnxm / pairlist.cpp

diff --git a/src/gromacs/nbnxm/pairlist.cpp b/src/gromacs/nbnxm/pairlist.cpp
index 253a4cd97ae770259d47d1b839b2afaf83c0bab2..ad09daed08485454e8bc888c9dc98cd60b7ab1ad 100644 (file)
--- a/src/gromacs/nbnxm/pairlist.cpp
+++ b/src/gromacs/nbnxm/pairlist.cpp
@@ -3894,7 +3894,7 @@ static Range<int> getIZoneRange(const Nbnxm::GridSet::DomainSetup& domainSetup,
 }
 
 /* Returns the j-zone range for pairlist construction for the give locality and i-zone */
-static Range<int> getJZoneRange(const gmx_domdec_zones_t& ddZones,
+static Range<int> getJZoneRange(const gmx_domdec_zones_t* ddZones,
                                 const InteractionLocality locality,
                                 const int                 iZone)
 {
@@ -3906,12 +3906,12 @@ static Range<int> getJZoneRange(const gmx_domdec_zones_t& ddZones,
     else if (iZone == 0)
     {
         /* Non-local: we need to avoid the local (zone 0 vs 0) interactions */
-        return { 1, *ddZones.iZones[iZone].jZoneRange.end() };
+        return { 1, *ddZones->iZones[iZone].jZoneRange.end() };
     }
     else
     {
         /* Non-local with non-local i-zone: use all j-zones */
-        return ddZones.iZones[iZone].jZoneRange;
+        return ddZones->iZones[iZone].jZoneRange;
     }
 }
 
@@ -3977,7 +3977,9 @@ void PairlistSet::constructPairlists(const Nbnxm::GridSet&         gridSet,
         }
     }
 
-    const gmx_domdec_zones_t& ddZones = *gridSet.domainSetup().zones;
+    const gmx_domdec_zones_t* ddZones = gridSet.domainSetup().zones;
+    GMX_ASSERT(locality_ == InteractionLocality::Local || ddZones != nullptr,
+               "Nonlocal interaction locality with null ddZones.");
 
     const auto iZoneRange = getIZoneRange(gridSet.domainSetup(), locality_);
 
@@ -4003,7 +4005,7 @@ void PairlistSet::constructPairlists(const Nbnxm::GridSet&         gridSet,
             /* With GPU: generate progressively smaller lists for
              * load balancing for local only or non-local with 2 zones.
              */
-            progBal = (locality_ == InteractionLocality::Local || ddZones.n <= 2);
+            progBal = (locality_ == InteractionLocality::Local || ddZones->n <= 2);
 
 #pragma omp parallel for num_threads(numLists) schedule(static)
             for (int th = 0; th < numLists; th++)