remove another over-optimization

gridder_cxx.h

@@ -1290,12 +1290,12 @@ template<typename Serv> void wminmax(const GridderConfig &gconf,
     }
   }
 
-template<typename T> void update_idx(vector<T> &v, vector<T> &vold,
-  const vector<T> &add, const vector<T> &del)
+template<typename T> void update_idx(vector<T> &v, const vector<T> &add,
+  const vector<T> &del)
   {
   myassert(v.size()>=del.size(), "must not happen");
-  vold.resize(0);
-  vold.reserve((v.size()+add.size())-del.size());
+  vector<T> res;
+  res.reserve((v.size()+add.size())-del.size());
   auto iin=v.begin(), ein=v.end();
   auto iadd=add.begin(), eadd=add.end();
   auto irem=del.begin(), erem=del.end();
@@ -1305,15 +1305,15 @@ template<typename T> void update_idx(vector<T> &v, vector<T> &vold,
     if ((irem!=erem) && (*iin==*irem))
       {  ++irem; ++iin; } // skip removed entry
     else if ((iadd!=eadd) && (*iadd<*iin))
-       vold.push_back(*(iadd++)); // add new entry
+       res.push_back(*(iadd++)); // add new entry
     else
-      vold.push_back(*(iin++));
+      res.push_back(*(iin++));
     }
   myassert(irem==erem, "must not happen");
   while(iadd!=eadd)
-    vold.push_back(*(iadd++));
-  myassert(vold.size()==(v.size()+add.size())-del.size(), "must not happen");
-  v.swap(vold);
+    res.push_back(*(iadd++));
+  myassert(res.size()==(v.size()+add.size())-del.size(), "must not happen");
+  v.swap(res);
   }
 
 template<typename Serv> void wstack_common(
@@ -1403,14 +1403,14 @@ template<typename T, typename Serv> void x2dirty(
     if (verbosity>0) cout << "Gridding using improved w-stacking" << endl;
     wstack_common(gconf, srv, wmin, dw, nplanes, minplane, verbosity);
     dirty.fill(0);
-    vector<idx_t> subidx, subidx_old;
+    vector<idx_t> subidx;
     tmpStorage<complex<T>,2> grid_({gconf.Nu(),gconf.Nv()});
     auto grid=grid_.getMav();
     tmpStorage<complex<T>,2> tdirty_(dirty.shape());
     auto tdirty=tdirty_.getMav();
     for (size_t iw=0; iw<nplanes; ++iw)
       {
-      update_idx(subidx, subidx_old, minplane[iw], iw>=supp ? minplane[iw-supp] : vector<idx_t>());
+      update_idx(subidx, minplane[iw], iw>=supp ? minplane[iw-supp] : vector<idx_t>());
       if (subidx.size()==0) continue;
       if (verbosity>1)
         cout << "Working on plane " << iw << " containing " << subidx.size()
@@ -1482,14 +1482,14 @@ template<typename T, typename Serv> void dirty2x(
     // correct for w gridding
     apply_wcorr(gconf, tdirty, ES_Kernel(supp, nthreads), dw);
 
-    vector<idx_t> subidx, subidx_old;
+    vector<idx_t> subidx;
     tmpStorage<complex<T>,2> grid_({gconf.Nu(),gconf.Nv()});
     auto grid=grid_.getMav();
     tmpStorage<complex<T>,2> tdirty2_({nx_dirty,ny_dirty});
     auto tdirty2=tdirty2_.getMav();
     for (size_t iw=0; iw<nplanes; ++iw)
       {
-      update_idx(subidx, subidx_old, minplane[iw], iw>=supp ? minplane[iw-supp] : vector<idx_t>());
+      update_idx(subidx, minplane[iw], iw>=supp ? minplane[iw-supp] : vector<idx_t>());
       if (subidx.size()==0) continue;
       if (verbosity>1)
         cout << "Working on plane " << iw << " containing " << subidx.size()