From 061e48fd73c63d924e8d777ab74287f7d69d7c2a Mon Sep 17 00:00:00 2001
From: Christopher Kelly <ckelly@phys.columbia.edu>
Date: Tue, 22 Aug 2017 18:12:12 -0400
Subject: [PATCH] Replaced slow unpack-repack in G-parity BC twist with
 intrinsics version

---
 lib/qcd/action/fermion/FermionOperatorImpl.h | 26 ++++++++++++++++++++
 1 file changed, 26 insertions(+)

diff --git a/lib/qcd/action/fermion/FermionOperatorImpl.h b/lib/qcd/action/fermion/FermionOperatorImpl.h
index 1e344521..5300063b 100644
--- a/lib/qcd/action/fermion/FermionOperatorImpl.h
+++ b/lib/qcd/action/fermion/FermionOperatorImpl.h
@@ -565,6 +565,7 @@ class GparityWilsonImpl : public ConjugateGaugeImpl<GaugeImplTypes<S, Nrepresent
 
  template<typename SiteSpinorType>
  void GparityTwistPermute(SiteSpinorType &into,  const SiteSpinorType &from, const int direction, const int distance, const int perm, GridBase* grid){
+#if 0
    typedef typename SiteSpinorType::scalar_object sobj;
    sobj stmp;
    std::vector<sobj> vals(grid->Nsimd());
@@ -589,6 +590,31 @@ class GparityWilsonImpl : public ConjugateGaugeImpl<GaugeImplTypes<S, Nrepresent
      }
    }
    merge(into,vals);
+#else
+   int permute_type = grid->PermuteType(direction);
+   typedef typename SiteSpinorType::vector_type vtype;
+   vtype tmp1, tmp2, tmp3, tmp4;
+
+   for(int s=0;s<Ns;s++){
+     for(int c=0;c<Nrepresentation;c++){
+       permute(tmp1, from(1)(s)(c), permute_type); //1l 1h -> 1h 1l
+       exchange(tmp2,tmp3, from(0)(s)(c), tmp1, permute_type); // 0l 0h , 1h 1l -> 0l 1h 0h,1l
+       permute(tmp4, tmp3, permute_type); //0h,1l -> 1l,0h
+              
+       if( (distance == 1 && !perm) || (distance == -1 && perm) ){
+	 //Pulled fermion through forwards face, GPBC on upper component
+	 //Need 0= 0l 1h   1= 1l 0h
+	 into(0)(s)(c) = tmp2;
+	 into(1)(s)(c) = tmp4;
+       }else if( (distance == -1 && !perm) || (distance == 1 && perm) ){
+	 //Pulled fermion through backwards face, GPBC on lower component
+	 //Need 0= 1l 0h   1= 0l 1h	 
+	 into(0)(s)(c) = tmp4;
+	 into(1)(s)(c) = tmp2;
+       }else assert(0);
+     }
+   }
+#endif
  }