Restore branchless 'and' operations [15_0_X]

CommonTools/RecoAlgos/BuildFile.xml

@@ -1,6 +1,7 @@
 <use name="SimGeneral/HepPDTRecord"/>
 <use name="FWCore/Framework"/>
 <use name="FWCore/ParameterSet"/>
+<use name="DataFormats/Math"/>
 <use name="DataFormats/TrackReco"/>
 <use name="DataFormats/MuonReco"/>
 <use name="DataFormats/TrackingRecHit"/>

CommonTools/RecoAlgos/interface/KDTreeLinkerAlgo.h

@@ -1,6 +1,8 @@
 #ifndef KDTreeLinkerAlgoTemplated_h
 #define KDTreeLinkerAlgoTemplated_h
 
+#include "DataFormats/Math/interface/logic.h"
+
 #include <cassert>
 #include <vector>
 #include <array>
@@ -229,7 +231,7 @@ void KDTreeLinkerAlgo<DATA, DIM>::recSearch(int current, const KDTreeBox<DIM> &t
       bool isInside = true;
       for (unsigned i = 0; i < DIM; ++i) {
         float dimCurr = nodePool_.dims[i][current];
-        isInside &= (dimCurr >= trackBox.dimmin[i]) && (dimCurr <= trackBox.dimmax[i]);
+        isInside &= reco::branchless_and(dimCurr >= trackBox.dimmin[i], dimCurr <= trackBox.dimmax[i]);
       }
       if (isInside) {
         closestNeighbour->push_back(nodePool_.data[current]);

DataFormats/Math/interface/logic.h

@@ -0,0 +1,13 @@
+#ifndef DataFormats_Math_logic_h
+#define DataFormats_Math_logic_h
+
+namespace reco {
+  // this function can be called with any boolean expressions as the parameters
+  // this forces the evaluation of both expressions (faster if the expressions are simple)
+  // and applying && to two bools avoids branching (jump instruction)
+  // whereas applying && to the two original expressions may cause branching
+  // this is an alternative to using the bitwise and operator (&), which never short-circuits
+  inline bool branchless_and(bool a, bool b) { return a && b; }
+}  // namespace reco
+
+#endif

RecoTracker/MeasurementDet/BuildFile.xml

@@ -4,6 +4,7 @@
 <use name="TrackingTools/GeomPropagators"/>
 <use name="CalibFormats/SiStripObjects"/>
 <use name="DataFormats/Common"/>
+<use name="DataFormats/Math"/>
 <use name="DataFormats/SiPixelCluster"/>
 <use name="FWCore/Framework"/>
 <use name="FWCore/ParameterSet"/>

RecoTracker/MeasurementDet/plugins/doubleMatch.icc

@@ -46,6 +46,7 @@ namespace {
 #include "RecHitPropagator.h"
 #include "DataFormats/GeometrySurface/interface/RectangularPlaneBounds.h"
 #include "DataFormats/GeometrySurface/interface/LocalError.h"
+#include "DataFormats/Math/interface/logic.h"
 
 namespace {
   inline void print(const char* where, const TrajectoryStateOnSurface& t1, const TrajectoryStateOnSurface& t2) {
@@ -128,7 +129,7 @@ void TkGluedMeasurementDet::doubleMatch(const TrajectoryStateOnSurface& ts,
     return;
   }
 
-  if ((!monoHits.empty()) && (!stereoHits.empty())) {
+  if (reco::branchless_and(!monoHits.empty(), !stereoHits.empty())) {
     const GluedGeomDet* gluedDet = &specificGeomDet();
     LocalVector trdir = (ts.isValid() ? ts.localDirection() : surface().toLocal(position() - GlobalPoint(0, 0, 0)));