LST CPU Optimizations - trig simplifications and redundant load removal

Author: GNiendorf

HeterogeneousCore/AlpakaMath/interface/deltaPhi.h

@@ -22,7 +22,7 @@ namespace cms::alpakatools {
 
   template <alpaka::concepts::Acc TAcc, typename T>
   ALPAKA_FN_HOST_ACC inline T deltaPhi(TAcc const& acc, T x1, T y1, T x2, T y2) {
-    return reducePhiRange(acc, alpaka::math::atan2(acc, -y2, -x2) - alpaka::math::atan2(acc, -y1, -x1));
+    return alpaka::math::atan2(acc, x1 * y2 - x2 * y1, x1 * x2 + y1 * y2);
   }
 
   template <alpaka::concepts::Acc TAcc, typename T>

RecoTracker/LSTCore/interface/alpaka/Common.h

@@ -40,6 +40,7 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
   HOST_DEVICE_CONSTANT float kStripPSZpitch = 2.4;
   HOST_DEVICE_CONSTANT float kStrip2SZpitch = 5.0;
   HOST_DEVICE_CONSTANT float kWidth2S = 0.009;
+  HOST_DEVICE_CONSTANT float kDisks2SMinRadius = 60.0;
   HOST_DEVICE_CONSTANT float kWidthPS = 0.01;
   HOST_DEVICE_CONSTANT float kPt_betaMax = 7.0;
   HOST_DEVICE_CONSTANT int kNTripletThreshold = 1000;

RecoTracker/LSTCore/src/alpaka/Kernels.h

@@ -247,7 +247,10 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
             if (quintuplets.isDup()[ix] & 1)
               continue;
 
-            bool isPT5_ix = quintuplets.partOfPT5()[ix];
+            const bool isPT5_ix = quintuplets.partOfPT5()[ix];
+            const float eta1 = __H2F(quintuplets.eta()[ix]);
+            const float phi1 = __H2F(quintuplets.phi()[ix]);
+            const float score_rphisum1 = __H2F(quintuplets.score_rphisum()[ix]);
 
             for (unsigned int jx1 = 0; jx1 < nQuintuplets_lowmod2; jx1++) {
               unsigned int jx = quintupletModuleIndices_lowmod2 + jx1;
@@ -257,31 +260,24 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
               if (quintuplets.isDup()[jx] & 1)
                 continue;
 
-              bool isPT5_jx = quintuplets.partOfPT5()[jx];
+              const bool isPT5_jx = quintuplets.partOfPT5()[jx];
 
               if (isPT5_ix && isPT5_jx)
                 continue;
 
-              float eta1 = __H2F(quintuplets.eta()[ix]);
-              float phi1 = __H2F(quintuplets.phi()[ix]);
-              float score_rphisum1 = __H2F(quintuplets.score_rphisum()[ix]);
-
-              float eta2 = __H2F(quintuplets.eta()[jx]);
-              float phi2 = __H2F(quintuplets.phi()[jx]);
-              float score_rphisum2 = __H2F(quintuplets.score_rphisum()[jx]);
-
-              float dEta = alpaka::math::abs(acc, eta1 - eta2);
-              float dPhi = cms::alpakatools::deltaPhi(acc, phi1, phi2);
-
+              const float eta2 = __H2F(quintuplets.eta()[jx]);
+              const float dEta = alpaka::math::abs(acc, eta1 - eta2);
               if (dEta > 0.1f)
                 continue;
 
+              const float phi2 = __H2F(quintuplets.phi()[jx]);
+              const float dPhi = cms::alpakatools::deltaPhi(acc, phi1, phi2);
               if (alpaka::math::abs(acc, dPhi) > 0.1f)
                 continue;
 
-              float dR2 = dEta * dEta + dPhi * dPhi;
-              int nMatched = checkHitsT5(ix, jx, quintuplets);
-              const int minNHitsForDup_T5 = 5;
+              const float dR2 = dEta * dEta + dPhi * dPhi;
+              const int nMatched = checkHitsT5(ix, jx, quintuplets);
+              constexpr int minNHitsForDup_T5 = 5;
 
               float d2 = 0.f;
               CMS_UNROLL_LOOP
@@ -291,6 +287,7 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
               }
 
               if (((dR2 < 0.001f || nMatched >= minNHitsForDup_T5) && d2 < 1.0f) || (dR2 < 0.02f && d2 < 0.1f)) {
+                const float score_rphisum2 = __H2F(quintuplets.score_rphisum()[jx]);
                 if (isPT5_jx || score_rphisum1 > score_rphisum2) {
                   rmQuintupletFromMemory(quintuplets, ix, true);
                 } else if (isPT5_ix || score_rphisum1 < score_rphisum2) {
@@ -458,11 +455,21 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE::lst {
     ALPAKA_FN_ACC void operator()(Acc2D const& acc, PixelQuintuplets pixelQuintuplets) const {
       unsigned int nPixelQuintuplets = pixelQuintuplets.nPixelQuintuplets();
       for (unsigned int ix : cms::alpakatools::uniform_elements_y(acc, nPixelQuintuplets)) {
+        float eta1 = __H2F(pixelQuintuplets.eta()[ix]);
+        float phi1 = __H2F(pixelQuintuplets.phi()[ix]);
         float score1 = __H2F(pixelQuintuplets.score()[ix]);
         for (unsigned int jx : cms::alpakatools::uniform_elements_x(acc, nPixelQuintuplets)) {
           if (ix == jx)
             continue;
 
+          float eta2 = __H2F(pixelQuintuplets.eta()[jx]);
+          if (alpaka::math::abs(acc, eta1 - eta2) > 0.2f)
+            continue;
+
+          float phi2 = __H2F(pixelQuintuplets.phi()[jx]);
+          if (alpaka::math::abs(acc, cms::alpakatools::deltaPhi(acc, phi1, phi2)) > 0.2f)
+            continue;
+
           int nMatched = checkHitspT5(ix, jx, pixelQuintuplets);
           float score2 = __H2F(pixelQuintuplets.score()[jx]);
           const int minNHitsForDup_pT5 = 7;