From cecd70b38e7ca34b8f85d5f06c8da6234be430bc Mon Sep 17 00:00:00 2001
From: Marco Rovere <marco.rovere@cern.ch>
Date: Tue, 7 Oct 2025 10:41:17 +0200
Subject: [PATCH] Avoid unnecessary memset.

Remove unnecessary memset operations on all cases in which the memory is
in any case written by the kernels w/o assuming any previous value. In
all other cases, leave the memset operations to preserve the correctness
of the algorithms.
---
 .../alpaka/HGCalLayerClustersAlgoWrapper.dev.cc      | 12 ------------
 .../alpaka/HGCalLayerClustersSoAAlgoWrapper.dev.cc   |  6 ------
 2 files changed, 18 deletions(-)

diff --git a/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersAlgoWrapper.dev.cc b/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersAlgoWrapper.dev.cc
index bd672655308a2..f9e0aacb0beff 100644
--- a/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersAlgoWrapper.dev.cc
+++ b/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersAlgoWrapper.dev.cc
@@ -25,18 +25,6 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE {
     CLUEAlgoAlpaka<ALPAKA_ACCELERATOR_NAMESPACE::Acc1D, Queue, HGCalSiliconTilesConstants, kHGCalLayers> algoStandalone(
         queue, dc, kappa, outlierDeltaFactor, false);
 
-    // Initialize output memory to 0
-    auto delta = cms::alpakatools::make_device_view<float>(queue, outputs.delta(), size);
-    alpaka::memset(queue, delta, 0x0);
-    auto rho = cms::alpakatools::make_device_view<float>(queue, outputs.rho(), size);
-    alpaka::memset(queue, rho, 0x0);
-    auto nearestHigher = cms::alpakatools::make_device_view<unsigned int>(queue, outputs.nearestHigher(), size);
-    alpaka::memset(queue, nearestHigher, 0x0);
-    auto clusterIndex = cms::alpakatools::make_device_view<int>(queue, outputs.clusterIndex(), size);
-    alpaka::memset(queue, clusterIndex, kInvalidClusterByte);
-    auto isSeed = cms::alpakatools::make_device_view<uint8_t>(queue, outputs.isSeed(), size);
-    alpaka::memset(queue, isSeed, 0x0);
-
     algoStandalone.makeClustersCMSSW(size,
                                      inputs.dim1(),
                                      inputs.dim2(),
diff --git a/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersSoAAlgoWrapper.dev.cc b/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersSoAAlgoWrapper.dev.cc
index e1cdff5480004..52653063e2e2a 100644
--- a/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersSoAAlgoWrapper.dev.cc
+++ b/RecoLocalCalo/HGCalRecProducers/plugins/alpaka/HGCalLayerClustersSoAAlgoWrapper.dev.cc
@@ -155,10 +155,6 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE {
     alpaka::memset(queue, x, 0x0);
     auto y = cms::alpakatools::make_device_view<float>(queue, outputs.y(), size);
     alpaka::memset(queue, y, 0x0);
-    auto z = cms::alpakatools::make_device_view<float>(queue, outputs.z(), size);
-    alpaka::memset(queue, z, 0x0);
-    auto seed = cms::alpakatools::make_device_view<int>(queue, outputs.seed(), size);
-    alpaka::memset(queue, seed, 0x0);
     auto energy = cms::alpakatools::make_device_view<float>(queue, outputs.energy(), size);
     alpaka::memset(queue, energy, 0x0);
     auto cells = cms::alpakatools::make_device_view<int>(queue, outputs.cells(), size);
@@ -167,8 +163,6 @@ namespace ALPAKA_ACCELERATOR_NAMESPACE {
     alpaka::memset(queue, total_weight, 0x0);
     auto total_weight_log = cms::alpakatools::make_device_view<float>(queue, outputs_service.total_weight_log(), size);
     alpaka::memset(queue, total_weight_log, 0x0);
-    auto maxEnergyValue = cms::alpakatools::make_device_view<float>(queue, outputs_service.maxEnergyValue(), size);
-    alpaka::memset(queue, maxEnergyValue, 0x0);
     auto maxEnergyIndex = cms::alpakatools::make_device_view<int>(queue, outputs_service.maxEnergyIndex(), size);
     alpaka::memset(queue, maxEnergyIndex, kInvalidIndexByte);