From 9fa44eab010ff42041154fb8cc6ce904947ecafd Mon Sep 17 00:00:00 2001
From: Artur Gainullin <artur.gainullin@intel.com>
Date: Mon, 19 Oct 2026 15:47:28 -0700
Subject: [PATCH] [SYCL][E2E] Match big-data reduction work group sizing to
 runtime
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This test exercises reductions with large element types. Match the
runtime’s reduGetMaxWGSize() calculation by applying the device cap before
conditionally halving, so the chosen work-group size stays within the
runtime limit.

Assisted-By: OpenCode, GPT-6.1-Sol
---
 .../test-e2e/Reduction/reduction_big_data.cpp | 19 ++++++++++++++-----
 1 file changed, 14 insertions(+), 5 deletions(-)

diff --git a/sycl/test-e2e/Reduction/reduction_big_data.cpp b/sycl/test-e2e/Reduction/reduction_big_data.cpp
index f317bea555d6c..399fed980ae4c 100644
--- a/sycl/test-e2e/Reduction/reduction_big_data.cpp
+++ b/sycl/test-e2e/Reduction/reduction_big_data.cpp
@@ -20,7 +20,11 @@ size_t getSafeMaxWGSize(size_t MaxWGSize, size_t MemSize, size_t OneElemSize) {
   size_t MaxNumElems = MemSize / OneElemSize;
   if ((MaxNumElems & (MaxNumElems - 1)) != 0)
     MaxNumElems--; // Need 1 additional element in mem if not pow of 2
-  return std::min(MaxNumElems / 2, MaxWGSize);
+  // Match the runtime's reduGetMaxWGSize() for memory-limited reductions.
+  size_t WGSize = std::min(MaxNumElems, MaxWGSize);
+  if (WGSize >= 4 && MaxNumElems < MaxWGSize * 2)
+    WGSize /= 2;
+  return WGSize;
 }
 
 template <typename Name, typename T, int Dim, class BinaryOperation>
@@ -66,15 +70,16 @@ int test(queue &Q, T Identity) {
   return checkResults(Q, BOp, NDRange, ComputedOut, CorrectOut);
 }
 
-template <typename T> struct BigCustomVec : public CustomVec<T> {
+template <typename T, size_t Size = 512>
+struct BigCustomVec : public CustomVec<T> {
   BigCustomVec() : CustomVec<T>() {}
   BigCustomVec(T X, T Y) : CustomVec<T>(X, Y) {}
   BigCustomVec(T V) : CustomVec<T>(V) {}
-  unsigned char OtherData[512 - sizeof(CustomVec<T>)];
+  unsigned char OtherData[Size - sizeof(CustomVec<T>)];
 };
 
-template <class T> struct BigCustomVecPlus {
-  using CV = BigCustomVec<T>;
+template <class T, size_t Size = 512> struct BigCustomVecPlus {
+  using CV = BigCustomVec<T, Size>;
   CV operator()(const CV &A, const CV &B) const {
     return CV(A.X + B.X, A.Y + B.Y);
   }
@@ -89,6 +94,10 @@ int main() {
   using BCV = BigCustomVec<long long>;
   NumErrors += test<class A2, BCV, 1, BigCustomVecPlus<long long>>(Q, BCV(0));
 
+  using CV96 = BigCustomVec<long long, 96>;
+  NumErrors +=
+      test<class A3, CV96, 1, BigCustomVecPlus<long long, 96>>(Q, CV96(0));
+
   printFinalStatus(NumErrors);
   return NumErrors;
 }