hotfix for large ecntt (#448)

 hotfix for large ECNTTs

icicle/appUtils/ntt/ntt.cu

@@ -11,12 +11,16 @@
 
 #include <mutex>
 
+#define IS_ECNTT std::is_same_v<E, curve_config::projective_t>
+
 namespace ntt {
 
   namespace {
-
-    const uint32_t MAX_NUM_THREADS = 512;   // TODO: hotfix - should be 1024, currently limits shared memory size
-    const uint32_t MAX_THREADS_BATCH = 512; // TODO: allows 100% occupancy for scalar NTT for sm_86..sm_89
+    // TODO: Set MAX THREADS based on GPU arch
+    const uint32_t MAX_NUM_THREADS = 512; // TODO: hotfix - should be 1024, currently limits shared memory size
+    const uint32_t MAX_THREADS_BATCH = 512;
+    const uint32_t MAX_THREADS_BATCH_ECNTT =
+      256; // TODO: hardcodded - allows (2^18 x 64) ECNTT for sm86, decrease this to allow larger batch or ecntt length
     const uint32_t MAX_SHARED_MEM_ELEMENT_SIZE = 32; // TODO: occupancy calculator, hardcoded for sm_86..sm_89
     const uint32_t MAX_SHARED_MEM = MAX_SHARED_MEM_ELEMENT_SIZE * MAX_NUM_THREADS;
 
@@ -291,7 +295,8 @@ namespace ntt {
 
       bool is_shared_mem_enabled = sizeof(E) <= MAX_SHARED_MEM_ELEMENT_SIZE;
       const int log2_shmem_elems = is_shared_mem_enabled ? int(log(int(MAX_SHARED_MEM / sizeof(E))) / log(2)) : logn;
-      int num_threads = max(min(min(n / 2, MAX_THREADS_BATCH), 1 << (log2_shmem_elems - 1)), 1);
+      int max_threads_batch = IS_ECNTT ? MAX_THREADS_BATCH_ECNTT : MAX_THREADS_BATCH;
+      int num_threads = max(min(min(n / 2, max_threads_batch), 1 << (log2_shmem_elems - 1)), 1);
       const int chunks = max(int((n / 2) / num_threads), 1);
       const int total_tasks = batch_size * chunks;
       int num_blocks = total_tasks;
@@ -651,7 +656,7 @@ namespace ntt {
 
     const bool is_inverse = dir == NTTDir::kInverse;
 
-    if constexpr (std::is_same_v<E, curve_config::projective_t>) {
+    if constexpr (IS_ECNTT) {
       CHK_IF_RETURN(ntt::radix2_ntt(
         d_input, d_output, domain.twiddles, size, domain.max_size, batch_size, is_inverse, config.ordering, coset,
         coset_index, stream));