try a different order for prefetches and loads

For the block read kernels, the order is now:
1. Prefetch A
2. Load B
3. Load A
4. Prefetch B

samples/99_matrixexperiments/matrix_kernel_tiled.cl

@@ -559,8 +559,8 @@ kernel void MM_KERNEL_NAME(bfloat16_dpas_blockread_rowmajor_tiled, 8, 16, MM, NN
 
  int prefetch_k = 0;
  for (int p = 0; p < PREFETCH_DISTANCE; p++) {
- HELPER_NAME(btile_prefetch_rowmajor, MM, NN)(B, tN, N, prefetch_k, n);
  HELPER_NAME(atile_block_prefetch_rowmajor, MM, NN)(A, tM, M, K, m, prefetch_k);
+ HELPER_NAME(btile_prefetch_rowmajor, MM, NN)(B, tN, N, prefetch_k, n);
  prefetch_k += tK * KK;
  }
 
@@ -575,23 +575,24 @@ kernel void MM_KERNEL_NAME(bfloat16_dpas_blockread_rowmajor_tiled, 8, 16, MM, NN
 
  for (int k = 0; k < K; k += tK * KK) {
  // TODO: skip prefetch on the last iterations.
- HELPER_NAME(btile_prefetch_rowmajor, MM, NN)(B, tN, N, prefetch_k, n);
-
- short8 aData[KK][MM];
- HELPER_NAME(atile_load_blockread_rowmajor, MM, NN)(A, tM, M, K, m, k, aData);
+ HELPER_NAME(atile_block_prefetch_rowmajor, MM, NN)(A, tM, M, K, m, prefetch_k);
 
  int8 bData[NN][KK];
  HELPER_NAME(btile_load_blockread_rowmajor, MM, NN)(B, tN, K, N, k, n, bData);
 
- HELPER_NAME(atile_block_prefetch_rowmajor, MM, NN)(A, tM, M, K, m, prefetch_k);
- prefetch_k += tK * KK;
+ short8 aData[KK][MM];
+ HELPER_NAME(atile_load_blockread_rowmajor, MM, NN)(A, tM, M, K, m, k, aData);
 
  for (int kk = 0; kk < KK; kk++) {
  for (int nn = 0; nn < NN; nn++) {
  for (int mm = 0; mm < MM; mm++) {
  sum[mm][nn] = mat_mul_sg16(aData[kk][mm], bData[nn][kk], sum[mm][nn]);
  }
  }
+ if (kk == 0) {
+ HELPER_NAME(btile_prefetch_rowmajor, MM, NN)(B, tN, N, prefetch_k, n);
+ prefetch_k += tK * KK;
+ }
  }
 
  split_barrier_wait();
@@ -636,23 +637,24 @@ kernel void MM_KERNEL_NAME(bfloat16_dpas_blockread_vnni_tiled, 8, 16, MM, NN)(gl
 
  for (int k = 0; k < K; k += tK * KK) {
  // TODO: skip prefetch on the last iterations.
- HELPER_NAME(btile_prefetch_vnni, MM, NN)(B, tN, N, prefetch_k, n);
-
- short8 aData[KK][MM];
- HELPER_NAME(atile_load_blockread_rowmajor, MM, NN)(A, tM, M, K, m, k, aData);
+ HELPER_NAME(atile_block_prefetch_rowmajor, MM, NN)(A, tM, M, K, m, prefetch_k);
 
  int8 bData[NN][KK];
  HELPER_NAME(btile_load_blockread_vnni, MM, NN)(B, tN, K, N, k, n, bData);
 
- HELPER_NAME(atile_block_prefetch_rowmajor, MM, NN)(A, tM, M, K, m, prefetch_k);
- prefetch_k += tK * KK;
+ short8 aData[KK][MM];
+ HELPER_NAME(atile_load_blockread_rowmajor, MM, NN)(A, tM, M, K, m, k, aData);
 
  for (int kk = 0; kk < KK; kk++) {
  for (int nn = 0; nn < NN; nn++) {
  for (int mm = 0; mm < MM; mm++) {
  sum[mm][nn] = mat_mul_sg16(aData[kk][mm], bData[nn][kk], sum[mm][nn]);
  }
  }
+ if (kk == 0) {
+ HELPER_NAME(btile_prefetch_vnni, MM, NN)(B, tN, N, prefetch_k, n);
+ prefetch_k += tK * KK;
+ }
  }
 
  split_barrier_wait();