#include int main() { int A[2][1000][1000]; int B[2][1000][1000]; #pragma scop { for (int i = 0; i < 256; ++i) for (int j = 0; j < 256; ++j) if (j % 8 <= 2 || j % 8 >= 6) A[1][i][j] = B[1][j][i]; } #pragma endscop /* When compiled with: ./ppcg tests/allow-sparse-copy-in.c --no-linearize-device-arrays --on-error=abort --sizes='{kernel[i]->tile[8,8]; kernel[i]->block[1,8]}' --max-shared-memory=-1 --unroll-copy-shared this originally resulted in the following copy-in code: shared_B[0][0][t1] = B[1][8 * b1][8 * b0 + t1]; shared_B[0][1][t1] = B[1][8 * b1 + 1][8 * b0 + t1]; shared_B[0][2][t1] = B[1][8 * b1 + 2][8 * b0 + t1]; shared_B[0][3][t1] = B[1][8 * b1 + 3][8 * b0 + t1]; shared_B[0][4][t1] = B[1][8 * b1 + 4][8 * b0 + t1]; shared_B[0][5][t1] = B[1][8 * b1 + 5][8 * b0 + t1]; shared_B[0][6][t1] = B[1][8 * b1 + 6][8 * b0 + t1]; shared_B[0][7][t1] = B[1][8 * b1 + 7][8 * b0 + t1]; whereas we only want to only perform copies that are actually needed: shared_B[0][0][t1] = B[1][8 * b1][8 * b0 + t1]; shared_B[0][1][t1] = B[1][8 * b1 + 1][8 * b0 + t1]; shared_B[0][2][t1] = B[1][8 * b1 + 2][8 * b0 + t1]; shared_B[0][6][t1] = B[1][8 * b1 + 6][8 * b0 + t1]; shared_B[0][7][t1] = B[1][8 * b1 + 7][8 * b0 + t1]; */ for (int i = 0; i < 100; ++i) if (A[1][0][i] != i) return EXIT_FAILURE; return EXIT_SUCCESS; }