81 lines
2.5 KiB
Common Lisp
81 lines
2.5 KiB
Common Lisp
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// super super slow sgemm kernel by heehoon
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#define VWIDTH 8
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#define TILE_ROW 32
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#define TILE_COL (TILE_ROW/VWIDTH)
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#define TS 32
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#define WPT 16
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#define RTS 2
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__kernel void sgemm(__global float *A, __global float *B, __global float *C, int M, int N, int K) {
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// Thread identifiers
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const int row = get_local_id(0); // Local row ID (max: TS)
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const int col = get_local_id(1); // Local col ID (max: TS/WPT == RTS)
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const int globalRow = TS*get_group_id(0) + row; // Row ID of C (0..M)
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const int globalCol = TS*get_group_id(1) + col; // Col ID of C (0..N)
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// Local memory to fit a tile of TS*TS elements of A and B
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__local float Asub[TS][TS];
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__local float Bsub[TS][TS];
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// Initialise the accumulation registers
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float acc[WPT];
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for (int w=0; w<WPT; w++) {
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acc[w] = 0.0f;
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}
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// Loop over all tiles
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const int numTiles = (K + TS - 1)/TS;
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for (int t=0; t<numTiles; t++) {
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// Load one tile of A and B into local memory
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const int tiledRow = TS*t + row;
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const int tiledCol = TS*t + col;
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if (M % TS == 0 && M == N && M == K) {
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for (int w=0; w<WPT; w++) {
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Asub[row + w*RTS][col] = A[(globalRow + w*RTS)*K + tiledCol];
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Bsub[row + w*RTS][col] = B[(tiledRow + w*RTS)*N + globalCol];
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}
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} else {
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for (int w=0; w<WPT; w++) {
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if (globalRow + w*RTS >= M || tiledCol >= K) {
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Asub[row + w*RTS][col] = 0.0f;
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} else {
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Asub[row + w*RTS][col] = A[(globalRow + w*RTS)*K + tiledCol];
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}
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if (tiledRow + w*RTS >= K || globalCol >= N) {
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Bsub[row + w*RTS][col] = 0.0f;
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} else {
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Bsub[row + w*RTS][col] = B[(tiledRow + w*RTS)*N + globalCol];
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}
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}
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}
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// Synchronise to make sure the tile is loaded
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barrier(CLK_LOCAL_MEM_FENCE);
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// Perform the computation for a single tile
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for (int k=0; k<TS; k++) {
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for (int w=0; w<WPT; w++) {
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acc[w] += Asub[row + w*RTS][k] * Bsub[k][col];
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}
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}
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// Synchronise before loading the next tile
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barrier(CLK_LOCAL_MEM_FENCE);
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}
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// Store the final results in C
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if (M % TS == 0 && M == N && M == K) {
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for (int w=0; w<WPT; w++) {
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C[(globalRow + w*RTS)*N + globalCol] = acc[w];
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}
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} else {
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for (int w=0; w<WPT; w++) {
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if (globalRow + w*RTS >= M || globalCol >= N) continue;
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C[(globalRow + w*RTS)*N + globalCol] = acc[w];
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}
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}
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}
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