Func GeneratorBase::call_extern(std::initializer_list<ExternFuncArgument> function_arguments,
std::string function_name){
Pipeline p = build_pipeline();
user_assert(p.outputs().size() == 1) \
<< "Can only call_extern Pipelines with a single output Func\n";
Func f = p.outputs()[0];
Func f_extern;
if (function_name.empty()) {
function_name = generator_name();
user_assert(!function_name.empty())
<< "call_extern: generator_name is empty\n";
}
f_extern.define_extern(function_name, function_arguments, f.output_types(), f.dimensions());
return f_extern;
}
// Merge sort contiguous chunks of size s in a 1d func.
Func merge_sort(Func input, int total_size) {
std::vector<Func> stages;
Func result;
const int parallel_work_size = 512;
Func parallel_stage("parallel_stage");
// First gather the input into a 2D array of width four where each row is sorted
{
assert(input.dimensions() == 1);
// Use a small sorting network
Expr a0 = input(4*y);
Expr a1 = input(4*y+1);
Expr a2 = input(4*y+2);
Expr a3 = input(4*y+3);
Expr b0 = min(a0, a1);
Expr b1 = max(a0, a1);
Expr b2 = min(a2, a3);
Expr b3 = max(a2, a3);
a0 = min(b0, b2);
a1 = max(b0, b2);
a2 = min(b1, b3);
a3 = max(b1, b3);
b0 = a0;
b1 = min(a1, a2);
b2 = max(a1, a2);
b3 = a3;
result(x, y) = select(x == 0, b0,
select(x == 1, b1,
select(x == 2, b2, b3)));
result.compute_at(parallel_stage, y).bound(x, 0, 4).unroll(x);
stages.push_back(result);
}
// Now build up to the total size, merging each pair of rows
for (int chunk_size = 4; chunk_size < total_size; chunk_size *= 2) {
// "result" contains the sorted halves
assert(result.dimensions() == 2);
// Merge pairs of rows from the partial result
Func merge_rows("merge_rows");
RDom r(0, chunk_size*2);
// The first dimension of merge_rows is within the chunk, and the
// second dimension is the chunk index. Keeps track of two
// pointers we're merging from and an output value.
merge_rows(x, y) = Tuple(0, 0, cast(input.value().type(), 0));
Expr candidate_a = merge_rows(r-1, y)[0];
Expr candidate_b = merge_rows(r-1, y)[1];
Expr valid_a = candidate_a < chunk_size;
Expr valid_b = candidate_b < chunk_size;
Expr value_a = result(clamp(candidate_a, 0, chunk_size-1), 2*y);
Expr value_b = result(clamp(candidate_b, 0, chunk_size-1), 2*y+1);
merge_rows(r, y) = tuple_select(valid_a && ((value_a < value_b) || !valid_b),
Tuple(candidate_a + 1, candidate_b, value_a),
Tuple(candidate_a, candidate_b + 1, value_b));
if (chunk_size <= parallel_work_size) {
merge_rows.compute_at(parallel_stage, y);
} else {
merge_rows.compute_root();
}
if (chunk_size == parallel_work_size) {
parallel_stage(x, y) = merge_rows(x, y)[2];
parallel_stage.compute_root().parallel(y);
result = parallel_stage;
} else {
result = lambda(x, y, merge_rows(x, y)[2]);
}
}
// Convert back to 1D
return lambda(x, result(x, 0));
}
int main(int argc, char **argv) {
Var x("x"), y("y"), z("z"), w("w");
ImageParam im1(Int(32), 3);
assert(im1.dimensions() == 3);
// im1 is a 3d imageparam
Image<int> im1_val = lambda(x, y, z, x*y*z).realize(10, 10, 10);
im1.set(im1_val);
Image<int> im2 = lambda(x, y, x+y).realize(10, 10);
assert(im2.dimensions() == 2);
assert(im2(4, 6) == 10);
// im2 is a 2d image
Func f;
f(x, _) = im1(_) + im2(x, _) + im2(_);
// Equivalent to
// f(x, i, j, k) = im1(i, j, k) + im2(x, i) + im2(i, j);
// f(x, i, j, k) = i*j*k + x+i + i+j;
Image<int> result1 = f.realize(2, 2, 2, 2);
for (int k = 0; k < 2; k++) {
for (int j = 0; j < 2; j++) {
for (int i = 0; i < 2; i++) {
for (int x = 0; x < 2; x++) {
int correct = i*j*k + x+i + i+j;
if (result1(x, i, j, k) != correct) {
printf("result1(%d, %d, %d, %d) = %d instead of %d\n",
x, i, j, k, result1(x, i, j, k), correct);
return -1;
}
}
}
}
}
// f is a 4d function (thanks to the first arg having 3 implicit arguments
assert(f.dimensions() == 4);
Func g;
g(_) = f(2, 2, _) + im2(Expr(1), _);
f.compute_root();
// Equivalent to
// g(i, j) = f(2, 2, i, j) + im2(1, i);
// g(i, j) = 2*i*j + 2+2 + 2+i + 1+i
assert(g.dimensions() == 2);
Image<int> result2 = g.realize(10, 10);
for (int j = 0; j < 10; j++) {
for (int i = 0; i < 10; i++) {
int correct = 2*i*j + 2+2 + 2+i + 1+i;
if (result2(i, j) != correct) {
printf("result2(%d, %d) = %d instead of %d\n",
i, j, result2(i, j), correct);
return -1;
}
}
}
// An image which ensures any transposition of unequal coordinates changes the value
Image<int> im3 = lambda(x, y, z, w, (x<<24)|(y<<16)|(z<<8)|w).realize(10, 10, 10, 10);
Func transpose_last_two;
transpose_last_two(_, x, y) = im3(_, y, x);
// Equivalent to transpose_last_two(_0, _1, x, y) = im3(_0, _1, x, y)
Image<int> transposed = transpose_last_two.realize(10, 10, 10, 10);
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
for (int k = 0; k < 10; k++) {
for (int l = 0; l < 10; l++) {
int correct = (i<<24)|(j<<16)|(l<<8)|k;
if (transposed(i, j, k, l) != correct) {
printf("transposed(%d, %d, %d, %d) = %d instead of %d\n",
i, j, k, l, transposed(i, j, k, l), correct);
return -1;
}
}
}
}
}
Func hairy_transpose;
hairy_transpose(_, x, y) = im3(y, _, x) + im3(y, x, _);
// Equivalent to hairy_transpose(_0, _1, x, y) = im3(y, _0, _1, x) +
// im3(y, x, _0, _1)
Image<int> hairy_transposed = hairy_transpose.realize(10, 10, 10, 10);
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
for (int k = 0; k < 10; k++) {
for (int l = 0; l < 10; l++) {
int correct1 = (l<<24)|(i<<16)|(j<<8)|k;
int correct2 = (l<<24)|(k<<16)|(i<<8)|j;
int correct = correct1 + correct2;
if (hairy_transposed(i, j, k, l) != correct) {
printf("hairy_transposed(%d, %d, %d, %d) = %d instead of %d\n",
i, j, k, l, hairy_transposed(i, j, k, l), correct);
return -1;
}
}
}
}
}
Func hairy_transpose2;
hairy_transpose2(_, x) = im3(_, x) + im3(x, x, _);
// Equivalent to hairy_transpose2(_0, _1, _2, x) = im3(_0, _1, _2, x) +
// im3(x, x, _0, _1)
Image<int> hairy_transposed2 = hairy_transpose2.realize(10, 10, 10, 10);
for (int i = 0; i < 10; i++) {
for (int j = 0; j < 10; j++) {
for (int k = 0; k < 10; k++) {
for (int l = 0; l < 10; l++) {
int correct1 = (i<<24)|(j<<16)|(k<<8)|l;
int correct2 = (l<<24)|(l<<16)|(i<<8)|j;
int correct = correct1 + correct2;
if (hairy_transposed2(i, j, k, l) != correct) {
printf("hairy_transposed2(%d, %d, %d, %d) = %d instead of %d\n",
i, j, k, l, hairy_transposed2(i, j, k, l), correct);
return -1;
}
}
}
}
}
printf("Success!\n");
return 0;
}
