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#include "Halide.h"
#include <stdio.h>
using namespace Halide;
int counter = 0;
extern "C" HALIDE_EXPORT_SYMBOL int call_count(int x) {
counter++;
assert(counter > 0);
return 99;
}
HalideExtern_1(int, call_count, int);
void check(Buffer<int> im) {
for (int y = 0; y < im.height(); y++) {
for (int x = 0; x < im.width(); x++) {
int correct = 99 * 3;
if (im(x, y) != correct) {
printf("Value at %d %d was %d instead of %d\n",
x, y, im(x, y), correct);
exit(1);
}
}
}
}
int main(int argc, char **argv) {
Var x, y;
{
// Could slide this reduction over y, but we don't, because it's
// too hard to implement bounds analysis on the intermediate
// stages.
Func f("f");
f(x, y) = x;
f(0, y) += f(1, y) + f(0, y);
f(x, y) = call_count(f(x, y));
Func g("g");
g(x, y) = f(x, y) + f(x, y - 1) + f(x, y - 2);
f.store_root().compute_at(g, y);
counter = 0;
check(g.realize({2, 10}));
int correct = 24;
if (counter != correct) {
printf("Failed sliding a reduction: %d evaluations instead of %d\n", counter, correct);
return 1;
}
}
{
// Can't slide this reduction over y, because the second stage scatters.
Func f("f");
f(x, y) = x;
f(x, x) += f(x, 0) + f(x, 1);
f(x, y) = call_count(f(x, y));
Func g("g");
g(x, y) = f(x, y) + f(x, y - 1) + f(x, y - 2);
f.store_root().compute_at(g, y);
counter = 0;
check(g.realize({2, 10}));
int correct = 60;
if (counter != correct) {
printf("Failed sliding a reduction: %d evaluations instead of %d\n", counter, correct);
return 1;
}
}
{
// Would be able to slide this so that we only have to compute
// one new row of f per row of g, but the unroll in the first
// stage forces evaluations of size two in y, which would
// clobber earlier values of the final stage of f, so we have
// to compute the final stage of f two rows at a time as well.
// The result is that we extend the loop to warm up f by 2
// iterations. This adds up to 2*(12*2) = 48 evaluations of f.
Func f("f");
f(x, y) = x;
f(0, y) += f(1, y) + f(2, y);
f(x, y) = call_count(f(x, y));
f.unroll(y, 2);
f.update(0).unscheduled();
f.update(1).unscheduled();
Func g("g");
g(x, y) = f(x, y) + f(x, y - 1) + f(x, y - 2);
f.store_root().compute_at(g, y);
counter = 0;
check(g.realize({2, 10}));
int correct = 48;
if (counter != correct) {
printf("Failed sliding a reduction: %d evaluations instead of %d\n", counter, correct);
return 1;
}
}
printf("Success!\n");
return 0;
}
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