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#include "Halide.h"
#include "halide_benchmark.h"
#include <cstdint>
#include <cstdio>
#include <random>
using namespace Halide;
using namespace Halide::Tools;
// Use std::mt19937 instead of rand() to ensure consistent behavior on all systems.
// Note that this returns an unsigned result of at-least-32 bits.
std::mt19937 rng(0);
template<typename T>
bool test(int w, bool div, bool round_to_zero) {
Func f, g, h;
Var x, y;
size_t bits = sizeof(T) * 8;
bool is_signed = (T)(-1) < (T)(0);
printf("%sInt(%2d, %2d) ",
is_signed ? " " : "U",
(int)bits, w);
int min_val = 2, num_vals = 254;
if (bits <= 8 && is_signed) {
// There are two types of integer division that cause runtime crashes:
// 1) Division by zero
// 2) Division of the smallest negative number by -1 (because
// the result overflows)
// In either case, let's avoid overflows to dodge such errors.
num_vals = 126;
}
Buffer<T> input(w, num_vals);
for (int y = 0; y < num_vals; y++) {
for (int x = 0; x < input.width(); x++) {
uint32_t bits = (uint32_t)rng();
input(x, y) = (T)bits;
// Round-to-zero faults on zero denominators
if (round_to_zero && (input(x, y) == 0)) {
input(x, y) = 1;
}
}
}
if (div) {
if (round_to_zero) {
// Test div. We'll unroll entirely across y to turn the denominator into a constant.
f(x, y) = div_round_to_zero(input(x, y), cast<T>(y + min_val));
// Reference good version. Not unrolled across y.
g(x, y) = div_round_to_zero(input(x, y), cast<T>(y + min_val));
// Version that uses fast_integer_divide
h(x, y) = Halide::fast_integer_divide_round_to_zero(input(x, y), cast<uint8_t>(y + min_val));
} else {
// Test div
f(x, y) = input(x, y) / cast<T>(y + min_val);
// Reference good version
g(x, y) = input(x, y) / cast<T>(y + min_val);
// Version that uses fast_integer_divide
h(x, y) = Halide::fast_integer_divide(input(x, y), cast<uint8_t>(y + min_val));
}
} else {
// Test mod
f(x, y) = input(x, y) % cast<T>(y + min_val);
// Reference good version
g(x, y) = input(x, y) % cast<T>(y + min_val);
// Version that uses fast_integer_modulo
h(x, y) = Halide::fast_integer_modulo(input(x, y), cast<uint8_t>(y + min_val));
}
// Try dividing by all the known constants using vectors
f.bound(y, 0, num_vals).bound(x, 0, input.width()).unroll(y);
h.bound(x, 0, input.width());
if (w > 1) {
f.vectorize(x);
h.vectorize(x);
}
Target t = get_jit_target_from_environment();
f.compile_jit(t);
g.compile_jit(t);
h.compile_jit(t);
Buffer<T> correct = g.realize({input.width(), num_vals});
double t_correct = benchmark([&]() { g.realize(correct); });
Buffer<T> fast = f.realize({input.width(), num_vals});
double t_fast = benchmark([&]() { f.realize(fast); });
Buffer<T> fast_dynamic = h.realize({input.width(), num_vals});
double t_fast_dynamic = benchmark([&]() { h.realize(fast_dynamic); });
printf("%6.3f %6.3f\n", t_correct / t_fast, t_correct / t_fast_dynamic);
for (int y = 0; y < num_vals; y++) {
for (int x = 0; x < input.width(); x++) {
if (fast(x, y) != correct(x, y)) {
printf("fast(%d, %d) = %lld instead of %lld (%lld/%d)\n",
x, y,
(long long int)fast(x, y),
(long long int)correct(x, y),
(long long int)input(x, y),
(T)(y + min_val));
return false;
}
}
}
return true;
}
int main(int argc, char **argv) {
Target target = get_jit_target_from_environment();
if (target.arch == Target::WebAssembly) {
printf("[SKIP] Performance tests are meaningless and/or misleading under WebAssembly interpreter.\n");
return 0;
}
int seed = argc > 1 ? atoi(argv[1]) : time(nullptr);
rng.seed(seed);
std::cout << "const_division test seed: " << seed << std::endl;
bool success = true;
for (int i = 0; i < 3; i++) {
switch (i) {
case 0:
printf("division rounding to negative infinity:\n");
break;
case 1:
printf("signed division rounding to zero:\n");
break;
case 2:
printf("modulus:\n");
break;
}
printf("type const-divisor speed-up runtime-divisor speed-up\n");
// Scalar
success = success && test<int32_t>(1, i == 0, i == 1);
success = success && test<int16_t>(1, i == 0, i == 1);
success = success && test<int8_t>(1, i == 0, i == 1);
if (i != 1) {
success = success && test<uint32_t>(1, i == 0, false);
success = success && test<uint16_t>(1, i == 0, false);
success = success && test<uint8_t>(1, i == 0, false);
}
// Vector
success = success && test<int32_t>(8, i == 0, i == 1);
success = success && test<int16_t>(16, i == 0, i == 1);
success = success && test<int8_t>(32, i == 0, i == 1);
if (i != 1) {
success = success && test<uint32_t>(8, i == 0, false);
success = success && test<uint16_t>(16, i == 0, false);
success = success && test<uint8_t>(32, i == 0, false);
}
}
if (!success) {
return 1;
}
printf("Success!\n");
return 0;
}
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