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remove simplify

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This commit is contained in:
Awni Hannun
2024-01-16 20:14:27 -08:00
parent 5c78c16f1c
commit 1c3f82ca17
6 changed files with 74 additions and 291 deletions
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163
mlx/transforms.cpp
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@@ -35,169 +35,6 @@ class Synchronizer : public Primitive {
// are currently under a function transformation. // are currently under a function transformation.
int detail::InTracing::tracing_counter{0}; int detail::InTracing::tracing_counter{0};
void simplify(const std::vector<array>& outputs) {
// Some notes about how this function works
//
// Step 1: Traverse the graph and build a tape. During the graph
// traversal we:
// - Build a map of inputs to their parents.
// - Record scalar inputs in a map in order to fuse them.
// Step 2: Process the tape. A node in the tape has inputs and outputs.
// - Scalar inputs are replaced with their canonical scalar
// - We check each inputs output nodes. Every output node that matches
// the current node gets fused into the current node.
std::function<void(const array&)> recurse;
std::queue<array> tape;
std::unordered_set<std::uintptr_t> cache;
std::unordered_map<std::uintptr_t, std::vector<std::pair<array, int>>>
parents_map;
// Helpers to identify identical scalars
std::map<std::pair<uint64_t, Dtype::Val>, array> scalars;
auto is_scalar = [](const array& a) {
return a.is_evaled() && a.ndim() == 0;
};
auto get_scalar_rep = [](const array& a) {
uint64_t v = 0;
int dtype;
switch (a.dtype().size) {
case 1:
v = *a.data<uint8_t>();
break;
case 4:
v = *a.data<uint32_t>();
break;
case 8:
v = *a.data<uint64_t>();
break;
}
return std::make_pair(v, a.dtype().val);
};
// DFS the graph to build the tape, and log parents and scalars
recurse = [&](const array& a) {
auto id = a.id();
if (cache.find(id) != cache.end()) {
return;
}
for (int i = 0; i < a.inputs().size(); i++) {
auto& in = a.inputs()[i];
parents_map[in.id()].push_back({a, i});
for (auto& s : a.siblings()) {
parents_map[in.id()].push_back({s, i});
}
recurse(in);
}
cache.insert(id);
for (auto& s : a.siblings()) {
cache.insert(s.id());
}
tape.push(a);
if (is_scalar(a)) {
scalars.insert({get_scalar_rep(a), a});
}
};
for (auto& a : outputs) {
recurse(a);
}
// Helper that fuses two arrays in the graph by setting the parents of the
// source to point to the destination
auto fuse = [&](array& dst, array& src) {
// Canonicalize the order of the primitives outputs
auto sources = src.outputs();
auto dests = dst.outputs();
// For each src parent, point it to the corresponding dest
for (int i = 0; i < sources.size(); ++i) {
auto src_parents = parents_map.find(sources[i].id());
if (src_parents == parents_map.end()) {
continue;
}
auto& pairs = parents_map[dests[i].id()];
for (auto& parent : src_parents->second) {
parent.first.inputs()[parent.second] = dests[i];
pairs.push_back(parent);
}
// Remove the source from the map to avoid fusing with it again
parents_map.erase(src_parents);
}
};
// Depth-1 array equivalence check.
auto array_equivalent = [](const array& a, const array& b) {
if (!a.has_primitive() || !b.has_primitive()) {
return false;
}
if (a.primitive_id() == b.primitive_id()) {
return false;
}
const auto& pa = a.primitive();
const auto& pb = b.primitive();
if (typeid(pa) != typeid(pb)) {
return false;
}
if (a.inputs().size() != b.inputs().size()) {
return false;
}
for (int i = 0; i < a.inputs().size(); i++) {
if (a.inputs()[i].id() != b.inputs()[i].id()) {
return false;
}
}
return pa.is_equivalent(pb);
};
// Walk the graph
while (!tape.empty()) {
auto arr = std::move(tape.front());
tape.pop();
// Check if we can fuse scalars
if (is_scalar(arr)) {
auto scalar = scalars.find(get_scalar_rep(arr));
if (scalar->second.id() != arr.id()) {
fuse(scalar->second, arr);
arr = scalar->second;
}
}
// Helper to check if we can fuse the parents of the
// given array
auto maybe_fuse_parents = [&](auto& a) {
auto parents = parents_map.find(a.id());
if (parents != parents_map.end()) {
auto N = parents->second.size();
std::vector<bool> mask(N, false);
for (int i = 0; i < N; i++) {
if (mask[i]) {
continue;
}
for (int j = i + 1; j < N; j++) {
if (mask[j]) {
continue;
}
auto& src = parents->second[j].first;
auto& dst = parents->second[i].first;
if (src.id() != dst.id() && array_equivalent(src, dst)) {
fuse(dst, src);
mask[j] = true;
}
}
}
}
};
maybe_fuse_parents(arr);
for (auto& s : arr.siblings()) {
maybe_fuse_parents(s);
}
}
}
void eval(const std::vector<array>& outputs) { void eval(const std::vector<array>& outputs) {
std::function<void(const array&)> recurse; std::function<void(const array&)> recurse;
std::queue<array> tape; std::queue<array> tape;

8
mlx/transforms.h
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@@ -21,14 +21,6 @@ void disable_compiler();
*/ */
void enable_compiler(); void enable_compiler();
/** Fuse equivalent arrays to avoid duplicate execution. */
void simplify(const std::vector<array>& outputs);
template <typename... Arrays>
void simplify(Arrays... outputs) {
simplify(std::vector<array>{std::forward<Arrays>(outputs)...});
}
void eval(const std::vector<array>& outputs); void eval(const std::vector<array>& outputs);
template <typename... Arrays> template <typename... Arrays>

39
python/src/transforms.cpp
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@@ -777,45 +777,6 @@ void init_transforms(py::module_& m) {
Returns: Returns:
function: The vectorized function. function: The vectorized function.
)pbdoc"); )pbdoc");
m.def(
"simplify",
[](const py::args& args) {
std::vector<array> arrays = tree_flatten(args);
simplify(arrays);
},
R"pbdoc(
simplify(*args) -> None
Simplify the graph that computes the arrays.
Run a few fast graph simplification operations to reuse computation and
reduce memory consumption. This function is meant to be run every time
so its overhead should be small, approximately 1ms for a graph with a
few thousand nodes.
.. code-block:: python
import mlx.core as mx
def foo(x):
y = x @ x
z = x @ x
return y + z
x = mx.ones((10, 10))
y = foo(x)
z = foo(x)
# Computes the matmul twice
mx.eval(y)
# Computes the matmul once
mx.simplify(z)
mx.eval(z)
Args:
args: Any number of arrays and/or trees of arrays to be simplified.
)pbdoc");
m.def( m.def(
"export_to_dot", "export_to_dot",
[](py::object file, const py::args& args) { [](py::object file, const py::args& args) {

1
tests/CMakeLists.txt
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@@ -25,7 +25,6 @@ target_sources(tests PRIVATE
device_tests.cpp device_tests.cpp
eval_tests.cpp eval_tests.cpp
fft_tests.cpp fft_tests.cpp
graph_optimize_tests.cpp
load_tests.cpp load_tests.cpp
ops_tests.cpp ops_tests.cpp
random_tests.cpp random_tests.cpp

74
tests/compile_tests.cpp
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@@ -104,3 +104,77 @@ TEST_CASE("test enable and disable compile") {
enable_compiler(); enable_compiler();
CHECK_THROWS(compile(nullptr)); CHECK_THROWS(compile(nullptr));
} }
TEST_CASE("test simplify scalars") {
{
auto a = array(-1.0f);
auto b = array(-1.0f);
auto c = abs(a);
auto d = abs(b);
simplify({c, d});
CHECK(c.inputs()[0].id() == d.inputs()[0].id());
}
{
auto a = array({-1.0f, 2.0f});
auto b = maximum(a, array(0.0f));
auto c = maximum(-a, array(0.0f));
auto d = b + c;
simplify({d});
CHECK(b.inputs()[1].id() == c.inputs()[1].id());
}
}
// TODO rework these tests for compile
/*TEST_CASE("test simplify") {
auto a = array({1.0f, 2.0f});
auto b = exp(a) + exp(a);
simplify(b);
CHECK(b.inputs()[0].id() == b.inputs()[1].id());
}
TEST_CASE("test no simplify") {
auto a = array({1.0f, 2.0f});
auto b = cos(a) + sin(a);
simplify(b);
CHECK(b.inputs()[0].id() != b.inputs()[1].id());
}
TEST_CASE("test simplify multi output") {
{
auto a = array(1.0);
auto b = array(2.0);
auto c = divmod(a, b);
auto d = divmod(a, b);
auto e = c[0] + d[0];
auto f = c[1] + d[1];
simplify({e, f});
CHECK_EQ(e.inputs()[0].id(), e.inputs()[1].id());
CHECK_EQ(f.inputs()[0].id(), f.inputs()[1].id());
}
{
auto a = array(1.0);
auto b = array(1.0);
auto c = divmod(a, b);
simplify(c);
CHECK_EQ(c[0].inputs()[0].id(), c[0].inputs()[1].id());
CHECK_EQ(c[0].inputs()[0].id(), c[1].inputs()[0].id());
CHECK_EQ(c[1].inputs()[0].id(), c[1].inputs()[1].id());
}
// Make sure the output order of multi-output primitives
// is respected in simplification
{
auto a = array(1.0);
auto b = array(2.0);
auto c = divmod(a, b);
auto d = divmod(a, b);
auto e = stack({c[0], c[1], d[0], d[1]});
simplify(e);
CHECK(array_equal(e, array({0.0f, 1.0f, 0.0f, 1.0f})).item<bool>());
CHECK_EQ(e.inputs()[0].id(), e.inputs()[2].id());
CHECK_EQ(e.inputs()[1].id(), e.inputs()[3].id());
}
}*/

80
tests/graph_optimize_tests.cpp
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@@ -1,80 +0,0 @@
// Copyright © 2023 Apple Inc.
#include "doctest/doctest.h"
#include "mlx/mlx.h"
using namespace mlx::core;
TEST_CASE("test simplify scalars") {
{
auto a = array(-1.0f);
auto b = array(-1.0f);
auto c = abs(a);
auto d = abs(b);
simplify({c, d});
CHECK(c.inputs()[0].id() == d.inputs()[0].id());
}
{
auto a = array({-1.0f, 2.0f});
auto b = maximum(a, array(0.0f));
auto c = maximum(-a, array(0.0f));
auto d = b + c;
simplify({d});
CHECK(b.inputs()[1].id() == c.inputs()[1].id());
}
}
TEST_CASE("test simplify") {
auto a = array({1.0f, 2.0f});
auto b = exp(a) + exp(a);
simplify(b);
CHECK(b.inputs()[0].id() == b.inputs()[1].id());
}
TEST_CASE("test no simplify") {
auto a = array({1.0f, 2.0f});
auto b = cos(a) + sin(a);
simplify(b);
CHECK(b.inputs()[0].id() != b.inputs()[1].id());
}
TEST_CASE("test simplify multi output") {
{
auto a = array(1.0);
auto b = array(2.0);
auto c = divmod(a, b);
auto d = divmod(a, b);
auto e = c[0] + d[0];
auto f = c[1] + d[1];
simplify({e, f});
CHECK_EQ(e.inputs()[0].id(), e.inputs()[1].id());
CHECK_EQ(f.inputs()[0].id(), f.inputs()[1].id());
}
{
auto a = array(1.0);
auto b = array(1.0);
auto c = divmod(a, b);
simplify(c);
CHECK_EQ(c[0].inputs()[0].id(), c[0].inputs()[1].id());
CHECK_EQ(c[0].inputs()[0].id(), c[1].inputs()[0].id());
CHECK_EQ(c[1].inputs()[0].id(), c[1].inputs()[1].id());
}
// Make sure the output order of multi-output primitives
// is respected in simplification
{
auto a = array(1.0);
auto b = array(2.0);
auto c = divmod(a, b);
auto d = divmod(a, b);
auto e = stack({c[0], c[1], d[0], d[1]});
simplify(e);
CHECK(array_equal(e, array({0.0f, 1.0f, 0.0f, 1.0f})).item<bool>());
CHECK_EQ(e.inputs()[0].id(), e.inputs()[2].id());
CHECK_EQ(e.inputs()[1].id(), e.inputs()[3].id());
}
}