CPU compile (#691)

* build and load shared object for cpu compile

* nits

* cpu compile tests pass

* cpu compile tests pass

* fix preamble for g++

* donation

* fix gpu buffer donation

* reuse prebuilt libraries

* faster contiguity conditoins

* fix test

* rid compiler warning

* fast erf

* Fix float16 for compile and add more types to cpu compile

* Remove a forgotten comment

* use cached libs

* nits

---------

Co-authored-by: Angelos Katharopoulos <a_katharopoulos@apple.com>

mlx/backend/common/compiled.h

@@ -0,0 +1,52 @@
+// Copyright © 2023-2024 Apple Inc.
+#pragma once
+
+#include <iomanip>
+#include <sstream>
+#include <unordered_set>
+
+#include "mlx/array.h"
+#include "mlx/primitives.h"
+
+namespace mlx::core {
+
+inline bool is_static_cast(const Primitive& p) {
+  return (
+      typeid(p) == typeid(Broadcast) || typeid(p) == typeid(Copy) ||
+      typeid(p) == typeid(StopGradient) || typeid(p) == typeid(AsType));
+}
+
+std::string build_lib_name(
+    const std::vector<array>& inputs,
+    const std::vector<array>& outputs,
+    const std::vector<array>& tape,
+    const std::unordered_set<uintptr_t>& constant_ids);
+
+std::string get_type_string(Dtype d);
+
+template <typename T>
+void print_float_constant(std::ostream& os, const array& x) {
+  auto old_precision = os.precision();
+  os << std::setprecision(std::numeric_limits<float>::digits10 + 1)
+     << x.item<T>() << std::setprecision(old_precision);
+}
+
+template <typename T>
+void print_int_constant(std::ostream& os, const array& x) {
+  os << x.item<T>();
+}
+
+template <typename T>
+void print_complex_constant(std::ostream& os, const array& x) {
+  auto old_precision = os.precision();
+  T constant = x.item<T>();
+
+  os << get_type_string(x.dtype()) << "("
+     << std::setprecision(std::numeric_limits<float>::digits10 + 1)
+     << constant.real() << ", " << constant.imag() << ")"
+     << std::setprecision(old_precision);
+}
+
+void print_constant(std::ostream& os, const array& x);
+
+} // namespace mlx::core