kernel cache (#2035)

* init compiled cache

* clang not compile to stdout

* use kwrags in compile

* remove some useless lines

* slimmer

* fix

* tabs

* retry

* remove decorator

* no race in hip

* smaller hip

* unused import

* unused pathlib

* path to str

* add test

* fix linter

* less lines?

* decorator is back

* update tests

* no hip version

* better comments

* a bit better test

* linter

* work wo decorator

* linter happy

* simpler return type

* more tests

* better comment

* readable

* readable

* readable

* compile returns bytes

* no ununsed imports

* readable

test/test_kernel_cache.py

@@ -0,0 +1,56 @@
+#!/usr/bin/env python
+import unittest
+import secrets
+import string
+import tempfile
+import pathlib
+from tinygrad.tensor import Tensor
+from tinygrad.ops import Device
+from tinygrad.helpers import cache_compiled
+import tinygrad.runtime.ops_clang
+
+def generate_random_string(length=16):
+  alphabet = string.ascii_letters + string.digits
+  return ''.join(secrets.choice(alphabet) for _ in range(length))
+
+class TestKernelCache(unittest.TestCase):
+  compile_call_count = 0
+
+  @cache_compiled
+  def __helper_test_compile(self, prg, output_file=pathlib.Path(tempfile.mktemp()), **kwargs):
+    self.compile_call_count += 1
+    return prg.encode()
+
+  def test_compile_cache(self):
+    prg1 = generate_random_string(64) + "a"
+    prg2 = generate_random_string(64) + "b"
+    cold_compile_res = self.__helper_test_compile(prg1)
+    warm_compile_res = self.__helper_test_compile(prg1)
+    assert cold_compile_res == warm_compile_res == prg1.encode()
+    assert self.compile_call_count == 1
+
+    prg2_res = self.__helper_test_compile(prg2)
+    assert prg2_res == prg2.encode()
+    assert self.compile_call_count == 2
+
+  def test_kernel_cache_in_action(self):
+    if Device.DEFAULT not in ["CLANG"]:
+      self.skipTest("No custom kernel cache is implemented")
+
+    a = Tensor.rand(4,4)
+    b = Tensor.rand(4,4)
+    x = a + b
+    x.realize()
+
+    orig_compile_func = tinygrad.runtime.ops_clang.ClangBuffer.runtime.compile
+    tinygrad.runtime.ops_clang.ClangBuffer.runtime.compile = None # making it not callable
+
+    a1 = Tensor.rand(4,4)
+    b1 = Tensor.rand(4,4)
+    x1 = a1 + b1
+    x1.realize() # Same kernel should be from cache.
+
+    tinygrad.runtime.ops_clang.ClangBuffer.runtime.compile = orig_compile_func
+
+if __name__ == "__main__":
+  unittest.main()