script to benchmark beam v hcopt (#3737)

the goal is that big enough beam should be faster than hcopt/tc

also this failed on tc opt
NUM=2 FILTER_REDUCE=1 TEST_N=20 BEAM=4 DEBUG=2 python test/external/speed_beam_v_hcopt.py

test/external/speed_beam_v_hcopt.py

@@ -0,0 +1,42 @@
+from tinygrad import Device
+from tinygrad.helpers import getenv, DEBUG, BEAM
+from tinygrad.features.search import beam_search, time_linearizer, bufs_from_lin
+from extra.optimization.helpers import load_worlds, ast_str_to_lin
+
+if __name__ == "__main__":
+  filter_reduce = bool(getenv("FILTER_REDUCE"))
+  ast_strs = load_worlds(filter_reduce=filter_reduce, filter_novariable=True)
+  dev = Device[Device.DEFAULT]
+
+  test_n = getenv("TEST_N", 10)
+  single = getenv("NUM", -1)
+  if single != -1: ast_strs = ast_strs[single:single+1]
+
+  beam_won, tested = 0, 0
+
+  for num, ast in enumerate(ast_strs[:test_n]):
+    def new_lin(): return ast_str_to_lin(ast, opts=dev.compiler.linearizer_opts)
+
+    k = new_lin()
+    # k.required_optimizations()
+
+    if not (used_tensor_cores:=k.apply_tensor_cores(getenv("TC", 1))): k.hand_coded_optimizations()
+
+    assert BEAM > 0
+
+    lins = [(("tc" if used_tensor_cores else "hc"), k)]
+    if used_tensor_cores:
+      lins.append(("hc", new_lin()))
+      lins[-1][1].hand_coded_optimizations()
+    kb = new_lin()
+    # kb.required_optimizations()
+    test_rawbuffers = bufs_from_lin(kb)    # allocate scratch buffers for optimization
+    lins.append((f"beam{BEAM.value}", beam_search(kb, test_rawbuffers, BEAM.value, bool(getenv("BEAM_ESTIMATE", 1)))))
+    timed = sorted([(nm, tk, time_linearizer(tk, test_rawbuffers, allow_test_size=False, clear_l2=True)) for nm, tk in lins], key=lambda x: x[2])
+    if DEBUG >= 1: print("  <  ".join(f"{nm:6s} : {lin.colored_shape(30, dense=True)} : {tm*1e6:8.2f} us" for nm, lin, tm in timed))
+
+    tested += 1
+    if timed[0][0].startswith("beam"):
+      beam_won += 1
+
+  print(f"{beam_won=} / {tested=} = {beam_won/tested:.3f}")