remove early THREEFRY const folding [PR] (#16850)

it folds automatically once decomposed

test/backend/test_const_folding.py

@@ -2,6 +2,7 @@ import unittest, math
 from tinygrad import Tensor, Device, dtypes
 from tinygrad.dtype import DTYPES_DICT
 from tinygrad.uop.ops import Ops, UOp
+from tinygrad.codegen.decomp.op import threefry2x32
 import numpy as np
 from test.helpers import not_support_multi_device
 
@@ -167,7 +168,8 @@ class TestMultiConstFolding(unittest.TestCase):
 
 class TestThreefryConstFolding(unittest.TestCase):
   def test_threefry(self):
-    x = UOp.const(dtypes.uint64, 5).threefry(UOp.const(dtypes.uint64, 10))
+    # THREEFRY(const,const) folds to a const once decomposed
+    x = threefry2x32(UOp.const(dtypes.uint64, 5), UOp.const(dtypes.uint64, 10))
     self.assertIs(x.simplify().op, Ops.CONST)
 
 class TestTautologicalCompare(unittest.TestCase):

tinygrad/uop/symbolic.py

@@ -7,7 +7,6 @@ from tinygrad.helpers import partition, all_same, prod, flatten, get_single_elem
 from tinygrad.uop.divandmod import div_and_mod_symbolic
 
 # TODO: symbolic shouldn't be importing from codegen
-from tinygrad.codegen.decomp.op import threefry2x32
 from tinygrad.codegen.decomp.transcendental import xpow
 
 # ******** phase 1 of symbolic used to live in ops, it's the most generic folding rules ********
@@ -130,9 +129,8 @@ symbolic_simple = propagate_invalid + PatternMatcher([
    lambda x: x.const_like(False).cast(dtypes.bool.vec(x.dtype.count))), # x != x -> False (only ints)
   # ** constant folding **
   (UPat(GroupOp.Unary, src=(UPat((Ops.CONST, Ops.STACK)),), name="a"), fold_const_alu),
+  # NOTE: THREEFRY(const,const) folds via its decomposition
   (UPat(GroupOp.Binary-{Ops.THREEFRY}, src=(UPat((Ops.CONST, Ops.STACK)),)*2, name="a"), fold_const_alu),
-  (UPat(Ops.THREEFRY, src=(UPat.cvar("x"), UPat.cvar("key")), name="a"),
-   lambda a, x, key: a.const_like(threefry2x32(x, key).simplify().arg)),
   (UPat(GroupOp.Ternary, src=(UPat((Ops.CONST, Ops.STACK)),)*3, name="a"), fold_const_alu),
   # bool MUL is AND, ADD/MAX is OR. prevents other rules to rewrite bool ADD/MUL incorrectly
   (UPat.var('x', dtype=dtypes.bool) * UPat.var('y', dtype=dtypes.bool), lambda x,y: x&y),