improve threefry codegen [pr] (#17379)

decomp uint64 can handle part of it

tinygrad/codegen/decomp/op.py

@@ -47,17 +47,17 @@ def fast_idiv(ren: Renderer, x: UOp, d: int, dont_cast=False) -> UOp|None:
 
 def threefry2x32(x: UOp, key: UOp):
   # split x and key from uint64 to two uint32
-  x0, x1 = (x & 0xffffffff).cast(dtypes.uint32), ((x // 2**32) & 0xffffffff).cast(dtypes.uint32)
-  key0, key1 = (key & 0xffffffff).cast(dtypes.uint32), ((key // 2**32) & 0xffffffff).cast(dtypes.uint32)
+  x0, x1 = x.cast(dtypes.uint32), (x >> 32).cast(dtypes.uint32)
+  key0, key1 = key.cast(dtypes.uint32), (key >> 32).cast(dtypes.uint32)
 
   rotations = [[13, 15, 26, 6], [17, 29, 16, 24]]
   ks = [key1, key0 ^ key1 ^ 0x1BD11BDA, key0]
   xr:list[UOp] = [x0 + ks[-1], x1 + ks[0]]
   for i in range(5):
-    for r in rotations[i % 2]: xr[0], xr[1] = (x0 := xr[0] + xr[1]), x0 ^ ((xr[1] * 2**r) + (xr[1] // 2**(32 - r)))
+    for r in rotations[i % 2]: xr[0], xr[1] = (x0 := xr[0] + xr[1]), x0 ^ ((xr[1] << r) + (xr[1] >> (32 - r)))
     xr = [(xr[0] + ks[i % 3]), (xr[1] + ks[(i + 1) % 3] + i + 1)]
 
-  return xr[1].cast(dtypes.uint64) * 2**32 | xr[0].cast(dtypes.uint64)
+  return (xr[1].cast(dtypes.uint64) << 32) | xr[0].cast(dtypes.uint64)
 
 # ***** decomposition patterns *****
 

tinygrad/mixin/rand.py

@@ -12,7 +12,7 @@ class RandMixin(OpMixin):
   def _threefry_random_bits(key, counts0, counts1):
     x = (counts1.cast(dtypes.uint64) << 32) | counts0.cast(dtypes.uint64)
     x = x.threefry((key[1].cast(dtypes.uint64) << 32) | key[0].cast(dtypes.uint64))
-    return (x & 0xffffffff).cast(dtypes.uint32).cat(((x >> 32) & 0xffffffff).cast(dtypes.uint32))
+    return x.cast(dtypes.uint32).cat((x >> 32).cast(dtypes.uint32))
 
   @classmethod
   def random_bits(cls, key:Self, counter:Self, num:int) -> Self:

tinygrad/uop/symbolic.py

@@ -127,7 +127,6 @@ symbolic_simple = pm_data_invalid + PatternMatcher([
   (UPat.var("x") ^ UPat.var("x"), lambda x: x.const_like(0)), # x^x -> 0
   (UPat.var("x") & 0, lambda x: x.const_like(0)), # x&0 -> 0
   # (x&mask)>>k -> x>>k when mask only clears bits below k
-  # TODO: combine this with "# rules for threefry" below
   ((UPat.var("x") & UPat.cvar("mask")) >> UPat.cvar("k"),
    lambda x,mask,k: x >> k.val if mask.val | ((1 << k.val) - 1) == -1 else None),
   ((UPat.var("x") & UPat.cvar("mask")) // UPat.cvar("c"),
@@ -168,13 +167,10 @@ symbolic_simple = pm_data_invalid + PatternMatcher([
   (UPat.var("x").alu(Ops.POW, UPat.cvar("c")), simplify_pow),
   # positive const ** x
   (UPat.cvar("c").alu(Ops.POW, UPat.var("x")), lambda c,x: c if c.val == 1 else (x*math.log2(c.val)).exp2() if c.val > 0 else None),
-  # rules for threefry
-  ((UPat.var('x', dtypes.uint64)&0xFFFFFFFF).cast(dtypes.uint32), lambda x: x.cast(dtypes.uint32)),
-  (((UPat.var(None, dtypes.uint64)*(1<<32)) | UPat.var('y',  dtypes.uint32).cast(dtypes.uint64)).cast(dtypes.uint32), lambda y: y),
-  (((UPat.var('x',  dtypes.uint64)*(1<<32)) | UPat.var(None, dtypes.uint32).cast(dtypes.uint64))//(1<<32), lambda x: x),
-  (((UPat.var(None, dtypes.uint64)<<32) | UPat.var('y',  dtypes.uint32).cast(dtypes.uint64)).cast(dtypes.uint32), lambda y: y),
-  (((UPat.var('x',  dtypes.uint64)<<32) | UPat.var(None, dtypes.uint32).cast(dtypes.uint64))//(1<<32), lambda x: x),
-  (((UPat.var('x',  dtypes.uint64)<<32) | UPat.var(None, dtypes.uint32).cast(dtypes.uint64))>>32, lambda x: x),
+  # unpack a uint64 packed from two uint32 (threefry)
+  (((UPat.var(None, dtypes.uint64)<<32) | UPat.var('y', dtypes.uint32).cast(dtypes.uint64)).cast(dtypes.uint32), lambda y: y),
+  (((UPat.var('x', dtypes.uint32).cast(dtypes.uint64)<<32) | UPat.var(None, dtypes.uint32).cast(dtypes.uint64))>>32,
+   lambda x: x.cast(dtypes.uint64)),
   # ** simple where folding **
   # a conditional with the same results either way is a noop, also fold const conditionals
   (UPat.var().where(UPat.var("val"), UPat.var("val")), lambda val: val),