disable fast_idiv on metal (#14137)

there's a metal compiler bug which was the root cause that keccak needs a contigous hack

test/external/fuzz_fast_idiv.py

@@ -1,6 +1,6 @@
 import random
 import z3
-from tinygrad import dtypes
+from tinygrad import dtypes, Device
 from tinygrad.uop.validate import uops_to_z3, z3_cdiv
 from tinygrad.uop.ops import UOp
 from tinygrad.uop.decompositions import fast_idiv
@@ -15,7 +15,7 @@ if __name__ == "__main__":
     u = UOp.variable('x', random.randint(dt.min, 0), random.randint(1, dt.max), dtype=dt)
     d = random.randint(1, max(1, u.arg[2]))
     if d in powers_of_two: continue
-    expr = fast_idiv(None, u, d)
+    expr = fast_idiv(Device.DEFAULT, u, d)
     if expr is None: continue
 
     solver = z3.Solver()

tinygrad/tensor.py

@@ -1881,7 +1881,6 @@ class Tensor(OpMixin):
         p = state.reshape(bs, 5, 5).transpose(2, 1)
         t1 = (p[:,:,0] ^ p[:,:,1] ^ p[:,:,2] ^ p[:,:,3] ^ p[:,:,4]).roll(-1, 1) # xor reduce
         state = state ^ (t1.roll(2, 1).bitwise_xor((t1 << 1) ^ (t1 >> 63)).unsqueeze(2).expand(bs, 5, 5).transpose(2, 1).flatten(1))
-        state = state.contiguous()  # required for correct indexing in π step # TODO: why is it needed?
         # ρ and π steps
         state = state[:, reorder_indexes]
         state = (state * rot_offsets_v0).bitwise_or(state // rot_offsets_v1).reshape(bs, 5, 5)

tinygrad/uop/decompositions.py

@@ -279,6 +279,8 @@ def magicgu(vmax:int, d:int) -> tuple[int,int]:
   assert False
 
 def fast_idiv(device: str, x: UOp, d: int, dont_cast=False) -> UOp|None:
+  # NOTE: disable for METAL due to compiler bug. keccak with -O0 works but not with optimization
+  if device.startswith("METAL"): return None
   # If d is a power of two this is not valid for signed ints!
   is_unsigned = x.vmin>=0 or x.dtype in dtypes.uints
   assert d>0, "Sign should have been taken out of divisor"