add canonicalization to View.create (#3280)

* Reapply "take merge views from corsix branch" (#3278)

This reverts commit d298916232.

* reintroduce merge views

* update second any

* isinstance -> not

* 25% less same but unequal

test/external/fuzz_shapetracker_math.py

@@ -31,6 +31,7 @@ if __name__ == "__main__":
   # random.seed(42)
   total = getenv("CNT", 1000)
   for fuzz in [globals()[f'fuzz_{x}'] for x in getenv("FUZZ", "invert,plus").split(",")]:
+    same_but_neq = 0
     for _ in trange(total, desc=f"{fuzz}"):
       st1, st2 = fuzz()
       eq = st_equal(st1, st2)
@@ -38,8 +39,10 @@ if __name__ == "__main__":
         print(colored("same but unequal", "yellow"))
         print(st1.simplify())
         print(st2.simplify())
+        same_but_neq += 1
       if DEBUG >= 1:
         print(f"EXP: {st1}")
         print(f"GOT: {st2}")
         print(colored("****", "green" if eq else "red"))
       if not eq: exit(0)
+    if getenv("CHECK_NEQ"): print(f"same but unequal {(same_but_neq/total)*100:.2f}%")

tinygrad/shape/view.py

@@ -85,10 +85,11 @@ class View:
     contiguous = offset == 0 and mask is None and strides == strides_for_shape(shape)
     # if any dimension has size >1, but is masked such that only one index in the dimension is unmasked
     # then its stride can also be set to 0, albeit with a corresponding adjustment required to the offset
-    #if mask and any(elim := [isinstance(b, int) and isinstance(e, int) and b+1 >= e for b,e in mask]):
-    #  if any(b >= e for b,e in mask): strides, offset, mask = (0,) * len(shape), 0, ((0,0),) * len(shape)
-    #  offset += sum((strides[i] * mask[i][0]) if e else 0 for i, e in enumerate(elim))
-    #  strides = tuple(0 if e else st for st,e in zip(strides, elim))
+    if mask and any(elim := [not (b+1 < e) for b,e in mask]):
+      if any(not (b < e) for b,e in mask):
+        strides, offset, mask = (0,) * len(shape), 0, ((0,0),) * len(shape)
+      offset += sum((strides[i] * mask[i][0]) if e else 0 for i, e in enumerate(elim))
+      strides = tuple(0 if e else st for st,e in zip(strides, elim))
     return View(shape, strides, offset, mask, contiguous)
 
   @functools.lru_cache(None)  # pylint: disable=method-cache-max-size-none