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}%")