chore: add rules to optimizer for comparisons with self

after this commit, safe add between anything and 0 results in a no-op.

Author: charles-cooper

tests/compiler/ir/test_optimize_ir.py

@@ -57,6 +57,14 @@
     (["le", 0, "x"], [1]),
     (["le", 0, ["sload", 0]], None),  # no-op
     (["ge", "x", 0], [1]),
+    (["le", "x", "x"], [1]),
+    (["ge", "x", "x"], [1]),
+    (["sle", "x", "x"], [1]),
+    (["sge", "x", "x"], [1]),
+    (["lt", "x", "x"], [0]),
+    (["gt", "x", "x"], [0]),
+    (["slt", "x", "x"], [0]),
+    (["sgt", "x", "x"], [0]),
     # boundary conditions
     (["slt", "x", -(2**255)], [0]),
     (["sle", "x", -(2**255)], ["eq", "x", -(2**255)]),

vyper/ir/optimizer.py

@@ -78,6 +78,11 @@ def _deep_contains(node_or_list, node):
 
 COMMUTATIVE_OPS = {"add", "mul", "eq", "ne", "and", "or", "xor"}
 COMPARISON_OPS = {"gt", "sgt", "ge", "sge", "lt", "slt", "le", "sle"}
+STRICT_COMPARISON_OPS = {t for t in COMPARISON_OPS if t.endswith("t")}
+UNSTRICT_COMPARISON_OPS = {t for t in COMPARISON_OPS if t.endswith("e")}
+
+assert not (STRICT_COMPARISON_OPS & UNSTRICT_COMPARISON_OPS)
+assert STRICT_COMPARISON_OPS | UNSTRICT_COMPARISON_OPS == COMPARISON_OPS
 
 
 def _flip_comparison_op(opname):
@@ -255,11 +260,15 @@ def _conservative_eq(x, y):
         # x + 0 == x - 0 == x | 0 == x ^ 0 == x
         return finalize("seq", [args[0]])
 
-    if binop in {"sub", "xor", "ne", "lt", "gt"} and _conservative_eq(args[0], args[1]):
-        # (x - x) == (x ^ x) == (x != x) == (x < x) == (x > x) == 0
+    if binop in {"sub", "xor", "ne"} and _conservative_eq(args[0], args[1]):
+        # (x - x) == (x ^ x) == (x != x) == 0
+        return finalize(0, [])
+
+    if binop in STRICT_COMPARISON_OPS and _conservative_eq(args[0], args[1]):
+        # (x < x) == (x > x) == 0
         return finalize(0, [])
 
-    if binop in ("eq", "le", "ge") and _conservative_eq(args[0], args[1]):
+    if binop in {"eq"} | UNSTRICT_COMPARISON_OPS and _conservative_eq(args[0], args[1]):
         # (x == x) == (x >= x) == (x <= x) == 1
         return finalize(1, [])