chore: improve optimizer rules for comparison operators (#3412)

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)]),
@@ -253,3 +261,10 @@ def test_ir_optimizer(ir):
 def test_static_assertions(ir, assert_compile_failed):
     ir = IRnode.from_list(ir)
     assert_compile_failed(lambda: optimizer.optimize(ir), StaticAssertionException)
+
+
+def test_operator_set_values():
+    # some sanity checks
+    assert optimizer.COMPARISON_OPS == {"lt", "gt", "le", "ge", "slt", "sgt", "sle", "sge"}
+    assert optimizer.STRICT_COMPARISON_OPS == {"lt", "gt", "slt", "sgt"}
+    assert optimizer.UNSTRICT_COMPARISON_OPS == {"le", "ge", "sle", "sge"}

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):
@@ -256,11 +261,15 @@ def _conservative_eq(x, y):
         return finalize("seq", [args[0]])
 
     if binop in {"sub", "xor", "ne"} and _conservative_eq(args[0], args[1]):
-        # x - x == x ^ x == x != x == 0
+        # (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 == "eq" and _conservative_eq(args[0], args[1]):
-        # (x == x) == 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, [])
 
     # TODO associativity rules