fix(fw): bytecode stack calculation

src/ethereum_test_tools/tests/test_vm.py

@@ -382,6 +382,23 @@ def test_macros():
         pytest.param(
             Op.POP(Op.CALL(1, 2, 3, 4, 5, 6, 7)), 0, 0, 7, 0, id="POP(CALL(1, 2, 3, 4, 5, 6, 7))"
         ),
+        pytest.param(Op.ADD + Op.RETF, 2, 1, 2, 2, id="Op.ADD + Op.RETF"),
+        pytest.param(
+            (Op.ADD + Op.RETF).with_min_stack_height(2),
+            2,
+            1,
+            2,
+            2,
+            id="(Op.ADD + Op.RETF).with_min_stack_height(2)",
+        ),
+        pytest.param(
+            (Op.ADD + Op.RETF).with_min_stack_height(3),
+            2,
+            1,
+            3,
+            3,
+            id="(Op.ADD + Op.RETF).with_min_stack_height(3)",
+        ),
     ],
 )
 def test_bytecode_properties(

src/ethereum_test_tools/vm/bytecode.py

@@ -137,15 +137,15 @@ def __add__(self, other: "Bytecode | int | None") -> "Bytecode":
             # Edge case for sum() function
             return self
         assert isinstance(other, Bytecode), "Can only concatenate Bytecode instances"
-        # Figure out the stack height after executing the two opcodes.
+        # Figure out the stack height after executing the two codes.
         a_pop, a_push = self.popped_stack_items, self.pushed_stack_items
         a_min, a_max = self.min_stack_height, self.max_stack_height
         b_pop, b_push = other.popped_stack_items, other.pushed_stack_items
         b_min, b_max = other.min_stack_height, other.max_stack_height
         a_out = a_min - a_pop + a_push
 
-        c_pop = max(0, a_pop + (b_pop - a_push))
-        c_push = max(0, a_push + b_push - b_pop)
+        c_pop = a_pop + (b_pop - a_push) if b_pop > a_push else a_pop
+        c_push = a_push + b_push - b_pop if a_push + b_push > b_pop else b_push
         c_min = a_min if a_out >= b_min else (b_min - a_out) + a_min
         c_max = max(a_max + max(0, b_min - a_out), b_max + max(0, a_out - b_min))
 
@@ -180,6 +180,22 @@ def __mul__(self, other: int) -> "Bytecode":
             output += self
         return output
 
+    def with_min_stack_height(self, min_stack_height: int) -> "Bytecode":
+        """
+        Set the minimum stack height required by the opcode.
+        """
+        assert min_stack_height >= 0
+        return (
+            Bytecode(
+                b"",
+                popped_stack_items=0,
+                pushed_stack_items=0,
+                min_stack_height=min_stack_height,
+                max_stack_height=min_stack_height,
+            )
+            + self
+        )
+
     def hex(self) -> str:
         """
         Return the hexadecimal representation of the opcode byte representation.