fix[codegen]: range bound check for signed integers (#3814)

tests/functional/codegen/features/iteration/test_for_range.py

@@ -414,3 +414,19 @@ def foo(a: {typ}) -> {typ}:
     assert c.foo(100) == 6
     assert c.foo(1) == 666
     assert c.foo(0) == 31337
+
+
+def test_for_range_signed_int_overflow(get_contract, tx_failed):
+    code = """
+@external
+def foo() -> DynArray[int256, 10]:
+    res: DynArray[int256, 10] = empty(DynArray[int256, 10])
+    x:int256 = max_value(int256)
+    y:int256 = min_value(int256)+2
+    for i:int256 in range(x,y , bound=10):
+        res.append(i)
+    return res
+    """
+    c = get_contract(code)
+    with tx_failed():
+        c.foo()

vyper/builtins/_convert.py

@@ -10,6 +10,7 @@
     bytes_data_ptr,
     clamp,
     clamp_basetype,
+    clamp_le,
     get_bytearray_length,
     int_clamp,
     is_bytes_m_type,
@@ -110,8 +111,7 @@ def _clamp_numeric_convert(arg, arg_bounds, out_bounds, arg_is_signed):
         # out_hi must be smaller than MAX_UINT256, so clample makes sense.
         # add an assertion, just in case this assumption ever changes.
         assert out_hi < 2**256 - 1, "bad assumption in numeric convert"
-        CLAMP_OP = "sle" if arg_is_signed else "le"
-        arg = clamp(CLAMP_OP, arg, out_hi)
+        arg = clamp_le(arg, out_hi, arg_is_signed)
 
     return arg
 

vyper/codegen/core.py

@@ -1226,6 +1226,11 @@ def clamp_nonzero(arg):
         return IRnode.from_list(b1.resolve(ret), typ=arg.typ)
 
 
+def clamp_le(arg, hi, signed):
+    LE = "sle" if signed else "le"
+    return clamp(LE, arg, hi)
+
+
 def clamp2(lo, arg, hi, signed):
     with IRnode.from_list(arg).cache_when_complex("clamp2_arg") as (b1, arg):
         GE = "sge" if signed else "ge"

vyper/codegen/stmt.py

@@ -10,7 +10,7 @@
     IRnode,
     append_dyn_array,
     check_assign,
-    clamp,
+    clamp_le,
     dummy_node_for_type,
     get_dyn_array_count,
     get_element_ptr,
@@ -255,7 +255,7 @@ def _parse_For_range(self):
             with end.cache_when_complex("end") as (b1, end):
                 # note: the check for rounds<=rounds_bound happens in asm
                 # generation for `repeat`.
-                clamped_start = clamp("le", start, end)
+                clamped_start = clamp_le(start, end, target_type.is_signed)
                 rounds = b1.resolve(IRnode.from_list(["sub", end, clamped_start]))
             rounds_bound = kwargs.pop("bound").int_value()
         else: