fix[codegen]: fix false positive in risky call detection

tests/functional/codegen/types/test_dynamic_array.py

@@ -1903,3 +1903,55 @@ def foo():
     c = get_contract(code)
     with tx_failed():
         c.foo()
+
+
+# should not trip risky overlap detector
+def test_risky_call_precompile():
+    code = """
+x: DynArray[uint256, 32]
+
+@deploy
+def __init__():
+    self.x = [1, 1, 1]
+
+@internal
+def bar() -> uint256:
+    self.x[0] = 1
+    return 0
+
+@external
+def foo() -> uint256:
+    self.x[
+        abi_decode(
+            slice(
+                concat(
+                    abi_encode(
+                        empty(uint256),
+                        method_id=method_id("foo()")),
+                    empty(bytes32)
+                ), 0, 32),
+            (uint256)
+        )] = self.bar()
+    return 0
+    """
+    assert compile_code(code) is not None
+
+
+# should not trip risky overlap detector
+def test_risky_call_precompile2():
+    code = """
+x: DynArray[uint256, 32]
+
+@internal
+def bar() -> uint256:
+    a: DynArray[uint256, 100] = []
+    b: DynArray[uint256, 100] = []
+    a = b
+    return 0
+
+@external
+def foo() -> uint256:
+    c: uint256 = self.x[self.bar()]
+    return 0
+    """
+    assert compile_code(code) is not None

vyper/codegen/ir_node.py

@@ -479,9 +479,29 @@
 
         return ret
 
+    @property
+    def is_call_opcode(self):
+        return self.value in ("call", "staticcall", "delegatecall")
+
+    @property
+    def is_precompile_call(self):
+        # whitelist for "safe" calls
+        assert self.is_call_opcode
+        target = self.args[1].value
+        PRECOMPILES = (
+            0x01,  # builtin ecrecover
+            0x02,  # builtin sha256
+            0x04,  # identify precompile
+            0x06,  # builtin ecadd
+            0x07,  # builtin ecmul
+            0x000000000000000000636F6E736F6C652E6C6F67,  # builtin print
+        )
+        return isinstance(target, int) and target in PRECOMPILES
+
     @cached_property
     def contains_risky_call(self):
-        ret = self.value in ("call", "delegatecall", "staticcall", "create", "create2")
+        ret = self.value in ("create", "create2")
+        ret |= self.is_call_opcode and not self.is_precompile_call
 
         for arg in self.args:
             ret |= arg.contains_risky_call