CFG: separate return statement with/without return value

Author: sipma

chb/app/CHVersion.py

@@ -1 +1 @@
-chbversion: str = "0.3.0-20250723"
+chbversion: str = "0.3.0-20250729"

chb/app/Cfg.py

@@ -724,8 +724,14 @@ def ast(self,
                         cstr = rv.constant.string_reference()
                         straddr = hex(rv.constant.value)
                         astexpr = astree.mk_string_constant(astexpr, cstr, straddr)
-                rtnstmt = astree.mk_return_stmt(astexpr, instr.iaddr, instr.bytestring)
-                blockstmts[n] = [blocknode, rtnstmt]
+                    rtnstmt = astree.mk_return_stmt(
+                        astexpr, instr.iaddr, instr.bytestring)
+                    astree.add_expr_reachingdefs(astexpr, instr.xdata.reachingdefs)
+                    blockstmts[n] = [blocknode, rtnstmt]
+                else:
+                    rtnstmt = astree.mk_return_stmt(
+                        None, instr.iaddr, instr.bytestring)
+                    blockstmts[n] = [blocknode, rtnstmt]
             else:
                 blockstmts[n] = [blocknode]