A method and system for code generation and inlining. The method includes: scanning a code, where the code includes a method; determining whether the method includes a branch if the method is too large in size to be inlined, where the branch is based on runtime types of argument; profiling runtime types of actual arguments at a call site in the method if the method includes the branch; generating a polymorphic inline cache (PIC) code from a plurality of arguments, where the plurality of arguments are based on a result of the profiling step; generating a specialized method for a frequently appearing combination of the runtime types of argument and arguments that can be invoked from the PIC code; and inlining body of the specialized method into the call site if the specialized method has a body size within a permissible range.