Emulating mixed-code programs using a virtual machine instance

In a computing environment, a method performed at least in part on at least one processor, comprising:

• receiving a program, including program code that comprises native code and custom code;
• processing, by a custom emulation component, at least one custom instruction block of the custom code into an intermediate language;
• processing, by a native code emulator component, at least one native instruction block of the native code into the intermediate language;
• dynamically switching between processing by the custom emulation component and the native component responsive to detection of at least one jump instruction in the program code;
• and
• outputting the custom instruction block in the intermediate language and the native instruction block in the intermediate language to an emulator component for emulation of the program.

One or more hardware computer-readable storage devices having computer-executable instructions, which when executed by a computer processor perform operations of a process, comprising:

• processing program code containing native code and custom code;
• translating, by a custom emulator component, at least one custom instruction block of the custom code into an intermediate language;
• translating, by a native component, at least one native instruction block of the native code into the intermediate language;
• dynamically switching between processing by the custom emulation component and the native component responsive to detection of at least one jump instruction in the program code;
• and
• emulating the program code using the translated at least one custom instruction block and the translated at least one native instruction block.