Fast emulation of virtually addressed control flow

Two or more processes for executing a source application are emulated using: a virtual trampoline memory in which each emulated process has a respective private trampoline memory; and a shared code heap memory. Each emulated process only sees the shared code heap and its respective private trampoline memory. A respective equivalent target instruction fragment for writing to the code heap is generated for each of multiple source instruction fragments from the application, each target instruction fragment being indexed by its physical address in the code heap. Each of at least one jump instruction in the fragment is replaced with a jump to a corresponding slot in the virtual trampoline memory. A trap is written to each corresponding private trampoline slot, each trap adapted to be replaced by a jump to an address in the code heap corresponding to the jump destination.