EAX EMULATION CODE

The guest registers are defined as values that live in the CPU state structure in the host memory, but TCG is smart enough not to write them back to memory until they actually need to be, so often the 'live' copy of a guest register will be in a host register. In the IR guest registers are represented with 'TCG values', which are sort of like variables in a higher level language.

EAX EMULATION CODE

Finally we do register allocation and generate native host code from the IR. Then a simple optimisation pass runs (this is where we figure out that 'load 2 add 3' simplifies to 'load 5'). All guest code is first translated into an intermediate representation. x86-to-x86 is not a special case and is handled like any other guest/host combination in the emulation. Please note that I'm referring to pure emulation in this case (Bochs or non-KVM QEMU) and not hardware virtualization. Would it just combine the two into a single mov eax, 5 instruction if it could determine that doing so would not alter the program's execution, since it executes programs by executing blocks of instructions instead of each instruction individually? I'd assume that there would be no reason not to, since the QEMU process is its own separate process (so it doesn't have to share general purpose registers with any other process) and since both the host and the guest architectures are the same and therefore have the same general purpose registers.ДЄlso, if I was to execute a program in QEMU that has two instructions: mov eax 3 I'm studying how emulators like Bochs and QEMU work and had a question - if I emulate an x86 guest operating system on an x86 host and the guest executes some instruction that assigns a register (for example, mov eax 3), is it guaranteed or even likely that the value will actually be assigned to the eax register on the actual hardware in code run by the emulator?

Eax emulation