On Sat, Dec 22, 2012 at 02:26:50PM +0200, Avi Kivity wrote: > The current arithmetic instruction emulation is fairly clumsy: after > decode, each instruction gets a switch (size), and for every size > we fetch the operands, prepare flags, emulate the instruction, then store > back the flags and operands. > > This patchset simplifies things by moving everything into common code > except the instruction itself. All the pre- and post- processing is > coded just once. The per-instrution code looks like: > > add %bl, %al > ret > > add %bx, %ax > ret > > add %ebx, %eax > ret > > add %rbx, %rax > ret > > The savings in size, for the ten instructions converted in this patchset, > are fairly large: > > text data bss dec hex filename > 63724 0 0 63724 f8ec arch/x86/kvm/emulate.o.before > 61268 0 0 61268 ef54 arch/x86/kvm/emulate.o.after > > - around 2500 bytes. > > Avi Kivity (7): > KVM: x86 emulator: framework for streamlining arithmetic opcodes > KVM: x86 emulator: Support for declaring single operand fastops > KVM: x86 emulator: introduce NoWrite flag > KVM: x86 emulator: mark CMP, CMPS, SCAS, TEST as NoWrite > KVM: x86 emulator: convert NOT, NEG to fastop > KVM: x86 emulator: add macros for defining 2-operand fastop emulation > KVM: x86 emulator: convert basic ALU ops to fastop > > arch/x86/kvm/emulate.c | 215 +++++++++++++++++++++++++++---------------------- > 1 file changed, 120 insertions(+), 95 deletions(-) > Looks good to me. -- Gleb. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
