Re: [Qemu-devel] [PATCH 05/14] i386: move eflags computation closer to gen_op_set_cc_op

[Richard Henderson <rth@twiddle.net>]

On 10/06/2012 05:30 AM, Paolo Bonzini wrote:
> In some cases this is just simple code movement, ensuring the invariant
> that cpu_cc_op matches s->cc_op when calling the helpers.  The next patches
> need this because gen_compute_eflags and gen_compute_eflags_c will take
> care of setting cpu_cc_op.
> 
> Also, for shifts, always compute EFLAGS first since it is needed whenever
> the shift is non-zero, i.e. most of the time.  This makes it possible
> to remove some writes of CC_OP_EFLAGS to cpu_cc_op and more importantly
> removes cases where s->cc_op becomes CC_OP_DYNAMIC.  These are slow and
> we want to avoid them: CC_OP_EFLAGS is quite efficient once we paid the
> initial cost of computing the flags.
> 
> Finally, always follow gen_compute_eflags(cpu_cc_src) by setting s->cc_op
> and discarding cpu_cc_dst.
> 
> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>

I was about to quibble with some of this, but I see you've
cleaned up all my quibbles with subsequent patches.

Reviewed-by: Richard Henderson <rth@twiddle.net>


r~