Re: [Qemu-devel] branches are expensive

[Avi Kivity]

Steffen Liebergeld wrote:
> Hi,
>
> while measuring the execution of an ARM guest, I encountered that branches are
> extremely expensive in terms of executed host instructions. A single ARM
> branch takes 148 to 152 host instructions. In my setup host and guest use the
> ARM instruction set architecture.
>
> My question is what makes branches so expensive? What code is run when
> executing a branch? Other instructions are translated to 14 to 40
> instructions.
>   

I'm no tcg guru, but if branches are not chained, you'd need an 
expensive lookup to find the next translation block.  If branches are 
chained they'll probably be much faster.

--
error compiling committee.c: too many arguments to function