Re: [Qemu-devel] op-helper.c vs helper.c

[Alexander Graf]

On 19.09.2011, at 14:06, Xin Tong Utoronto wrote:

> There are 2 files on helpers in target-ppc and target-i386 ( op-helper.c  
> helper.c), what are their differences ?

General rule:

  op_helper.c: Code snippets called from TCG generated code. Implement more 
complex operations that gcc gets better than TCG.
  helper.c: Helper functions specific to the CPU, but called from multiple 
places around QEMU. For example the MMU code belongs here.

> also, what kind of functions are typically emulated using helpers ?

IIRC the rule of thumb is anything containing branches or bigger than 10(?) TCG 
ops should be in a helper. But it's up to the target developer really.


Alex