Re: [4/7] v7: Update DWARF2

[Jason Merrill <jason at redhat dot com>]

H.J. Lu wrote:
> Joey, Xuepeng, please correct me if I am wrong. In case of DRAP,
> FP has aligned SP and CFA is defined with an expression.
>
>    0:	8d 4c 24 04          	lea    0x4(%esp),%ecx
>    4:	83 e4 f0             	and    $0xfffffff0,%esp
>    7:	ff 71 fc             	pushl  -0x4(%ecx)
>    a:	55                   	push   %ebp
>    b:	89 e5                	mov    %esp,%ebp
>    d:	83 ec 28             	sub    $0x28,%esp
>   10:	89 4c 24 1c          	mov    %ecx,0x1c(%esp)
>
> we still need to restore SP. Otherwise exceptions won't work.

The CFA value is the old SP, so we can (and typically do) use that to 
find it.

Jason