Hi,

The attached patch teaches GDB which registers are invalid in previous 
frames when the CFI does not say otherwise.

It does this using the SH4 ABI. This is backwards compatible with the 
sh1-sh3 and variants. I have not attempted to deal with the DSP 
registers as I don't know the ABI. They will be treated as ever.

The only thing this patch actually does is allow the 'info registers' 
command (and friends) to show '*invalid register*' when there is no way 
to know the true value.

Andrew Stubbs