Re: CALL_USED_REGISTERS & local_alloc

[Alessandro Lonardo <alessandro dot lonardo at roma1 dot infn dot it>]

James E Wilson wrote:

> Alessandro Lonardo wrote:
>
> > I defined CALL_USED_REGISTERS = FIXED_REGISTERS including all the 
> > stack related regs
> > along with some regs reserved for relevant constants.
>
>
> So you are saying that only the fixed registers are call-used?  That 
> means all other registers are call-saved, i.e. if a function uses 
> them, then it must save the old value on the stack in the function 
> prologue, and restore this value from the stack in the function epilogue.

Yes, that is the behaviour I was expecting.

> > It happens that one of the two reloads in v_inc get assigned the same 
> > (26) registers of i_0 which is therefore clobbered by function call.
>
>
> But r26 is call-saved, so it is ok to use it across a function call. 
> The problem here is that the function v_inc did not save/restore it in 
> the prologue/epilogue. 

I do agree.
I understand that the function_prologue/epilogue port does not have to 
contain explicit code to perform these operations, or do they have to 
contain it?

Thanks,

Alessandro