Re: 8-byte register values on a 32-bit machine

[Richard Earnshaw <rearnsha@arm.com>]

> On Sat, Mar 01, 2003 at 06:42:58PM -0500, Andrew Cagney wrote:
> > Mark,
> > 
> > Now that there is this loc_computed stuff, it is probably possible to 
> > modify stabs to, for the case in question, implement a loc_computed symbol.
> 
> Hmm, I'm not sure that's the right way to go.  DWARF-2 also will say
> that an eight byte value is in one register.  Why put the hacks in
> both readers?
> 
> By the way, assuming I can find the time (ugh) I'm not done with
> LOC_COMPUTED yet.  On my list so far:
>   - Location lists
>   - Turning locations into better defined objects
>   - Thus, allowing LOC_COMPUTED to return a non-computed "location"
>   - Allowing more complex locations, namely DW_OP_piece style.
>   - Eventually turning on more uses of DW_OP_piece in GCC.

The main reason gcc allocates objects to contiguous register ranges is 
because gdb can't handle anything else.  Fixing gdb to allow location 
lists would be a major step forward, since then gcc would be able to split 
double-register objects before register allocation and allocate each part 
individually.  That could be a major win on register starved machines.

R.