Re: Switch ARM, SPARC and i386 to generic dummy frames (PC_IN_CALL_DUMMY)?

[Daniel Jacobowitz <drow at mvista dot com>]

On Sun, Apr 14, 2002 at 10:51:36AM -0400, Andrew Cagney wrote:
> Hello,
> 
> If I remember one of those unwritten ``grand plans'' correctly, the 
> intent is to have all targets switched to ``generic dummy frames''.  True?
> 
> Among other things, generic dummy frames do not save/restore registers 
> on the target stack (instead they are cached locally) and this should 
> improve the overall performance of an inferior function call.
> 
> Anyway, the thing that prompts this is PC_IN_CALL_DUMMY(PC, SP, FP). 
> There are several implementations.  Only two:
> 
> - generic: looks for the FP in the list of dummy frames
> - stack: looks for PC in [FP..SP)
> 
> require the SP/FP parameters.  I've a patch to fix the first one (search 
> for the PC).  If the ARM, SPARC and i386 can switch to generic dummy 
> frames then those parameters can be eliminated and all calls simplified.

Wait a second.  Switch to searching for the PC?  Does that work
reliably if the PC being searched for is in more than one dummy frame?
I guess it does for PC_IN_CALL_DUMMY (a predicate), but does anything
else use the search code?

-- 
Daniel Jacobowitz                           Carnegie Mellon University
MontaVista Software                         Debian GNU/Linux Developer