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Re: Switch ARM, SPARC and i386 to generic dummy frames (PC_IN_CALL_DUMMY)?
- From: Daniel Jacobowitz <drow at mvista dot com>
- To: gdb at sources dot redhat dot com
- Date: Sun, 14 Apr 2002 11:18:54 -0400
- Subject: Re: Switch ARM, SPARC and i386 to generic dummy frames (PC_IN_CALL_DUMMY)?
- References: <3CB99778.email@example.com>
On Sun, Apr 14, 2002 at 10:51:36AM -0400, Andrew Cagney wrote:
> 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