Re: Unable to step over (n and ni) on mipsel-linux...

[Daniel Jacobowitz <drow@false.org>]

On Mon, Aug 23, 2004 at 11:38:39AM -0700, David Daney wrote:
> Andrew Cagney wrote:
> >>
> >>Currently GDB examines the next instruction to see if it is a branch (or
> >>  jal or jalr..) to see where to place a temporary breakpoint for single
> >>stepping.
> > 
> > 
> >>Instead of stepping into a function and checking to see if we are in a
> >>different frame (settting a breakpoint at the return address location),
> >>why not set the breakpoint at the return location before making the
> >>function call?
> > 
> > 
> > That would mean examining every instruction to determine if it is a call 
> > - effectively s/w single step.  GDB tries to do avoid doing that so that 
> > single-step is faster.
> > 
> 
> For my configuration, for some reason it is already doing this.  Thus my
> comment.  If we are doing s/w single step, we would not have to examine
> the stack frames.
> 
> Could there are some configuration problems?

GDB already does this on all MIPS targets.

> This implies that if I write assembly language I cannot expect GDB's ni
> instruction to work.

It should work OK.  You have to have some stack frame anyway, and GDB
has a prologue analyzer.

> I am doing testing with at least three different compiler versions.  GDB
> 5.3 seems to work well except for crashing when I don't use
> -fno-var-tracking.
> 
> GDB 6.x seems to be a bit of a down-grade.

GDB 6.2 and MIPS do not get along very well.  I ran out of time to work
on the MIPS unwinder, but Joel and others have done some work, and I
hope to get back to testing it sometime.

-- 
Daniel Jacobowitz