On Wed, Jun 04, 2003 at 04:16:48PM +0200, Maciej W. Rozycki wrote:

On Wed, 4 Jun 2003, Ralf Baechle wrote:

quoted

quoted

But the need is to raise an exception after instr1 (at addr1) is executed.
One solution is using a break at instr2 (at addr2).
But suppose instr1 is a jmp then there is no point
in keeping a break at addr2.
(inorder to raise an exception after instr1 is executed).

You understood correctly.  Now jumps and even more so the conditional
branches are sort of the ugly part of the whole thing.  The easiest
method is probably inserting a branch at the jump's destination address
or in case of a branch at the branch target and the instruction following
it's delay slot.  So that's a lot of inserting and removing of
breakpoints ...

 In a more finegrained but also more complicated example, you probably
want to insert a breakpoint in the delay slot first and at the second step
evaluate the branch's condition and put a breakpoint at the next
instruction to be executed.  I'm not sure if the current version of gdb
does the first step, but it inserts a single breakpoint in the second one
only.  For branch likely instructions adjust the two steps as necessary. 

Does that actually work reliably across MIPS processors?  I don't
believe that it will.  I suppose you could re-execute the branch to get
the delay slot executed...

GDB simply executes the branch and its delay slot as a unit.

-- 
Daniel Jacobowitz
MontaVista Software                         Debian GNU/Linux Developer