Re: Save the length of inserted breakpoints

[Eli Zaretskii <eliz at gnu dot org>]

> Date: Wed, 12 Apr 2006 14:47:17 -0400
> From: Daniel Jacobowitz <drow@false.org>
> Cc: gdb-patches@sourceware.org
> 
> > int target_insert_breakpoint(CORE_ADDR addr, gdb_byte *buf, int *size);
> > int target_remove_breakpoint(CORE_ADDR addr, gdb_byte *buf, int size);
> 
> And then if you come up with a reason, you're going to need to hand
> edit every one of these targets again.  It's not a bundle of fun.  Is
> that really necessary?
> 
> You need an address because the address at which the breakpoint is
> inserted may not match the requested address.  This happens in several
> different places in the breakpoint infrastructure (I believe I counted
> three disjoint hooks for it), but I am particularly looking at
> BREAKPOINT_FROM_PC, which takes the PC by reference.  In the ARM case,
> given 0x4001, it strips the low bit off and returns a two byte
> breakpoint.  If we don't allow the target to save the
> actually-inserted-at address, then it has to call BREAKPOINT_FROM_PC
> again.  It feels much more robust to me to save this address when we
> initially adjust it.  Here's where we inserted the breakpoint, so
> that's where we should remove it from.
> 
> I can think of plenty of other places where another constant might
> be useful.  You might want to record which hardware breakpoint
> registers were used, for instance, instead of digging around
> to figure out which ones to clear.  Adding a new member to
> "struct bp_target" for that would be easy.

FWIW, I agree with Daniel: it is better to pass a struct than its
individual members, especially if we expect different targets to use
different members of that struct.  In other words, passing a struct
eases future maintenance pains.