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Re: RFA/ARM: Switch mode when setting PC

On Fri, Jan 16, 2004 at 09:10:40AM -0500, Daniel Jacobowitz wrote:

> The ari contains this yellow card:
> > write pc
> Replace write_pc() with get_frame_base_address or get_frame_id; at > present the inferior function call code still uses this when doing a > DECR_PC_AFTER_BREAK
> > the concern is with the way write_pc is being called to perform two > different operations:
> > - decrement the pc just after the target stops
> Arrrg!
> - jump to a specific address
> As with an inferior function call or jump.
> > I think it would be better to have two methods so that it's clear that > this case only applies when doing a jump.

Well, it'd be better to rip out the current DECR_PC_AFTER_BREAK and handle it completely within the four (roughly) affected targets, thereby removing the overloading of write_pc. IMVHO.

It's been on everyones wish list for too long. Last time I tried I got bogged down due to a lack of ia32 doco - that's now been fixed though.

Hi Andrew,

Is this patch OK (write_pc isn't deprecated yet!)?  Cleaning up the
existing DECR_PC_AFTER_BREAK handling is going to be a touchy job, and
I don't really want to try it today :)  I'll try to look into it later,

I was suggesting "two methods so that it's clear that this case only applies when doing a jump". This won't involve anything like deprecating /removing decr_pc_after_break _+ write_pc but will involve the addition of a new method like:
set_resume_address (arch, targ or tpid or regs)
that could somehow default to a legacy call to write_pc. Significantly, this will avoid making the changes conditional on the elimination of decr-pc (your concern).

Why is this better? It clearly separates the [apparently] legetimate resume case from the decr-pc case. This in turn opens the way for the deprecate / delete decr-pc "write_pc" code while at the same time ensuring that the work can't break the arm.


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