Re: [PATCH 3/3] [AArch64] Remove tag from address for watchpoint

[Yao Qi <qiyaoltc at gmail dot com>]

On 17-11-09 20:30:42, Pedro Alves wrote:
> And then at places where we need to save or compare memory addresses,
> like in the watchpoint location addresses case we strip out / ignore
> non-significant bits.
> 
> And the next question is: if you're adding a gdbarch hook such as
> this one (either significant_addr_bit or addr_tag_remove)
> why not use it for all the cases handled by the different patches in
> this series, instead of using different solutions for each case?
> I.e., for memory access, saving breakpoint and watchpoint
> location addresses, the dcache, and any other future case we run
> into, like e.g., maybe agent expressions.

I thought about this, using this new added gdbarch method everywhere.
The reason I didn't do that is due to breakpoint location address
comparison (I think I can use the new gdbarch method for the rest,
watchpoint location and dcache).

As I wrote in patch #2,

> When program hits a breakpoint, the stopped pc reported by Linux kernle is
> the address *without* tag, so it is better the address recorded in
> breakpoint location is the one without tag too, so we can still match
> breakpoint location address and stopped pc reported by Linux kernel, by
> simple compare.  I did try the different approach, that is keep the tag in
> the address saved in the breakpoint location, but I need to change many
> places of "loc->address == pc", so I give up on this way.

I remember code pattern "loc->address == pc" exists many places in
breakpoint.c.  I can give a try again.

-- 
Yao (齐尧)