[review] jit: remove bp locations when unregistering jit code

["Mihails Strasuns (Code Review)" <gerrit@gnutoolchain-gerrit.osci.io>]

Mihails Strasuns has posted comments on this change.

Change URL: https://gnutoolchain-gerrit.osci.io/r/c/binutils-gdb/+/704
......................................................................


Patch Set 1:

> Patch Set 1:
> 
> Just trying to understand the problem better.  From what I understand, when the breakpoint locations must be updated following a code change event (e.g. solib getting loaded or unloaded), we call breakpoint_re_set, which goes through all breakpoint locations and sees if they must be updated.  Have you tryied calling this from jit_unregister_code?

Have tried it now, just in case - it doesn't work. As far as I understand the problem here is that from the gdb PoV breakpoint locations with the same address are the same and `locations_are_equal (existing_locations, b->loc)` condition is true. Because of that updating breakpoint locations won't actually install breakpoint traps - gdb will still think that it is already installed. However in JIT case that instruction memory was overwritten and doesn't have a trap anymore.

Sadly I don't have enough knowledge about gdb architecture to reason if the same problem can possibly manifest with non-jit object files.


-- 
Gerrit-Project: binutils-gdb
Gerrit-Branch: master
Gerrit-Change-Id: Id9133540d67fa0c4619ac88324b0349b89e4b2b1
Gerrit-Change-Number: 704
Gerrit-PatchSet: 1
Gerrit-Owner: Mihails Strasuns <mihails.strasuns@intel.com>
Gerrit-Reviewer: Mihails Strasuns <mihails.strasuns@intel.com>
Gerrit-CC: Simon Marchi <simon.marchi@polymtl.ca>
Gerrit-Comment-Date: Tue, 26 Nov 2019 11:01:59 +0000
Gerrit-HasComments: No
Gerrit-Has-Labels: No
Gerrit-MessageType: comment