Re: GDB 8.2 release 2018-08-21 status update

[Simon Marchi <simon.marchi@polymtl.ca>]

On 2018-08-21 13:51, Joel Brobecker wrote:
>   * [KevinB] PR gdb/23021
>     Setting breakpoints with -freorder-blocks-and-partition
>     https://sourceware.org/bugzilla/show_bug.cgi?id=23021
> 
> 	Identified as needed in the previous release, but couldn't do it
>         in time. We should be very close, now:
>         [v3] 
> https://sourceware.org/ml/gdb-patches/2018-08/msg00467.html
> 
>         I'm wondering how reasonable it's going to be to backport
>         those changes onto the branch, though... Any thoughts on that?
>         Kevin? Simon?

The changeset does indeed look scary :).  But I think Kevin was careful 
to keep the existing behaviour for contiguous blocks.

Patches 1 and 2 look harmless.

Patches 3 and 4 mostly added some branches for the contiguous and the 
non-contiguous case, where the contiguous case keeps the former 
behaviour.  If you have an executable with only contiguous blocks, it 
*should* therefore work the same way as before.  If you have an 
executable with non-contiguous blocks, well it would be broken with GDB 
8.1, so anything is an improvement.

Patch 5 changes BLOCK_START for BLOCK_ENTRY_PC, which is supposed to be 
the same for contiguous blocks, so again no changes expected there.

I'm not sure about the impact of patch 6.

Patch 7 modifies the block range data, which is only used in the 
non-contiguous branches.  So again, no impact on existing 
contiguous-only executables.

So from my point of view, it would be fine to include it in 8.2.  I'm 
just wondering though why this was considered as a blocker for 8.2 in 
the first place.  It's not really a regression, it's more like a new 
feature.  Was it to make sure we get the feature to users faster, before 
the new gcc that emits code like this by default starts to spread too 
much?

Simon