Locating a commit from its ChangeLog entry (was Re: How to migrate ggc_alloc_XXX for GCC v8.x (git-20170816)?)

Fri Aug 18 18:32:00 GMT 2017

Hi,

My first question would be why are you using the ChangeLog files at all?
It seems like it would be a lot more straight forward to just look at
blame for the thing that changed.

thanks

Trev

On Fri, Aug 18, 2017 at 09:32:34AM +0800, Leslie Zhai wrote:
> 
> 
> åœ¨ 2017å¹´08æœˆ17æ—¥ 23:10, David Malcolm å†™é“:
> > On Thu, 2017-08-17 at 09:52 +0800, Leslie Zhai wrote:
> > > Hi Trevor,
> > > 
> > > Thanks for your kind response!
> > > 
> > > 
> > > åœ¨ 2017å¹´08æœˆ16æ—¥ 20:02, Trevor Saunders å†™é“:
> > > > On Wed, Aug 16, 2017 at 05:32:10PM +0800, Leslie Zhai wrote:
> > > > > Hi GCC developers,
> > > > > 
> > > > > GCC v4.6's gengtype will auto-generate Allocators for known
> > > > > structs and
> > > > > unions, for example: ggc_alloc_tree2WeakVH for tree2WeakVH https:
> > > > > //github.com/xiangzhai/dragonegg/blob/master/include/dragonegg/gt
> > > > > -cache-4.6.inc#L24
> > > > > 
> > > > > but gengtype will not auto-generate ggc_alloc_XXX for GCC v6.x or
> > > > > v8.x
> > > > > (git-20170816), for example: struct GTY((for_user)) tree2WeakVH h
> > > > > ttps://github.com/xiangzhai/dragonegg/blob/master/include/dragone
> > > > > gg/gt-cache-8.0.inc#L1284
> > > > > 
> > > > > As ChangeLog-2014 mentioned:
> > > > > 
> > > > > 2014-05-17  Trevor Saunders <tsaunders@mozilla.com>
> > > > > 
> > > > >       ...
> > > > >       (ggc_alloc): Install the type's destructor as the finalizer
> > > > > if it
> > > > >       might do something.
> > > > > 
> > > > > Please give me some hint about ggc_alloc migration, thanks a lot!
> > > > if you look at the patches they convert ggc_alloc_foo to
> > > > ggc_alloc<foo>
> > > > and you should do the same.
> > > Thanks for your hint! I do the same :)
> > > https://github.com/xiangzhai/dragonegg/blob/master/src/Cache.cpp#L255
> > > PS: how to find the relative patch for the ChangeLog's item? I use
> > > Google, for example: (ggc_alloc): Install the type's destructor as
> > > the
> > > finalizer if it might do something.
> > Another way is to use "git blame" on the ChangeLog to find the commit
> > that added the ChangeLog entry.
> > 
> > For "archived" ChangeLog files like "ChangeLog-2014" that will just
> > tell you which commit moved all of the entries for that years ChangeLog
> > entries to "ChangeLog-2014", so you can use "git log":
> > 
> >    git log gcc/ChangeLog-2014
> > 
> > to identify the commit that archived the ChangeLog:
> > 
> > commit e64e0023b9a6796858262f8fd38005a08d234d82
> > Author: green <green@138bc75d-0d04-0410-961f-82ee72b054a4>
> > Date:   Thu Jan 1 15:43:47 2015 +0000
> > 
> >      Roll ChangeLog file.  Limit offsets to 16 bits for moxie.
> > 
> > 
> > Once you have that commit you can use "^" to find the prior state of
> > the tree, and then use git blame:
> > 
> >    git blame e64e0023b9a6796858262f8fd38005a08d234d82^ gcc/ChangeLog
> 
> Thanks for your hint!
> 
> > 
> > and then search for the text of interest:
> > 
> > 9296020474 (tbsaunde      2014-05-17 23:15:55 +0000 38073) 2014-05-17  Trevor Saunders  <tsaunders@mozilla.com>
> > 9296020474 (tbsaunde      2014-05-17 23:15:55 +0000 38074)
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38075)      * ggc-common.c (ggc_internal_cleared_alloc): Adjust.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38076)      * ggc-none.c (ggc_internal_alloc): Assert if a finalizer is passed.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38077)      (ggc_internal_cleared_alloc): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38078)      * ggc-page.c (finalizer): New class.
> > b540cb16c9 (uros          2014-05-18 07:24:24 +0000 38079)      (vec_finalizer): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38080)      (globals::finalizers): New member.
> > b540cb16c9 (uros          2014-05-18 07:24:24 +0000 38081)      (globals::vec_finalizers): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38082)      (ggc_internal_alloc): Record the finalizer if any for the block bei
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38083)      allocated.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38084)      (ggc_handle_finalizers): New function.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38085)      (ggc_collect): Call ggc_handle_finalizers.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38086)      * ggc.h (ggc_internal_alloc): Add arguments to allow installing a
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38087)      finalizer.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38088)      (ggc_internal_cleared_alloc): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38089)      (finalize): New function.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38090)      (need_finalization_p): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38091)      (ggc_alloc): Install the type's destructor as the finalizer if it
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38092)      might do something.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38093)      (ggc_cleared_alloc): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38094)      (ggc_vec_alloc): Likewise.
> > 92f06184bb (tbsaunde      2014-05-17 23:08:00 +0000 38095)      (ggc_cleared_vec_alloc): Likewise.
> > 
> > which identifies the commit as 92f06184bb.
> > 
> > "git show 92f06184bb" shows the commit you're looking for, and contains this line:
> > 
> >      git-svn-id: svn+ssh://gcc.gnu.org/svn/gcc/trunk@210568 138bc75d-0d04-0410-961f-82ee72b054a4
> > 
> > from which you can see (if you need to) that the SVN commit was r210568.
> > 
> > > Dave
> 
> -- 
> Regards,
> Leslie Zhai - a LLVM developer https://reviews.llvm.org/p/xiangzhai/
> 
> 
> 