[llvm] r294349 - ADT: Add explicit conversions for reverse ilist iterators

[Hans Wennborg via llvm-commits]

Okay, you sold me :-) Merged together with r294357 in r294477.

Committed your release notes in r294478.

Thanks,
Hans

On Tue, Feb 7, 2017 at 6:00 PM, Duncan P. N. Exon Smith
<dexonsmith at apple.com> wrote:
> It's fixing an API regression; previously, ilist::reverse_iterator had an explicit conversion constructor (with these semantics) from ilist::iterator.  Since I removed it, there have been a number of complaints that it *should* exist in its old form.
>
> Those upgrading from LLVM 3.9 to LLVM 4.0 will have less code to update if we take this patch, and the instructions for how to update it are simpler as a result of it.
>
>> On 2017-Feb-07, at 15:03, Hans Wennborg <hans at chromium.org> wrote:
>>
>> Since it's not fixing a regression from 3.9, I'd prefer not to merge
>> it at this stage, but let it be part of the next release instead.
>>
>> On Tue, Feb 7, 2017 at 2:48 PM, Duncan P. N. Exon Smith
>> <dexonsmith at apple.com> wrote:
>>> Hans, can we take this commit (r294349) and David's fixup in r294357 into the LLVM 4.0 branch?
>>>
>>> I've also attached a patch for the release notes that attempt to summarize the ilist changes.
>>>
>>> Thanks!
>>> Duncan
>>>
>>>
>>>
>>>
>>>> On 2017-Feb-07, at 13:03, Duncan P. N. Exon Smith via llvm-commits <llvm-commits at lists.llvm.org> wrote:
>>>>
>>>> Author: dexonsmith
>>>> Date: Tue Feb  7 15:03:50 2017
>>>> New Revision: 294349
>>>>
>>>> URL: http://llvm.org/viewvc/llvm-project?rev=294349&view=rev
>>>> Log:
>>>> ADT: Add explicit conversions for reverse ilist iterators
>>>>
>>>> Add explicit conversions between forward and reverse ilist iterators.
>>>> These follow the conversion conventions of std::reverse_iterator, which
>>>> are off-by-one: the newly-constructed "reverse" iterator dereferences to
>>>> the previous node of the one sent in.  This has the benefit of
>>>> converting reverse ranges in place:
>>>> - If [I, E) is a valid range,
>>>> - then [reverse(E), reverse(I)) gives the same range in reverse order.
>>>>
>>>> ilist_iterator::getReverse() is unchanged: it returns a reverse iterator
>>>> to the *same* node.
>>>>
>>>> Modified:
>>>>   llvm/trunk/include/llvm/ADT/ilist_iterator.h
>>>>   llvm/trunk/include/llvm/CodeGen/MachineInstrBundleIterator.h
>>>>   llvm/trunk/unittests/ADT/IListIteratorTest.cpp
>>>>   llvm/trunk/unittests/CodeGen/MachineInstrBundleIteratorTest.cpp