llvm dev - Jan 2015 - [LLVMdev] [cfe-dev] [RFC] Raising LLVM minimum required MSVC version to 2013 for trunk

If we have no other major users who require VS 2012 support, I think
it's reasonable to officially switch now. We might want to wait for
3.6 to go out the door, just to reduce possible issues with porting
fixes, but that may be overly cautious.

~Aaron

On Wed, Jan 28, 2015 at 7:16 AM, Greg Bedwell <gregbedwell at gmail.com>
wrote:
> This thread seems to have stalled again without resolution :).  Is there
> anything else left blocking this change?  We've had our PS4 toolchain
builds
> switched over to VS2013 since I reported back in October without any
issues.
>
> -Greg
>
> On 8 October 2014 at 18:35, Aaron Ballman <aaron at aaronballman.com>
wrote:
>>
>> On Wed, Oct 8, 2014 at 12:17 PM, Greg Bedwell <gregbedwell at
gmail.com>
>> wrote:
>> > Hi,
>> >
>> > To follow up from Paul last week:
>> >
>> >> I'm expecting to have our internal builds switched over
later this
>> >> week.  Our investigations have shown no problems.
>> >
>> > We've now updated our internal builds from 2012.4 (cl.exe
17.0.61030) to
>> > 2013.3 (cl.exe 18.00.30723).  Our automated testing over the
weekend
>> > hasn't
>> > shown any correctness issues so we plan to continue using it now..
>> >
>> > From some of the stats I've collected it seems to be a
worthwhile
>> > update.
>> > On my own machine, the time for a full rebuild from clean of
ALL_BUILD
>> > (LLVM
>> > & Clang, Release + asserts + debug info, not using ninja) has
improved
>> > by
>> > 20%.  Doing a like-for-like build of various benchmarks and games
using
>> > clang built by VS2012 and VS2013, the clang build speed of a
typical -O2
>> > -g
>> > build is somewhere between in the noise and 1% faster with VS2013.
>> > We've
>> > not yet observed any regressions in the speed of clang since
upgrading.
>>
>> Great, thank you for the feedback!
>>
>> ~Aaron
>
>

+Alex Bradbury

Sounds to me like we have no known users still on VS 2012.

So, how about we plan to move forward again with Chandler’s proposal for making
this transition. For those who don’t want to dig through to the beginning here’s
the basic plan:

1) Loop in cfe-dev and lldb-dev (Done!)
2) Wait until this email fully circulates in digests and LLVM Weekly so that
everyone who has an objection can voice it
3) If there are no objections, Commit a change to the CMake build which errors
on old MSVC versions
4) Revert and fix buildbots
5) Repeat 3 & 4 until no issues
6) Once the change is live for a week with no issues, update the documentation
to reflect the minimum required MSVC version as 2013

Alex, can you please make sure that this plan makes it into the next LLVM
Weekly? If there are no objections this time I will update CMake files a few
days after the LLVM Weekly goes out.

Thanks Greg and Aaron for keeping this thread going.

-Chris

> On Jan 28, 2015, at 8:11 AM, Aaron Ballman <aaron at
aaronballman.com> wrote:
> 
> If we have no other major users who require VS 2012 support, I think
> it's reasonable to officially switch now. We might want to wait for
> 3.6 to go out the door, just to reduce possible issues with porting
> fixes, but that may be overly cautious.
> 
> ~Aaron
> 
> On Wed, Jan 28, 2015 at 7:16 AM, Greg Bedwell <gregbedwell at
gmail.com> wrote:
>> This thread seems to have stalled again without resolution :).  Is
there
>> anything else left blocking this change?  We've had our PS4
toolchain builds
>> switched over to VS2013 since I reported back in October without any
issues.
>> 
>> -Greg
>> 
>> On 8 October 2014 at 18:35, Aaron Ballman <aaron at
aaronballman.com> wrote:
>>> 
>>> On Wed, Oct 8, 2014 at 12:17 PM, Greg Bedwell <gregbedwell at
gmail.com>
>>> wrote:
>>>> Hi,
>>>> 
>>>> To follow up from Paul last week:
>>>> 
>>>>> I'm expecting to have our internal builds switched over
later this
>>>>> week.  Our investigations have shown no problems.
>>>> 
>>>> We've now updated our internal builds from 2012.4 (cl.exe
17.0.61030) to
>>>> 2013.3 (cl.exe 18.00.30723).  Our automated testing over the
weekend
>>>> hasn't
>>>> shown any correctness issues so we plan to continue using it
now..
>>>> 
>>>> From some of the stats I've collected it seems to be a
worthwhile
>>>> update.
>>>> On my own machine, the time for a full rebuild from clean of
ALL_BUILD
>>>> (LLVM
>>>> & Clang, Release + asserts + debug info, not using ninja)
has improved
>>>> by
>>>> 20%.  Doing a like-for-like build of various benchmarks and
games using
>>>> clang built by VS2012 and VS2013, the clang build speed of a
typical -O2
>>>> -g
>>>> build is somewhere between in the noise and 1% faster with
VS2013.
>>>> We've
>>>> not yet observed any regressions in the speed of clang since
upgrading.
>>> 
>>> Great, thank you for the feedback!
>>> 
>>> ~Aaron
>> 
>>

On Fri, Jan 30, 2015 at 6:51 PM, Chris Bieneman <cbieneman at apple.com>
wrote:
> +Alex Bradbury
>
> Sounds to me like we have no known users still on VS 2012.
>
> So, how about we plan to move forward again with Chandler’s proposal for
making this transition. For those who don’t want to dig through to the beginning
here’s the basic plan:
>
> 1) Loop in cfe-dev and lldb-dev (Done!)
> 2) Wait until this email fully circulates in digests and LLVM Weekly so
that everyone who has an objection can voice it
> 3) If there are no objections, Commit a change to the CMake build which
errors on old MSVC versions
> 4) Revert and fix buildbots
> 5) Repeat 3 & 4 until no issues
> 6) Once the change is live for a week with no issues, update the
documentation to reflect the minimum required MSVC version as 2013
Also:

7) Update the documentation as to what minimum set of C++11 features
are allowed in the code base.
> Alex, can you please make sure that this plan makes it into the next LLVM
Weekly? If there are no objections this time I will update CMake files a few
days after the LLVM Weekly goes out.
Can you also handle the documentation updates a few days after the
CMake changes have been made live?

Thanks!

~Aaron