[PATCH] D48518: ADT: Shrink SmallVector by 8B on 64-bit platforms

[Duncan P. N. Exon Smith via llvm-commits]

Hi Peter,

Thanks for the heads up.  I tend to agree with your intuition/conclusion (i.e., it seems like a bug in 3.8.1 and not worth reverting for).  But, FYI, I'll be OOO for a couple of weeks.  If for some reason your conclusion changes, please don't wait for my response before reverting.  I already know it won't revert cleanly because I committed r337820 (https://reviews.llvm.org/D49163 <https://reviews.llvm.org/D49163>) on top, but it should be pretty easy to resolve the conflict (you should just have to fine-tune the static_asserts).

Good luck,
Duncan


> On Jul. 25, 2018, at 10:32, Peter Smith via Phabricator <reviews at reviews.llvm.org> wrote:
> 
> peter.smith added a comment.
> 
> This patch is causing the http://lab.llvm.org:8011/builders/clang-cmake-aarch64-lld to fail. Unfortunately (for me) the failures seems to be restricted to older versions of clang and are not reproducible on Arm or X86. The buildbot itself is using the default /usr/bin/clang for Ubuntu 16.04 LTS (clang version 3.8.0-2ubuntu4 (tags/RELEASE_380/final). The failures go away if I use the 3.9.1 release (No failures on 4.0.1, 6.0.0 or built from master). At this stage I think that this could be a code-gen bug in the AArch64 backend of clang 3.8.1 so I don't think it is worth reverting, but I'm mentioning it here just in case there is a subtle problem that is only being exposed by that version.
> 
> The failures on the bot are all a llvm::unreachable in checkDeducedTemplateArguments() clang/lib/Sema/SemaTemplateDeduction.cpp:367. The only way that I can see that the unreachable gets hit is if there is some kind of corruption of the ArgKind.
> 
> A stripped down bit of code that will cause a clang built with 3.8.1 on AArch64 to fail is:
> 
>  template<typename T, typename U>
>  class test_attach30 { };
> 
>  template<typename T>
>  class test_attach30<T, int> { };
> 
>  $ clang++ -fsyntax-only test.cpp
>  Invalid TemplateArgument Kind!
>  UNREACHABLE executed at
>  clang/lib/Sema/SemaTemplateDeduction.cpp:367!
> 
> 
> https://reviews.llvm.org/D48518
> 
> 
> 

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20180726/137eb2fd/attachment.html>