<div dir="ltr">Just be aware that those ifdefs were recommitted and reverted several times, so I'm not sure what the state is.</div><br><div class="gmail_quote"><div dir="ltr">On Fri, Sep 28, 2018 at 8:48 AM Alastair Murray via llvm-dev <<a href="mailto:llvm-dev@lists.llvm.org">llvm-dev@lists.llvm.org</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div text="#000000" bgcolor="#FFFFFF">
<p>Hi Kern,</p>
<p>We also had issues with mixing GCC/Clang builds when testing the
7.0 release branch.</p>
<p>My colleague submitted a patch that fixed the issue for us:<br>
* <a class="m_-7403740192623216969moz-txt-link-freetext" href="https://reviews.llvm.org/D50710" target="_blank">https://reviews.llvm.org/D50710</a><br>
<br>
I no longer have a copy of the error we were seeing to see if it
was the same, but the fix is to llvm::OptionalStorage and your
error message involves llvm::Optional. The patch removes a GCC
specific ifdef, and hopefully fixes the issue that made that
necessary in the first place, but we never really knew how the GCC
miscompilation was expressed.</p>
<p>It would be interesting to know whether this resolves your issue,
but regardless we should give the patch a prod.<br>
<br>
Regards,<br>
Alastair Murray.<br>
</p>
<br>
<div class="m_-7403740192623216969moz-cite-prefix">On 27/09/18 08:46, Kern Handa via
llvm-dev wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div dir="ltr">
<div>Hi folks,</div>
<div><br>
</div>
<div>Not sure if this is the right mailing list target, but
I'm trying out the new LLVM 7.0 packages found at <a href="http://apt.llvm.org" target="_blank">http://apt.llvm.org</a>
by porting over an existing LLVM 6.0 project of ours to the
new version. In doing so, I found that the executable always
segfaulted at the same spot with no explanation:</div>
<div><br>
</div>
<div>0x0000000000fefe33 in
llvm::RegisterTargetMachine<llvm::X86TargetMachine>::Allocator(llvm::Target
const&, llvm::Triple const&, llvm::StringRef,
llvm::StringRef, llvm::TargetOptions const&,
llvm::Optional<llvm::R<br>
eloc::Model>,
llvm::Optional<llvm::CodeModel::Model>,
llvm::CodeGenOpt::Level, bool) ()</div>
<div><br>
</div>
<div>This happens if I build my project and link it against
LLVM 7.0 with either clang++ 6.1 or clang++ 7.0. This does
not happen if I build my project with g++ 8. <br>
</div>
<div><br>
</div>
<div>I have also confirmed that building LLVM 7.0 with clang++
and then using that private build of the libraries fixes the
issue.</div>
<div><br>
</div>
<div>To summarize, it seems that there's an ABI
incompatibility introduced somewhere, which means LLVM 7.0
compiled with gcc can only be used by other projects also
built with gcc. Is this something that's being investigated
and to be resolved as a fix in 7.1? If not, is there any
official release note that's remarking on this
incompatibility?</div>
<div><br>
</div>
<div>Thanks,</div>
<div>Kern<br>
</div>
</div>
</div>
<br>
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