[llvm] r204107 - DwarfDebug: Only unique retained types instead of all types.

[WenHan Gu (谷汶翰)]

Finally I found a way to reproduce this not depending on my local project.
I cannot submit this to bugzilla, the post_bug.cgi seems break.

Could you help reproduce this? IMHO this may be a bug.

If I #include <chrono> and <locale> to the same file, then llc works.
but if I #include them separately on a.cpp and c.cpp, then after llvm-link,
llc crashes.
My workstation is x86_64, ubuntu13.10, 3.11.0-15-generic.

Thanks!


HOWTO:

$ cat a.cpp
#include <chrono>

$ cat b.cpp
#include <locale>

$ clang -g -emit-llvm -std=c++11 -c a.cpp b.cpp
$ llvm-link a.bc b.bc | llc

llc: /home/mtk03872/works/llvm/lib/CodeGen/AsmPrinter/DwarfUnit.cpp:984:
llvm::DIE *llvm::DwarfUnit::getOrCreateTypeDIE(const llvm::MDNode *):
Assertion `Ty == resolve(Ty.getRef()) && "type was not uniqued, possible
ODR violation."' failed.
0  llc             0x00000000011a2255 llvm::sys::PrintStackTrace(_IO_FILE*)
+ 37
1  llc             0x00000000011a29a3
2  libpthread.so.0 0x00007f271ef28bb0
3  libc.so.6       0x00007f271df3cf77 gsignal + 55
4  libc.so.6       0x00007f271df405e8 abort + 328
5  libc.so.6       0x00007f271df35d43
6  libc.so.6       0x00007f271df35df2
7  llc             0x0000000000ca3dd4
8  llc             0x0000000000c87579
llvm::DwarfDebug::constructImportedEntityDIE(llvm::DwarfCompileUnit*,
llvm::DIImportedEntity const&, llvm::DIE*) + 281
9  llc             0x0000000000c83ff2 llvm::DwarfDebug::beginModule() + 1234
10 llc             0x0000000000c83a79
llvm::DwarfDebug::DwarfDebug(llvm::AsmPrinter*, llvm::Module*) + 1801
11 llc             0x0000000000c73e70
llvm::AsmPrinter::doInitialization(llvm::Module&) + 1008
12 llc             0x000000000113bc86
llvm::FPPassManager::doInitialization(llvm::Module&) + 86
13 llc             0x000000000113c09e
llvm::legacy::PassManagerImpl::run(llvm::Module&) + 734
14 llc             0x0000000000561622 main + 6370
15 libc.so.6       0x00007f271df27de5 __libc_start_main + 245
16 llc             0x000000000055ea2d
Stack dump:
0.      Program arguments: llc
Aborted


2014-03-28 0:51 GMT+08:00 Adrian Prantl <aprantl at apple.com>:

>
> On Mar 27, 2014, at 9:43 AM, David Blaikie <dblaikie at gmail.com> wrote:
>
> > On Thu, Mar 27, 2014 at 9:39 AM, Adrian Prantl <aprantl at apple.com>
> wrote:
> >>
> >> On Mar 26, 2014, at 11:15 PM, WenHan Gu (谷汶翰) <wenhan.gu at gmail.com>
> wrote:
> >>
> >>> Hi Adrian,
> >>>
> >>> After this commit, there's sometimes assert fail on large bitcodes on
> my environment.
> >>
> >> Is there any chance you can provide me with a reduced example that
> reproduces this?
> >>
> >>> According to my result, two types seems the same, and I take out the
> assert fail can still build and run.
> >>> Is any possible that the contained MDNode is not the same (since it is
> a pointer comparison indeed) but this is reasonable?
> >>> Thanks!
> >>
> >> Since the MDNodes are kept in a FoldingSet there should be no two
> identical nodes. What may happen in your case is that the source code
> contains two conflicting definitions of the same type in two compilation
> units. This is illegal C++ (violation of the ODR), but the compiler
> currently has no way to diagnose such a situation.
> >>
> >> On a related note, this made me realize that this assertion should only
> be enabled for C++ compilation units; I will fix this soon. This will not
> fix your problem, unfortunately.
> >
> > Hmm? The assertion should still be true in any case, shouldn't it?
> > (the 'reference' will just be a straight MDNode when we don't have a
> > mangled name there) But perhaps I'm forgetting the exact schema.
> You’re right, while there may be conflicting definitions for a type in a
> non-ODR-language, resolve() would also be a noop (no such thing as an ID
> field in a C DIType), so this would still be safe.
>
> -- adrian




-- 
Best Regards,
WenHan Gu (Nowar)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.llvm.org/pipermail/llvm-commits/attachments/20140328/9cde21d6/attachment.html>