[llvm-dev] [DebugInfo]Crash during building openmpi4.0.0

[Tomar, Sourabh Singh via llvm-dev]

Thank You for suggestion Adrian!

Generated reproducer for the crash using clang reproducer and CReduce.
::Attachment:: C file.
NIT: some clean up is done on this file just to silent some compiler warnings(like implicit declaration etc.)

Crash can be reproduced using above test case with following commandline:
$clang -g -O3 -mllvm –enable-partial-inlining creducegenerated-cleaned.c -c
---CRASH---
$clang -g -O3 creducegenerated-cleaned.c -c
Working fine.

Or you may also try as:
$opt -partial-inliner creduce-O3.ll -S | llc >/dev/null
---CRASH---

Thank You,
Sourabh.

From: Adrian Prantl <aprantl at apple.com>
Sent: Friday, November 13, 2020 6:18 AM
To: Tomar, Sourabh Singh <SourabhSingh.Tomar at amd.com>
Cc: llvm-dev at lists.llvm.org; Vedant <vsk at apple.com>
Subject: Re: [DebugInfo]Crash during building openmpi4.0.0

[CAUTION: External Email]
A good way to start is to let Clang generate a crash reproducer, then you have a single file on which to run delta or creduce on. Once you have a reduced testcase, we can try and help you figure out what is triggering the assertion.

-- adrian


On Nov 12, 2020, at 9:02 AM, Tomar, Sourabh Singh <SourabhSingh.Tomar at amd.com<mailto:SourabhSingh.Tomar at amd.com>> wrote:

Hi folks,

While building openmpi.4.0.0(Optimized debug build), using trunk clang we encountered a crash(assertion failure).

Initially assertion seems trivial:
[…]
void llvm::DwarfExpression::addFragmentOffset(const llvm::DIExpression*): Assertion `FragmentOffset >= OffsetInBits && "overlapping or duplicate fragments"' failed.
[…]

But, narrowing to RC. We discovered “-O3 -enable-partial-inlining” pass which is doing some DebugInfo manipulation, later triggering this.

Reproducibility:
$ wget https://download.open-mpi.org/release/open-mpi/v4.0/openmpi-4.0.0.tar.bz2<https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdownload.open-mpi.org%2Frelease%2Fopen-mpi%2Fv4.0%2Fopenmpi-4.0.0.tar.bz2&data=04%7C01%7CSourabhSingh.Tomar%40amd.com%7C599946b75b0e476fd93408d8876dbd74%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637408252682837448%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C1000&sdata=PLf5BzKSwoyMv2KqMIYFpzFksn%2FbR0F%2FUv9VhkMvHvA%3D&reserved=0>
$ tar -xf openmpi-4.0.0
$ cd openmpi-4.0.0
$ ./configure --enable-mpi-fortran=no OMPI_CC=/home/sourabh/mirror-upstream/build/release/bin/clang OMPI_CXX=clang++ CXX=clang++ CC=clang CFLAGS="="-g -O3 -mllvm -enable-partial-inlining " CXXFLAGS="-g -O3 -mllvm -enable-partial-inlining" AR=llvm-ar RANLIB=llvm-ranlib NM=llvm-nm
$ make -jN
----CRASH----

Details of Narrowing:
$ cd ompi/mca/vprotocol/pessimist
$ clang -DHAVE_CONFIG_H -I. -I../../../../opal/include -I../../../../ompi/include -I../../../../oshmem/include -I../../../../opal/mca/hwloc/hwloc201/hwloc/include/private/autogen -I../../../../opal/mca/hwloc/hwloc201/hwloc/include/hwloc/autogen -I../../../../ompi/mpiext/cuda/c -I../../../.. -I../../../../orte/include -I/home/regressions/openmpi-4.0.0/opal/mca/event/libevent2022/libevent -I/home/regressions/openmpi-4.0.0/opal/mca/event/libevent2022/libevent/include -I/home/regressions/openmpi-4.0.0/opal/mca/hwloc/hwloc201/hwloc/include -DNDEBUG -g -O3 -mllvm -enable-partial-inlining -finline-functions -fno-strict-aliasing -mcx16 -pthread -MT vprotocol_pessimist_recv.lo -MD -MP -MF .deps/vprotocol_pessimist_recv.Tpo -c vprotocol_pessimist_recv.c -S
--CRASH—

Note: Entire application and above file compiling fine if we remove “—enable-partial-inlining”.

I attempted to come-up with a more reduced case but that was in vain. This pass “-partial-inliner” is disabled by default(even at O3) and not much of content or sample test cases as to what this transformation actually do.

I’ll be filing a BUG, as soon as someone from community confirms this.

Thanks You,
Sourabh.

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