TableGen crash when building LLVM with EXPENSIVE_CHECKS enabled

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1

Hello,
I'm trying to run checks with EXPENSIVE_CHECKS enabled, but it crashes when
generating some intrinsics file with TableGen.

cd /home/luke/Source/llvm-project/build && /home/luke/Source/llvm-
project/build/bin/llvm-tblgen -gen-intrinsic-impl -I /home/luke/Source/llvm-
project/llvm/include/llvm/IR -I /home/luke/Source/llvm-project/llvm/include
/home/luke/Source/llvm-project/llvm/include/llvm/IR/Intrinsics.td -o
include/llvm/IR/IntrinsicImpl.inc -d include/llvm/IR/IntrinsicImpl.inc.d
/usr/bin/../lib/gcc/x86_64-linux-
gnu/8/../../../../include/c++/8/debug/safe_container.h:83:
Error: attempt to self move assign.

Objects involved in the operation:
    sequence "this" @ 0x0x7fe3b3070468 {
    }

The command I've been using to configure it is

cmake ../llvm -G Ninja \
  -DCMAKE_BUILD_TYPE=Debug \
  -DLLVM_ENABLE_LLD=On \
  -DLLVM_ENABLE_EXPENSIVE_CHECKS=On

Removing the -DLLVM_ENABLE_EXPENSIVE_CHECKS=On allows it to build. Is there
something wrong with the version on libstdc++ on my system? (Debian testing)
This was happening on revision 5857bf5d1e5a5ffe5ae51a38514ee55495c0cc69

2

I briefly dug into this and I can reproduce it, the issue appears to
be the implementation of std::shuffle (which is called by llvm::sort
with expensive checks).

Sounds like you should file a bug against libstdc++.

Cheers,
Nicolai

3

This looks like https://bugs.llvm.org/show_bug.cgi?id=37652 to me. I added a workaround (https://github.com/CTSRD-CHERI/llvm-project/commit/a7e68c6baf9967cfb288ca6c53c43b29581d27d8) to our fork but never got around to submitting a review.

If adding a copy of the libc++ implementation as llvm::shuffle seems like a valid approach I’ll upload the patch to phabricator.

Alex

4

FYI I just hit this, but found that adding -DLLVM_OPTIMIZED_TABLEGEN=ON when I configured llvm fixed/hid the issue. Not sure why, but I found this flag when examining how one of the expensive-checks bots was configured.

Teresa