[BUG] armv7a + simd ld.lld segmentation fault during linking NEON code

[arturbac]

Description

With ndk r-21.* clang ld.lld started to fail generating neon instructions when source code uses neon intrinsics for armeabi-v7a. With ndk r-20 there is no problem and no segmentation fault during linking stage.
ndk-r21 still generates proper code for armv-8a

1.  Running pass 'Function Pass Manager' on module 'ld-temp.o'.
   

2.  Running pass 'ARM Instruction Selection' on function '@_ZN4conv27yCrCb2rgb_aarch64_yps1_chs1E18yuv_data_info_tmplIPKSt4byteEPhj'
   

#0 0x0000000000e59f92 (/opt/android-sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/bin/ld.lld+0xe59f92)
#1 0x0000000000e5a727 (/opt/android-sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/bin/ld.lld+0xe5a727)
#2 0x00007f0ddea1b0b0 __restore_rt (/lib64/libpthread.so.0+0x130b0)
#3 0x000000000143b92d (/opt/android-sdk/ndk/21.1.6352462/toolchains/llvm/prebuilt/linux-x86_64/bin/ld.lld+0x143b92d)
#4 0x00007ffc234315f0
clang++: error: unable to execute command: Segmentation fault (core dumped)
clang++: error: linker command failed due to signal (use -v to see invocation)
ninja: build stopped: subcommand failed.

Environment Details

• NDK Version: 21.* (0 and 1)
• Host OS: Linux, gentoo
• ABI: armeabi-v7a
• NDK API level: 21

I attached linking output with seg fault and preprocessed source code of function mentioned in linker fault. I cannot narrow down more what causes seg fault than preprocessed source file.
linking_fault.txt

yuv_to_rgb_alligned.cc.txt

[DanAlbert]

I think clang usually generates a tarball of the repro case for a crash. Does LLD not do that? If you have that, that'll help. Otherwise, it looks like we have the preprocessed source and the build commands, so hopefully that's enough (thanks for providing those!)

[DanAlbert]

r21c is already being finalized, so this will be in r21d at the earliest.

[arturbac]

I think clang usually generates a tarball of the repro case for a crash.

Not in case of linker failure (ld.lld segfault), ld.lld fails at the end of entire build when starts generating assembly from precompiled byte code. The only clue is hopefully source function name.
I had to generate preprocessed output of source explicitly by myself taking into account this function name.

[arturbac]

BTW: If You need any other output just let me know and supply clang/ld.lld command to execute.

[stephenhines]

The input file here isn't enough to reproduce the issue unfortunately. If you pass -v to the failing command line, you can get it to dump the exact subcommands that are being run. Then, the ld.lldcommand in there can be run with the --reproduce=repro.tar option to create a repro.tar file that will include all the necessary inputs. You can verify that it reproduces for you by untarring that file and then running ld.lld @response.txt inside of that directory.

[arturbac]

Cant attach it here, after compressing with xz it take 62MB and here is 10MB file limit
So I put it into my web server, let me know when I can delete it.
http://ebasoft.com.pl/repro.tar.xz

[stephenhines]

Wow, ok. I just pulled it down locally here. I can attach it internally to a bug as needed, so that others can look if necessary. You can remove your copy from your server. Thanks.