I've never had to report any binutils bugs (the wonders of old platforms ;)) so I'm not exactly sure how to proceed.
I've encountered the following bug related to gold and LTO:
which only happens during LTO bootstrap on a Cortex A53 CPU (S905 SoC). Using normal bootstrap or switching to ld.bfd is sufficient to complete the LTO build.
I rebuilt binutils yesterday (184.108.40.20670117) but the produced code still crashes.
What I missed previously is the following kernel debug message which might be relevant here. Any suggestions for exonerating gold and implicating the kernel welcome:
[ 4802.696081] cc1: unhandled level 2 translation fault (11) at 0x00000000, esr 0x92000006
[ 4802.696092] pgd = ffffffc055a2c000
[ 4802.700620]  *pgd=0000000055693003, *pmd=0000000000000000
[ 4802.709039] CPU: 0 PID: 14840 Comm: cc1 Not tainted 3.14.29-amlogics905x-gb122fc2-dirty #9
[ 4802.709043] task: ffffffc054b62000 ti: ffffffc065e3c000 task.ti: ffffffc065e3c000
[ 4802.709052] PC is at 0xffb8d0
[ 4802.709059] LR is at 0xffb638
[ 4802.709063] pc : [<0000000000ffb8d0>] lr : [<0000000000ffb638>] pstate: 60000000
[ 4802.709066] sp : 0000007ff62c4d00
[ 4802.709069] x29: 0000007ff62c5c30 x28: 0000000000000000
[ 4802.709074] x27: 0000007ff62c51f0 x26: 000000000148fb40
[ 4802.709079] x25: 0000007ff62c55b0 x24: 00000000013dd000
[ 4802.709083] x23: 0000000000743c10 x22: 0000007ff62c5c50
[ 4802.709087] x21: 0000007ff62c55b0 x20: 0000007ff62c4d70
[ 4802.709092] x19: 0000007ff62c55b0 x18: 000000000000001d
[ 4802.709096] x17: 0000007f8c274a40 x16: 00000000013e0058
[ 4802.709100] x15: 0000000000000001 x14: 0000000000000000
[ 4802.709104] x13: 0000000000000000 x12: 0000000000000000
[ 4802.709109] x11: 0000000000000000 x10: 0000000000000000
[ 4802.709113] x9 : 0000000000000000 x8 : 0000000000000000
[ 4802.709117] x7 : 0000000000000000 x6 : 0000007ff62c5130
[ 4802.709121] x5 : ffffffffffffffc0 x4 : 0000000000000000
[ 4802.709126] x3 : 0000000000743e34 x2 : 0000000000000008
[ 4802.709130] x1 : 00000000014bad88 x0 : 0000000000000008
Just in case, here's the configure command line used to build binutils:
I'm seeing what I think is the same bug; it manifests itself building Swift on aarch64 (96-core Packet 2A server, with a Cavium ThunderX CPU).
/usr/bin/ld.gold: internal error in relocate_tls, at ../../gold/aarch64.cc:7419
is the error message. Suggestions where to go to help report this more carefully would be welcomed.
That's a different issue, ld.gold never crashes in mine.
OK, so I've managed to identify the root cause of this bug, namely, the -mfix-cortex-a53-843419 erratum workaround, which happens via the linker.
To recap, ld.gold produces crashing code if both LTO and -mfix-cortex-a53-843419 are used at the same time. Removing the workaround switch or using ld.bfd allows to bootstrap GCC using LTO (--with-build-config=bootstrap-lto).
So, a compiler built with --enable-fix-cortex-a53-843419 needs just -mcpu/mtune=cortex-a53 to trigger the workaround.
In my tests, it made code produced that way slower on a currently available revision of A53, which is not mentioned in the documentation. Otherwise I would have found out if it was still necessary a long time ago :)
This is binutils PR gold/21491.
(In reply to Edward Vielmetti from comment #2)
> I'm seeing what I think is the same bug; it manifests itself building Swift
> on aarch64 (96-core Packet 2A server, with a Cavium ThunderX CPU).
> /usr/bin/ld.gold: internal error in relocate_tls, at
> is the error message. Suggestions where to go to help report this more
> carefully would be welcomed.
This may be PR gold/19353. It's already been fixed, but perhaps your version of gold is older. If you still see the problem in the latest gold, please open a new PR at sourceware.org/bugzilla.