Investigate BFD linker crashes possibly related to TLSDESC

[xen0n]

Example: Debian mesa 24.2.0-2 build crash

This may be linked to the usage of TLSDESC, but I'm not sure at present.

On Gentoo I also noticed bus errors linking something while building sys-libs/glibc, with -mtls-dialect=desc globally set. On another box without TLSDESC enabled, glibc built without problems, so this is again highly suspect.

[xry111]

When I built Glibc with -mtls-dialect=desc there was no strange crashes. Note that the Glibc library code is built with -ftls-model=initial-exec so only some tests use TLS descriptor.

[xen0n]

Important finding: I have specifically enabled additional CFLAGS for source debugging for glibc -- namely -ggdb3.

These CFLAGS work:

• -O2 -pipe -march=la464 -mtune=la464 -mtls-dialect=desc
• -O2 -pipe -march=la464 -mtune=la464 -mtls-dialect=desc -g
• -O2 -pipe -march=la464 -mtune=la464 -mtls-dialect=desc -ggdb
• -O2 -pipe -march=la464 -mtls-dialect=desc -ggdb
• -O2 -pipe -march=loongarch64 -ggdb3
• -O2 -pipe -march=la464 -ggdb3

These don't:

• -O2 -pipe -march=la464 -mtls-dialect=desc -ggdb3
• -O2 -pipe -march=loongarch64 -mtls-dialect=desc -ggdb3

So it's the combination of -mtls-dialect=desc -ggdb3 that produces the object code eventually crashing the BFD linker. Not related to code generation.

[xry111]

Is there a reduced test case (one or several .s file(s))?

[ywgrit]

This issue has been fixed, refefence:https://patchwork.sourceware.org/project/binutils/patch/20240906010012.910300-1-wangxin03@loongson.cn/