[lld] [LLD][COFF] Add support for ARM64X same-address thunks (PR #151255)

[via llvm-commits]

dyung wrote:

Hi @cjacek, I have been seeing some random crashes in a test on one of my build bots which after bisecting it back, I think this change seems to be causing it.

The crash seems to mainly affect Windows (although I have seen it twice I think on my linux bot) with some recent examples from the Windows bot here:
 - https://lab.llvm.org/buildbot/#/builders/46/builds/21132
 - https://lab.llvm.org/buildbot/#/builders/46/builds/21130
 - https://lab.llvm.org/buildbot/#/builders/46/builds/21129
 - https://lab.llvm.org/buildbot/#/builders/46/builds/21127
 - https://lab.llvm.org/buildbot/#/builders/46/builds/21126

The affected test seems to be `lld\test\COFF\import_weak_alias.test` and the test hits a crash in the linker:
```
******************** TEST 'lld :: COFF/import_weak_alias.test' FAILED ********************
Exit Code: 3221225477
Command Output (stdout):
--
# RUN: at line 3
split-file Z:\b\llvm-clang-x86_64-sie-win\llvm-project\lld\test\COFF\import_weak_alias.test Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir
# executed command: split-file 'Z:\b\llvm-clang-x86_64-sie-win\llvm-project\lld\test\COFF\import_weak_alias.test' 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir'
# note: command had no output on stdout or stderr
# RUN: at line 4
z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe --filetype=obj -triple=x86_64-windows-msvc Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir/foo.s -o Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.foo.obj
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe' --filetype=obj -triple=x86_64-windows-msvc 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir/foo.s' -o 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.foo.obj'
# note: command had no output on stdout or stderr
# RUN: at line 5
z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe --filetype=obj -triple=x86_64-windows-msvc Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir/qux.s -o Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.qux.obj
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\llvm-mc.exe' --filetype=obj -triple=x86_64-windows-msvc 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dir/qux.s' -o 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.qux.obj'
# note: command had no output on stdout or stderr
# RUN: at line 6
z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.qux.obj Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.foo.obj -out:Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dll -dll
# executed command: 'z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe' 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.qux.obj' 'Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.foo.obj' '-out:Z:\b\llvm-clang-x86_64-sie-win\build\tools\lld\test\COFF\Output\import_weak_alias.test.tmp.dll' -dll
# .---command stderr------------
# | PLEASE submit a bug report to https://github.com/llvm/llvm-project/issues/ and include the crash backtrace.
# | Stack dump:
# | 0.	Program arguments: z:\\b\\llvm-clang-x86_64-sie-win\\build\\bin\\lld-link.exe Z:\\b\\llvm-clang-x86_64-sie-win\\build\\tools\\lld\\test\\COFF\\Output\\import_weak_alias.test.tmp.qux.obj Z:\\b\\llvm-clang-x86_64-sie-win\\build\\tools\\lld\\test\\COFF\\Output\\import_weak_alias.test.tmp.foo.obj -out:Z:\\b\\llvm-clang-x86_64-sie-win\\build\\tools\\lld\\test\\COFF\\Output\\import_weak_alias.test.tmp.dll -dll
# | Exception Code: 0xC0000005
# | #0 0x00007ff8e5361b39 (C:\Windows\System32\KERNELBASE.dll+0x41b39)
# | #1 0x00007ff64855bb18 (z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe+0xcbb18)
# | #2 0x00007ff6485e32db (z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe+0x1532db)
# | #3 0x00007ff64853d9aa (z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe+0xad9aa)
# | #4 0x00007ff64853da14 (z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe+0xada14)
# | #5 0x00007ff64acaf254 (z:\b\llvm-clang-x86_64-sie-win\build\bin\lld-link.exe+0x281f254)
# | #6 0x00007ff8e7947ac4 (C:\Windows\System32\KERNEL32.DLL+0x17ac4)
# | #7 0x00007ff8e879a8c1 (C:\Windows\SYSTEM32\ntdll.dll+0x5a8c1)
# `-----------------------------
# error: command failed with exit status: 0xc0000005
--
********************
```
Any idea what might be happening here?

https://github.com/llvm/llvm-project/pull/151255