[llvm-bugs] [Bug 44277] New: LLD segfaults when linking the Aarch64 Linux kernel with ThinLTO

[via llvm-bugs]

https://bugs.llvm.org/show_bug.cgi?id=44277

            Bug ID: 44277
           Summary: LLD segfaults when linking the Aarch64 Linux kernel
                    with ThinLTO
           Product: new-bugs
           Version: trunk
          Hardware: PC
                OS: Linux
            Status: NEW
          Severity: normal
          Priority: P
         Component: new bugs
          Assignee: vsk at apple.com
          Reporter: samitolvanen at google.com
                CC: htmldeveloper at gmail.com, llvm-bugs at lists.llvm.org,
                    ndesaulniers at google.com, ruiu at google.com,
                    tejohnson at google.com

Starting with commit 30038da15b18ac4e34b9ea7a648382ae481e4770 ("[DWARF] Allow
cross-CU references of subprogram definitions"), building the Linux kernel with
ThinLTO and LLD fails with a segmentation fault:

  ...
  LTO     vmlinux.o
Stack dump:
0.      Running pass 'Function Pass Manager' on module
'arch/arm64/built-in.a(kernel/time.o at 4094)'.
1.      Running pass 'AArch64 Assembly Printer' on function '@time_init'
LLVM ERROR: Failed to rename temporary file .thinlto-cache/Thin-d28bbb.tmp.o to
.thinlto-cache/llvmcache-C22016E1D1853F1DBC0C29919ED2F9B7CDF8E084: No such file
or directory

LLVM ERROR: Failed to rename temporary file .thinlto-cache/Thin-d9b995.tmp.o to
.thinlto-cache/llvmcache-BE7211A526D6D732AC88F1C1BCEC23592806F256: No such file
or directory

LLVM ERROR: Failed to rename temporary file .thinlto-cache/Thin-99c344.tmp.o to
.thinlto-cache/llvmcache-C7FECFD0C0C51CF353CF7961D21F44C1A8E02A6A: No such file
or directory

scripts/link-vmlinux.sh: line 71: 100211 Segmentation fault      ${LD}
${KBUILD_LDFLAGS} -r -o ${1} $(lto_lds) ${objects}
make: *** [Makefile:1136: vmlinux] Error 139


Steps to reproduce:

 $ git clone https://github.com/samitolvanen/linux.git
 $ cd linux
 $ git checkout clang-lto
 $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CC=clang LD=ld.lld 
 defconfig
 $ ./scripts/config -e LTO_CLANG -e THINLTO
 $ make ARCH=arm64 CROSS_COMPILE=aarch64-linux-gnu- CC=clang LD=ld.lld -j110


I've confirmed that reverting commit 30038da15b18ac4e34b9ea7a648382ae481e4770
fixes the issue.

Note that not passing --thinlto-cache-dir to LLD removes the "Failed to rename
temporary file" errors, but still results in a segfault.

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