[Bug ld/29424] New: ld chokes on DW_FORM_rnglistx

[ro at gcc dot gnu.org]

https://sourceware.org/bugzilla/show_bug.cgi?id=29424

            Bug ID: 29424
           Summary: ld chokes on DW_FORM_rnglistx
           Product: binutils
           Version: 2.39
            Status: NEW
          Severity: normal
          Priority: P2
         Component: ld
          Assignee: unassigned at sourceware dot org
          Reporter: ro at gcc dot gnu.org
  Target Milestone: ---
              Host: sparc64-unknown-linux-gnu
            Target: sparc64-unknown-linux-gnu
             Build: sparc64-unknown-linux-gnu

When building LLVM main on Debian 11/sparc64, I ran into a very weird error
linking one of the compiler-rt testcases, Sanitizer-sparc-Test (the 32-bit
version): I see several instances of

/usr/bin/ld: /usr/bin/ld: DWARF error: invalid or unhandled FORM value: 0x23

where 0x23 is DW_FORM_rnglistx, which clang emits with -gdwarf-5 (the default).
Initially, I used a patch to default to -gdwarf-4 on this target, which avoids
emitting DW_FORM_rnglistx:

    https://reviews.llvm.org/D130566

to avoid this.  I couldn't reproduce the problem on Ubuntu 20.04, however.

Later on, it turned out that the error only happens when there are several
undefined referenes to libatomic functions.  When I do link with -latomic, both
the references become resolved and the DWARF error vanishes.

I've originally seen this with the bundled GNU ld 2.38.50.20220707, but it also
reprodues with 2.38.90.20220728.

I cannot tell what to do about this error: ignore the problem, stating `don't
do
this'.  I don't have (and probably won't have the time to create) a smaller
testcase: the bundle of objects (sparc64-rnglistx.tar.xz) is ca. 1.5 MB, too
large to attach here.  I've done this on gcc202 in the GCC cfarm, just in case.

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