[clang] [llvm] [dwarf] make dwarf fission compatible with RISCV relaxations (PR #164128)

[via llvm-commits]

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+; RUN: llc -dwarf-version=5 -split-dwarf-file=foo.dwo -O0 %s -mtriple=riscv64-unknown-linux-gnu -filetype=obj -o %t
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dlav-sc wrote:

> Could you generalize this test with multiple RUN lines

This patch only affects SplitDWARFv5 and shouldn't modify DWARFv4 and DWARFv5. As far as I know, Split DWARFv4 doesn't exist, as DWARF fission was initially introduced only in DWARFv5.

> I think we have an existing test somewhere that checks there are no relocations in .dwo files

Yes, I found a test (`llvm/test/DebugInfo/X86/fission-ranges.ll`) that uses objdump to ensure that .dwo file doesn't contain any relocations. I can try to make something similar.

https://github.com/llvm/llvm-project/pull/164128