[LLD][COFF] Implement /nodbgdirmerge

[namazso]

MSVC link has a hidden flag called /nodbgdirmerge. It causes debug directory contents to be emitted into a .cvinfo section, rather than just .rdata. It would be great if lld-link supported the same flag.

In LLD the section to use is picked here:

llvm-project/lld/COFF/Writer.cpp

Line 1215 in 1c3cff9

debugInfoSec = config->mingw ? buildidSec : rdataSec;

The two options are either adding something in there to make a new section, or just always making a new .cvinfo instead and using the builtin default merges from here to merge it into rdata by default:

llvm-project/lld/COFF/Driver.cpp

Line 2024 in 1c3cff9

parseMerge(".idata=.rdata");

I'm not sure which would be the better option.

[llvmbot]

@llvm/issue-subscribers-lld-coff

Author: None (namazso)

MSVC link has a hidden flag called `/nodbgdirmerge`. It causes debug directory contents to be emitted into a `.cvinfo` section, rather than just `.rdata`. It would be great if lld-link supported the same flag.

In LLD the section to use is picked here:

llvm-project/lld/COFF/Writer.cpp

Line 1215 in 1c3cff9

debugInfoSec = config->mingw ? buildidSec : rdataSec;

The two options are either adding something in there to make a new section, or just always making a new .cvinfo instead and using the builtin default merges from here to merge it into rdata by default:

llvm-project/lld/COFF/Driver.cpp

Line 2024 in 1c3cff9

parseMerge(".idata=.rdata");

I'm not sure which would be the better option.