[clang] [lld] [llvm] [Windows] Add support for emitting PGO/LTO magic strings in the Windows PE debug directory (PR #114260)

[Alexandre Ganea via cfe-commits]

aganea wrote:

> I would like to benchmark `lld` after this change, since I have added a loop that goes through every section of every object file. Could someone point in the direction of a good benchmark for that? I was thinking I can benchmark on the linking of `clang` or any other big project as a reference

I think benchmarking clang.exe itself would be a good testbed. Build the toolchain once in Release (first stage) then in another build folder, build it a second time (second stage), but using clang-cl.exe and LLd -link.exe from the first build folder (use ninja not MSBuild. Once the second stage has completed, delete clang.exe from output folder and pass `ninja clang -v -d keeprsp`. That will show the LLD command line which you can profile. You can also use —time-trace and add  proper instrumentation if not already done.
If you have trouble build all this I can provide more detailed instructions, please let me know.

https://github.com/llvm/llvm-project/pull/114260