tree 00aecfa4e065a5bc728b30baa2be51301ed38010
parent 79d34bb7a877627c478e3b2f7c20142ba1af0539
author Fangrui Song <i@maskray.me> 1706038695 -0800
committer Copybara-Service <copybara-worker@google.com> 1706038796 -0800

[ELF] --save-temps --lto-emit-asm: derive ELF/asm file names from bitcode file names

Port COFF's https://reviews.llvm.org/D78221 and
https://reviews.llvm.org/D137217 to ELF. For the in-process ThinLTO
link, `ld.lld --save-temps a.o d/b.o -o out` will create
ELF relocatable files `out.lto.a.o`/`d/out.lto.b.o` instead of
`out1.lto.o`/`out2.lto.o`. Deriving the LTO-generated relocatable file
name from bitcode file names helps debugging.

The relocatable file name from the first regular LTO partition does not
change: `out.lto.o`. The second, if present due to `--lto-partition=`,
changes from `out1.lto.o` to `lto.1.o`.

For an archive member, e.g. `d/a.a(coll.o at 8)`,
the relocatable file is `d/out.lto.a.a(coll.o at 8).o`.

`--lto-emit-asm` file names are changed similarly. `--lto-emit-asm -o
out` now creates `out.lto.s` instead of `out`, therefore the
`--lto-emit-asm -o -` idiom no longer works. However, I think this new
behavior (which matches COFF) is better since keeping or removing
`--lto-emit-asm` will dump different files, instead of overwriting the
`-o` output file from an executable/shared object to an assembly file.

Reviewers: rnk, igorkudrin, xur-llvm, teresajohnson, ZequanWu

Reviewed By: teresajohnson

Pull Request: https://github.com/llvm/llvm-project/pull/78835

GitOrigin-RevId: f7669ba3d9443bc95dd63fa25beea13e6265fdc5