[PATCH] D54747: Discard debuginfo for object files empty after GC

[Fangrui Song via Phabricator via llvm-commits]

MaskRay added a comment.

In D54747#1342666 <https://reviews.llvm.org/D54747#1342666>, @rocallahan wrote:

> Here are some results for the rusoto test in https://github.com/rust-lang/rust/issues/56068#issue-382175735:
>
> | LLD                       | Binary size in bytes |
> | LLD 6.0.1                 | 43,791,192           |
> | LLD 8.0.0 1cfcf404f6b23943405bc3c5bb5940b10b914624               | 43,861,056           |
> | LLD 8.0.0 1cfcf404f6b23943405bc3c5bb5940b10b914624 `--start-lib` | 43,844,760           |
> | LLD 8.0.0 1cfcf404f6b23943405bc3c5bb5940b10b914624 + this patch  | 6,281,488            |
> |
>
> For `--start-lib` I wrapped `--start-lib`/`--end-lib` around all object files.
>
> As I expected `--start-lib` didn't make much difference. The dependencies containing debuginfo that I want to be GCed away are already packaged into static libraries before being passed to the final link.


The improvement of this patch looks really promising! Do you have numbers with ld.bfd and gold?



================
Comment at: lld/ELF/MarkLive.cpp:195
+    return;
+  if (!Sec->File || !ObjFile<ELFT>::classof(Sec->File))
+    return;
----------------
> `!ObjFile<ELFT>::classof(Sec->File)`

Can this happen?


================
Comment at: lld/ELF/MarkLive.cpp:199
+    Sec->getFile<ELFT>()->HasLiveCodeOrData = true;
+  }
+}
----------------
The brace is redundant.


Repository:
  rLLD LLVM Linker

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  https://reviews.llvm.org/D54747/new/

https://reviews.llvm.org/D54747