c05126bdfc
Summary: The LTO pass and LLD linker have logic in them that forces extraction and prevent internalization of needed runtime calls. However, these currently take all RTLibcalls into account, even if the target does not support them. The target opts-out of a libcall if it sets its name to nullptr. This patch pulls this logic out into a class in the header so that LTO / lld can use it to determine if a symbol actually needs to be kept. This is important for targets like AMDGPU that want to be able to use `lld` to perform the final link step, but does not want the overhead of uncalled functions. (This adds like a second to the link time trivially)
LLVM Linker (lld)
This directory and its subdirectories contain source code for the LLVM Linker, a modular cross platform linker which is built as part of the LLVM compiler infrastructure project.
lld is open source software. You may freely distribute it under the terms of the license agreement found in LICENSE.txt.
Benchmarking
In order to make sure various developers can evaluate patches over the same tests, we create a collection of self contained programs.
It is hosted at https://s3-us-west-2.amazonaws.com/linker-tests/lld-speed-test.tar.xz
The current sha256 is 10eec685463d5a8bbf08d77f4ca96282161d396c65bd97dc99dbde644a31610f.