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llvm / lld / d75aa4903ff00bb2f95fbdfc6923f978e5858148
commitd75aa4903ff00bb2f95fbdfc6923f978e5858148[log] [tgz]
authorRui Ueyama <ruiu@google.com>Wed Dec 05 19:13:31 2018 +0000
committerRui Ueyama <ruiu@google.com>Wed Dec 05 19:13:31 2018 +0000
treea96cf634fd788036d6a516eb2beccdd5d6ed92a4
parent45524b4fb1827487968f8cdb754071fc4c1f75b8 [diff]
Do not use a hash table to uniquify mergeable strings.

Previously, we have a hash table containing strings and their offsets
to manage mergeable strings. Technically we can live without that, because
we can do binary search on a vector of mergeable strings to find a mergeable
strings.

We did have both the hash table and the binary search because we thought
that that is faster.

We recently observed that lld tend to consume more memory than gold when
building an output with debug info. A few percent of memory is consumed by
the hash table. So, we needed to reevaluate whether or not having the extra
hash table is a good CPU/memory tradeoff. I run a few benchmarks with and
without the hash table.

I got a mixed result for the benchmark. We observed a regression for some
programs by removing the hash table (that's what we expected), but we also
observed that performance imrpovements for some programs. This is perhaps
due to reduced memory usage.

Differential Revision: https://reviews.llvm.org/D55234

git-svn-id: https://llvm.org/svn/llvm-project/lld/trunk@348401 91177308-0d34-0410-b5e6-96231b3b80d8
2 files changed
tree: a96cf634fd788036d6a516eb2beccdd5d6ed92a4
  1. cmake/
  2. COFF/
  3. Common/
  4. docs/
  5. ELF/
  6. include/
  7. lib/
  8. MinGW/
  9. test/
  10. tools/
  11. unittests/
  12. utils/
  13. wasm/
  14. .arcconfig
  15. .clang-format
  16. .gitignore
  17. CMakeLists.txt
  18. CODE_OWNERS.TXT
  19. LICENSE.TXT
  20. README.md
README.md

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.