Teresa Johnson f345d54a63 [ThinLTO] Efficiency improvement when writing module path string table ...

Summary:
When writing the combined index, we are walking the entire module
path StringMap in the full index, and checking whether each one should be
included in the index being written. For distributed backends, where we
write an individual combined index for each file, each with only a few
module paths, this is incredibly inefficient. Add a method that takes
a callback and hides the details of whether we are writing the full
combined index, or just a slice, and in the latter case it walks the set
of modules to include instead of the entire index.

For a huge application with around 23K files (i.e. where we were iterating
through the 23K-entry modulePath StringMap 23K times), this change improved
the thin link time by a whopping 48%.

Reviewers: pcc

Subscribers: Prazek, inglorion, llvm-commits

Differential Revision: https://reviews.llvm.org/D33813

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@304516 91177308-0d34-0410-b5e6-96231b3b80d8

2017-06-02 01:56:02 +00:00

..

Reader

(NFC) Track global summary liveness in GVFlags.

2017-06-01 20:30:06 +00:00

Writer

[ThinLTO] Efficiency improvement when writing module path string table

2017-06-02 01:56:02 +00:00

CMakeLists.txt

Move library stuff out of the toplevel CMakeLists.txt file.

2011-02-18 22:06:14 +00:00

LLVMBuild.txt

LLVMBuild: Introduce a common section which currently has a list of the

2011-12-12 22:45:54 +00:00