Teresa Johnson 2d320e58a9 Restore "Resolution-based LTO API."
This restores commit r278330, with fixes for a few bot failures:
- Fix a late change I had made to the save temps output file that I
  missed due to existing files sitting on my disk
- Fix a bunch of Windows bot failures with "ambiguous call to overloaded
  function" due to confusion between llvm::make_unique vs
  std::make_unique (preface the new make_unique calls with "llvm::")
- Attempt to fix a modules bot failure by adding a missing include
  to LTO/Config.h.

Original change:

Resolution-based LTO API.

Summary:
This introduces a resolution-based LTO API. The main advantage of this API over
existing APIs is that it allows the linker to supply a resolution for each
symbol in each object, rather than the combined object as a whole. This will
become increasingly important for use cases such as ThinLTO which require us
to process symbol resolutions in a more complicated way than just adjusting
linkage.

Patch by Peter Collingbourne.

Reviewers: rafael, tejohnson, mehdi_amini

Subscribers: lhames, tejohnson, mehdi_amini, llvm-commits

Differential Revision: https://reviews.llvm.org/D20268

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@278338 91177308-0d34-0410-b5e6-96231b3b80d8
2016-08-11 14:58:12 +00:00
..

The LLVM Gold LTO Plugin
========================

This directory contains a plugin that is designed to work with binutils
gold linker. At present time, this is not the default linker in
binutils, and the default build of gold does not support plugins.

See docs/GoldPlugin.html for complete build and usage instructions.

NOTE: libLTO and LLVMgold aren't built without PIC because they would fail
to link on x86-64 with a relocation error: PIC and non-PIC can't be combined.
As an alternative to passing --enable-pic, you can use 'make ENABLE_PIC=1' in
your entire LLVM build.