[PATCH] D27775: [ThinLTO] Import composite types as declarations

[Teresa Johnson via Phabricator via llvm-commits]

tejohnson created this revision.
tejohnson added reviewers: mehdi_amini, dblaikie, aprantl.
tejohnson added a subscriber: llvm-commits.

When reading the metadata bitcode, create a type declaration when
possible for composite types when we are importing. Doing this in
the bitcode reader saves memory. Also it works naturally in the case
when the type ODR map contains a definition for the same composite type
because it was used in the importing module (buildODRType will
automatically use the existing definition and not create a type
declaration).

For Chromium built with -g2, this reduces the aggregate size of the
generated native object files by 66% (from 31G to 10G). It reduced
the time through the ThinLTO link and backend phases by about 20% on
my machine.


https://reviews.llvm.org/D27775

Files:
  include/llvm/Bitcode/BitcodeReader.h
  lib/Bitcode/Reader/BitcodeReader.cpp
  lib/Bitcode/Reader/MetadataLoader.cpp
  lib/Bitcode/Reader/MetadataLoader.h
  lib/LTO/LTOBackend.cpp
  lib/LTO/ThinLTOCodeGenerator.cpp
  test/ThinLTO/X86/Inputs/debuginfo-compositetype-import.ll
  test/ThinLTO/X86/debuginfo-compositetype-import.ll

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