llvm-project/llvm/lib/Bitcode/Writer
Teresa Johnson 620c140a9b [ThinLTO] Always emit a summary when compiling in ThinLTO mode
Summary:
Emit an empty summary section, instead of no summary section, when
there are no global variables in the index. This ensures that LTO
will treat these files as ThinLTO inputs, instead of as regular
LTO inputs.

In addition to not being what the user likely intended when
compiling with -flto=thin, the current behavior is problematic for
distributed build systems that expect to get ThinLTO index and imports
files back for each input compiled with -flto=thin. Combining into
a single regular LTO module also reduces the backend parallelism.
And in the case where the index was suppressed due to uses in
inline assembly, combining into a single LTO module could provoke
renaming of duplicates that we were trying to prevent by suppressing
the index.

This change required a couple of fixes to handle the empty summary
section.

Reviewers: mehdi_amini

Subscribers: mehdi_amini, llvm-commits, pcc

Differential Revision: https://reviews.llvm.org/D24779

llvm-svn: 282037
2016-09-20 23:07:17 +00:00
..
BitWriter.cpp Introduce LLVMWriteBitcodeToMemoryBuffer C API function. 2014-10-14 00:30:59 +00:00
BitcodeWriter.cpp [ThinLTO] Always emit a summary when compiling in ThinLTO mode 2016-09-20 23:07:17 +00:00
BitcodeWriterPass.cpp [PM] Port ModuleSummaryIndex analysis to new pass manager 2016-08-12 13:53:02 +00:00
CMakeLists.txt modules: Add explicit dependency on intrinsics_gen 2015-06-16 00:44:12 +00:00
LLVMBuild.txt [ThinLTO] BitcodeWriter still requires Analysis library 2016-04-11 14:59:07 +00:00
ValueEnumerator.cpp Add an assertion for the value enumerator (bitcode writer) NFC 2016-07-08 01:13:41 +00:00
ValueEnumerator.h IR: Allow metadata attachments on declarations, and fix lazy loaded metadata issue with globals. 2016-06-21 23:42:48 +00:00