llvm/lib/Bitcode/Writer
Adrian Prantl 4eeaa0da04 [PR27284] Reverse the ownership between DICompileUnit and DISubprogram.
Currently each Function points to a DISubprogram and DISubprogram has a
scope field. For member functions the scope is a DICompositeType. DIScopes
point to the DICompileUnit to facilitate type uniquing.

Distinct DISubprograms (with isDefinition: true) are not part of the type
hierarchy and cannot be uniqued. This change removes the subprograms
list from DICompileUnit and instead adds a pointer to the owning compile
unit to distinct DISubprograms. This would make it easy for ThinLTO to
strip unneeded DISubprograms and their transitively referenced debug info.

Motivation
----------

Materializing DISubprograms is currently the most expensive operation when
doing a ThinLTO build of clang.

We want the DISubprogram to be stored in a separate Bitcode block (or the
same block as the function body) so we can avoid having to expensively
deserialize all DISubprograms together with the global metadata. If a
function has been inlined into another subprogram we need to store a
reference the block containing the inlined subprogram.

Attached to https://llvm.org/bugs/show_bug.cgi?id=27284 is a python script
that updates LLVM IR testcases to the new format.

http://reviews.llvm.org/D19034
<rdar://problem/25256815>

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@266446 91177308-0d34-0410-b5e6-96231b3b80d8
2016-04-15 15:57:41 +00:00
..
BitcodeWriter.cpp [PR27284] Reverse the ownership between DICompileUnit and DISubprogram. 2016-04-15 15:57:41 +00:00
BitcodeWriterPass.cpp [ThinLTO] Move summary computation from BitcodeWriter to new pass 2016-04-11 13:58:45 +00:00
BitWriter.cpp Introduce LLVMWriteBitcodeToMemoryBuffer C API function. 2014-10-14 00:30:59 +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 [GCC] Attribute ifunc support in llvm 2016-04-07 12:32:19 +00:00
ValueEnumerator.h Bitcode: Try to emit metadata in function blocks 2016-04-02 15:22:57 +00:00