[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>
llvm-svn: 266446
diff --git a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
index 1b90c88..0d10282 100644
--- a/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
+++ b/llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
@@ -1098,7 +1098,7 @@
Record.push_back(N->getEmissionKind());
Record.push_back(VE.getMetadataOrNullID(N->getEnumTypes().get()));
Record.push_back(VE.getMetadataOrNullID(N->getRetainedTypes().get()));
- Record.push_back(VE.getMetadataOrNullID(N->getSubprograms().get()));
+ Record.push_back(/* subprograms */ 0);
Record.push_back(VE.getMetadataOrNullID(N->getGlobalVariables().get()));
Record.push_back(VE.getMetadataOrNullID(N->getImportedEntities().get()));
Record.push_back(N->getDWOId());
@@ -1127,6 +1127,7 @@
Record.push_back(N->getVirtualIndex());
Record.push_back(N->getFlags());
Record.push_back(N->isOptimized());
+ Record.push_back(VE.getMetadataOrNullID(N->getRawUnit()));
Record.push_back(VE.getMetadataOrNullID(N->getTemplateParams().get()));
Record.push_back(VE.getMetadataOrNullID(N->getDeclaration()));
Record.push_back(VE.getMetadataOrNullID(N->getVariables().get()));