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[PR27284] Reverse the ownership between DICompileUnit and DISubprogram.

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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
This commit is contained in:
Adrian Prantl
2016-04-15 15:57:41 +00:00
parent e76bda544b
commit 75819aedf6
540 changed files with 1780 additions and 2314 deletions
Download Patch File Download Diff File Expand all files Collapse all files

3
llvm/lib/Bitcode/Writer/BitcodeWriter.cpp
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@@ -1098,7 +1098,7 @@ static void writeDICompileUnit(const DICompileUnit *N,
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 @@ static void writeDISubprogram(const DISubprogram *N, const ValueEnumerator &VE,
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()));