[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/Reader/BitcodeReader.cpp b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
index 321c775..c832283 100644
--- a/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
+++ b/llvm/lib/Bitcode/Reader/BitcodeReader.cpp
@@ -1948,6 +1948,7 @@
if (Stream.EnterSubBlock(bitc::METADATA_BLOCK_ID))
return error("Invalid record");
+ std::vector<std::pair<DICompileUnit *, Metadata *>> CUSubprograms;
SmallVector<uint64_t, 64> Record;
auto getMD = [&](unsigned ID) -> Metadata * {
@@ -1976,6 +1977,13 @@
case BitstreamEntry::Error:
return error("Malformed block");
case BitstreamEntry::EndBlock:
+ // Upgrade old-style CU <-> SP pointers to point from SP to CU.
+ for (auto CU_SP : CUSubprograms)
+ if (auto *SPs = dyn_cast_or_null<MDTuple>(CU_SP.second))
+ for (auto &Op : SPs->operands())
+ if (auto *SP = dyn_cast_or_null<MDNode>(Op))
+ SP->replaceOperandWith(7, CU_SP.first);
+
MetadataList.tryToResolveCycles();
return std::error_code();
case BitstreamEntry::Record:
@@ -2232,24 +2240,32 @@
// Ignore Record[0], which indicates whether this compile unit is
// distinct. It's always distinct.
- MetadataList.assignValue(
- DICompileUnit::getDistinct(
- Context, Record[1], getMDOrNull(Record[2]),
- getMDString(Record[3]), Record[4], getMDString(Record[5]),
- Record[6], getMDString(Record[7]), Record[8],
- getMDOrNull(Record[9]), getMDOrNull(Record[10]),
- getMDOrNull(Record[11]), getMDOrNull(Record[12]),
- getMDOrNull(Record[13]),
- Record.size() <= 15 ? nullptr : getMDOrNull(Record[15]),
- Record.size() <= 14 ? 0 : Record[14]),
- NextMetadataNo++);
+ auto *CU = DICompileUnit::getDistinct(
+ Context, Record[1], getMDOrNull(Record[2]), getMDString(Record[3]),
+ Record[4], getMDString(Record[5]), Record[6], getMDString(Record[7]),
+ Record[8], getMDOrNull(Record[9]), getMDOrNull(Record[10]),
+ getMDOrNull(Record[12]), getMDOrNull(Record[13]),
+ Record.size() <= 15 ? nullptr : getMDOrNull(Record[15]),
+ Record.size() <= 14 ? 0 : Record[14]);
+
+ MetadataList.assignValue(CU, NextMetadataNo++);
+
+ // Move the Upgrade the list of subprograms.
+ if (Metadata *SPs = getMDOrNull(Record[11]))
+ CUSubprograms.push_back({CU, SPs});
break;
}
case bitc::METADATA_SUBPROGRAM: {
if (Record.size() != 18 && Record.size() != 19)
return error("Invalid record");
- bool HasFn = Record.size() == 19;
+ // Version 1 has a Function as Record[15].
+ // Version 2 has removed Record[15].
+ // Version 3 has the Unit as Record[15].
+ Metadata *CUorFn = getMDOrNull(Record[15]);
+ unsigned Offset = Record.size() == 19 ? 1 : 0;
+ bool HasFn = Offset && dyn_cast_or_null<ConstantAsMetadata>(CUorFn);
+ bool HasCU = Offset && !HasFn;
DISubprogram *SP = GET_OR_DISTINCT(
DISubprogram,
Record[0] || Record[8], // All definitions should be distinct.
@@ -2257,13 +2273,14 @@
getMDString(Record[3]), getMDOrNull(Record[4]), Record[5],
getMDOrNull(Record[6]), Record[7], Record[8], Record[9],
getMDOrNull(Record[10]), Record[11], Record[12], Record[13],
- Record[14], getMDOrNull(Record[15 + HasFn]),
- getMDOrNull(Record[16 + HasFn]), getMDOrNull(Record[17 + HasFn])));
+ Record[14], HasCU ? CUorFn : nullptr,
+ getMDOrNull(Record[15 + Offset]), getMDOrNull(Record[16 + Offset]),
+ getMDOrNull(Record[17 + Offset])));
MetadataList.assignValue(SP, NextMetadataNo++);
// Upgrade sp->function mapping to function->sp mapping.
- if (HasFn && Record[15]) {
- if (auto *CMD = dyn_cast<ConstantAsMetadata>(getMDOrNull(Record[15])))
+ if (HasFn) {
+ if (auto *CMD = dyn_cast<ConstantAsMetadata>(CUorFn))
if (auto *F = dyn_cast<Function>(CMD->getValue())) {
if (F->isMaterializable())
// Defer until materialized; unmaterialized functions may not have
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()));