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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

49
llvm/lib/Bitcode/Reader/BitcodeReader.cpp
View File

@@ -1948,6 +1948,7 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
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 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
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 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
// 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 @@ std::error_code BitcodeReader::parseMetadata(bool ModuleLevel) {
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