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author | David Blaikie <dblaikie@gmail.com> | 2014-01-03 04:20:26 +0000 |
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committer | David Blaikie <dblaikie@gmail.com> | 2014-01-03 04:20:26 +0000 |
commit | 5df1dd410e9426600ef123d6d48dceeb9d75d1ca (patch) | |
tree | a723d9c36adaf8973621a1042ee454045f07649c /lib | |
parent | 32abfefd9b7cbbf759a5b5d61f251e9515e465bf (diff) | |
download | llvm-5df1dd410e9426600ef123d6d48dceeb9d75d1ca.tar.gz llvm-5df1dd410e9426600ef123d6d48dceeb9d75d1ca.tar.bz2 llvm-5df1dd410e9426600ef123d6d48dceeb9d75d1ca.tar.xz |
Debug Info: Type Units: Simplify type hashing using IR-provided unique names.
What's good for LTO metadata size problems ought to be good for non-LTO
debug info size too, so let's rely on the same uniqueness in both cases.
If it's insufficient for non-LTO for whatever reason (since we now won't
be uniquing CU-local types or any C types - but these are likely to not
be the most significant contributors to type bloat) we should consider a
frontend solution that'll help both LTO and non-LTO alike, rather than
using DWARF-level DIE-hashing that only helps non-LTO debug info size.
It's also much simpler this way and benefits C++ even more since we can
deduplicate lexically separate definitions of the same C++ type since
they have the same mangled name.
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@198397 91177308-0d34-0410-b5e6-96231b3b80d8
Diffstat (limited to 'lib')
-rw-r--r-- | lib/CodeGen/AsmPrinter/DwarfDebug.cpp | 62 | ||||
-rw-r--r-- | lib/CodeGen/AsmPrinter/DwarfDebug.h | 3 | ||||
-rw-r--r-- | lib/CodeGen/AsmPrinter/DwarfUnit.cpp | 47 |
3 files changed, 19 insertions, 93 deletions
diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp index a0052f605d..e8e1e50c9b 100644 --- a/lib/CodeGen/AsmPrinter/DwarfDebug.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfDebug.cpp @@ -58,11 +58,6 @@ static cl::opt<bool> UnknownLocations( cl::desc("Make an absence of debug location information explicit."), cl::init(false)); -static cl::opt<bool> -GenerateODRHash("generate-odr-hash", cl::Hidden, - cl::desc("Add an ODR hash to external type DIEs."), - cl::init(false)); - static cl::opt<bool> GenerateCUHash("generate-cu-hash", cl::Hidden, cl::desc("Add the CU hash as the dwo_id."), cl::init(false)); @@ -1019,41 +1014,6 @@ void DwarfDebug::collectDeadVariables() { } } -// Type Signature [7.27] and ODR Hash code. - -/// \brief Grabs the string in whichever attribute is passed in and returns -/// a reference to it. Returns "" if the attribute doesn't exist. -static StringRef getDIEStringAttr(DIE *Die, unsigned Attr) { - DIEValue *V = Die->findAttribute(Attr); - - if (DIEString *S = dyn_cast_or_null<DIEString>(V)) - return S->getString(); - - return StringRef(""); -} - -/// Return true if the current DIE is contained within an anonymous namespace. -static bool isContainedInAnonNamespace(DIE *Die) { - DIE *Parent = Die->getParent(); - - while (Parent) { - if (Parent->getTag() == dwarf::DW_TAG_namespace && - getDIEStringAttr(Parent, dwarf::DW_AT_name) == "") - return true; - Parent = Parent->getParent(); - } - - return false; -} - -/// Test if the current CU language is C++ and that we have -/// a named type that is not contained in an anonymous namespace. -static bool shouldAddODRHash(DwarfTypeUnit *CU, DIE *Die) { - return CU->getLanguage() == dwarf::DW_LANG_C_plus_plus && - getDIEStringAttr(Die, dwarf::DW_AT_name) != "" && - !isContainedInAnonNamespace(Die); -} - void DwarfDebug::finalizeModuleInfo() { // Collect info for variables that were optimized out. collectDeadVariables(); @@ -3041,8 +3001,8 @@ void DwarfDebug::emitDebugStrDWO() { OffSec, StrSym); } -void DwarfDebug::addDwarfTypeUnitType(uint16_t Language, DIE *RefDie, - DICompositeType CTy) { +void DwarfDebug::addDwarfTypeUnitType(uint16_t Language, StringRef Identifier, + DIE *RefDie, DICompositeType CTy) { const DwarfTypeUnit *&TU = DwarfTypeUnits[CTy]; if (!TU) { DIE *UnitDie = new DIE(dwarf::DW_TAG_type_unit); @@ -3057,16 +3017,14 @@ void DwarfDebug::addDwarfTypeUnitType(uint16_t Language, DIE *RefDie, DIE *Die = NewTU->createTypeDIE(CTy); - if (GenerateODRHash && shouldAddODRHash(NewTU, Die)) - NewTU->addUInt(UnitDie, dwarf::DW_AT_GNU_odr_signature, - dwarf::DW_FORM_data8, - DIEHash().computeDIEODRSignature(*Die)); - // FIXME: This won't handle circularly referential structures, as the DIE - // may have references to other DIEs still under construction and missing - // their signature. Hashing should walk through the signatures to their - // referenced type, or possibly walk the precomputed hashes of related types - // at the end. - uint64_t Signature = DIEHash().computeTypeSignature(*Die); + MD5 Hash; + Hash.update(Identifier); + // ... take the least significant 8 bytes and return those. Our MD5 + // implementation always returns its results in little endian, swap bytes + // appropriately. + MD5::MD5Result Result; + Hash.final(Result); + uint64_t Signature = *reinterpret_cast<uint64_t *>(Result + 8); NewTU->setTypeSignature(Signature); NewTU->setType(Die); diff --git a/lib/CodeGen/AsmPrinter/DwarfDebug.h b/lib/CodeGen/AsmPrinter/DwarfDebug.h index b81688ea3f..84d9cae7a1 100644 --- a/lib/CodeGen/AsmPrinter/DwarfDebug.h +++ b/lib/CodeGen/AsmPrinter/DwarfDebug.h @@ -695,7 +695,8 @@ public: /// \brief Add a DIE to the set of types that we're going to pull into /// type units. - void addDwarfTypeUnitType(uint16_t Language, DIE *Die, DICompositeType CTy); + void addDwarfTypeUnitType(uint16_t Language, StringRef Identifier, DIE *Die, + DICompositeType CTy); /// \brief Add a label so that arange data can be generated for it. void addArangeLabel(SymbolCU SCU) { ArangeLabels.push_back(SCU); } diff --git a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp index 0e3db3c508..7de4b1e187 100644 --- a/lib/CodeGen/AsmPrinter/DwarfUnit.cpp +++ b/lib/CodeGen/AsmPrinter/DwarfUnit.cpp @@ -928,41 +928,6 @@ DIE *DwarfUnit::createTypeDIE(DICompositeType Ty) { return TyDIE; } -/// Return true if the type is appropriately scoped to be contained inside -/// its own type unit. -static bool isDwarfTypeUnitScoped(DIType Ty, const DwarfDebug *DD) { - DIScope Parent = DD->resolve(Ty.getContext()); - while (Parent) { - // Don't generate a hash for anything scoped inside a function. - if (Parent.isSubprogram()) - return false; - Parent = DD->resolve(Parent.getContext()); - } - return true; -} - -/// Return true if the type should be split out into a type unit. -static bool shouldCreateDwarfTypeUnit(DICompositeType CTy, - const DwarfDebug *DD) { - if (!GenerateDwarfTypeUnits) - return false; - - uint16_t Tag = CTy.getTag(); - - switch (Tag) { - case dwarf::DW_TAG_structure_type: - case dwarf::DW_TAG_union_type: - case dwarf::DW_TAG_enumeration_type: - case dwarf::DW_TAG_class_type: - // If this is a class, structure, union, or enumeration type - // that is a definition (not a declaration), and not scoped - // inside a function then separate this out as a type unit. - return !CTy.isForwardDecl() && isDwarfTypeUnitScoped(CTy, DD); - default: - return false; - } -} - /// getOrCreateTypeDIE - Find existing DIE or create new DIE for the /// given DIType. DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) { @@ -989,11 +954,13 @@ DIE *DwarfUnit::getOrCreateTypeDIE(const MDNode *TyNode) { constructTypeDIE(*TyDIE, DIBasicType(Ty)); else if (Ty.isCompositeType()) { DICompositeType CTy(Ty); - if (shouldCreateDwarfTypeUnit(CTy, DD)) { - DD->addDwarfTypeUnitType(getLanguage(), TyDIE, CTy); - // Skip updating the accellerator tables since this is not the full type - return TyDIE; - } + if (GenerateDwarfTypeUnits && !Ty.isForwardDecl()) + if (MDString *TypeId = CTy.getIdentifier()) { + DD->addDwarfTypeUnitType(getLanguage(), TypeId->getString(), TyDIE, + CTy); + // Skip updating the accellerator tables since this is not the full type + return TyDIE; + } constructTypeDIE(*TyDIE, CTy); } else { assert(Ty.isDerivedType() && "Unknown kind of DIType"); |