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[dsymutil] Prevent non-determinism due to threading.
Before this patch, analyzeContext called getCanonicalDIEOffset(), for which the result depends on the timings of the setCanonicalDIEOffset() calls in the cloneLambda. This can lead to slightly different output between runs due to threading. To prevent this from happening, we now record the output debug info size after importing the modules (before any concurrent processing takes place). This value, named the ModulesEndOffset is used to compare the canonical DIE offset against. If the value is greater than this offset, the canonical DIE offset has been updated during cloning, and should therefore not be considered for pruning. Differential revision: https://reviews.llvm.org/D51443 llvm-svn: 341649
This commit is contained in:
Jonas Devlieghere
parent
2d11f5dd93
commit
e226b57357
@ -256,6 +256,7 @@ static bool analyzeContextInfo(const DWARFDie &DIE, unsigned ParentIdx,
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CompileUnit &CU, DeclContext *CurrentDeclContext,
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UniquingStringPool &StringPool,
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DeclContextTree &Contexts,
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uint64_t ModulesEndOffset,
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bool InImportedModule = false) {
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unsigned MyIdx = CU.getOrigUnit().getDIEIndex(DIE);
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CompileUnit::DIEInfo &Info = CU.getInfo(MyIdx);
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@ -296,8 +297,9 @@ static bool analyzeContextInfo(const DWARFDie &DIE, unsigned ParentIdx,
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Info.Prune = InImportedModule;
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if (DIE.hasChildren())
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for (auto Child : DIE.children())
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Info.Prune &= analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext,
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StringPool, Contexts, InImportedModule);
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Info.Prune &=
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analyzeContextInfo(Child, MyIdx, CU, CurrentDeclContext, StringPool,
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Contexts, ModulesEndOffset, InImportedModule);
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// Prune this DIE if it is either a forward declaration inside a
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// DW_TAG_module or a DW_TAG_module that contains nothing but
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@ -306,11 +308,16 @@ static bool analyzeContextInfo(const DWARFDie &DIE, unsigned ParentIdx,
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(isTypeTag(DIE.getTag()) &&
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dwarf::toUnsigned(DIE.find(dwarf::DW_AT_declaration), 0));
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// Don't prune it if there is no definition for the DIE.
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Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
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// Only prune forward declarations inside a DW_TAG_module for which a
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// definition exists elsewhere.
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if (ModulesEndOffset == 0)
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Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset();
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else
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Info.Prune &= Info.Ctxt && Info.Ctxt->getCanonicalDIEOffset() > 0 &&
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Info.Ctxt->getCanonicalDIEOffset() <= ModulesEndOffset;
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return Info.Prune;
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}
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} // namespace dsymutil
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static bool dieNeedsChildrenToBeMeaningful(uint32_t Tag) {
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switch (Tag) {
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@ -2025,7 +2032,7 @@ bool DwarfLinker::registerModuleReference(
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const DWARFDie &CUDie, const DWARFUnit &Unit, DebugMap &ModuleMap,
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const DebugMapObject &DMO, RangesTy &Ranges, OffsetsStringPool &StringPool,
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UniquingStringPool &UniquingStringPool, DeclContextTree &ODRContexts,
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unsigned &UnitID, unsigned Indent, bool Quiet) {
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uint64_t ModulesEndOffset, unsigned &UnitID, unsigned Indent, bool Quiet) {
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std::string PCMfile = dwarf::toString(
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CUDie.find({dwarf::DW_AT_dwo_name, dwarf::DW_AT_GNU_dwo_name}), "");
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if (PCMfile.empty())
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@ -2067,9 +2074,10 @@ bool DwarfLinker::registerModuleReference(
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// Cyclic dependencies are disallowed by Clang, but we still
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// shouldn't run into an infinite loop, so mark it as processed now.
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ClangModules.insert({PCMfile, DwoId});
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if (Error E = loadClangModule(PCMfile, PCMpath, Name, DwoId, ModuleMap, DMO,
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Ranges, StringPool, UniquingStringPool,
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ODRContexts, UnitID, Indent + 2, Quiet)) {
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if (Error E =
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loadClangModule(PCMfile, PCMpath, Name, DwoId, ModuleMap, DMO, Ranges,
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StringPool, UniquingStringPool, ODRContexts,
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ModulesEndOffset, UnitID, Indent + 2, Quiet)) {
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consumeError(std::move(E));
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return false;
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}
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@ -2103,7 +2111,7 @@ Error DwarfLinker::loadClangModule(
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uint64_t DwoId, DebugMap &ModuleMap, const DebugMapObject &DMO,
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RangesTy &Ranges, OffsetsStringPool &StringPool,
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UniquingStringPool &UniquingStringPool, DeclContextTree &ODRContexts,
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unsigned &UnitID, unsigned Indent, bool Quiet) {
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uint64_t ModulesEndOffset, unsigned &UnitID, unsigned Indent, bool Quiet) {
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SmallString<80> Path(Options.PrependPath);
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if (sys::path::is_relative(Filename))
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sys::path::append(Path, ModulePath, Filename);
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@ -2164,8 +2172,8 @@ Error DwarfLinker::loadClangModule(
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if (!CUDie)
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continue;
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if (!registerModuleReference(CUDie, *CU, ModuleMap, DMO, Ranges, StringPool,
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UniquingStringPool, ODRContexts, UnitID,
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Indent, Quiet)) {
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UniquingStringPool, ODRContexts,
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ModulesEndOffset, UnitID, Indent, Quiet)) {
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if (Unit) {
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std::string Err =
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(Filename +
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@ -2194,7 +2202,7 @@ Error DwarfLinker::loadClangModule(
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ModuleName);
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Unit->setHasInterestingContent();
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analyzeContextInfo(CUDie, 0, *Unit, &ODRContexts.getRoot(),
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UniquingStringPool, ODRContexts);
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UniquingStringPool, ODRContexts, ModulesEndOffset);
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// Keep everything.
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Unit->markEverythingAsKept();
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}
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@ -2469,7 +2477,7 @@ bool DwarfLinker::link(const DebugMap &Map) {
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if (CUDie && !LLVM_UNLIKELY(Options.Update))
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registerModuleReference(CUDie, *CU, ModuleMap, LinkContext.DMO,
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LinkContext.Ranges, OffsetsStringPool,
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UniquingStringPool, ODRContexts, UnitID);
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UniquingStringPool, ODRContexts, 0, UnitID);
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}
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}
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@ -2477,6 +2485,13 @@ bool DwarfLinker::link(const DebugMap &Map) {
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if (MaxDwarfVersion == 0)
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MaxDwarfVersion = 3;
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// At this point we know how much data we have emitted. We use this value to
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// compare canonical DIE offsets in analyzeContextInfo to see if a definition
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// is already emitted, without being affected by canonical die offsets set
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// later. This prevents undeterminism when analyze and clone execute
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// concurrently, as clone set the canonical DIE offset and analyze reads it.
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const uint64_t ModulesEndOffset = OutputDebugInfoSize;
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// These variables manage the list of processed object files.
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// The mutex and condition variable are to ensure that this is thread safe.
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std::mutex ProcessedFilesMutex;
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@ -2503,8 +2518,8 @@ bool DwarfLinker::link(const DebugMap &Map) {
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if (!CUDie || LLVM_UNLIKELY(Options.Update) ||
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!registerModuleReference(CUDie, *CU, ModuleMap, LinkContext.DMO,
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LinkContext.Ranges, OffsetsStringPool,
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UniquingStringPool, ODRContexts, UnitID,
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Quiet)) {
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UniquingStringPool, ODRContexts,
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ModulesEndOffset, UnitID, Quiet)) {
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LinkContext.CompileUnits.push_back(llvm::make_unique<CompileUnit>(
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*CU, UnitID++, !Options.NoODR && !Options.Update, ""));
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}
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@ -2517,7 +2532,7 @@ bool DwarfLinker::link(const DebugMap &Map) {
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continue;
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analyzeContextInfo(CurrentUnit->getOrigUnit().getUnitDIE(), 0,
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*CurrentUnit, &ODRContexts.getRoot(),
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UniquingStringPool, ODRContexts);
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UniquingStringPool, ODRContexts, ModulesEndOffset);
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}
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};
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@ -199,7 +199,8 @@ private:
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RangesTy &Ranges,
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OffsetsStringPool &OffsetsStringPool,
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UniquingStringPool &UniquingStringPoolStringPool,
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DeclContextTree &ODRContexts, unsigned &UnitID,
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DeclContextTree &ODRContexts,
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uint64_t ModulesEndOffset, unsigned &UnitID,
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unsigned Indent = 0, bool Quiet = false);
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/// Recursively add the debug info in this clang module .pcm
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@ -210,8 +211,9 @@ private:
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DebugMap &ModuleMap, const DebugMapObject &DMO,
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RangesTy &Ranges, OffsetsStringPool &OffsetsStringPool,
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UniquingStringPool &UniquingStringPool,
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DeclContextTree &ODRContexts, unsigned &UnitID,
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unsigned Indent = 0, bool Quiet = false);
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DeclContextTree &ODRContexts, uint64_t ModulesEndOffset,
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unsigned &UnitID, unsigned Indent = 0,
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bool Quiet = false);
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/// Flags passed to DwarfLinker::lookForDIEsToKeep
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enum TraversalFlags {
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