#include "llvm/ADT/DenseMap.h" #include "llvm/ADT/StringExtras.h" #include "llvm/ADT/StringSet.h" #include "llvm/DebugInfo/DIContext.h" #include "llvm/DebugInfo/DWARF/DWARFContext.h" #include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h" #include "llvm/Object/ObjectFile.h" #include "llvm/Support/JSON.h" #define DEBUG_TYPE "dwarfdump" using namespace llvm; using namespace object; /// This represents the number of categories of debug location coverage being /// calculated. The first category is the number of variables with 0% location /// coverage, but the last category is the number of variables with 100% /// location coverage. constexpr int NumOfCoverageCategories = 12; /// Holds statistics for one function (or other entity that has a PC range and /// contains variables, such as a compile unit). struct PerFunctionStats { /// Number of inlined instances of this function. unsigned NumFnInlined = 0; /// Number of inlined instances that have abstract origins. unsigned NumAbstractOrigins = 0; /// Number of variables and parameters with location across all inlined /// instances. unsigned TotalVarWithLoc = 0; /// Number of constants with location across all inlined instances. unsigned ConstantMembers = 0; /// List of all Variables and parameters in this function. StringSet<> VarsInFunction; /// Compile units also cover a PC range, but have this flag set to false. bool IsFunction = false; /// Verify function definition has PC addresses (for detecting when /// a function has been inlined everywhere). bool HasPCAddresses = false; /// Function has source location information. bool HasSourceLocation = false; /// Number of function parameters. unsigned NumParams = 0; /// Number of function parameters with source location. unsigned NumParamSourceLocations = 0; /// Number of function parameters with type. unsigned NumParamTypes = 0; /// Number of function parameters with a DW_AT_location. unsigned NumParamLocations = 0; /// Number of variables. unsigned NumVars = 0; /// Number of variables with source location. unsigned NumVarSourceLocations = 0; /// Number of variables with type. unsigned NumVarTypes = 0; /// Number of variables with DW_AT_location. unsigned NumVarLocations = 0; }; /// Holds accumulated global statistics about DIEs. struct GlobalStats { /// Total number of PC range bytes covered by DW_AT_locations. unsigned ScopeBytesCovered = 0; /// Total number of PC range bytes in each variable's enclosing scope. unsigned ScopeBytes = 0; /// Total number of PC range bytes covered by DW_AT_locations with /// the debug entry values (DW_OP_entry_value). unsigned ScopeEntryValueBytesCovered = 0; /// Total number of PC range bytes covered by DW_AT_locations of /// formal parameters. unsigned ParamScopeBytesCovered = 0; /// Total number of PC range bytes in each variable's enclosing scope /// (only for parameters). unsigned ParamScopeBytes = 0; /// Total number of PC range bytes covered by DW_AT_locations with /// the debug entry values (DW_OP_entry_value) (only for parameters). unsigned ParamScopeEntryValueBytesCovered = 0; /// Total number of PC range bytes covered by DW_AT_locations (only for local /// variables). unsigned VarScopeBytesCovered = 0; /// Total number of PC range bytes in each variable's enclosing scope /// (only for local variables). unsigned VarScopeBytes = 0; /// Total number of PC range bytes covered by DW_AT_locations with /// the debug entry values (DW_OP_entry_value) (only for local variables). unsigned VarScopeEntryValueBytesCovered = 0; /// Total number of call site entries (DW_AT_call_file & DW_AT_call_line). unsigned CallSiteEntries = 0; /// Total number of call site DIEs (DW_TAG_call_site). unsigned CallSiteDIEs = 0; /// Total number of call site parameter DIEs (DW_TAG_call_site_parameter). unsigned CallSiteParamDIEs = 0; /// Total byte size of concrete functions. This byte size includes /// inline functions contained in the concrete functions. unsigned FunctionSize = 0; /// Total byte size of inlined functions. This is the total number of bytes /// for the top inline functions within concrete functions. This can help /// tune the inline settings when compiling to match user expectations. unsigned InlineFunctionSize = 0; }; /// Holds accumulated debug location statistics about local variables and /// formal parameters. struct LocationStats { /// Map the scope coverage decile to the number of variables in the decile. /// The first element of the array (at the index zero) represents the number /// of variables with the no debug location at all, but the last element /// in the vector represents the number of fully covered variables within /// its scope. std::vector VarParamLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// Map non debug entry values coverage. std::vector VarParamNonEntryValLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// The debug location statistics for formal parameters. std::vector ParamLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// Map non debug entry values coverage for formal parameters. std::vector ParamNonEntryValLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// The debug location statistics for local variables. std::vector VarLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// Map non debug entry values coverage for local variables. std::vector VarNonEntryValLocStats{ std::vector(NumOfCoverageCategories, 0)}; /// Total number of local variables and function parameters processed. unsigned NumVarParam = 0; /// Total number of formal parameters processed. unsigned NumParam = 0; /// Total number of local variables processed. unsigned NumVar = 0; }; /// Collect debug location statistics for one DIE. static void collectLocStats(uint64_t BytesCovered, uint64_t BytesInScope, std::vector &VarParamLocStats, std::vector &ParamLocStats, std::vector &VarLocStats, bool IsParam, bool IsLocalVar) { auto getCoverageBucket = [BytesCovered, BytesInScope]() -> unsigned { // No debug location at all for the variable. if (BytesCovered == 0) return 0; // Fully covered variable within its scope. if (BytesCovered >= BytesInScope) return NumOfCoverageCategories - 1; // Get covered range (e.g. 20%-29%). unsigned LocBucket = 100 * (double)BytesCovered / BytesInScope; LocBucket /= 10; return LocBucket + 1; }; unsigned CoverageBucket = getCoverageBucket(); VarParamLocStats[CoverageBucket]++; if (IsParam) ParamLocStats[CoverageBucket]++; else if (IsLocalVar) VarLocStats[CoverageBucket]++; } /// Construct an identifier for a given DIE from its Prefix, Name, DeclFileName /// and DeclLine. The identifier aims to be unique for any unique entities, /// but keeping the same among different instances of the same entity. static std::string constructDieID(DWARFDie Die, StringRef Prefix = StringRef()) { std::string IDStr; llvm::raw_string_ostream ID(IDStr); ID << Prefix << Die.getName(DINameKind::LinkageName); // Prefix + Name is enough for local variables and parameters. if (!Prefix.empty() && !Prefix.equals("g")) return ID.str(); auto DeclFile = Die.findRecursively(dwarf::DW_AT_decl_file); std::string File; if (DeclFile) { DWARFUnit *U = Die.getDwarfUnit(); if (const auto *LT = U->getContext().getLineTableForUnit(U)) if (LT->getFileNameByIndex( dwarf::toUnsigned(DeclFile, 0), U->getCompilationDir(), DILineInfoSpecifier::FileLineInfoKind::AbsoluteFilePath, File)) File = sys::path::filename(File); } ID << ":" << (File.empty() ? "/" : File); ID << ":" << dwarf::toUnsigned(Die.findRecursively(dwarf::DW_AT_decl_line), 0); return ID.str(); } /// Collect debug info quality metrics for one DIE. static void collectStatsForDie(DWARFDie Die, std::string FnPrefix, std::string VarPrefix, uint64_t BytesInScope, uint32_t InlineDepth, StringMap &FnStatMap, GlobalStats &GlobalStats, LocationStats &LocStats) { bool HasLoc = false; bool HasSrcLoc = false; bool HasType = false; bool IsArtificial = false; uint64_t BytesCovered = 0; uint64_t BytesEntryValuesCovered = 0; auto &FnStats = FnStatMap[FnPrefix]; bool IsParam = Die.getTag() == dwarf::DW_TAG_formal_parameter; bool IsLocalVar = Die.getTag() == dwarf::DW_TAG_variable; if (Die.getTag() == dwarf::DW_TAG_call_site || Die.getTag() == dwarf::DW_TAG_GNU_call_site) { GlobalStats.CallSiteDIEs++; return; } if (Die.getTag() == dwarf::DW_TAG_call_site_parameter || Die.getTag() == dwarf::DW_TAG_GNU_call_site_parameter) { GlobalStats.CallSiteParamDIEs++; return; } if (!IsParam && !IsLocalVar && Die.getTag() != dwarf::DW_TAG_member) { // Not a variable or constant member. return; } if (Die.findRecursively(dwarf::DW_AT_decl_file) && Die.findRecursively(dwarf::DW_AT_decl_line)) HasSrcLoc = true; if (Die.findRecursively(dwarf::DW_AT_type)) HasType = true; if (Die.find(dwarf::DW_AT_artificial)) IsArtificial = true; auto IsEntryValue = [&](ArrayRef D) -> bool { DWARFUnit *U = Die.getDwarfUnit(); DataExtractor Data(toStringRef(D), Die.getDwarfUnit()->getContext().isLittleEndian(), 0); DWARFExpression Expression(Data, U->getAddressByteSize()); // Consider the expression containing the DW_OP_entry_value as // an entry value. return llvm::any_of(Expression, [](DWARFExpression::Operation &Op) { return Op.getCode() == dwarf::DW_OP_entry_value || Op.getCode() == dwarf::DW_OP_GNU_entry_value; }); }; if (Die.find(dwarf::DW_AT_const_value)) { // This catches constant members *and* variables. HasLoc = true; BytesCovered = BytesInScope; } else { if (Die.getTag() == dwarf::DW_TAG_member) { // Non-const member. return; } // Handle variables and function arguments. Expected> Loc = Die.getLocations(dwarf::DW_AT_location); if (!Loc) { consumeError(Loc.takeError()); } else { HasLoc = true; // Get PC coverage. auto Default = find_if( *Loc, [](const DWARFLocationExpression &L) { return !L.Range; }); if (Default != Loc->end()) { // Assume the entire range is covered by a single location. BytesCovered = BytesInScope; } else { for (auto Entry : *Loc) { uint64_t BytesEntryCovered = Entry.Range->HighPC - Entry.Range->LowPC; BytesCovered += BytesEntryCovered; if (IsEntryValue(Entry.Expr)) BytesEntryValuesCovered += BytesEntryCovered; } } } } // Calculate the debug location statistics. if (BytesInScope) { LocStats.NumVarParam++; if (IsParam) LocStats.NumParam++; else if (IsLocalVar) LocStats.NumVar++; collectLocStats(BytesCovered, BytesInScope, LocStats.VarParamLocStats, LocStats.ParamLocStats, LocStats.VarLocStats, IsParam, IsLocalVar); // Non debug entry values coverage statistics. collectLocStats(BytesCovered - BytesEntryValuesCovered, BytesInScope, LocStats.VarParamNonEntryValLocStats, LocStats.ParamNonEntryValLocStats, LocStats.VarNonEntryValLocStats, IsParam, IsLocalVar); } // Collect PC range coverage data. if (DWARFDie D = Die.getAttributeValueAsReferencedDie(dwarf::DW_AT_abstract_origin)) Die = D; std::string VarID = constructDieID(Die, VarPrefix); FnStats.VarsInFunction.insert(VarID); if (BytesInScope) { FnStats.TotalVarWithLoc += (unsigned)HasLoc; // Turns out we have a lot of ranges that extend past the lexical scope. GlobalStats.ScopeBytesCovered += std::min(BytesInScope, BytesCovered); GlobalStats.ScopeBytes += BytesInScope; GlobalStats.ScopeEntryValueBytesCovered += BytesEntryValuesCovered; if (IsParam) { GlobalStats.ParamScopeBytesCovered += std::min(BytesInScope, BytesCovered); GlobalStats.ParamScopeBytes += BytesInScope; GlobalStats.ParamScopeEntryValueBytesCovered += BytesEntryValuesCovered; } else if (IsLocalVar) { GlobalStats.VarScopeBytesCovered += std::min(BytesInScope, BytesCovered); GlobalStats.VarScopeBytes += BytesInScope; GlobalStats.VarScopeEntryValueBytesCovered += BytesEntryValuesCovered; } assert(GlobalStats.ScopeBytesCovered <= GlobalStats.ScopeBytes); } else if (Die.getTag() == dwarf::DW_TAG_member) { FnStats.ConstantMembers++; } else { FnStats.TotalVarWithLoc += (unsigned)HasLoc; } if (!IsArtificial) { if (IsParam) { FnStats.NumParams++; if (HasType) FnStats.NumParamTypes++; if (HasSrcLoc) FnStats.NumParamSourceLocations++; if (HasLoc) FnStats.NumParamLocations++; } else if (IsLocalVar) { FnStats.NumVars++; if (HasType) FnStats.NumVarTypes++; if (HasSrcLoc) FnStats.NumVarSourceLocations++; if (HasLoc) FnStats.NumVarLocations++; } } } /// Recursively collect debug info quality metrics. static void collectStatsRecursive(DWARFDie Die, std::string FnPrefix, std::string VarPrefix, uint64_t BytesInScope, uint32_t InlineDepth, StringMap &FnStatMap, GlobalStats &GlobalStats, LocationStats &LocStats) { const dwarf::Tag Tag = Die.getTag(); // Skip function types. if (Tag == dwarf::DW_TAG_subroutine_type) return; // Handle any kind of lexical scope. const bool IsFunction = Tag == dwarf::DW_TAG_subprogram; const bool IsBlock = Tag == dwarf::DW_TAG_lexical_block; const bool IsInlinedFunction = Tag == dwarf::DW_TAG_inlined_subroutine; if (IsFunction || IsInlinedFunction || IsBlock) { // Reset VarPrefix when entering a new function. if (Die.getTag() == dwarf::DW_TAG_subprogram || Die.getTag() == dwarf::DW_TAG_inlined_subroutine) VarPrefix = "v"; // Ignore forward declarations. if (Die.find(dwarf::DW_AT_declaration)) return; // Check for call sites. if (Die.find(dwarf::DW_AT_call_file) && Die.find(dwarf::DW_AT_call_line)) GlobalStats.CallSiteEntries++; // PC Ranges. auto RangesOrError = Die.getAddressRanges(); if (!RangesOrError) { llvm::consumeError(RangesOrError.takeError()); return; } auto Ranges = RangesOrError.get(); uint64_t BytesInThisScope = 0; for (auto Range : Ranges) BytesInThisScope += Range.HighPC - Range.LowPC; // Count the function. if (!IsBlock) { // Skip over abstract origins. if (Die.find(dwarf::DW_AT_inline)) return; std::string FnID = constructDieID(Die); // We've seen an (inlined) instance of this function. auto &FnStats = FnStatMap[FnID]; FnStats.IsFunction = true; if (IsInlinedFunction) { FnStats.NumFnInlined++; if (Die.findRecursively(dwarf::DW_AT_abstract_origin)) FnStats.NumAbstractOrigins++; } if (BytesInThisScope && !IsInlinedFunction) FnStats.HasPCAddresses = true; if (Die.findRecursively(dwarf::DW_AT_decl_file) && Die.findRecursively(dwarf::DW_AT_decl_line)) FnStats.HasSourceLocation = true; // Update function prefix. FnPrefix = FnID; } if (BytesInThisScope) { BytesInScope = BytesInThisScope; if (IsFunction) GlobalStats.FunctionSize += BytesInThisScope; else if (IsInlinedFunction && InlineDepth == 0) GlobalStats.InlineFunctionSize += BytesInThisScope; } } else { // Not a scope, visit the Die itself. It could be a variable. collectStatsForDie(Die, FnPrefix, VarPrefix, BytesInScope, InlineDepth, FnStatMap, GlobalStats, LocStats); } // Set InlineDepth correctly for child recursion if (IsFunction) InlineDepth = 0; else if (IsInlinedFunction) ++InlineDepth; // Traverse children. unsigned LexicalBlockIndex = 0; DWARFDie Child = Die.getFirstChild(); while (Child) { std::string ChildVarPrefix = VarPrefix; if (Child.getTag() == dwarf::DW_TAG_lexical_block) ChildVarPrefix += toHex(LexicalBlockIndex++) + '.'; collectStatsRecursive(Child, FnPrefix, ChildVarPrefix, BytesInScope, InlineDepth, FnStatMap, GlobalStats, LocStats); Child = Child.getSibling(); } } /// Print machine-readable output. /// The machine-readable format is single-line JSON output. /// \{ static void printDatum(raw_ostream &OS, const char *Key, json::Value Value) { OS << ",\"" << Key << "\":" << Value; LLVM_DEBUG(llvm::dbgs() << Key << ": " << Value << '\n'); } static void printLocationStats(raw_ostream &OS, const char *Key, std::vector &LocationStats) { OS << ",\"" << Key << " with 0% of its scope covered\":" << LocationStats[0]; LLVM_DEBUG(llvm::dbgs() << Key << " with 0% of its scope covered: " << LocationStats[0] << '\n'); OS << ",\"" << Key << " with (0%,10%) of its scope covered\":" << LocationStats[1]; LLVM_DEBUG(llvm::dbgs() << Key << " with (0%,10%) of its scope covered: " << LocationStats[1] << '\n'); for (unsigned i = 2; i < NumOfCoverageCategories - 1; ++i) { OS << ",\"" << Key << " with [" << (i - 1) * 10 << "%," << i * 10 << "%) of its scope covered\":" << LocationStats[i]; LLVM_DEBUG(llvm::dbgs() << Key << " with [" << (i - 1) * 10 << "%," << i * 10 << "%) of its scope covered: " << LocationStats[i]); } OS << ",\"" << Key << " with 100% of its scope covered\":" << LocationStats[NumOfCoverageCategories - 1]; LLVM_DEBUG(llvm::dbgs() << Key << " with 100% of its scope covered: " << LocationStats[NumOfCoverageCategories - 1]); } /// \} /// Collect debug info quality metrics for an entire DIContext. /// /// Do the impossible and reduce the quality of the debug info down to a few /// numbers. The idea is to condense the data into numbers that can be tracked /// over time to identify trends in newer compiler versions and gauge the effect /// of particular optimizations. The raw numbers themselves are not particularly /// useful, only the delta between compiling the same program with different /// compilers is. bool collectStatsForObjectFile(ObjectFile &Obj, DWARFContext &DICtx, Twine Filename, raw_ostream &OS) { StringRef FormatName = Obj.getFileFormatName(); GlobalStats GlobalStats; LocationStats LocStats; StringMap Statistics; for (const auto &CU : static_cast(&DICtx)->compile_units()) if (DWARFDie CUDie = CU->getNonSkeletonUnitDIE(false)) collectStatsRecursive(CUDie, "/", "g", 0, 0, Statistics, GlobalStats, LocStats); /// The version number should be increased every time the algorithm is changed /// (including bug fixes). New metrics may be added without increasing the /// version. unsigned Version = 4; unsigned VarParamTotal = 0; unsigned VarParamUnique = 0; unsigned VarParamWithLoc = 0; unsigned NumFunctions = 0; unsigned NumInlinedFunctions = 0; unsigned NumFuncsWithSrcLoc = 0; unsigned NumAbstractOrigins = 0; unsigned ParamTotal = 0; unsigned ParamWithType = 0; unsigned ParamWithLoc = 0; unsigned ParamWithSrcLoc = 0; unsigned VarTotal = 0; unsigned VarWithType = 0; unsigned VarWithSrcLoc = 0; unsigned VarWithLoc = 0; for (auto &Entry : Statistics) { PerFunctionStats &Stats = Entry.getValue(); unsigned TotalVars = Stats.VarsInFunction.size() * Stats.NumFnInlined; // Count variables in concrete out-of-line functions and in global scope. if (Stats.HasPCAddresses || !Stats.IsFunction) TotalVars += Stats.VarsInFunction.size(); unsigned Constants = Stats.ConstantMembers; VarParamWithLoc += Stats.TotalVarWithLoc + Constants; VarParamTotal += TotalVars; VarParamUnique += Stats.VarsInFunction.size(); LLVM_DEBUG(for (auto &V : Stats.VarsInFunction) llvm::dbgs() << Entry.getKey() << ": " << V.getKey() << "\n"); NumFunctions += Stats.IsFunction; NumFuncsWithSrcLoc += Stats.HasSourceLocation; NumInlinedFunctions += Stats.IsFunction * Stats.NumFnInlined; NumAbstractOrigins += Stats.IsFunction * Stats.NumAbstractOrigins; ParamTotal += Stats.NumParams; ParamWithType += Stats.NumParamTypes; ParamWithLoc += Stats.NumParamLocations; ParamWithSrcLoc += Stats.NumParamSourceLocations; VarTotal += Stats.NumVars; VarWithType += Stats.NumVarTypes; VarWithLoc += Stats.NumVarLocations; VarWithSrcLoc += Stats.NumVarSourceLocations; } // Print summary. OS.SetBufferSize(1024); OS << "{\"version\":" << Version; LLVM_DEBUG(llvm::dbgs() << "Variable location quality metrics\n"; llvm::dbgs() << "---------------------------------\n"); printDatum(OS, "file", Filename.str()); printDatum(OS, "format", FormatName); printDatum(OS, "source functions", NumFunctions); printDatum(OS, "source functions with location", NumFuncsWithSrcLoc); printDatum(OS, "inlined functions", NumInlinedFunctions); printDatum(OS, "inlined funcs with abstract origins", NumAbstractOrigins); printDatum(OS, "unique source variables", VarParamUnique); printDatum(OS, "source variables", VarParamTotal); printDatum(OS, "variables with location", VarParamWithLoc); printDatum(OS, "call site entries", GlobalStats.CallSiteEntries); printDatum(OS, "call site DIEs", GlobalStats.CallSiteDIEs); printDatum(OS, "call site parameter DIEs", GlobalStats.CallSiteParamDIEs); printDatum(OS, "scope bytes total", GlobalStats.ScopeBytes); printDatum(OS, "scope bytes covered", GlobalStats.ScopeBytesCovered); printDatum(OS, "entry value scope bytes covered", GlobalStats.ScopeEntryValueBytesCovered); printDatum(OS, "formal params scope bytes total", GlobalStats.ParamScopeBytes); printDatum(OS, "formal params scope bytes covered", GlobalStats.ParamScopeBytesCovered); printDatum(OS, "formal params entry value scope bytes covered", GlobalStats.ParamScopeEntryValueBytesCovered); printDatum(OS, "vars scope bytes total", GlobalStats.VarScopeBytes); printDatum(OS, "vars scope bytes covered", GlobalStats.VarScopeBytesCovered); printDatum(OS, "vars entry value scope bytes covered", GlobalStats.VarScopeEntryValueBytesCovered); printDatum(OS, "total function size", GlobalStats.FunctionSize); printDatum(OS, "total inlined function size", GlobalStats.InlineFunctionSize); printDatum(OS, "total formal params", ParamTotal); printDatum(OS, "formal params with source location", ParamWithSrcLoc); printDatum(OS, "formal params with type", ParamWithType); printDatum(OS, "formal params with binary location", ParamWithLoc); printDatum(OS, "total vars", VarTotal); printDatum(OS, "vars with source location", VarWithSrcLoc); printDatum(OS, "vars with type", VarWithType); printDatum(OS, "vars with binary location", VarWithLoc); printDatum(OS, "total variables procesed by location statistics", LocStats.NumVarParam); printLocationStats(OS, "variables", LocStats.VarParamLocStats); printLocationStats(OS, "variables (excluding the debug entry values)", LocStats.VarParamNonEntryValLocStats); printDatum(OS, "total params procesed by location statistics", LocStats.NumParam); printLocationStats(OS, "params", LocStats.ParamLocStats); printLocationStats(OS, "params (excluding the debug entry values)", LocStats.ParamNonEntryValLocStats); printDatum(OS, "total vars procesed by location statistics", LocStats.NumVar); printLocationStats(OS, "vars", LocStats.VarLocStats); printLocationStats(OS, "vars (excluding the debug entry values)", LocStats.VarNonEntryValLocStats); OS << "}\n"; LLVM_DEBUG( llvm::dbgs() << "Total Availability: " << (int)std::round((VarParamWithLoc * 100.0) / VarParamTotal) << "%\n"; llvm::dbgs() << "PC Ranges covered: " << (int)std::round((GlobalStats.ScopeBytesCovered * 100.0) / GlobalStats.ScopeBytes) << "%\n"); return true; }