Statistics.cpp | Explore in Territory

//===-- Statistics.cpp - Debug Info quality metrics -----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#include "llvm-dwarfdump.h"
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/DenseSet.h"
#include "llvm/ADT/StringSet.h"
#include "llvm/DebugInfo/DWARF/DWARFContext.h"
#include "llvm/DebugInfo/DWARF/DWARFDebugLoc.h"
#include "llvm/DebugInfo/DWARF/DWARFExpression.h"
#include "llvm/Object/ObjectFile.h"
#include "llvm/Support/JSON.h"

#define DEBUG_TYPE …
usingnamespacellvm;
usingnamespacellvm::dwarfdump;
usingnamespacellvm::object;

namespace {
/// 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 = …;

/// This is used for zero location coverage bucket.
constexpr unsigned ZeroCoverageBucket = …;

/// The UINT64_MAX is used as an indication of the overflow.
constexpr uint64_t OverflowValue = …;

/// This represents variables DIE offsets.
AbstractOriginVarsTy;
/// This maps function DIE offset to its variables.
AbstractOriginVarsTyMap;
/// This represents function DIE offsets containing an abstract_origin.
FunctionsWithAbstractOriginTy;

/// This represents a data type for the stats and it helps us to
/// detect an overflow.
/// NOTE: This can be implemented as a template if there is an another type
/// needing this.
struct SaturatingUINT64 { … };

/// Utility struct to store the full location of a DIE - its CU and offset.
struct DIELocation { … };
/// This represents DWARF locations of CrossCU referencing DIEs.
CrossCUReferencingDIELocationTy;

/// This maps function DIE offset to its DWARF CU.
FunctionDIECUTyMap;

/// Holds statistics for one function (or other entity that has a PC range and
/// contains variables, such as a compile unit).
struct PerFunctionStats { … };

/// Holds accumulated global statistics about DIEs.
struct GlobalStats { … };

/// Holds accumulated debug location statistics about local variables and
/// formal parameters.
struct LocationStats { … };

/// Holds accumulated debug line statistics across all CUs.
struct LineStats { … };
} // namespace

/// Collect debug location statistics for one DIE.
static void collectLocStats(uint64_t ScopeBytesCovered, uint64_t BytesInScope,
                            std::vector<SaturatingUINT64> &VarParamLocStats,
                            std::vector<SaturatingUINT64> &ParamLocStats,
                            std::vector<SaturatingUINT64> &LocalVarLocStats,
                            bool IsParam, bool IsLocalVar) { … }

/// 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()) { … }

/// Return the number of bytes in the overlap of ranges A and B.
static uint64_t calculateOverlap(DWARFAddressRange A, DWARFAddressRange B) { … }

/// Collect debug info quality metrics for one DIE.
static void collectStatsForDie(DWARFDie Die, const std::string &FnPrefix,
                               const std::string &VarPrefix,
                               uint64_t BytesInScope, uint32_t InlineDepth,
                               StringMap<PerFunctionStats> &FnStatMap,
                               GlobalStats &GlobalStats,
                               LocationStats &LocStats,
                               AbstractOriginVarsTy *AbstractOriginVariables) { … }

/// Recursively collect variables from subprogram with DW_AT_inline attribute.
static void collectAbstractOriginFnInfo(
    DWARFDie Die, uint64_t SPOffset,
    AbstractOriginVarsTyMap &GlobalAbstractOriginFnInfo,
    AbstractOriginVarsTyMap &LocalAbstractOriginFnInfo) { … }

/// Recursively collect debug info quality metrics.
static void collectStatsRecursive(
    DWARFDie Die, std::string FnPrefix, std::string VarPrefix,
    uint64_t BytesInScope, uint32_t InlineDepth,
    StringMap<PerFunctionStats> &FnStatMap, GlobalStats &GlobalStats,
    LocationStats &LocStats, FunctionDIECUTyMap &AbstractOriginFnCUs,
    AbstractOriginVarsTyMap &GlobalAbstractOriginFnInfo,
    AbstractOriginVarsTyMap &LocalAbstractOriginFnInfo,
    FunctionsWithAbstractOriginTy &FnsWithAbstractOriginToBeProcessed,
    AbstractOriginVarsTy *AbstractOriginVarsPtr = nullptr) { … }

/// Print human-readable output.
/// \{
static void printDatum(json::OStream &J, const char *Key, json::Value Value) { … }

static void printLocationStats(json::OStream &J, const char *Key,
                               std::vector<SaturatingUINT64> &LocationStats) { … }

static void printSectionSizes(json::OStream &J, const SectionSizes &Sizes) { … }

/// Stop tracking variables that contain abstract_origin with a location.
/// This is used for out-of-order DW_AT_inline subprograms only.
static void updateVarsWithAbstractOriginLocCovInfo(
    DWARFDie FnDieWithAbstractOrigin,
    AbstractOriginVarsTy &AbstractOriginVars) { … }

/// Collect zero location coverage for inlined variables which refer to
/// a DW_AT_inline copy of subprogram that is out of order in the DWARF.
/// Also cover the variables of a concrete function (represented with
/// the DW_TAG_subprogram) with an abstract_origin attribute.
static void collectZeroLocCovForVarsWithAbstractOrigin(
    DWARFUnit *DwUnit, GlobalStats &GlobalStats, LocationStats &LocStats,
    AbstractOriginVarsTyMap &LocalAbstractOriginFnInfo,
    FunctionsWithAbstractOriginTy &FnsWithAbstractOriginToBeProcessed) { … }

/// Collect zero location coverage for inlined variables which refer to
/// a DW_AT_inline copy of subprogram that is in a different CU.
static void collectZeroLocCovForVarsWithCrossCUReferencingAbstractOrigin(
    LocationStats &LocStats, FunctionDIECUTyMap AbstractOriginFnCUs,
    AbstractOriginVarsTyMap &GlobalAbstractOriginFnInfo,
    CrossCUReferencingDIELocationTy &CrossCUReferencesToBeResolved) { … }

/// \}

/// 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 dwarfdump::collectStatsForObjectFile(ObjectFile &Obj, DWARFContext &DICtx,
                                          const Twine &Filename,
                                          raw_ostream &OS) { … }
llvm/llvm/tools/llvm-dwarfdump/Statistics.cpp
