| //===- SampleProfReader.h - Read LLVM sample profile data -------*- C++ -*-===// |
| // |
| // 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 |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file contains definitions needed for reading sample profiles. |
| // |
| // NOTE: If you are making changes to this file format, please remember |
| // to document them in the Clang documentation at |
| // tools/clang/docs/UsersManual.rst. |
| // |
| // Text format |
| // ----------- |
| // |
| // Sample profiles are written as ASCII text. The file is divided into |
| // sections, which correspond to each of the functions executed at runtime. |
| // Each section has the following format |
| // |
| // function1:total_samples:total_head_samples |
| // offset1[.discriminator]: number_of_samples [fn1:num fn2:num ... ] |
| // offset2[.discriminator]: number_of_samples [fn3:num fn4:num ... ] |
| // ... |
| // offsetN[.discriminator]: number_of_samples [fn5:num fn6:num ... ] |
| // offsetA[.discriminator]: fnA:num_of_total_samples |
| // offsetA1[.discriminator]: number_of_samples [fn7:num fn8:num ... ] |
| // ... |
| // |
| // This is a nested tree in which the identation represents the nesting level |
| // of the inline stack. There are no blank lines in the file. And the spacing |
| // within a single line is fixed. Additional spaces will result in an error |
| // while reading the file. |
| // |
| // Any line starting with the '#' character is completely ignored. |
| // |
| // Inlined calls are represented with indentation. The Inline stack is a |
| // stack of source locations in which the top of the stack represents the |
| // leaf function, and the bottom of the stack represents the actual |
| // symbol to which the instruction belongs. |
| // |
| // Function names must be mangled in order for the profile loader to |
| // match them in the current translation unit. The two numbers in the |
| // function header specify how many total samples were accumulated in the |
| // function (first number), and the total number of samples accumulated |
| // in the prologue of the function (second number). This head sample |
| // count provides an indicator of how frequently the function is invoked. |
| // |
| // There are two types of lines in the function body. |
| // |
| // * Sampled line represents the profile information of a source location. |
| // * Callsite line represents the profile information of a callsite. |
| // |
| // Each sampled line may contain several items. Some are optional (marked |
| // below): |
| // |
| // a. Source line offset. This number represents the line number |
| // in the function where the sample was collected. The line number is |
| // always relative to the line where symbol of the function is |
| // defined. So, if the function has its header at line 280, the offset |
| // 13 is at line 293 in the file. |
| // |
| // Note that this offset should never be a negative number. This could |
| // happen in cases like macros. The debug machinery will register the |
| // line number at the point of macro expansion. So, if the macro was |
| // expanded in a line before the start of the function, the profile |
| // converter should emit a 0 as the offset (this means that the optimizers |
| // will not be able to associate a meaningful weight to the instructions |
| // in the macro). |
| // |
| // b. [OPTIONAL] Discriminator. This is used if the sampled program |
| // was compiled with DWARF discriminator support |
| // (http://wiki.dwarfstd.org/index.php?title=Path_Discriminators). |
| // DWARF discriminators are unsigned integer values that allow the |
| // compiler to distinguish between multiple execution paths on the |
| // same source line location. |
| // |
| // For example, consider the line of code ``if (cond) foo(); else bar();``. |
| // If the predicate ``cond`` is true 80% of the time, then the edge |
| // into function ``foo`` should be considered to be taken most of the |
| // time. But both calls to ``foo`` and ``bar`` are at the same source |
| // line, so a sample count at that line is not sufficient. The |
| // compiler needs to know which part of that line is taken more |
| // frequently. |
| // |
| // This is what discriminators provide. In this case, the calls to |
| // ``foo`` and ``bar`` will be at the same line, but will have |
| // different discriminator values. This allows the compiler to correctly |
| // set edge weights into ``foo`` and ``bar``. |
| // |
| // c. Number of samples. This is an integer quantity representing the |
| // number of samples collected by the profiler at this source |
| // location. |
| // |
| // d. [OPTIONAL] Potential call targets and samples. If present, this |
| // line contains a call instruction. This models both direct and |
| // number of samples. For example, |
| // |
| // 130: 7 foo:3 bar:2 baz:7 |
| // |
| // The above means that at relative line offset 130 there is a call |
| // instruction that calls one of ``foo()``, ``bar()`` and ``baz()``, |
| // with ``baz()`` being the relatively more frequently called target. |
| // |
| // Each callsite line may contain several items. Some are optional. |
| // |
| // a. Source line offset. This number represents the line number of the |
| // callsite that is inlined in the profiled binary. |
| // |
| // b. [OPTIONAL] Discriminator. Same as the discriminator for sampled line. |
| // |
| // c. Number of samples. This is an integer quantity representing the |
| // total number of samples collected for the inlined instance at this |
| // callsite |
| // |
| // |
| // Binary format |
| // ------------- |
| // |
| // This is a more compact encoding. Numbers are encoded as ULEB128 values |
| // and all strings are encoded in a name table. The file is organized in |
| // the following sections: |
| // |
| // MAGIC (uint64_t) |
| // File identifier computed by function SPMagic() (0x5350524f463432ff) |
| // |
| // VERSION (uint32_t) |
| // File format version number computed by SPVersion() |
| // |
| // SUMMARY |
| // TOTAL_COUNT (uint64_t) |
| // Total number of samples in the profile. |
| // MAX_COUNT (uint64_t) |
| // Maximum value of samples on a line. |
| // MAX_FUNCTION_COUNT (uint64_t) |
| // Maximum number of samples at function entry (head samples). |
| // NUM_COUNTS (uint64_t) |
| // Number of lines with samples. |
| // NUM_FUNCTIONS (uint64_t) |
| // Number of functions with samples. |
| // NUM_DETAILED_SUMMARY_ENTRIES (size_t) |
| // Number of entries in detailed summary |
| // DETAILED_SUMMARY |
| // A list of detailed summary entry. Each entry consists of |
| // CUTOFF (uint32_t) |
| // Required percentile of total sample count expressed as a fraction |
| // multiplied by 1000000. |
| // MIN_COUNT (uint64_t) |
| // The minimum number of samples required to reach the target |
| // CUTOFF. |
| // NUM_COUNTS (uint64_t) |
| // Number of samples to get to the desrired percentile. |
| // |
| // NAME TABLE |
| // SIZE (uint32_t) |
| // Number of entries in the name table. |
| // NAMES |
| // A NUL-separated list of SIZE strings. |
| // |
| // FUNCTION BODY (one for each uninlined function body present in the profile) |
| // HEAD_SAMPLES (uint64_t) [only for top-level functions] |
| // Total number of samples collected at the head (prologue) of the |
| // function. |
| // NOTE: This field should only be present for top-level functions |
| // (i.e., not inlined into any caller). Inlined function calls |
| // have no prologue, so they don't need this. |
| // NAME_IDX (uint32_t) |
| // Index into the name table indicating the function name. |
| // SAMPLES (uint64_t) |
| // Total number of samples collected in this function. |
| // NRECS (uint32_t) |
| // Total number of sampling records this function's profile. |
| // BODY RECORDS |
| // A list of NRECS entries. Each entry contains: |
| // OFFSET (uint32_t) |
| // Line offset from the start of the function. |
| // DISCRIMINATOR (uint32_t) |
| // Discriminator value (see description of discriminators |
| // in the text format documentation above). |
| // SAMPLES (uint64_t) |
| // Number of samples collected at this location. |
| // NUM_CALLS (uint32_t) |
| // Number of non-inlined function calls made at this location. In the |
| // case of direct calls, this number will always be 1. For indirect |
| // calls (virtual functions and function pointers) this will |
| // represent all the actual functions called at runtime. |
| // CALL_TARGETS |
| // A list of NUM_CALLS entries for each called function: |
| // NAME_IDX (uint32_t) |
| // Index into the name table with the callee name. |
| // SAMPLES (uint64_t) |
| // Number of samples collected at the call site. |
| // NUM_INLINED_FUNCTIONS (uint32_t) |
| // Number of callees inlined into this function. |
| // INLINED FUNCTION RECORDS |
| // A list of NUM_INLINED_FUNCTIONS entries describing each of the inlined |
| // callees. |
| // OFFSET (uint32_t) |
| // Line offset from the start of the function. |
| // DISCRIMINATOR (uint32_t) |
| // Discriminator value (see description of discriminators |
| // in the text format documentation above). |
| // FUNCTION BODY |
| // A FUNCTION BODY entry describing the inlined function. |
| //===----------------------------------------------------------------------===// |
| |
| #ifndef LLVM_PROFILEDATA_SAMPLEPROFREADER_H |
| #define LLVM_PROFILEDATA_SAMPLEPROFREADER_H |
| |
| #include "llvm/ADT/SmallVector.h" |
| #include "llvm/ADT/StringMap.h" |
| #include "llvm/ADT/StringRef.h" |
| #include "llvm/ADT/Twine.h" |
| #include "llvm/IR/DiagnosticInfo.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/LLVMContext.h" |
| #include "llvm/IR/ProfileSummary.h" |
| #include "llvm/ProfileData/GCOV.h" |
| #include "llvm/ProfileData/SampleProf.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorOr.h" |
| #include "llvm/Support/MemoryBuffer.h" |
| #include "llvm/Support/SymbolRemappingReader.h" |
| #include <algorithm> |
| #include <cstdint> |
| #include <memory> |
| #include <string> |
| #include <system_error> |
| #include <vector> |
| |
| namespace llvm { |
| |
| class raw_ostream; |
| |
| namespace sampleprof { |
| |
| /// Sample-based profile reader. |
| /// |
| /// Each profile contains sample counts for all the functions |
| /// executed. Inside each function, statements are annotated with the |
| /// collected samples on all the instructions associated with that |
| /// statement. |
| /// |
| /// For this to produce meaningful data, the program needs to be |
| /// compiled with some debug information (at minimum, line numbers: |
| /// -gline-tables-only). Otherwise, it will be impossible to match IR |
| /// instructions to the line numbers collected by the profiler. |
| /// |
| /// From the profile file, we are interested in collecting the |
| /// following information: |
| /// |
| /// * A list of functions included in the profile (mangled names). |
| /// |
| /// * For each function F: |
| /// 1. The total number of samples collected in F. |
| /// |
| /// 2. The samples collected at each line in F. To provide some |
| /// protection against source code shuffling, line numbers should |
| /// be relative to the start of the function. |
| /// |
| /// The reader supports two file formats: text and binary. The text format |
| /// is useful for debugging and testing, while the binary format is more |
| /// compact and I/O efficient. They can both be used interchangeably. |
| class SampleProfileReader { |
| public: |
| SampleProfileReader(std::unique_ptr<MemoryBuffer> B, LLVMContext &C, |
| SampleProfileFormat Format = SPF_None) |
| : Profiles(0), Ctx(C), Buffer(std::move(B)), Format(Format) {} |
| |
| virtual ~SampleProfileReader() = default; |
| |
| /// Read and validate the file header. |
| virtual std::error_code readHeader() = 0; |
| |
| /// Read sample profiles from the associated file. |
| virtual std::error_code read() = 0; |
| |
| /// Print the profile for \p FName on stream \p OS. |
| void dumpFunctionProfile(StringRef FName, raw_ostream &OS = dbgs()); |
| |
| virtual void collectFuncsToUse(const Module &M) {} |
| |
| /// Print all the profiles on stream \p OS. |
| void dump(raw_ostream &OS = dbgs()); |
| |
| /// Return the samples collected for function \p F. |
| FunctionSamples *getSamplesFor(const Function &F) { |
| // The function name may have been updated by adding suffix. In sample |
| // profile, the function names are all stripped, so we need to strip |
| // the function name suffix before matching with profile. |
| return getSamplesFor(F.getName().split('.').first); |
| } |
| |
| /// Return the samples collected for function \p F. |
| virtual FunctionSamples *getSamplesFor(StringRef Fname) { |
| std::string FGUID; |
| Fname = getRepInFormat(Fname, getFormat(), FGUID); |
| auto It = Profiles.find(Fname); |
| if (It != Profiles.end()) |
| return &It->second; |
| return nullptr; |
| } |
| |
| /// Return all the profiles. |
| StringMap<FunctionSamples> &getProfiles() { return Profiles; } |
| |
| /// Report a parse error message. |
| void reportError(int64_t LineNumber, Twine Msg) const { |
| Ctx.diagnose(DiagnosticInfoSampleProfile(Buffer->getBufferIdentifier(), |
| LineNumber, Msg)); |
| } |
| |
| /// Create a sample profile reader appropriate to the file format. |
| static ErrorOr<std::unique_ptr<SampleProfileReader>> |
| create(const Twine &Filename, LLVMContext &C); |
| |
| /// Create a sample profile reader from the supplied memory buffer. |
| static ErrorOr<std::unique_ptr<SampleProfileReader>> |
| create(std::unique_ptr<MemoryBuffer> &B, LLVMContext &C); |
| |
| /// Return the profile summary. |
| ProfileSummary &getSummary() { return *(Summary.get()); } |
| |
| /// \brief Return the profile format. |
| SampleProfileFormat getFormat() { return Format; } |
| |
| protected: |
| /// Map every function to its associated profile. |
| /// |
| /// The profile of every function executed at runtime is collected |
| /// in the structure FunctionSamples. This maps function objects |
| /// to their corresponding profiles. |
| StringMap<FunctionSamples> Profiles; |
| |
| /// LLVM context used to emit diagnostics. |
| LLVMContext &Ctx; |
| |
| /// Memory buffer holding the profile file. |
| std::unique_ptr<MemoryBuffer> Buffer; |
| |
| /// Profile summary information. |
| std::unique_ptr<ProfileSummary> Summary; |
| |
| /// Take ownership of the summary of this reader. |
| static std::unique_ptr<ProfileSummary> |
| takeSummary(SampleProfileReader &Reader) { |
| return std::move(Reader.Summary); |
| } |
| |
| /// Compute summary for this profile. |
| void computeSummary(); |
| |
| /// \brief The format of sample. |
| SampleProfileFormat Format = SPF_None; |
| }; |
| |
| class SampleProfileReaderText : public SampleProfileReader { |
| public: |
| SampleProfileReaderText(std::unique_ptr<MemoryBuffer> B, LLVMContext &C) |
| : SampleProfileReader(std::move(B), C, SPF_Text) {} |
| |
| /// Read and validate the file header. |
| std::error_code readHeader() override { return sampleprof_error::success; } |
| |
| /// Read sample profiles from the associated file. |
| std::error_code read() override; |
| |
| /// Return true if \p Buffer is in the format supported by this class. |
| static bool hasFormat(const MemoryBuffer &Buffer); |
| }; |
| |
| class SampleProfileReaderBinary : public SampleProfileReader { |
| public: |
| SampleProfileReaderBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C, |
| SampleProfileFormat Format = SPF_None) |
| : SampleProfileReader(std::move(B), C, Format) {} |
| |
| /// Read and validate the file header. |
| virtual std::error_code readHeader() override; |
| |
| /// Read sample profiles from the associated file. |
| std::error_code read() override; |
| |
| protected: |
| /// Read a numeric value of type T from the profile. |
| /// |
| /// If an error occurs during decoding, a diagnostic message is emitted and |
| /// EC is set. |
| /// |
| /// \returns the read value. |
| template <typename T> ErrorOr<T> readNumber(); |
| |
| /// Read a numeric value of type T from the profile. The value is saved |
| /// without encoded. |
| template <typename T> ErrorOr<T> readUnencodedNumber(); |
| |
| /// Read a string from the profile. |
| /// |
| /// If an error occurs during decoding, a diagnostic message is emitted and |
| /// EC is set. |
| /// |
| /// \returns the read value. |
| ErrorOr<StringRef> readString(); |
| |
| /// Read the string index and check whether it overflows the table. |
| template <typename T> inline ErrorOr<uint32_t> readStringIndex(T &Table); |
| |
| /// Return true if we've reached the end of file. |
| bool at_eof() const { return Data >= End; } |
| |
| /// Read the next function profile instance. |
| std::error_code readFuncProfile(); |
| |
| /// Read the contents of the given profile instance. |
| std::error_code readProfile(FunctionSamples &FProfile); |
| |
| /// Points to the current location in the buffer. |
| const uint8_t *Data = nullptr; |
| |
| /// Points to the end of the buffer. |
| const uint8_t *End = nullptr; |
| |
| private: |
| std::error_code readSummaryEntry(std::vector<ProfileSummaryEntry> &Entries); |
| virtual std::error_code verifySPMagic(uint64_t Magic) = 0; |
| |
| /// Read profile summary. |
| std::error_code readSummary(); |
| |
| /// Read the whole name table. |
| virtual std::error_code readNameTable() = 0; |
| |
| /// Read a string indirectly via the name table. |
| virtual ErrorOr<StringRef> readStringFromTable() = 0; |
| }; |
| |
| class SampleProfileReaderRawBinary : public SampleProfileReaderBinary { |
| private: |
| /// Function name table. |
| std::vector<StringRef> NameTable; |
| virtual std::error_code verifySPMagic(uint64_t Magic) override; |
| virtual std::error_code readNameTable() override; |
| /// Read a string indirectly via the name table. |
| virtual ErrorOr<StringRef> readStringFromTable() override; |
| |
| public: |
| SampleProfileReaderRawBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C) |
| : SampleProfileReaderBinary(std::move(B), C, SPF_Binary) {} |
| |
| /// \brief Return true if \p Buffer is in the format supported by this class. |
| static bool hasFormat(const MemoryBuffer &Buffer); |
| }; |
| |
| class SampleProfileReaderCompactBinary : public SampleProfileReaderBinary { |
| private: |
| /// Function name table. |
| std::vector<std::string> NameTable; |
| /// The table mapping from function name to the offset of its FunctionSample |
| /// towards file start. |
| DenseMap<StringRef, uint64_t> FuncOffsetTable; |
| /// The set containing the functions to use when compiling a module. |
| DenseSet<StringRef> FuncsToUse; |
| virtual std::error_code verifySPMagic(uint64_t Magic) override; |
| virtual std::error_code readNameTable() override; |
| /// Read a string indirectly via the name table. |
| virtual ErrorOr<StringRef> readStringFromTable() override; |
| virtual std::error_code readHeader() override; |
| std::error_code readFuncOffsetTable(); |
| |
| public: |
| SampleProfileReaderCompactBinary(std::unique_ptr<MemoryBuffer> B, |
| LLVMContext &C) |
| : SampleProfileReaderBinary(std::move(B), C, SPF_Compact_Binary) {} |
| |
| /// \brief Return true if \p Buffer is in the format supported by this class. |
| static bool hasFormat(const MemoryBuffer &Buffer); |
| |
| /// Read samples only for functions to use. |
| std::error_code read() override; |
| |
| /// Collect functions to be used when compiling Module \p M. |
| void collectFuncsToUse(const Module &M) override; |
| }; |
| |
| using InlineCallStack = SmallVector<FunctionSamples *, 10>; |
| |
| // Supported histogram types in GCC. Currently, we only need support for |
| // call target histograms. |
| enum HistType { |
| HIST_TYPE_INTERVAL, |
| HIST_TYPE_POW2, |
| HIST_TYPE_SINGLE_VALUE, |
| HIST_TYPE_CONST_DELTA, |
| HIST_TYPE_INDIR_CALL, |
| HIST_TYPE_AVERAGE, |
| HIST_TYPE_IOR, |
| HIST_TYPE_INDIR_CALL_TOPN |
| }; |
| |
| class SampleProfileReaderGCC : public SampleProfileReader { |
| public: |
| SampleProfileReaderGCC(std::unique_ptr<MemoryBuffer> B, LLVMContext &C) |
| : SampleProfileReader(std::move(B), C, SPF_GCC), |
| GcovBuffer(Buffer.get()) {} |
| |
| /// Read and validate the file header. |
| std::error_code readHeader() override; |
| |
| /// Read sample profiles from the associated file. |
| std::error_code read() override; |
| |
| /// Return true if \p Buffer is in the format supported by this class. |
| static bool hasFormat(const MemoryBuffer &Buffer); |
| |
| protected: |
| std::error_code readNameTable(); |
| std::error_code readOneFunctionProfile(const InlineCallStack &InlineStack, |
| bool Update, uint32_t Offset); |
| std::error_code readFunctionProfiles(); |
| std::error_code skipNextWord(); |
| template <typename T> ErrorOr<T> readNumber(); |
| ErrorOr<StringRef> readString(); |
| |
| /// Read the section tag and check that it's the same as \p Expected. |
| std::error_code readSectionTag(uint32_t Expected); |
| |
| /// GCOV buffer containing the profile. |
| GCOVBuffer GcovBuffer; |
| |
| /// Function names in this profile. |
| std::vector<std::string> Names; |
| |
| /// GCOV tags used to separate sections in the profile file. |
| static const uint32_t GCOVTagAFDOFileNames = 0xaa000000; |
| static const uint32_t GCOVTagAFDOFunction = 0xac000000; |
| }; |
| |
| /// A profile data reader proxy that remaps the profile data from another |
| /// sample profile data reader, by applying a provided set of equivalences |
| /// between components of the symbol names in the profile. |
| class SampleProfileReaderItaniumRemapper : public SampleProfileReader { |
| public: |
| SampleProfileReaderItaniumRemapper( |
| std::unique_ptr<MemoryBuffer> B, LLVMContext &C, |
| std::unique_ptr<SampleProfileReader> Underlying) |
| : SampleProfileReader(std::move(B), C, Underlying->getFormat()) { |
| Profiles = std::move(Underlying->getProfiles()); |
| Summary = takeSummary(*Underlying); |
| // Keep the underlying reader alive; the profile data may contain |
| // StringRefs referencing names in its name table. |
| UnderlyingReader = std::move(Underlying); |
| } |
| |
| /// Create a remapped sample profile from the given remapping file and |
| /// underlying samples. |
| static ErrorOr<std::unique_ptr<SampleProfileReader>> |
| create(const Twine &Filename, LLVMContext &C, |
| std::unique_ptr<SampleProfileReader> Underlying); |
| |
| /// Read and validate the file header. |
| std::error_code readHeader() override { return sampleprof_error::success; } |
| |
| /// Read remapping file and apply it to the sample profile. |
| std::error_code read() override; |
| |
| /// Return the samples collected for function \p F. |
| FunctionSamples *getSamplesFor(StringRef FunctionName) override; |
| using SampleProfileReader::getSamplesFor; |
| |
| private: |
| SymbolRemappingReader Remappings; |
| DenseMap<SymbolRemappingReader::Key, FunctionSamples*> SampleMap; |
| std::unique_ptr<SampleProfileReader> UnderlyingReader; |
| }; |
| |
| } // end namespace sampleprof |
| |
| } // end namespace llvm |
| |
| #endif // LLVM_PROFILEDATA_SAMPLEPROFREADER_H |