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Diffstat (limited to 'lib/ProfileData/SampleProfReader.cpp')
| -rw-r--r-- | lib/ProfileData/SampleProfReader.cpp | 399 |
1 files changed, 399 insertions, 0 deletions
diff --git a/lib/ProfileData/SampleProfReader.cpp b/lib/ProfileData/SampleProfReader.cpp new file mode 100644 index 0000000..b39bfd6 --- /dev/null +++ b/lib/ProfileData/SampleProfReader.cpp @@ -0,0 +1,399 @@ +//===- SampleProfReader.cpp - Read LLVM sample profile data ---------------===// +// +// The LLVM Compiler Infrastructure +// +// This file is distributed under the University of Illinois Open Source +// License. See LICENSE.TXT for details. +// +//===----------------------------------------------------------------------===// +// +// This file implements the class that reads LLVM sample profiles. It +// supports two file formats: text and binary. The textual representation +// is useful for debugging and testing purposes. The binary representation +// is more compact, resulting in smaller file sizes. However, they can +// both be used interchangeably. +// +// NOTE: If you are making changes to the 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 ... ] +// +// The file may contain blank lines between sections and within a +// section. However, the spacing within a single line is fixed. Additional +// spaces will result in an error while reading the file. +// +// 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. +// +// 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. +// +//===----------------------------------------------------------------------===// + +#include "llvm/ProfileData/SampleProfReader.h" +#include "llvm/Support/Debug.h" +#include "llvm/Support/ErrorOr.h" +#include "llvm/Support/LEB128.h" +#include "llvm/Support/LineIterator.h" +#include "llvm/Support/MemoryBuffer.h" +#include "llvm/Support/Regex.h" + +using namespace llvm::sampleprof; +using namespace llvm; + +/// \brief Print the samples collected for a function on stream \p OS. +/// +/// \param OS Stream to emit the output to. +void FunctionSamples::print(raw_ostream &OS) { + OS << TotalSamples << ", " << TotalHeadSamples << ", " << BodySamples.size() + << " sampled lines\n"; + for (const auto &SI : BodySamples) { + LineLocation Loc = SI.first; + const SampleRecord &Sample = SI.second; + OS << "\tline offset: " << Loc.LineOffset + << ", discriminator: " << Loc.Discriminator + << ", number of samples: " << Sample.getSamples(); + if (Sample.hasCalls()) { + OS << ", calls:"; + for (const auto &I : Sample.getCallTargets()) + OS << " " << I.first() << ":" << I.second; + } + OS << "\n"; + } + OS << "\n"; +} + +/// \brief Dump the function profile for \p FName. +/// +/// \param FName Name of the function to print. +/// \param OS Stream to emit the output to. +void SampleProfileReader::dumpFunctionProfile(StringRef FName, + raw_ostream &OS) { + OS << "Function: " << FName << ": "; + Profiles[FName].print(OS); +} + +/// \brief Dump all the function profiles found on stream \p OS. +void SampleProfileReader::dump(raw_ostream &OS) { + for (const auto &I : Profiles) + dumpFunctionProfile(I.getKey(), OS); +} + +/// \brief Load samples from a text file. +/// +/// See the documentation at the top of the file for an explanation of +/// the expected format. +/// +/// \returns true if the file was loaded successfully, false otherwise. +std::error_code SampleProfileReaderText::read() { + line_iterator LineIt(*Buffer, /*SkipBlanks=*/true, '#'); + + // Read the profile of each function. Since each function may be + // mentioned more than once, and we are collecting flat profiles, + // accumulate samples as we parse them. + Regex HeadRE("^([^0-9].*):([0-9]+):([0-9]+)$"); + Regex LineSampleRE("^([0-9]+)\\.?([0-9]+)?: ([0-9]+)(.*)$"); + Regex CallSampleRE(" +([^0-9 ][^ ]*):([0-9]+)"); + while (!LineIt.is_at_eof()) { + // Read the header of each function. + // + // Note that for function identifiers we are actually expecting + // mangled names, but we may not always get them. This happens when + // the compiler decides not to emit the function (e.g., it was inlined + // and removed). In this case, the binary will not have the linkage + // name for the function, so the profiler will emit the function's + // unmangled name, which may contain characters like ':' and '>' in its + // name (member functions, templates, etc). + // + // The only requirement we place on the identifier, then, is that it + // should not begin with a number. + SmallVector<StringRef, 4> Matches; + if (!HeadRE.match(*LineIt, &Matches)) { + reportParseError(LineIt.line_number(), + "Expected 'mangled_name:NUM:NUM', found " + *LineIt); + return sampleprof_error::malformed; + } + assert(Matches.size() == 4); + StringRef FName = Matches[1]; + unsigned NumSamples, NumHeadSamples; + Matches[2].getAsInteger(10, NumSamples); + Matches[3].getAsInteger(10, NumHeadSamples); + Profiles[FName] = FunctionSamples(); + FunctionSamples &FProfile = Profiles[FName]; + FProfile.addTotalSamples(NumSamples); + FProfile.addHeadSamples(NumHeadSamples); + ++LineIt; + + // Now read the body. The body of the function ends when we reach + // EOF or when we see the start of the next function. + while (!LineIt.is_at_eof() && isdigit((*LineIt)[0])) { + if (!LineSampleRE.match(*LineIt, &Matches)) { + reportParseError( + LineIt.line_number(), + "Expected 'NUM[.NUM]: NUM[ mangled_name:NUM]*', found " + *LineIt); + return sampleprof_error::malformed; + } + assert(Matches.size() == 5); + unsigned LineOffset, NumSamples, Discriminator = 0; + Matches[1].getAsInteger(10, LineOffset); + if (Matches[2] != "") + Matches[2].getAsInteger(10, Discriminator); + Matches[3].getAsInteger(10, NumSamples); + + // If there are function calls in this line, generate a call sample + // entry for each call. + std::string CallsLine(Matches[4]); + while (CallsLine != "") { + SmallVector<StringRef, 3> CallSample; + if (!CallSampleRE.match(CallsLine, &CallSample)) { + reportParseError(LineIt.line_number(), + "Expected 'mangled_name:NUM', found " + CallsLine); + return sampleprof_error::malformed; + } + StringRef CalledFunction = CallSample[1]; + unsigned CalledFunctionSamples; + CallSample[2].getAsInteger(10, CalledFunctionSamples); + FProfile.addCalledTargetSamples(LineOffset, Discriminator, + CalledFunction, CalledFunctionSamples); + CallsLine = CallSampleRE.sub("", CallsLine); + } + + FProfile.addBodySamples(LineOffset, Discriminator, NumSamples); + ++LineIt; + } + } + + return sampleprof_error::success; +} + +template <typename T> ErrorOr<T> SampleProfileReaderBinary::readNumber() { + unsigned NumBytesRead = 0; + std::error_code EC; + uint64_t Val = decodeULEB128(Data, &NumBytesRead); + + if (Val > std::numeric_limits<T>::max()) + EC = sampleprof_error::malformed; + else if (Data + NumBytesRead > End) + EC = sampleprof_error::truncated; + else + EC = sampleprof_error::success; + + if (EC) { + reportParseError(0, EC.message()); + return EC; + } + + Data += NumBytesRead; + return static_cast<T>(Val); +} + +ErrorOr<StringRef> SampleProfileReaderBinary::readString() { + std::error_code EC; + StringRef Str(reinterpret_cast<const char *>(Data)); + if (Data + Str.size() + 1 > End) { + EC = sampleprof_error::truncated; + reportParseError(0, EC.message()); + return EC; + } + + Data += Str.size() + 1; + return Str; +} + +std::error_code SampleProfileReaderBinary::read() { + while (!at_eof()) { + auto FName(readString()); + if (std::error_code EC = FName.getError()) + return EC; + + Profiles[*FName] = FunctionSamples(); + FunctionSamples &FProfile = Profiles[*FName]; + + auto Val = readNumber<unsigned>(); + if (std::error_code EC = Val.getError()) + return EC; + FProfile.addTotalSamples(*Val); + + Val = readNumber<unsigned>(); + if (std::error_code EC = Val.getError()) + return EC; + FProfile.addHeadSamples(*Val); + + // Read the samples in the body. + auto NumRecords = readNumber<unsigned>(); + if (std::error_code EC = NumRecords.getError()) + return EC; + for (unsigned I = 0; I < *NumRecords; ++I) { + auto LineOffset = readNumber<uint64_t>(); + if (std::error_code EC = LineOffset.getError()) + return EC; + + auto Discriminator = readNumber<uint64_t>(); + if (std::error_code EC = Discriminator.getError()) + return EC; + + auto NumSamples = readNumber<uint64_t>(); + if (std::error_code EC = NumSamples.getError()) + return EC; + + auto NumCalls = readNumber<unsigned>(); + if (std::error_code EC = NumCalls.getError()) + return EC; + + for (unsigned J = 0; J < *NumCalls; ++J) { + auto CalledFunction(readString()); + if (std::error_code EC = CalledFunction.getError()) + return EC; + + auto CalledFunctionSamples = readNumber<uint64_t>(); + if (std::error_code EC = CalledFunctionSamples.getError()) + return EC; + + FProfile.addCalledTargetSamples(*LineOffset, *Discriminator, + *CalledFunction, + *CalledFunctionSamples); + } + + FProfile.addBodySamples(*LineOffset, *Discriminator, *NumSamples); + } + } + + return sampleprof_error::success; +} + +std::error_code SampleProfileReaderBinary::readHeader() { + Data = reinterpret_cast<const uint8_t *>(Buffer->getBufferStart()); + End = Data + Buffer->getBufferSize(); + + // Read and check the magic identifier. + auto Magic = readNumber<uint64_t>(); + if (std::error_code EC = Magic.getError()) + return EC; + else if (*Magic != SPMagic()) + return sampleprof_error::bad_magic; + + // Read the version number. + auto Version = readNumber<uint64_t>(); + if (std::error_code EC = Version.getError()) + return EC; + else if (*Version != SPVersion()) + return sampleprof_error::unsupported_version; + + return sampleprof_error::success; +} + +bool SampleProfileReaderBinary::hasFormat(const MemoryBuffer &Buffer) { + const uint8_t *Data = + reinterpret_cast<const uint8_t *>(Buffer.getBufferStart()); + uint64_t Magic = decodeULEB128(Data); + return Magic == SPMagic(); +} + +/// \brief Prepare a memory buffer for the contents of \p Filename. +/// +/// \returns an error code indicating the status of the buffer. +static ErrorOr<std::unique_ptr<MemoryBuffer>> +setupMemoryBuffer(std::string Filename) { + auto BufferOrErr = MemoryBuffer::getFileOrSTDIN(Filename); + if (std::error_code EC = BufferOrErr.getError()) + return EC; + auto Buffer = std::move(BufferOrErr.get()); + + // Sanity check the file. + if (Buffer->getBufferSize() > std::numeric_limits<unsigned>::max()) + return sampleprof_error::too_large; + + return std::move(Buffer); +} + +/// \brief Create a sample profile reader based on the format of the input file. +/// +/// \param Filename The file to open. +/// +/// \param Reader The reader to instantiate according to \p Filename's format. +/// +/// \param C The LLVM context to use to emit diagnostics. +/// +/// \returns an error code indicating the status of the created reader. +ErrorOr<std::unique_ptr<SampleProfileReader>> +SampleProfileReader::create(StringRef Filename, LLVMContext &C) { + auto BufferOrError = setupMemoryBuffer(Filename); + if (std::error_code EC = BufferOrError.getError()) + return EC; + + auto Buffer = std::move(BufferOrError.get()); + std::unique_ptr<SampleProfileReader> Reader; + if (SampleProfileReaderBinary::hasFormat(*Buffer)) + Reader.reset(new SampleProfileReaderBinary(std::move(Buffer), C)); + else + Reader.reset(new SampleProfileReaderText(std::move(Buffer), C)); + + if (std::error_code EC = Reader->readHeader()) + return EC; + + return std::move(Reader); +} |