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Re-factor sample profile reader into lib/ProfileData.

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Summary:
This patch moves the profile reading logic out of the Sample Profile
transformation into a generic profile reader facility in
lib/ProfileData.

The intent is to use this new reader to implement a sample profile
reader/writer that can be used to convert sample profiles from external
sources into LLVM.

This first patch introduces no functional changes. It moves the profile
reading code from lib/Transforms/SampleProfile.cpp into
lib/ProfileData/SampleProfReader.cpp.

In subsequent patches I will:

- Add a bitcode format for sample profiles to allow for more efficient
  encoding of the profile.
- Add a writer for both text and bitcode format profiles.
- Add a 'convert' command to llvm-profdata to be able to convert between
  the two (and serve as entry point for other sample profile formats).

Reviewers: bogner, echristo

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5250

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@217437 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Diego Novillo 2014-09-09 12:40:50 +00:00
parent 052538124f
commit 40c949a1b4
6 changed files with 501 additions and 394 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
include/llvm/IR/DiagnosticInfo.h
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@ -18,6 +18,7 @@
#include "llvm-c/Core.h"
#include "llvm/ADT/ArrayRef.h"
#include "llvm/IR/DebugLoc.h"
#include "llvm/IR/Module.h"
#include "llvm/Support/Casting.h"
namespace llvm {

194
include/llvm/ProfileData/SampleProfReader.h Normal file
View File

@ -0,0 +1,194 @@
//===- SampleProfReader.h - 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 contains definitions needed for reading sample profiles.
//
//===----------------------------------------------------------------------===//
#ifndef LLVM_PROFILEDATA_SAMPLEPROFREADER_H
#define LLVM_PROFILEDATA_SAMPLEPROFREADER_H
#include "llvm/ADT/DenseMap.h"
#include "llvm/IR/DiagnosticInfo.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/LLVMContext.h"
#include "llvm/IR/Module.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/ADT/Twine.h"
#include "llvm/Support/ErrorHandling.h"
#include "llvm/Support/raw_ostream.h"
using namespace llvm;
namespace sampleprof {
/// \brief Represents the relative location of an instruction.
///
/// Instruction locations are specified by the line offset from the
/// beginning of the function (marked by the line where the function
/// header is) and the discriminator value within that line.
///
/// The discriminator value is useful to distinguish instructions
/// that are on the same line but belong to different basic blocks
/// (e.g., the two post-increment instructions in "if (p) x++; else y++;").
struct LineLocation {
LineLocation(int L, unsigned D) : LineOffset(L), Discriminator(D) {}
int LineOffset;
unsigned Discriminator;
};
} // End namespace sampleprof
namespace llvm {
template <> struct DenseMapInfo<sampleprof::LineLocation> {
typedef DenseMapInfo<int> OffsetInfo;
typedef DenseMapInfo<unsigned> DiscriminatorInfo;
static inline sampleprof::LineLocation getEmptyKey() {
return sampleprof::LineLocation(OffsetInfo::getEmptyKey(),
DiscriminatorInfo::getEmptyKey());
}
static inline sampleprof::LineLocation getTombstoneKey() {
return sampleprof::LineLocation(OffsetInfo::getTombstoneKey(),
DiscriminatorInfo::getTombstoneKey());
}
static inline unsigned getHashValue(sampleprof::LineLocation Val) {
return DenseMapInfo<std::pair<int, unsigned>>::getHashValue(
std::pair<int, unsigned>(Val.LineOffset, Val.Discriminator));
}
static inline bool isEqual(sampleprof::LineLocation LHS,
sampleprof::LineLocation RHS) {
return LHS.LineOffset == RHS.LineOffset &&
LHS.Discriminator == RHS.Discriminator;
}
};
}
namespace sampleprof {
typedef DenseMap<LineLocation, unsigned> BodySampleMap;
/// \brief Representation of the samples collected for a function.
///
/// This data structure contains all the collected samples for the body
/// of a function. Each sample corresponds to a LineLocation instance
/// within the body of the function.
class FunctionSamples {
public:
FunctionSamples()
: TotalSamples(0), TotalHeadSamples(0) {}
void print(raw_ostream & OS);
void addTotalSamples(unsigned Num) { TotalSamples += Num; }
void addHeadSamples(unsigned Num) { TotalHeadSamples += Num; }
void addBodySamples(int LineOffset, unsigned Discriminator, unsigned Num) {
assert(LineOffset >= 0);
BodySamples[LineLocation(LineOffset, Discriminator)] += Num;
}
/// \brief Return the number of samples collected at the given location.
/// Each location is specified by \p LineOffset and \p Discriminator.
unsigned samplesAt(int LineOffset, unsigned Discriminator) {
return BodySamples.lookup(LineLocation(LineOffset, Discriminator));
}
bool empty() { return BodySamples.empty(); }
private:
/// \brief Total number of samples collected inside this function.
///
/// Samples are cumulative, they include all the samples collected
/// inside this function and all its inlined callees.
unsigned TotalSamples;
/// \brief Total number of samples collected at the head of the function.
unsigned TotalHeadSamples;
/// \brief Map instruction locations to collected samples.
///
/// Each entry in this map contains the number of samples
/// collected at the corresponding line offset. All line locations
/// are an offset from the start of the function.
BodySampleMap BodySamples;
};
/// \brief 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 bitcode. The text format
/// is useful for debugging and testing, while the bitcode format is more
/// compact. They can both be used interchangeably.
class SampleProfileReader {
public:
SampleProfileReader(const Module &M, StringRef F)
: Profiles(0), Filename(F), M(M) {}
/// \brief Print all the profiles to dbgs().
void dump();
/// \brief Load sample profiles from the associated file.
bool load();
/// \brief Print the profile for \p FName on stream \p OS.
void printFunctionProfile(raw_ostream &OS, StringRef FName);
/// \brief Print the profile for \p FName on dbgs().
void dumpFunctionProfile(StringRef FName);
/// \brief Return the samples collected for function \p F.
FunctionSamples *getSamplesFor(const Function &F) {
return &Profiles[F.getName()];
}
/// \brief Report a parse error message.
void reportParseError(int64_t LineNumber, Twine Msg) const {
DiagnosticInfoSampleProfile Diag(Filename.data(), LineNumber, Msg);
M.getContext().diagnose(Diag);
}
protected:
bool loadText();
bool loadBitcode() { llvm_unreachable("not implemented"); }
/// \brief 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;
/// \brief Path name to the file holding the profile data.
StringRef Filename;
/// \brief Module being compiled. Used to access the current
/// LLVM context for diagnostics.
const Module &M;
};
} // End namespace sampleprof
#endif // LLVM_PROFILEDATA_SAMPLEPROFREADER_H

1
lib/ProfileData/CMakeLists.txt
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@ -5,4 +5,5 @@ add_llvm_library(LLVMProfileData
CoverageMapping.cpp
CoverageMappingWriter.cpp
CoverageMappingReader.cpp
SampleProfReader.cpp
)

238
lib/ProfileData/SampleProfReader.cpp Normal file
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@ -0,0 +1,238 @@
//===- 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 bitcode. The textual representation
// is useful for debugging and testing purposes. The bitcode 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/MemoryBuffer.h"
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/Regex.h"
using namespace 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 (BodySampleMap::const_iterator SI = BodySamples.begin(),
SE = BodySamples.end();
SI != SE; ++SI)
OS << "\tline offset: " << SI->first.LineOffset
<< ", discriminator: " << SI->first.Discriminator
<< ", number of samples: " << SI->second << "\n";
OS << "\n";
}
/// \brief Print the function profile for \p FName on stream \p OS.
///
/// \param OS Stream to emit the output to.
/// \param FName Name of the function to print.
void SampleProfileReader::printFunctionProfile(raw_ostream &OS,
StringRef FName) {
OS << "Function: " << FName << ":\n";
Profiles[FName].print(OS);
}
/// \brief Dump the function profile for \p FName.
///
/// \param FName Name of the function to print.
void SampleProfileReader::dumpFunctionProfile(StringRef FName) {
printFunctionProfile(dbgs(), FName);
}
/// \brief Dump all the function profiles found.
void SampleProfileReader::dump() {
for (StringMap<FunctionSamples>::const_iterator I = Profiles.begin(),
E = Profiles.end();
I != E; ++I)
dumpFunctionProfile(I->getKey());
}
/// \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.
bool SampleProfileReader::loadText() {
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
MemoryBuffer::getFile(Filename);
if (std::error_code EC = BufferOrErr.getError()) {
std::string Msg(EC.message());
M.getContext().diagnose(DiagnosticInfoSampleProfile(Filename.data(), Msg));
return false;
}
MemoryBuffer &Buffer = *BufferOrErr.get();
line_iterator LineIt(Buffer, '#');
// 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]+)$");
Regex LineSample("^([0-9]+)\\.?([0-9]+)?: ([0-9]+)(.*)$");
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, 3> Matches;
if (!HeadRE.match(*LineIt, &Matches)) {
reportParseError(LineIt.line_number(),
"Expected 'mangled_name:NUM:NUM', found " + *LineIt);
return false;
}
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 (!LineSample.match(*LineIt, &Matches)) {
reportParseError(
LineIt.line_number(),
"Expected 'NUM[.NUM]: NUM[ mangled_name:NUM]*', found " + *LineIt);
return false;
}
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);
// FIXME: Handle called targets (in Matches[4]).
// When dealing with instruction weights, we use the value
// zero to indicate the absence of a sample. If we read an
// actual zero from the profile file, return it as 1 to
// avoid the confusion later on.
if (NumSamples == 0)
NumSamples = 1;
FProfile.addBodySamples(LineOffset, Discriminator, NumSamples);
++LineIt;
}
}
return true;
}
/// \brief Load execution samples from a file.
///
/// This function examines the header of the given file to determine
/// whether to use the text or the bitcode loader.
bool SampleProfileReader::load() {
// TODO Actually detect the file format.
return loadText();
}

2
lib/Transforms/Scalar/LLVMBuild.txt
View File

@ -20,4 +20,4 @@ type = Library
name = Scalar
parent = Transforms
library_name = ScalarOpts
required_libraries = Analysis Core IPA InstCombine Support Target TransformUtils
required_libraries = Analysis Core IPA InstCombine Support Target TransformUtils ProfileData

459
lib/Transforms/Scalar/SampleProfile.cpp
View File

@ -26,7 +26,6 @@
#include "llvm/ADT/DenseMap.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/StringMap.h"
#include "llvm/ADT/StringRef.h"
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/PostDominators.h"
@ -42,15 +41,14 @@
#include "llvm/IR/Metadata.h"
#include "llvm/IR/Module.h"
#include "llvm/Pass.h"
#include "llvm/ProfileData/SampleProfReader.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/LineIterator.h"
#include "llvm/Support/MemoryBuffer.h"
#include "llvm/Support/Regex.h"
#include "llvm/Support/raw_ostream.h"
#include <cctype>
using namespace llvm;
using namespace sampleprof;
#define DEBUG_TYPE "sample-profile"
@ -65,76 +63,48 @@ static cl::opt<unsigned> SampleProfileMaxPropagateIterations(
"sample block/edge weights through the CFG."));
namespace {
/// \brief Represents the relative location of an instruction.
///
/// Instruction locations are specified by the line offset from the
/// beginning of the function (marked by the line where the function
/// header is) and the discriminator value within that line.
///
/// The discriminator value is useful to distinguish instructions
/// that are on the same line but belong to different basic blocks
/// (e.g., the two post-increment instructions in "if (p) x++; else y++;").
struct InstructionLocation {
InstructionLocation(int L, unsigned D) : LineOffset(L), Discriminator(D) {}
int LineOffset;
unsigned Discriminator;
};
}
namespace llvm {
template <> struct DenseMapInfo<InstructionLocation> {
typedef DenseMapInfo<int> OffsetInfo;
typedef DenseMapInfo<unsigned> DiscriminatorInfo;
static inline InstructionLocation getEmptyKey() {
return InstructionLocation(OffsetInfo::getEmptyKey(),
DiscriminatorInfo::getEmptyKey());
}
static inline InstructionLocation getTombstoneKey() {
return InstructionLocation(OffsetInfo::getTombstoneKey(),
DiscriminatorInfo::getTombstoneKey());
}
static inline unsigned getHashValue(InstructionLocation Val) {
return DenseMapInfo<std::pair<int, unsigned>>::getHashValue(
std::pair<int, unsigned>(Val.LineOffset, Val.Discriminator));
}
static inline bool isEqual(InstructionLocation LHS, InstructionLocation RHS) {
return LHS.LineOffset == RHS.LineOffset &&
LHS.Discriminator == RHS.Discriminator;
}
};
}
namespace {
typedef DenseMap<InstructionLocation, unsigned> BodySampleMap;
typedef DenseMap<BasicBlock *, unsigned> BlockWeightMap;
typedef DenseMap<BasicBlock *, BasicBlock *> EquivalenceClassMap;
typedef std::pair<BasicBlock *, BasicBlock *> Edge;
typedef DenseMap<Edge, unsigned> EdgeWeightMap;
typedef DenseMap<BasicBlock *, SmallVector<BasicBlock *, 8>> BlockEdgeMap;
/// \brief Representation of the runtime profile for a function.
/// \brief Sample profile pass.
///
/// This data structure contains the runtime profile for a given
/// function. It contains the total number of samples collected
/// in the function and a map of samples collected in every statement.
class SampleFunctionProfile {
/// This pass reads profile data from the file specified by
/// -sample-profile-file and annotates every affected function with the
/// profile information found in that file.
class SampleProfileLoader : public FunctionPass {
public:
SampleFunctionProfile()
: TotalSamples(0), TotalHeadSamples(0), HeaderLineno(0), DT(nullptr),
PDT(nullptr), LI(nullptr), Ctx(nullptr) {}
// Class identification, replacement for typeinfo
static char ID;
SampleProfileLoader(StringRef Name = SampleProfileFile)
: FunctionPass(ID), DT(nullptr), PDT(nullptr), LI(nullptr), Ctx(nullptr),
Reader(), Samples(nullptr), Filename(Name), ProfileIsValid(false) {
initializeSampleProfileLoaderPass(*PassRegistry::getPassRegistry());
}
bool doInitialization(Module &M) override;
void dump() { Reader->dump(); }
const char *getPassName() const override { return "Sample profile pass"; }
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<PostDominatorTree>();
}
protected:
unsigned getFunctionLoc(Function &F);
bool emitAnnotations(Function &F, DominatorTree *DomTree,
PostDominatorTree *PostDomTree, LoopInfo *Loops);
bool emitAnnotations(Function &F);
unsigned getInstWeight(Instruction &I);
unsigned getBlockWeight(BasicBlock *B);
void addTotalSamples(unsigned Num) { TotalSamples += Num; }
void addHeadSamples(unsigned Num) { TotalHeadSamples += Num; }
void addBodySamples(int LineOffset, unsigned Discriminator, unsigned Num) {
assert(LineOffset >= 0);
BodySamples[InstructionLocation(LineOffset, Discriminator)] += Num;
}
void print(raw_ostream &OS);
void printEdgeWeight(raw_ostream &OS, Edge E);
void printBlockWeight(raw_ostream &OS, BasicBlock *BB);
void printBlockEquivalence(raw_ostream &OS, BasicBlock *BB);
@ -147,32 +117,11 @@ public:
unsigned visitEdge(Edge E, unsigned *NumUnknownEdges, Edge *UnknownEdge);
void buildEdges(Function &F);
bool propagateThroughEdges(Function &F);
bool empty() { return BodySamples.empty(); }
protected:
/// \brief Total number of samples collected inside this function.
///
/// Samples are cumulative, they include all the samples collected
/// inside this function and all its inlined callees.
unsigned TotalSamples;
/// \brief Total number of samples collected at the head of the function.
/// FIXME: Use head samples to estimate a cold/hot attribute for the function.
unsigned TotalHeadSamples;
/// \brief Line number for the function header. Used to compute relative
/// line numbers from the absolute line LOCs found in instruction locations.
/// The relative line numbers are needed to address the samples from the
/// profile file.
/// \brief Line number for the function header. Used to compute absolute
/// line numbers from the relative line numbers found in the profile.
unsigned HeaderLineno;
/// \brief Map line offsets to collected samples.
///
/// Each entry in this map contains the number of samples
/// collected at the corresponding line offset. All line locations
/// are an offset from the start of the function.
BodySampleMap BodySamples;
/// \brief Map basic blocks to their computed weights.
///
/// The weight of a basic block is defined to be the maximum
@ -212,105 +161,12 @@ protected:
/// \brief LLVM context holding the debug data we need.
LLVMContext *Ctx;
};
/// \brief 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.
class SampleModuleProfile {
public:
SampleModuleProfile(const Module &M, StringRef F)
: Profiles(0), Filename(F), M(M) {}
void dump();
bool loadText();
void loadNative() { llvm_unreachable("not implemented"); }
void printFunctionProfile(raw_ostream &OS, StringRef FName);
void dumpFunctionProfile(StringRef FName);
SampleFunctionProfile &getProfile(const Function &F) {
return Profiles[F.getName()];
}
/// \brief Report a parse error message.
void reportParseError(int64_t LineNumber, Twine Msg) const {
DiagnosticInfoSampleProfile Diag(Filename.data(), LineNumber, Msg);
M.getContext().diagnose(Diag);
}
protected:
/// \brief Map every function to its associated profile.
///
/// The profile of every function executed at runtime is collected
/// in the structure SampleFunctionProfile. This maps function objects
/// to their corresponding profiles.
StringMap<SampleFunctionProfile> Profiles;
/// \brief Path name to the file holding the profile data.
///
/// The format of this file is defined by each profiler
/// independently. If possible, the profiler should have a text
/// version of the profile format to be used in constructing test
/// cases and debugging.
StringRef Filename;
/// \brief Module being compiled. Used mainly to access the current
/// LLVM context for diagnostics.
const Module &M;
};
/// \brief Sample profile pass.
///
/// This pass reads profile data from the file specified by
/// -sample-profile-file and annotates every affected function with the
/// profile information found in that file.
class SampleProfileLoader : public FunctionPass {
public:
// Class identification, replacement for typeinfo
static char ID;
SampleProfileLoader(StringRef Name = SampleProfileFile)
: FunctionPass(ID), Profiler(), Filename(Name), ProfileIsValid(false) {
initializeSampleProfileLoaderPass(*PassRegistry::getPassRegistry());
}
bool doInitialization(Module &M) override;
void dump() { Profiler->dump(); }
const char *getPassName() const override { return "Sample profile pass"; }
bool runOnFunction(Function &F) override;
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.setPreservesCFG();
AU.addRequired<LoopInfo>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addRequired<PostDominatorTree>();
}
protected:
/// \brief Profile reader object.
std::unique_ptr<SampleModuleProfile> Profiler;
std::unique_ptr<SampleProfileReader> Reader;
/// \brief Samples collected for the body of this function.
FunctionSamples *Samples;
/// \brief Name of the profile file to load.
StringRef Filename;
@ -320,26 +176,11 @@ protected:
};
}
/// \brief Print this function profile on stream \p OS.
///
/// \param OS Stream to emit the output to.
void SampleFunctionProfile::print(raw_ostream &OS) {
OS << TotalSamples << ", " << TotalHeadSamples << ", " << BodySamples.size()
<< " sampled lines\n";
for (BodySampleMap::const_iterator SI = BodySamples.begin(),
SE = BodySamples.end();
SI != SE; ++SI)
OS << "\tline offset: " << SI->first.LineOffset
<< ", discriminator: " << SI->first.Discriminator
<< ", number of samples: " << SI->second << "\n";
OS << "\n";
}
/// \brief Print the weight of edge \p E on stream \p OS.
///
/// \param OS Stream to emit the output to.
/// \param E Edge to print.
void SampleFunctionProfile::printEdgeWeight(raw_ostream &OS, Edge E) {
void SampleProfileLoader::printEdgeWeight(raw_ostream &OS, Edge E) {
OS << "weight[" << E.first->getName() << "->" << E.second->getName()
<< "]: " << EdgeWeights[E] << "\n";
}
@ -348,8 +189,8 @@ void SampleFunctionProfile::printEdgeWeight(raw_ostream &OS, Edge E) {
///
/// \param OS Stream to emit the output to.
/// \param BB Block to print.
void SampleFunctionProfile::printBlockEquivalence(raw_ostream &OS,
BasicBlock *BB) {
void SampleProfileLoader::printBlockEquivalence(raw_ostream &OS,
BasicBlock *BB) {
BasicBlock *Equiv = EquivalenceClass[BB];
OS << "equivalence[" << BB->getName()
<< "]: " << ((Equiv) ? EquivalenceClass[BB]->getName() : "NONE") << "\n";
@ -359,174 +200,10 @@ void SampleFunctionProfile::printBlockEquivalence(raw_ostream &OS,
///
/// \param OS Stream to emit the output to.
/// \param BB Block to print.
void SampleFunctionProfile::printBlockWeight(raw_ostream &OS, BasicBlock *BB) {
void SampleProfileLoader::printBlockWeight(raw_ostream &OS, BasicBlock *BB) {
OS << "weight[" << BB->getName() << "]: " << BlockWeights[BB] << "\n";
}
/// \brief Print the function profile for \p FName on stream \p OS.
///
/// \param OS Stream to emit the output to.
/// \param FName Name of the function to print.
void SampleModuleProfile::printFunctionProfile(raw_ostream &OS,
StringRef FName) {
OS << "Function: " << FName << ":\n";
Profiles[FName].print(OS);
}
/// \brief Dump the function profile for \p FName.
///
/// \param FName Name of the function to print.
void SampleModuleProfile::dumpFunctionProfile(StringRef FName) {
printFunctionProfile(dbgs(), FName);
}
/// \brief Dump all the function profiles found.
void SampleModuleProfile::dump() {
for (StringMap<SampleFunctionProfile>::const_iterator I = Profiles.begin(),
E = Profiles.end();
I != E; ++I)
dumpFunctionProfile(I->getKey());
}
/// \brief Load samples from a text file.
///
/// The file contains a list of samples for every function executed at
/// runtime. Each function profile 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 ... ]
///
/// 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
/// at the prologue of the function (second number). This head sample
/// count provides an indicator of how frequent is the function 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.
///
/// 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)
///
/// c- Number of samples. This is 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
/// indirect calls. Each called target is listed together with the
/// 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 frequent call target.
///
/// FIXME: This is currently unhandled, but it has a lot of
/// potential for aiding the inliner.
///
///
/// Since this is a flat profile, a function that shows up more than
/// once gets all its samples aggregated across all its instances.
///
/// FIXME: flat profiles are too imprecise to provide good optimization
/// opportunities. Convert them to context-sensitive profile.
///
/// This textual representation is useful to generate unit tests and
/// for debugging purposes, but it should not be used to generate
/// profiles for large programs, as the representation is extremely
/// inefficient.
///
/// \returns true if the file was loaded successfully, false otherwise.
bool SampleModuleProfile::loadText() {
ErrorOr<std::unique_ptr<MemoryBuffer>> BufferOrErr =
MemoryBuffer::getFile(Filename);
if (std::error_code EC = BufferOrErr.getError()) {
std::string Msg(EC.message());
M.getContext().diagnose(DiagnosticInfoSampleProfile(Filename.data(), Msg));
return false;
}
MemoryBuffer &Buffer = *BufferOrErr.get();
line_iterator LineIt(Buffer, '#');
// 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]+)$");
Regex LineSample("^([0-9]+)\\.?([0-9]+)?: ([0-9]+)(.*)$");
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, 3> Matches;
if (!HeadRE.match(*LineIt, &Matches)) {
reportParseError(LineIt.line_number(),
"Expected 'mangled_name:NUM:NUM', found " + *LineIt);
return false;
}
assert(Matches.size() == 4);
StringRef FName = Matches[1];
unsigned NumSamples, NumHeadSamples;
Matches[2].getAsInteger(10, NumSamples);
Matches[3].getAsInteger(10, NumHeadSamples);
Profiles[FName] = SampleFunctionProfile();
SampleFunctionProfile &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 (!LineSample.match(*LineIt, &Matches)) {
reportParseError(
LineIt.line_number(),
"Expected 'NUM[.NUM]: NUM[ mangled_name:NUM]*', found " + *LineIt);
return false;
}
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);
// FIXME: Handle called targets (in Matches[4]).
// When dealing with instruction weights, we use the value
// zero to indicate the absence of a sample. If we read an
// actual zero from the profile file, return it as 1 to
// avoid the confusion later on.
if (NumSamples == 0)
NumSamples = 1;
FProfile.addBodySamples(LineOffset, Discriminator, NumSamples);
++LineIt;
}
}
return true;
}
/// \brief Get the weight for an instruction.
///
/// The "weight" of an instruction \p Inst is the number of samples
@ -538,7 +215,7 @@ bool SampleModuleProfile::loadText() {
/// \param Inst Instruction to query.
///
/// \returns The profiled weight of I.
unsigned SampleFunctionProfile::getInstWeight(Instruction &Inst) {
unsigned SampleProfileLoader::getInstWeight(Instruction &Inst) {
DebugLoc DLoc = Inst.getDebugLoc();
unsigned Lineno = DLoc.getLine();
if (Lineno < HeaderLineno)
@ -547,8 +224,7 @@ unsigned SampleFunctionProfile::getInstWeight(Instruction &Inst) {
DILocation DIL(DLoc.getAsMDNode(*Ctx));
int LOffset = Lineno - HeaderLineno;
unsigned Discriminator = DIL.getDiscriminator();
unsigned Weight =
BodySamples.lookup(InstructionLocation(LOffset, Discriminator));
unsigned Weight = Samples->samplesAt(LOffset, Discriminator);
DEBUG(dbgs() << " " << Lineno << "." << Discriminator << ":" << Inst
<< " (line offset: " << LOffset << "." << Discriminator
<< " - weight: " << Weight << ")\n");
@ -564,7 +240,7 @@ unsigned SampleFunctionProfile::getInstWeight(Instruction &Inst) {
/// \param B The basic block to query.
///
/// \returns The computed weight of B.
unsigned SampleFunctionProfile::getBlockWeight(BasicBlock *B) {
unsigned SampleProfileLoader::getBlockWeight(BasicBlock *B) {
// If we've computed B's weight before, return it.
std::pair<BlockWeightMap::iterator, bool> Entry =
BlockWeights.insert(std::make_pair(B, 0));
@ -588,7 +264,7 @@ unsigned SampleFunctionProfile::getBlockWeight(BasicBlock *B) {
/// the weights of every basic block in the CFG.
///
/// \param F The function to query.
bool SampleFunctionProfile::computeBlockWeights(Function &F) {
bool SampleProfileLoader::computeBlockWeights(Function &F) {
bool Changed = false;
DEBUG(dbgs() << "Block weights\n");
for (Function::iterator B = F.begin(), E = F.end(); B != E; ++B) {
@ -623,7 +299,7 @@ bool SampleFunctionProfile::computeBlockWeights(Function &F) {
/// \param DomTree Opposite dominator tree. If \p Descendants is filled
/// with blocks from \p BB1's dominator tree, then
/// this is the post-dominator tree, and vice versa.
void SampleFunctionProfile::findEquivalencesFor(
void SampleProfileLoader::findEquivalencesFor(
BasicBlock *BB1, SmallVector<BasicBlock *, 8> Descendants,
DominatorTreeBase<BasicBlock> *DomTree) {
for (SmallVectorImpl<BasicBlock *>::iterator I = Descendants.begin(),
@ -660,7 +336,7 @@ void SampleFunctionProfile::findEquivalencesFor(
/// dominates B2, B2 post-dominates B1 and both are in the same loop.
///
/// \param F The function to query.
void SampleFunctionProfile::findEquivalenceClasses(Function &F) {
void SampleProfileLoader::findEquivalenceClasses(Function &F) {
SmallVector<BasicBlock *, 8> DominatedBBs;
DEBUG(dbgs() << "\nBlock equivalence classes\n");
// Find equivalence sets based on dominance and post-dominance information.
@ -731,8 +407,8 @@ void SampleFunctionProfile::findEquivalenceClasses(Function &F) {
/// \param UnknownEdge Set if E has not been visited before.
///
/// \returns E's weight, if known. Otherwise, return 0.
unsigned SampleFunctionProfile::visitEdge(Edge E, unsigned *NumUnknownEdges,
Edge *UnknownEdge) {
unsigned SampleProfileLoader::visitEdge(Edge E, unsigned *NumUnknownEdges,
Edge *UnknownEdge) {
if (!VisitedEdges.count(E)) {
(*NumUnknownEdges)++;
*UnknownEdge = E;
@ -753,7 +429,7 @@ unsigned SampleFunctionProfile::visitEdge(Edge E, unsigned *NumUnknownEdges,
/// \param F Function to process.
///
/// \returns True if new weights were assigned to edges or blocks.
bool SampleFunctionProfile::propagateThroughEdges(Function &F) {
bool SampleProfileLoader::propagateThroughEdges(Function &F) {
bool Changed = false;
DEBUG(dbgs() << "\nPropagation through edges\n");
for (Function::iterator BI = F.begin(), EI = F.end(); BI != EI; ++BI) {
@ -857,7 +533,7 @@ bool SampleFunctionProfile::propagateThroughEdges(Function &F) {
///
/// We are interested in unique edges. If a block B1 has multiple
/// edges to another block B2, we only add a single B1->B2 edge.
void SampleFunctionProfile::buildEdges(Function &F) {
void SampleProfileLoader::buildEdges(Function &F) {
for (Function::iterator I = F.begin(), E = F.end(); I != E; ++I) {
BasicBlock *B1 = I;
@ -900,7 +576,7 @@ void SampleFunctionProfile::buildEdges(Function &F) {
/// known, the weight for that edge is set to the weight of the block
/// minus the weight of the other incoming edges to that block (if
/// known).
void SampleFunctionProfile::propagateWeights(Function &F) {
void SampleProfileLoader::propagateWeights(Function &F) {
bool Changed = true;
unsigned i = 0;
@ -965,7 +641,7 @@ void SampleFunctionProfile::propagateWeights(Function &F) {
///
/// \returns the line number where \p F is defined. If it returns 0,
/// it means that there is no debug information available for \p F.
unsigned SampleFunctionProfile::getFunctionLoc(Function &F) {
unsigned SampleProfileLoader::getFunctionLoc(Function &F) {
NamedMDNode *CUNodes = F.getParent()->getNamedMetadata("llvm.dbg.cu");
if (CUNodes) {
for (unsigned I = 0, E1 = CUNodes->getNumOperands(); I != E1; ++I) {
@ -1031,11 +707,10 @@ unsigned SampleFunctionProfile::getFunctionLoc(Function &F) {
/// metadata on B using the computed values for each of its branches.
///
/// \param F The function to query.
/// \param S The set of samples collected during \p F's execution.
///
/// \returns true if \p F was modified. Returns false, otherwise.
bool SampleFunctionProfile::emitAnnotations(Function &F, DominatorTree *DomTree,
PostDominatorTree *PostDomTree,
LoopInfo *Loops) {
bool SampleProfileLoader::emitAnnotations(Function &F) {
bool Changed = false;
// Initialize invariants used during computation and propagation.
@ -1045,10 +720,6 @@ bool SampleFunctionProfile::emitAnnotations(Function &F, DominatorTree *DomTree,
DEBUG(dbgs() << "Line number for the first instruction in " << F.getName()
<< ": " << HeaderLineno << "\n");
DT = DomTree;
PDT = PostDomTree;
LI = Loops;
Ctx = &F.getParent()->getContext();
// Compute basic block weights.
Changed |= computeBlockWeights(F);
@ -1075,8 +746,8 @@ INITIALIZE_PASS_END(SampleProfileLoader, "sample-profile",
"Sample Profile loader", false, false)
bool SampleProfileLoader::doInitialization(Module &M) {
Profiler.reset(new SampleModuleProfile(M, Filename));
ProfileIsValid = Profiler->loadText();
Reader.reset(new SampleProfileReader(M, Filename));
ProfileIsValid = Reader->load();
return true;
}
@ -1091,11 +762,13 @@ FunctionPass *llvm::createSampleProfileLoaderPass(StringRef Name) {
bool SampleProfileLoader::runOnFunction(Function &F) {
if (!ProfileIsValid)
return false;
DominatorTree *DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
PostDominatorTree *PDT = &getAnalysis<PostDominatorTree>();
LoopInfo *LI = &getAnalysis<LoopInfo>();
SampleFunctionProfile &FunctionProfile = Profiler->getProfile(F);
if (!FunctionProfile.empty())
return FunctionProfile.emitAnnotations(F, DT, PDT, LI);
DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();
PDT = &getAnalysis<PostDominatorTree>();
LI = &getAnalysis<LoopInfo>();
Ctx = &F.getParent()->getContext();
Samples = Reader->getSamplesFor(F);
if (!Samples->empty())
return emitAnnotations(F);
return false;
}