1 //===- SampleProfReader.h - Read LLVM sample profile data -------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file contains definitions needed for reading sample profiles.
12 // NOTE: If you are making changes to this file format, please remember
13 // to document them in the Clang documentation at
14 // tools/clang/docs/UsersManual.rst.
19 // Sample profiles are written as ASCII text. The file is divided into
20 // sections, which correspond to each of the functions executed at runtime.
21 // Each section has the following format
23 // function1:total_samples:total_head_samples
24 // offset1[.discriminator]: number_of_samples [fn1:num fn2:num ... ]
25 // offset2[.discriminator]: number_of_samples [fn3:num fn4:num ... ]
27 // offsetN[.discriminator]: number_of_samples [fn5:num fn6:num ... ]
28 // offsetA[.discriminator]: fnA:num_of_total_samples
29 // offsetA1[.discriminator]: number_of_samples [fn7:num fn8:num ... ]
32 // This is a nested tree in which the identation represents the nesting level
33 // of the inline stack. There are no blank lines in the file. And the spacing
34 // within a single line is fixed. Additional spaces will result in an error
35 // while reading the file.
37 // Any line starting with the '#' character is completely ignored.
39 // Inlined calls are represented with indentation. The Inline stack is a
40 // stack of source locations in which the top of the stack represents the
41 // leaf function, and the bottom of the stack represents the actual
42 // symbol to which the instruction belongs.
44 // Function names must be mangled in order for the profile loader to
45 // match them in the current translation unit. The two numbers in the
46 // function header specify how many total samples were accumulated in the
47 // function (first number), and the total number of samples accumulated
48 // in the prologue of the function (second number). This head sample
49 // count provides an indicator of how frequently the function is invoked.
51 // There are two types of lines in the function body.
53 // * Sampled line represents the profile information of a source location.
54 // * Callsite line represents the profile information of a callsite.
56 // Each sampled line may contain several items. Some are optional (marked
59 // a. Source line offset. This number represents the line number
60 // in the function where the sample was collected. The line number is
61 // always relative to the line where symbol of the function is
62 // defined. So, if the function has its header at line 280, the offset
63 // 13 is at line 293 in the file.
65 // Note that this offset should never be a negative number. This could
66 // happen in cases like macros. The debug machinery will register the
67 // line number at the point of macro expansion. So, if the macro was
68 // expanded in a line before the start of the function, the profile
69 // converter should emit a 0 as the offset (this means that the optimizers
70 // will not be able to associate a meaningful weight to the instructions
73 // b. [OPTIONAL] Discriminator. This is used if the sampled program
74 // was compiled with DWARF discriminator support
75 // (http://wiki.dwarfstd.org/index.php?title=Path_Discriminators).
76 // DWARF discriminators are unsigned integer values that allow the
77 // compiler to distinguish between multiple execution paths on the
78 // same source line location.
80 // For example, consider the line of code ``if (cond) foo(); else bar();``.
81 // If the predicate ``cond`` is true 80% of the time, then the edge
82 // into function ``foo`` should be considered to be taken most of the
83 // time. But both calls to ``foo`` and ``bar`` are at the same source
84 // line, so a sample count at that line is not sufficient. The
85 // compiler needs to know which part of that line is taken more
88 // This is what discriminators provide. In this case, the calls to
89 // ``foo`` and ``bar`` will be at the same line, but will have
90 // different discriminator values. This allows the compiler to correctly
91 // set edge weights into ``foo`` and ``bar``.
93 // c. Number of samples. This is an integer quantity representing the
94 // number of samples collected by the profiler at this source
97 // d. [OPTIONAL] Potential call targets and samples. If present, this
98 // line contains a call instruction. This models both direct and
99 // number of samples. For example,
101 // 130: 7 foo:3 bar:2 baz:7
103 // The above means that at relative line offset 130 there is a call
104 // instruction that calls one of ``foo()``, ``bar()`` and ``baz()``,
105 // with ``baz()`` being the relatively more frequently called target.
107 // Each callsite line may contain several items. Some are optional.
109 // a. Source line offset. This number represents the line number of the
110 // callsite that is inlined in the profiled binary.
112 // b. [OPTIONAL] Discriminator. Same as the discriminator for sampled line.
114 // c. Number of samples. This is an integer quantity representing the
115 // total number of samples collected for the inlined instance at this
122 // This is a more compact encoding. Numbers are encoded as ULEB128 values
123 // and all strings are encoded in a name table. The file is organized in
124 // the following sections:
127 // File identifier computed by function SPMagic() (0x5350524f463432ff)
129 // VERSION (uint32_t)
130 // File format version number computed by SPVersion()
133 // TOTAL_COUNT (uint64_t)
134 // Total number of samples in the profile.
135 // MAX_COUNT (uint64_t)
136 // Maximum value of samples on a line.
137 // MAX_FUNCTION_COUNT (uint64_t)
138 // Maximum number of samples at function entry (head samples).
139 // NUM_COUNTS (uint64_t)
140 // Number of lines with samples.
141 // NUM_FUNCTIONS (uint64_t)
142 // Number of functions with samples.
143 // NUM_DETAILED_SUMMARY_ENTRIES (size_t)
144 // Number of entries in detailed summary
146 // A list of detailed summary entry. Each entry consists of
148 // Required percentile of total sample count expressed as a fraction
149 // multiplied by 1000000.
150 // MIN_COUNT (uint64_t)
151 // The minimum number of samples required to reach the target
153 // NUM_COUNTS (uint64_t)
154 // Number of samples to get to the desrired percentile.
158 // Number of entries in the name table.
160 // A NUL-separated list of SIZE strings.
162 // FUNCTION BODY (one for each uninlined function body present in the profile)
163 // HEAD_SAMPLES (uint64_t) [only for top-level functions]
164 // Total number of samples collected at the head (prologue) of the
166 // NOTE: This field should only be present for top-level functions
167 // (i.e., not inlined into any caller). Inlined function calls
168 // have no prologue, so they don't need this.
169 // NAME_IDX (uint32_t)
170 // Index into the name table indicating the function name.
171 // SAMPLES (uint64_t)
172 // Total number of samples collected in this function.
174 // Total number of sampling records this function's profile.
176 // A list of NRECS entries. Each entry contains:
178 // Line offset from the start of the function.
179 // DISCRIMINATOR (uint32_t)
180 // Discriminator value (see description of discriminators
181 // in the text format documentation above).
182 // SAMPLES (uint64_t)
183 // Number of samples collected at this location.
184 // NUM_CALLS (uint32_t)
185 // Number of non-inlined function calls made at this location. In the
186 // case of direct calls, this number will always be 1. For indirect
187 // calls (virtual functions and function pointers) this will
188 // represent all the actual functions called at runtime.
190 // A list of NUM_CALLS entries for each called function:
191 // NAME_IDX (uint32_t)
192 // Index into the name table with the callee name.
193 // SAMPLES (uint64_t)
194 // Number of samples collected at the call site.
195 // NUM_INLINED_FUNCTIONS (uint32_t)
196 // Number of callees inlined into this function.
197 // INLINED FUNCTION RECORDS
198 // A list of NUM_INLINED_FUNCTIONS entries describing each of the inlined
201 // Line offset from the start of the function.
202 // DISCRIMINATOR (uint32_t)
203 // Discriminator value (see description of discriminators
204 // in the text format documentation above).
206 // A FUNCTION BODY entry describing the inlined function.
207 //===----------------------------------------------------------------------===//
209 #ifndef LLVM_PROFILEDATA_SAMPLEPROFREADER_H
210 #define LLVM_PROFILEDATA_SAMPLEPROFREADER_H
212 #include "llvm/ADT/SmallVector.h"
213 #include "llvm/ADT/StringMap.h"
214 #include "llvm/ADT/StringRef.h"
215 #include "llvm/ADT/Twine.h"
216 #include "llvm/IR/DiagnosticInfo.h"
217 #include "llvm/IR/Function.h"
218 #include "llvm/IR/LLVMContext.h"
219 #include "llvm/IR/ProfileSummary.h"
220 #include "llvm/ProfileData/GCOV.h"
221 #include "llvm/ProfileData/SampleProf.h"
222 #include "llvm/Support/Debug.h"
223 #include "llvm/Support/ErrorOr.h"
224 #include "llvm/Support/MemoryBuffer.h"
229 #include <system_error>
236 namespace sampleprof {
238 /// Sample-based profile reader.
240 /// Each profile contains sample counts for all the functions
241 /// executed. Inside each function, statements are annotated with the
242 /// collected samples on all the instructions associated with that
245 /// For this to produce meaningful data, the program needs to be
246 /// compiled with some debug information (at minimum, line numbers:
247 /// -gline-tables-only). Otherwise, it will be impossible to match IR
248 /// instructions to the line numbers collected by the profiler.
250 /// From the profile file, we are interested in collecting the
251 /// following information:
253 /// * A list of functions included in the profile (mangled names).
255 /// * For each function F:
256 /// 1. The total number of samples collected in F.
258 /// 2. The samples collected at each line in F. To provide some
259 /// protection against source code shuffling, line numbers should
260 /// be relative to the start of the function.
262 /// The reader supports two file formats: text and binary. The text format
263 /// is useful for debugging and testing, while the binary format is more
264 /// compact and I/O efficient. They can both be used interchangeably.
265 class SampleProfileReader {
267 SampleProfileReader(std::unique_ptr<MemoryBuffer> B, LLVMContext &C,
268 SampleProfileFormat Format = SPF_None)
269 : Profiles(0), Ctx(C), Buffer(std::move(B)), Format(Format) {}
271 virtual ~SampleProfileReader() = default;
273 /// Read and validate the file header.
274 virtual std::error_code readHeader() = 0;
276 /// Read sample profiles from the associated file.
277 virtual std::error_code read() = 0;
279 /// Print the profile for \p FName on stream \p OS.
280 void dumpFunctionProfile(StringRef FName, raw_ostream &OS = dbgs());
282 /// Print all the profiles on stream \p OS.
283 void dump(raw_ostream &OS = dbgs());
285 /// Return the samples collected for function \p F.
286 FunctionSamples *getSamplesFor(const Function &F) {
287 // The function name may have been updated by adding suffix. In sample
288 // profile, the function names are all stripped, so we need to strip
289 // the function name suffix before matching with profile.
290 StringRef Fname = F.getName().split('.').first;
292 Fname = getRepInFormat(Fname, getFormat(), FGUID);
293 if (Profiles.count(Fname))
294 return &Profiles[Fname];
298 /// Return all the profiles.
299 StringMap<FunctionSamples> &getProfiles() { return Profiles; }
301 /// Report a parse error message.
302 void reportError(int64_t LineNumber, Twine Msg) const {
303 Ctx.diagnose(DiagnosticInfoSampleProfile(Buffer->getBufferIdentifier(),
307 /// Create a sample profile reader appropriate to the file format.
308 static ErrorOr<std::unique_ptr<SampleProfileReader>>
309 create(const Twine &Filename, LLVMContext &C);
311 /// Create a sample profile reader from the supplied memory buffer.
312 static ErrorOr<std::unique_ptr<SampleProfileReader>>
313 create(std::unique_ptr<MemoryBuffer> &B, LLVMContext &C);
315 /// Return the profile summary.
316 ProfileSummary &getSummary() { return *(Summary.get()); }
318 /// \brief Return the profile format.
319 SampleProfileFormat getFormat() { return Format; }
322 /// Map every function to its associated profile.
324 /// The profile of every function executed at runtime is collected
325 /// in the structure FunctionSamples. This maps function objects
326 /// to their corresponding profiles.
327 StringMap<FunctionSamples> Profiles;
329 /// LLVM context used to emit diagnostics.
332 /// Memory buffer holding the profile file.
333 std::unique_ptr<MemoryBuffer> Buffer;
335 /// Profile summary information.
336 std::unique_ptr<ProfileSummary> Summary;
338 /// Compute summary for this profile.
339 void computeSummary();
341 /// \brief The format of sample.
342 SampleProfileFormat Format = SPF_None;
345 class SampleProfileReaderText : public SampleProfileReader {
347 SampleProfileReaderText(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
348 : SampleProfileReader(std::move(B), C, SPF_Text) {}
350 /// Read and validate the file header.
351 std::error_code readHeader() override { return sampleprof_error::success; }
353 /// Read sample profiles from the associated file.
354 std::error_code read() override;
356 /// Return true if \p Buffer is in the format supported by this class.
357 static bool hasFormat(const MemoryBuffer &Buffer);
360 class SampleProfileReaderBinary : public SampleProfileReader {
362 SampleProfileReaderBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C,
363 SampleProfileFormat Format = SPF_None)
364 : SampleProfileReader(std::move(B), C, Format) {}
366 /// Read and validate the file header.
367 std::error_code readHeader() override;
369 /// Read sample profiles from the associated file.
370 std::error_code read() override;
373 /// Read a numeric value of type T from the profile.
375 /// If an error occurs during decoding, a diagnostic message is emitted and
378 /// \returns the read value.
379 template <typename T> ErrorOr<T> readNumber();
381 /// Read a string from the profile.
383 /// If an error occurs during decoding, a diagnostic message is emitted and
386 /// \returns the read value.
387 ErrorOr<StringRef> readString();
389 /// Read the string index and check whether it overflows the table.
390 template <typename T> inline ErrorOr<uint32_t> readStringIndex(T &Table);
392 /// Return true if we've reached the end of file.
393 bool at_eof() const { return Data >= End; }
395 /// Read the contents of the given profile instance.
396 std::error_code readProfile(FunctionSamples &FProfile);
398 /// Points to the current location in the buffer.
399 const uint8_t *Data = nullptr;
401 /// Points to the end of the buffer.
402 const uint8_t *End = nullptr;
405 std::error_code readSummaryEntry(std::vector<ProfileSummaryEntry> &Entries);
406 virtual std::error_code verifySPMagic(uint64_t Magic) = 0;
408 /// Read profile summary.
409 std::error_code readSummary();
411 /// Read the whole name table.
412 virtual std::error_code readNameTable() = 0;
414 /// Read a string indirectly via the name table.
415 virtual ErrorOr<StringRef> readStringFromTable() = 0;
418 class SampleProfileReaderRawBinary : public SampleProfileReaderBinary {
420 /// Function name table.
421 std::vector<StringRef> NameTable;
422 virtual std::error_code verifySPMagic(uint64_t Magic) override;
423 virtual std::error_code readNameTable() override;
424 /// Read a string indirectly via the name table.
425 virtual ErrorOr<StringRef> readStringFromTable() override;
428 SampleProfileReaderRawBinary(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
429 : SampleProfileReaderBinary(std::move(B), C, SPF_Binary) {}
431 /// \brief Return true if \p Buffer is in the format supported by this class.
432 static bool hasFormat(const MemoryBuffer &Buffer);
435 class SampleProfileReaderCompactBinary : public SampleProfileReaderBinary {
437 /// Function name table.
438 std::vector<std::string> NameTable;
439 virtual std::error_code verifySPMagic(uint64_t Magic) override;
440 virtual std::error_code readNameTable() override;
441 /// Read a string indirectly via the name table.
442 virtual ErrorOr<StringRef> readStringFromTable() override;
445 SampleProfileReaderCompactBinary(std::unique_ptr<MemoryBuffer> B,
447 : SampleProfileReaderBinary(std::move(B), C, SPF_Compact_Binary) {}
449 /// \brief Return true if \p Buffer is in the format supported by this class.
450 static bool hasFormat(const MemoryBuffer &Buffer);
453 using InlineCallStack = SmallVector<FunctionSamples *, 10>;
455 // Supported histogram types in GCC. Currently, we only need support for
456 // call target histograms.
460 HIST_TYPE_SINGLE_VALUE,
461 HIST_TYPE_CONST_DELTA,
462 HIST_TYPE_INDIR_CALL,
465 HIST_TYPE_INDIR_CALL_TOPN
468 class SampleProfileReaderGCC : public SampleProfileReader {
470 SampleProfileReaderGCC(std::unique_ptr<MemoryBuffer> B, LLVMContext &C)
471 : SampleProfileReader(std::move(B), C, SPF_GCC),
472 GcovBuffer(Buffer.get()) {}
474 /// Read and validate the file header.
475 std::error_code readHeader() override;
477 /// Read sample profiles from the associated file.
478 std::error_code read() override;
480 /// Return true if \p Buffer is in the format supported by this class.
481 static bool hasFormat(const MemoryBuffer &Buffer);
484 std::error_code readNameTable();
485 std::error_code readOneFunctionProfile(const InlineCallStack &InlineStack,
486 bool Update, uint32_t Offset);
487 std::error_code readFunctionProfiles();
488 std::error_code skipNextWord();
489 template <typename T> ErrorOr<T> readNumber();
490 ErrorOr<StringRef> readString();
492 /// Read the section tag and check that it's the same as \p Expected.
493 std::error_code readSectionTag(uint32_t Expected);
495 /// GCOV buffer containing the profile.
496 GCOVBuffer GcovBuffer;
498 /// Function names in this profile.
499 std::vector<std::string> Names;
501 /// GCOV tags used to separate sections in the profile file.
502 static const uint32_t GCOVTagAFDOFileNames = 0xaa000000;
503 static const uint32_t GCOVTagAFDOFunction = 0xac000000;
506 } // end namespace sampleprof
508 } // end namespace llvm
510 #endif // LLVM_PROFILEDATA_SAMPLEPROFREADER_H