[llvm] Make YAML serialization up to 2.5 times faster
This patch significantly improves performance of the YAML serializer by optimizing `YAML::isNumeric` function. This function is called on the most strings and is highly inefficient for two reasons: * It uses `Regex`, which is parsed and compiled each time this function is called * It uses multiple passes which are not necessary This patch introduces stateful ad hoc YAML number parser which does not rely on `Regex`. It also fixes YAML number format inconsistency: current implementation supports C-stile octal number format (`01234567`) which was present in YAML 1.0 specialization (http://yaml.org/spec/1.0/), [Section 2.4. Tags, Example 2.19] but was deprecated and is no longer present in latest YAML 1.2 specification (http://yaml.org/spec/1.2/spec.html), see [Section 10.3.2. Tag Resolution]. Since the rest of the rest of the implementation does not support other deprecated YAML 1.0 numeric features such as sexagecimal numbers, commas as delimiters it is treated as inconsistency and not longer supported. This patch also adds unit tests to ensure the validity of proposed implementation. This performance bottleneck was identified while profiling Clangd's global-symbol-builder tool with my colleague @ilya-biryukov. The substantial part of the runtime was spent during a single-thread Reduce phase, which concludes with YAML serialization of collected symbol collection. Regex matching was accountable for approximately 45% of the whole runtime (which involves sharded Map phase), now it is reduced to 18% (which is spent in `clang::clangd::CanonicalIncludes` and can be also optimized because all used regexes are in fact either suffix matches or exact matches). `llvm-yaml-numeric-parser-fuzzer` was used to ensure the validity of the proposed regex replacement. Fuzzing for ~60 hours using 10 threads did not expose any bugs. Benchmarking `global-symbol-builder` (using `hyperfine --warmup 2 --min-runs 5 'command 1' 'command 2'`) tool by processing a reasonable amount of code (26 source files matched by `clang-tools-extra/clangd/*.cpp` with all transitive includes) confirmed our understanding of the performance bottleneck nature as it speeds up the command by the factor of 1.6x: | Command | Mean [s] | Min…Max [s] | | this patch (D50839) | 84.7 ± 0.6 | 83.3…84.7 | | master (rL339849) | 133.1 ± 0.8 | 132.4…134.6 | Using smaller samples (e.g. by collecting symbols from `clang-tools-extra/clangd/AST.cpp` only) yields even better performance improvement, which is expected because Map phase takes less time compared to Reduce and is 2.05x faster and therefore would significantly improve the performance of standalone YAML serializations. | Command | Mean [ms] | Min…Max [ms] | | this patch (D50839) | 3702.2 ± 48.7 | 3635.1…3752.3 | | master (rL339849) | 7607.6 ± 109.5 | 7533.3…7796.4 | Reviewed by: zturner, ilya-biryukov Differential revision: https://reviews.llvm.org/D50839 llvm-svn: 340154
This commit is contained in:
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@ -27,6 +27,7 @@
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#include <cctype>
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#include <cstddef>
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#include <cstdint>
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#include <iterator>
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#include <map>
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#include <memory>
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#include <new>
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@ -449,46 +450,100 @@ public:
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static bool const value = (sizeof(test<DocumentListTraits<T>>(nullptr))==1);
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};
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inline bool isNumber(StringRef S) {
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static const char OctalChars[] = "01234567";
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if (S.startswith("0") &&
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S.drop_front().find_first_not_of(OctalChars) == StringRef::npos)
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return true;
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if (S.startswith("0o") &&
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S.drop_front(2).find_first_not_of(OctalChars) == StringRef::npos)
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return true;
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static const char HexChars[] = "0123456789abcdefABCDEF";
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if (S.startswith("0x") &&
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S.drop_front(2).find_first_not_of(HexChars) == StringRef::npos)
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return true;
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static const char DecChars[] = "0123456789";
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if (S.find_first_not_of(DecChars) == StringRef::npos)
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return true;
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if (S.equals(".inf") || S.equals(".Inf") || S.equals(".INF"))
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return true;
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Regex FloatMatcher("^(\\.[0-9]+|[0-9]+(\\.[0-9]*)?)([eE][-+]?[0-9]+)?$");
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if (FloatMatcher.match(S))
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return true;
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return false;
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}
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inline bool isNumeric(StringRef S) {
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if ((S.front() == '-' || S.front() == '+') && isNumber(S.drop_front()))
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return true;
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const static auto skipDigits = [](StringRef Input) {
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return Input.drop_front(
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std::min(Input.find_first_not_of("0123456789"), Input.size()));
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};
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if (isNumber(S))
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return true;
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// Make S.front() and S.drop_front().front() (if S.front() is [+-]) calls
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// safe.
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if (S.empty() || S.equals("+") || S.equals("-"))
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return false;
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if (S.equals(".nan") || S.equals(".NaN") || S.equals(".NAN"))
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return true;
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return false;
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// Infinity and decimal numbers can be prefixed with sign.
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StringRef Tail = (S.front() == '-' || S.front() == '+') ? S.drop_front() : S;
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// Check for infinity first, because checking for hex and oct numbers is more
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// expensive.
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if (Tail.equals(".inf") || Tail.equals(".Inf") || Tail.equals(".INF"))
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return true;
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// Section 10.3.2 Tag Resolution
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// YAML 1.2 Specification prohibits Base 8 and Base 16 numbers prefixed with
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// [-+], so S should be used instead of Tail.
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if (S.startswith("0o"))
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return S.size() > 2 &&
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S.drop_front(2).find_first_not_of("01234567") == StringRef::npos;
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if (S.startswith("0x"))
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return S.size() > 2 && S.drop_front(2).find_first_not_of(
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"0123456789abcdefABCDEF") == StringRef::npos;
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// Parse float: [-+]? (\. [0-9]+ | [0-9]+ (\. [0-9]* )?) ([eE] [-+]? [0-9]+)?
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S = Tail;
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// Handle cases when the number starts with '.' and hence needs at least one
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// digit after dot (as opposed by number which has digits before the dot), but
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// doesn't have one.
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if (S.startswith(".") &&
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(S.equals(".") ||
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(S.size() > 1 && std::strchr("0123456789", S[1]) == nullptr)))
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return false;
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if (S.startswith("E") || S.startswith("e"))
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return false;
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enum ParseState {
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Default,
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FoundDot,
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FoundExponent,
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};
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ParseState State = Default;
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S = skipDigits(S);
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// Accept decimal integer.
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if (S.empty())
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return true;
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if (S.front() == '.') {
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State = FoundDot;
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S = S.drop_front();
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} else if (S.front() == 'e' || S.front() == 'E') {
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State = FoundExponent;
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S = S.drop_front();
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} else {
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return false;
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}
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if (State == FoundDot) {
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S = skipDigits(S);
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if (S.empty())
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return true;
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if (S.front() == 'e' || S.front() == 'E') {
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State = FoundExponent;
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S = S.drop_front();
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} else {
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return false;
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}
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}
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assert(FoundExponent && "Should have found exponent at this point.");
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if (S.empty())
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return false;
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if (S.front() == '+' || S.front() == '-') {
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S = S.drop_front();
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if (S.empty())
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return false;
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}
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return skipDigits(S).empty();
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}
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inline bool isNull(StringRef S) {
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@ -0,0 +1,9 @@
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set(LLVM_LINK_COMPONENTS
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Support
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FuzzMutate
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)
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add_llvm_fuzzer(llvm-yaml-numeric-parser-fuzzer
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yaml-numeric-parser-fuzzer.cpp
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DUMMY_MAIN DummyYAMLNumericParserFuzzer.cpp
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)
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@ -0,0 +1,19 @@
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//===--- DummyYAMLNumericParserFuzzer.cpp ---------------------------------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// Implementation of main so we can build and test without linking libFuzzer.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/FuzzMutate/FuzzerCLI.h"
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size);
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int main(int argc, char *argv[]) {
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return llvm::runFuzzerOnInputs(argc, argv, LLVMFuzzerTestOneInput);
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}
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@ -0,0 +1,47 @@
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//===--- special-case-list-fuzzer.cpp - Fuzzer for special case lists -----===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/ADT/StringRef.h"
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#include "llvm/Support/Regex.h"
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#include "llvm/Support/YAMLTraits.h"
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#include <cassert>
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#include <string>
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llvm::Regex Infinity("^[-+]?(\\.inf|\\.Inf|\\.INF)$");
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llvm::Regex Base8("^0o[0-7]+$");
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llvm::Regex Base16("^0x[0-9a-fA-F]+$");
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llvm::Regex Float("^[-+]?(\\.[0-9]+|[0-9]+(\\.[0-9]*)?)([eE][-+]?[0-9]+)?$");
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inline bool isNumericRegex(llvm::StringRef S) {
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if (S.equals(".nan") || S.equals(".NaN") || S.equals(".NAN"))
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return true;
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if (Infinity.match(S))
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return true;
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if (Base8.match(S))
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return true;
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if (Base16.match(S))
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return true;
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if (Float.match(S))
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return true;
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return false;
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}
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extern "C" int LLVMFuzzerTestOneInput(const uint8_t *Data, size_t Size) {
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std::string Input(reinterpret_cast<const char *>(Data), Size);
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Input.erase(std::remove(Input.begin(), Input.end(), 0), Input.end());
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if (!Input.empty() && llvm::yaml::isNumeric(Input) != isNumericRegex(Input))
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__builtin_trap();
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return 0;
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}
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@ -16,16 +16,17 @@
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#include "gmock/gmock.h"
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#include "gtest/gtest.h"
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using llvm::yaml::Input;
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using llvm::yaml::Output;
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using llvm::yaml::IO;
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using llvm::yaml::MappingTraits;
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using llvm::yaml::MappingNormalization;
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using llvm::yaml::ScalarTraits;
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using llvm::yaml::Hex8;
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using llvm::yaml::Hex16;
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using llvm::yaml::Hex32;
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using llvm::yaml::Hex64;
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using llvm::yaml::Hex8;
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using llvm::yaml::Input;
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using llvm::yaml::IO;
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using llvm::yaml::isNumeric;
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using llvm::yaml::MappingNormalization;
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using llvm::yaml::MappingTraits;
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using llvm::yaml::Output;
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using llvm::yaml::ScalarTraits;
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using ::testing::StartsWith;
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TestEscaped((char const *)foobar, "\"foo\\u200Bbar\"");
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}
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}
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TEST(YAMLIO, Numeric) {
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EXPECT_TRUE(isNumeric(".inf"));
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EXPECT_TRUE(isNumeric(".INF"));
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EXPECT_TRUE(isNumeric(".Inf"));
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EXPECT_TRUE(isNumeric("-.inf"));
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EXPECT_TRUE(isNumeric("+.inf"));
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EXPECT_TRUE(isNumeric(".nan"));
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EXPECT_TRUE(isNumeric(".NaN"));
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EXPECT_TRUE(isNumeric(".NAN"));
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EXPECT_TRUE(isNumeric("0"));
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EXPECT_TRUE(isNumeric("0."));
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EXPECT_TRUE(isNumeric("0.0"));
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EXPECT_TRUE(isNumeric("-0.0"));
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EXPECT_TRUE(isNumeric("+0.0"));
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EXPECT_TRUE(isNumeric("12345"));
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EXPECT_TRUE(isNumeric("012345"));
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EXPECT_TRUE(isNumeric("+12.0"));
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EXPECT_TRUE(isNumeric(".5"));
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EXPECT_TRUE(isNumeric("+.5"));
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EXPECT_TRUE(isNumeric("-1.0"));
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EXPECT_TRUE(isNumeric("2.3e4"));
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EXPECT_TRUE(isNumeric("-2E+05"));
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EXPECT_TRUE(isNumeric("+12e03"));
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EXPECT_TRUE(isNumeric("6.8523015e+5"));
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EXPECT_TRUE(isNumeric("1.e+1"));
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EXPECT_TRUE(isNumeric(".0e+1"));
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EXPECT_TRUE(isNumeric("0x2aF3"));
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EXPECT_TRUE(isNumeric("0o01234567"));
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EXPECT_FALSE(isNumeric("not a number"));
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EXPECT_FALSE(isNumeric("."));
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EXPECT_FALSE(isNumeric(".e+1"));
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EXPECT_FALSE(isNumeric(".1e"));
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EXPECT_FALSE(isNumeric(".1e+"));
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EXPECT_FALSE(isNumeric(".1e++1"));
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EXPECT_FALSE(isNumeric("ABCD"));
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EXPECT_FALSE(isNumeric("+0x2AF3"));
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EXPECT_FALSE(isNumeric("-0x2AF3"));
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EXPECT_FALSE(isNumeric("0x2AF3Z"));
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EXPECT_FALSE(isNumeric("0o012345678"));
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EXPECT_FALSE(isNumeric("0xZ"));
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EXPECT_FALSE(isNumeric("-0o012345678"));
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EXPECT_FALSE(isNumeric("000003A8229434B839616A25C16B0291F77A438B"));
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EXPECT_FALSE(isNumeric(""));
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EXPECT_FALSE(isNumeric("."));
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EXPECT_FALSE(isNumeric(".e+1"));
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EXPECT_FALSE(isNumeric(".e+"));
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EXPECT_FALSE(isNumeric(".e"));
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EXPECT_FALSE(isNumeric("e1"));
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// Deprecated formats: as for YAML 1.2 specification, the following are not
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// valid numbers anymore:
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//
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// * Sexagecimal numbers
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// * Decimal numbers with comma s the delimiter
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// * "inf", "nan" without '.' prefix
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EXPECT_FALSE(isNumeric("3:25:45"));
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EXPECT_FALSE(isNumeric("+12,345"));
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EXPECT_FALSE(isNumeric("-inf"));
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EXPECT_FALSE(isNumeric("1,230.15"));
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}
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