Deterministic YulStringRepository using string hashes.

This commit is contained in:
Daniel Kirchner 2018-11-09 20:21:26 +01:00
parent 09f8ff27fc
commit 74557ceb0e
5 changed files with 71 additions and 44 deletions

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@ -106,7 +106,6 @@ void CompilerStack::reset(bool _keepSources)
m_stackState = Empty; m_stackState = Empty;
m_sources.clear(); m_sources.clear();
} }
yul::YulStringRepository::instance().reset();
m_libraries.clear(); m_libraries.clear();
m_evmVersion = EVMVersion(); m_evmVersion = EVMVersion();
m_optimize = false; m_optimize = false;

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@ -22,7 +22,7 @@
#include <boost/noncopyable.hpp> #include <boost/noncopyable.hpp>
#include <map> #include <unordered_map>
#include <memory> #include <memory>
#include <vector> #include <vector>
#include <string> #include <string>
@ -32,72 +32,101 @@ namespace dev
namespace yul namespace yul
{ {
/// Repository for YulStrings.
/// Owns the string data for all YulStrings, which can be referenced by a Handle.
/// A Handle consists of an ID (that depends on the insertion order of YulStrings and is potentially
/// non-deterministic) and a deterministic string hash.
class YulStringRepository: boost::noncopyable class YulStringRepository: boost::noncopyable
{ {
public: public:
YulStringRepository() struct Handle
{ {
reset(); size_t id;
} std::uint64_t hash;
};
YulStringRepository():
m_strings{std::make_shared<std::string>()},
m_hashToID{std::make_pair(emptyHash(), 0)}
{}
static YulStringRepository& instance() static YulStringRepository& instance()
{ {
static YulStringRepository inst; static YulStringRepository inst;
return inst; return inst;
} }
size_t stringToId(std::string const& _string) Handle stringToHandle(std::string const& _string)
{ {
if (_string.empty()) if (_string.empty())
return 0; return { 0, emptyHash() };
size_t& id = m_ids[_string]; std::uint64_t h = hash(_string);
if (id == 0) auto range = m_hashToID.equal_range(h);
for (auto it = range.first; it != range.second; ++it)
if (*m_strings[it->second] == _string)
return Handle{it->second, h};
m_strings.emplace_back(std::make_shared<std::string>(_string));
size_t id = m_strings.size() - 1;
m_hashToID.emplace_hint(range.second, std::make_pair(h, id));
return Handle{id, h};
}
std::string const& idToString(size_t _id) const { return *m_strings.at(_id); }
static std::uint64_t hash(std::string const& v)
{
// FNV hash - can be replaced by a better one, e.g. xxhash64
std::uint64_t hash = emptyHash();
for (auto c: v)
{ {
m_strings.emplace_back(std::make_shared<std::string>(_string)); hash *= 1099511628211u;
id = m_strings.size() - 1; hash ^= c;
} }
return id;
}
std::string const& idToString(size_t _id) const
{
return *m_strings.at(_id);
}
void reset() return hash;
{
m_strings.clear();
m_ids.clear();
m_strings.emplace_back(std::make_shared<std::string>());
m_ids[std::string{}] = 0;
} }
static constexpr std::uint64_t emptyHash() { return 14695981039346656037u; }
private: private:
std::vector<std::shared_ptr<std::string>> m_strings; std::vector<std::shared_ptr<std::string>> m_strings;
std::map<std::string, size_t> m_ids; std::unordered_multimap<std::uint64_t, size_t> m_hashToID;
}; };
/// Wrapper around handles into the YulString repository.
/// Equality of two YulStrings is determined by comparing their ID.
/// The <-operator depends on the string hash and is not consistent
/// with string comparisons (however, it is still deterministic).
class YulString class YulString
{ {
public: public:
YulString() = default; YulString() = default;
explicit YulString(std::string const& _s): m_id(YulStringRepository::instance().stringToId(_s)) {} explicit YulString(std::string const& _s): m_handle(YulStringRepository::instance().stringToHandle(_s)) {}
YulString(YulString const&) = default; YulString(YulString const&) = default;
YulString(YulString&&) = default; YulString(YulString&&) = default;
YulString& operator=(YulString const&) = default; YulString& operator=(YulString const&) = default;
YulString& operator=(YulString&&) = default; YulString& operator=(YulString&&) = default;
/// This is not consistent with the string <-operator! /// This is not consistent with the string <-operator!
bool operator<(YulString const& _other) const { return m_id < _other.m_id; } /// First compares the string hashes. If they are equal
bool operator==(YulString const& _other) const { return m_id == _other.m_id; } /// it checks for identical IDs (only identical strings have
bool operator!=(YulString const& _other) const { return m_id != _other.m_id; } /// identical IDs and identical strings do not compare as "less").
/// If the hashes are identical and the strings are distinct, it
/// falls back to string comparison.
bool operator<(YulString const& _other) const
{
if (m_handle.hash < _other.m_handle.hash) return true;
if (_other.m_handle.hash < m_handle.hash) return false;
if (m_handle.id == _other.m_handle.id) return false;
return str() < _other.str();
}
/// Equality is determined based on the string ID.
bool operator==(YulString const& _other) const { return m_handle.id == _other.m_handle.id; }
bool operator!=(YulString const& _other) const { return m_handle.id != _other.m_handle.id; }
bool empty() const { return m_id == 0; } bool empty() const { return m_handle.id == 0; }
std::string const& str() const std::string const& str() const
{ {
return YulStringRepository::instance().idToString(m_id); return YulStringRepository::instance().idToString(m_handle.id);
} }
private: private:
/// ID of the string. Assumes that the empty string has ID zero. /// Handle of the string. Assumes that the empty string has ID zero.
size_t m_id = 0; YulStringRepository::Handle m_handle{ 0, YulStringRepository::emptyHash() };
}; };
} }

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@ -71,7 +71,7 @@ BOOST_AUTO_TEST_CASE(simple)
BOOST_CHECK_EQUAL(inlinableFunctions("{" BOOST_CHECK_EQUAL(inlinableFunctions("{"
"function g(a:u256) -> b:u256 { b := a }" "function g(a:u256) -> b:u256 { b := a }"
"function f() -> x:u256 { x := g(2:u256) }" "function f() -> x:u256 { x := g(2:u256) }"
"}"), "f,g"); "}"), "g,f");
} }
BOOST_AUTO_TEST_CASE(simple_inside_structures) BOOST_AUTO_TEST_CASE(simple_inside_structures)
@ -82,7 +82,7 @@ BOOST_AUTO_TEST_CASE(simple_inside_structures)
"function g(a:u256) -> b:u256 { b := a }" "function g(a:u256) -> b:u256 { b := a }"
"function f() -> x:u256 { x := g(2:u256) }" "function f() -> x:u256 { x := g(2:u256) }"
"}" "}"
"}"), "f,g"); "}"), "g,f");
BOOST_CHECK_EQUAL(inlinableFunctions("{" BOOST_CHECK_EQUAL(inlinableFunctions("{"
"for {" "for {"
"function g(a:u256) -> b:u256 { b := a }" "function g(a:u256) -> b:u256 { b := a }"
@ -92,7 +92,7 @@ BOOST_AUTO_TEST_CASE(simple_inside_structures)
"{" "{"
"function h() -> y:u256 { y := 2:u256 }" "function h() -> y:u256 { y := 2:u256 }"
"}" "}"
"}"), "f,g,h"); "}"), "h,g,f");
} }
BOOST_AUTO_TEST_CASE(negative) BOOST_AUTO_TEST_CASE(negative)

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@ -90,8 +90,6 @@ YulOptimizerTest::YulOptimizerTest(string const& _filename)
bool YulOptimizerTest::run(ostream& _stream, string const& _linePrefix, bool const _formatted) bool YulOptimizerTest::run(ostream& _stream, string const& _linePrefix, bool const _formatted)
{ {
yul::YulStringRepository::instance().reset();
assembly::AsmPrinter printer{m_yul}; assembly::AsmPrinter printer{m_yul};
shared_ptr<Block> ast; shared_ptr<Block> ast;
shared_ptr<assembly::AsmAnalysisInfo> analysisInfo; shared_ptr<assembly::AsmAnalysisInfo> analysisInfo;

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@ -41,18 +41,19 @@
// h_t := 2 // h_t := 2
// mstore(7, h_t) // mstore(7, h_t)
// let g_x_1 := 10 // let g_x_1 := 10
// f(1) // let g_f_x_8 := 1
// mstore(0, g_f_x_8)
// mstore(7, h())
// g(10)
// mstore(1, g_f_x_8)
// mstore(1, x) // mstore(1, x)
// } // }
// function g(x_1) // function g(x_1)
// { // {
// let f_x_8 := 1 // let f_x_8 := 1
// mstore(0, f_x_8) // mstore(0, f_x_8)
// let f_h_t // mstore(7, h())
// f_h_t := 2 // g(10)
// mstore(7, f_h_t)
// let f_g_x_1 := 10
// f(1)
// mstore(1, f_x_8) // mstore(1, f_x_8)
// } // }
// function h() -> t // function h() -> t