diff options
| -rw-r--r-- | Changelog.md | 3 | ||||
| -rw-r--r-- | libevmasm/Assembly.cpp | 2 | ||||
| -rw-r--r-- | libevmasm/PeepholeOptimiser.cpp | 193 | ||||
| -rw-r--r-- | test/libsolidity/SolidityOptimizer.cpp | 48 |
4 files changed, 179 insertions, 67 deletions
diff --git a/Changelog.md b/Changelog.md index 0b10cd0c..b5e48173 100644 --- a/Changelog.md +++ b/Changelog.md @@ -1,5 +1,8 @@ ### 0.4.7 (unreleased) +Features: + * Optimizer: Some dead code elimination. + Bugfixes: * Type checker: string literals that are not valid UTF-8 cannot be converted to string type diff --git a/libevmasm/Assembly.cpp b/libevmasm/Assembly.cpp index 96306750..edbb9828 100644 --- a/libevmasm/Assembly.cpp +++ b/libevmasm/Assembly.cpp @@ -337,7 +337,7 @@ map<u256, u256> Assembly::optimiseInternal(bool _enable, bool _isCreation, size_ count = 0; PeepholeOptimiser peepOpt(m_items); - if (peepOpt.optimise()) + while (peepOpt.optimise()) count++; if (!_enable) diff --git a/libevmasm/PeepholeOptimiser.cpp b/libevmasm/PeepholeOptimiser.cpp index 901e310e..b96b0295 100644 --- a/libevmasm/PeepholeOptimiser.cpp +++ b/libevmasm/PeepholeOptimiser.cpp @@ -30,51 +30,96 @@ using namespace dev; // TODO: Extend this to use the tools from ExpressionClasses.cpp -struct Identity +struct OptimiserState +{ + AssemblyItems const& items; + size_t i; + std::back_insert_iterator<AssemblyItems> out; +}; + +template <class Method, size_t Arguments> +struct ApplyRule { - static size_t windowSize() { return 1; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) +}; +template <class Method> +struct ApplyRule<Method, 3> +{ + static bool applyRule(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) { - *_out = *_in; - return true; + return Method::applySimple(_in[0], _in[1], _in[2], _out); + } +}; +template <class Method> +struct ApplyRule<Method, 2> +{ + static bool applyRule(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) + { + return Method::applySimple(_in[0], _in[1], _out); + } +}; +template <class Method> +struct ApplyRule<Method, 1> +{ + static bool applyRule(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) + { + return Method::applySimple(_in[0], _out); } }; -struct PushPop +template <class Method, size_t WindowSize> +struct SimplePeepholeOptimizerMethod { - static size_t windowSize() { return 2; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems>) + static bool apply(OptimiserState& _state) { - auto t = _in[0].type(); - if (_in[1] == Instruction::POP && ( - SemanticInformation::isDupInstruction(_in[0]) || - t == Push || t == PushString || t == PushTag || t == PushSub || - t == PushSubSize || t == PushProgramSize || t == PushData || t == PushLibraryAddress - )) + if ( + _state.i + WindowSize <= _state.items.size() && + ApplyRule<Method, WindowSize>::applyRule(_state.items.begin() + _state.i, _state.out) + ) + { + _state.i += WindowSize; return true; + } else return false; } }; -struct AddPop +struct Identity: SimplePeepholeOptimizerMethod<Identity, 1> { - static size_t windowSize() { return 2; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) + static bool applySimple(AssemblyItem const& _item, std::back_insert_iterator<AssemblyItems> _out) { - if (_in[1] == Instruction::POP && - _in[0].type() == Operation - ) + *_out = _item; + return true; + } +}; + +struct PushPop: SimplePeepholeOptimizerMethod<PushPop, 2> +{ + static bool applySimple(AssemblyItem const& _push, AssemblyItem const& _pop, std::back_insert_iterator<AssemblyItems>) + { + auto t = _push.type(); + return _pop == Instruction::POP && ( + SemanticInformation::isDupInstruction(_push) || + t == Push || t == PushString || t == PushTag || t == PushSub || + t == PushSubSize || t == PushProgramSize || t == PushData || t == PushLibraryAddress + ); + } +}; + +struct OpPop: SimplePeepholeOptimizerMethod<OpPop, 2> +{ + static bool applySimple( + AssemblyItem const& _op, + AssemblyItem const& _pop, + std::back_insert_iterator<AssemblyItems> _out + ) + { + if (_pop == Instruction::POP && _op.type() == Operation) { - Instruction i0 = _in[0].instruction(); - if (instructionInfo(i0).ret == 1 && - !SemanticInformation::invalidatesMemory(i0) && - !SemanticInformation::invalidatesStorage(i0) && - !SemanticInformation::altersControlFlow(i0) && - !instructionInfo(i0).sideEffects - ) + Instruction instr = _op.instruction(); + if (instructionInfo(instr).ret == 1 && !instructionInfo(instr).sideEffects) { - for (int j = 0; j < instructionInfo(i0).args; j++) + for (int j = 0; j < instructionInfo(instr).args; j++) *_out = Instruction::POP; return true; } @@ -83,33 +128,33 @@ struct AddPop } }; -struct DoubleSwap +struct DoubleSwap: SimplePeepholeOptimizerMethod<DoubleSwap, 2> { - static size_t windowSize() { return 2; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems>) + static size_t applySimple(AssemblyItem const& _s1, AssemblyItem const& _s2, std::back_insert_iterator<AssemblyItems>) { - if (_in[0] == _in[1] && SemanticInformation::isSwapInstruction(_in[0])) - return true; - else - return false; + return _s1 == _s2 && SemanticInformation::isSwapInstruction(_s1); } }; -struct JumpToNext +struct JumpToNext: SimplePeepholeOptimizerMethod<JumpToNext, 3> { - static size_t windowSize() { return 3; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) + static size_t applySimple( + AssemblyItem const& _pushTag, + AssemblyItem const& _jump, + AssemblyItem const& _tag, + std::back_insert_iterator<AssemblyItems> _out + ) { if ( - _in[0].type() == PushTag && - (_in[1] == Instruction::JUMP || _in[1] == Instruction::JUMPI) && - _in[2].type() == Tag && - _in[0].data() == _in[2].data() + _pushTag.type() == PushTag && + (_jump == Instruction::JUMP || _jump == Instruction::JUMPI) && + _tag.type() == Tag && + _pushTag.data() == _tag.data() ) { - if (_in[1] == Instruction::JUMPI) - *_out = AssemblyItem(Instruction::POP, _in[1].location()); - *_out = _in[2]; + if (_jump == Instruction::JUMPI) + *_out = AssemblyItem(Instruction::POP, _jump.location()); + *_out = _tag; return true; } else @@ -117,19 +162,23 @@ struct JumpToNext } }; -struct TagConjunctions +struct TagConjunctions: SimplePeepholeOptimizerMethod<TagConjunctions, 3> { - static size_t windowSize() { return 3; } - static bool apply(AssemblyItems::const_iterator _in, std::back_insert_iterator<AssemblyItems> _out) + static bool applySimple( + AssemblyItem const& _pushTag, + AssemblyItem const& _pushConstant, + AssemblyItem const& _and, + std::back_insert_iterator<AssemblyItems> _out + ) { if ( - _in[0].type() == PushTag && - _in[2] == Instruction::AND && - _in[1].type() == Push && - (_in[1].data() & u256(0xFFFFFFFF)) == u256(0xFFFFFFFF) + _pushTag.type() == PushTag && + _and == Instruction::AND && + _pushConstant.type() == Push && + (_pushConstant.data() & u256(0xFFFFFFFF)) == u256(0xFFFFFFFF) ) { - *_out = _in[0]; + *_out = _pushTag; return true; } else @@ -137,11 +186,35 @@ struct TagConjunctions } }; -struct OptimiserState +/// Removes everything after a JUMP (or similar) until the next JUMPDEST. +struct UnreachableCode { - AssemblyItems const& items; - size_t i; - std::back_insert_iterator<AssemblyItems> out; + static bool apply(OptimiserState& _state) + { + auto it = _state.items.begin() + _state.i; + auto end = _state.items.end(); + if (it == end) + return false; + if ( + it[0] != Instruction::JUMP && + it[0] != Instruction::RETURN && + it[0] != Instruction::STOP && + it[0] != Instruction::SUICIDE + ) + return false; + + size_t i = 1; + while (it + i != end && it[i].type() != Tag) + i++; + if (i > 1) + { + *_state.out = it[0]; + _state.i += i; + return true; + } + else + return false; + } }; void applyMethods(OptimiserState&) @@ -152,9 +225,7 @@ void applyMethods(OptimiserState&) template <typename Method, typename... OtherMethods> void applyMethods(OptimiserState& _state, Method, OtherMethods... _other) { - if (_state.i + Method::windowSize() <= _state.items.size() && Method::apply(_state.items.begin() + _state.i, _state.out)) - _state.i += Method::windowSize(); - else + if (!Method::apply(_state)) applyMethods(_state, _other...); } @@ -162,7 +233,7 @@ bool PeepholeOptimiser::optimise() { OptimiserState state {m_items, 0, std::back_inserter(m_optimisedItems)}; while (state.i < m_items.size()) - applyMethods(state, PushPop(), AddPop(), DoubleSwap(), JumpToNext(), TagConjunctions(), Identity()); + applyMethods(state, PushPop(), OpPop(), DoubleSwap(), JumpToNext(), UnreachableCode(), TagConjunctions(), Identity()); if (m_optimisedItems.size() < m_items.size()) { m_items = std::move(m_optimisedItems); diff --git a/test/libsolidity/SolidityOptimizer.cpp b/test/libsolidity/SolidityOptimizer.cpp index ecb44272..a53a2638 100644 --- a/test/libsolidity/SolidityOptimizer.cpp +++ b/test/libsolidity/SolidityOptimizer.cpp @@ -20,17 +20,21 @@ * Tests for the Solidity optimizer. */ -#include <string> -#include <tuple> -#include <memory> -#include <boost/test/unit_test.hpp> -#include <boost/lexical_cast.hpp> #include <test/libsolidity/SolidityExecutionFramework.h> + #include <libevmasm/CommonSubexpressionEliminator.h> +#include <libevmasm/PeepholeOptimiser.h> #include <libevmasm/ControlFlowGraph.h> #include <libevmasm/Assembly.h> #include <libevmasm/BlockDeduplicator.h> +#include <boost/test/unit_test.hpp> +#include <boost/lexical_cast.hpp> + +#include <string> +#include <tuple> +#include <memory> + using namespace std; using namespace dev::eth; @@ -1121,6 +1125,40 @@ BOOST_AUTO_TEST_CASE(block_deduplicator_loops) BOOST_CHECK_EQUAL(pushTags.size(), 1); } +BOOST_AUTO_TEST_CASE(clear_unreachable_code) +{ + AssemblyItems items{ + AssemblyItem(PushTag, 1), + Instruction::JUMP, + u256(0), + Instruction::SLOAD, + AssemblyItem(Tag, 2), + u256(5), + u256(6), + Instruction::SSTORE, + AssemblyItem(PushTag, 1), + Instruction::JUMP, + u256(5), + u256(6) + }; + AssemblyItems expectation{ + AssemblyItem(PushTag, 1), + Instruction::JUMP, + AssemblyItem(Tag, 2), + u256(5), + u256(6), + Instruction::SSTORE, + AssemblyItem(PushTag, 1), + Instruction::JUMP + }; + PeepholeOptimiser peepOpt(items); + BOOST_REQUIRE(peepOpt.optimise()); + BOOST_CHECK_EQUAL_COLLECTIONS( + items.begin(), items.end(), + expectation.begin(), expectation.end() + ); +} + BOOST_AUTO_TEST_CASE(computing_constants) { char const* sourceCode = R"( |