From 6777f7a57fed6b39128773f13084da729dd64588 Mon Sep 17 00:00:00 2001 From: chriseth Date: Thu, 8 Mar 2018 19:41:29 +0100 Subject: Optimize across MLOAD if MSIZE is not used. --- libsolidity/ast/Types.h | 13 +++++++++++ libsolidity/codegen/CompilerUtils.cpp | 36 +++++++++++++++++++++++------- libsolidity/codegen/ExpressionCompiler.cpp | 21 ++++------------- 3 files changed, 45 insertions(+), 25 deletions(-) (limited to 'libsolidity') diff --git a/libsolidity/ast/Types.h b/libsolidity/ast/Types.h index b7e64891..2c392705 100644 --- a/libsolidity/ast/Types.h +++ b/libsolidity/ast/Types.h @@ -229,6 +229,9 @@ public: /// i.e. it behaves differently in lvalue context and in value context. virtual bool isValueType() const { return false; } virtual unsigned sizeOnStack() const { return 1; } + /// If it is possible to initialize such a value in memory by just writing zeros + /// of the size memoryHeadSize(). + virtual bool hasSimpleZeroValueInMemory() const { return true; } /// @returns the mobile (in contrast to static) type corresponding to the given type. /// This returns the corresponding IntegerType or FixedPointType for RationalNumberType /// and the pointer type for storage reference types. @@ -568,6 +571,7 @@ public: virtual TypePointer mobileType() const override { return copyForLocation(m_location, true); } virtual bool dataStoredIn(DataLocation _location) const override { return m_location == _location; } + virtual bool hasSimpleZeroValueInMemory() const override { return false; } /// Storage references can be pointers or bound references. In general, local variables are of /// pointer type, state variables are bound references. Assignments to pointers or deleting @@ -855,6 +859,7 @@ public: virtual u256 storageSize() const override; virtual bool canLiveOutsideStorage() const override { return false; } virtual unsigned sizeOnStack() const override; + virtual bool hasSimpleZeroValueInMemory() const override { return false; } virtual TypePointer mobileType() const override; /// Converts components to their temporary types and performs some wildcard matching. virtual TypePointer closestTemporaryType(TypePointer const& _targetType) const override; @@ -999,6 +1004,7 @@ public: virtual bool isValueType() const override { return true; } virtual bool canLiveOutsideStorage() const override { return m_kind == Kind::Internal || m_kind == Kind::External; } virtual unsigned sizeOnStack() const override; + virtual bool hasSimpleZeroValueInMemory() const override { return false; } virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override; virtual TypePointer encodingType() const override; virtual TypePointer interfaceType(bool _inLibrary) const override; @@ -1104,6 +1110,8 @@ public: return _inLibrary ? shared_from_this() : TypePointer(); } virtual bool dataStoredIn(DataLocation _location) const override { return _location == DataLocation::Storage; } + /// Cannot be stored in memory, but just in case. + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } TypePointer const& keyType() const { return m_keyType; } TypePointer const& valueType() const { return m_valueType; } @@ -1132,6 +1140,7 @@ public: virtual u256 storageSize() const override; virtual bool canLiveOutsideStorage() const override { return false; } virtual unsigned sizeOnStack() const override; + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } virtual std::string toString(bool _short) const override { return "type(" + m_actualType->toString(_short) + ")"; } virtual MemberList::MemberMap nativeMembers(ContractDefinition const* _currentScope) const override; @@ -1154,6 +1163,7 @@ public: virtual u256 storageSize() const override; virtual bool canLiveOutsideStorage() const override { return false; } virtual unsigned sizeOnStack() const override { return 0; } + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } virtual std::string richIdentifier() const override; virtual bool operator==(Type const& _other) const override; virtual std::string toString(bool _short) const override; @@ -1179,6 +1189,7 @@ public: virtual bool operator==(Type const& _other) const override; virtual bool canBeStored() const override { return false; } virtual bool canLiveOutsideStorage() const override { return true; } + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } virtual unsigned sizeOnStack() const override { return 0; } virtual MemberList::MemberMap nativeMembers(ContractDefinition const*) const override; @@ -1209,6 +1220,7 @@ public: virtual bool operator==(Type const& _other) const override; virtual bool canBeStored() const override { return false; } virtual bool canLiveOutsideStorage() const override { return true; } + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } virtual unsigned sizeOnStack() const override { return 0; } virtual MemberList::MemberMap nativeMembers(ContractDefinition const*) const override; @@ -1238,6 +1250,7 @@ public: virtual bool canLiveOutsideStorage() const override { return false; } virtual bool isValueType() const override { return true; } virtual unsigned sizeOnStack() const override { return 1; } + virtual bool hasSimpleZeroValueInMemory() const override { solAssert(false, ""); } virtual std::string toString(bool) const override { return "inaccessible dynamic type"; } virtual TypePointer decodingType() const override { return std::make_shared(256); } }; diff --git a/libsolidity/codegen/CompilerUtils.cpp b/libsolidity/codegen/CompilerUtils.cpp index 676d5d4e..deaef017 100644 --- a/libsolidity/codegen/CompilerUtils.cpp +++ b/libsolidity/codegen/CompilerUtils.cpp @@ -495,14 +495,34 @@ void CompilerUtils::abiDecodeV2(TypePointers const& _parameterTypes, bool _fromM void CompilerUtils::zeroInitialiseMemoryArray(ArrayType const& _type) { - auto repeat = m_context.newTag(); - m_context << repeat; - pushZeroValue(*_type.baseType()); - storeInMemoryDynamic(*_type.baseType()); - m_context << Instruction::SWAP1 << u256(1) << Instruction::SWAP1; - m_context << Instruction::SUB << Instruction::SWAP1; - m_context << Instruction::DUP2; - m_context.appendConditionalJumpTo(repeat); + if (_type.baseType()->hasSimpleZeroValueInMemory()) + { + solAssert(_type.baseType()->isValueType(), ""); + Whiskers templ(R"({ + let size := mul(length, ) + // cheap way of zero-initializing a memory range + codecopy(memptr, codesize(), size) + memptr := add(memptr, size) + })"); + templ("element_size", to_string(_type.baseType()->memoryHeadSize())); + m_context.appendInlineAssembly(templ.render(), {"length", "memptr"}); + } + else + { + // TODO: Potential optimization: + // When we create a new multi-dimensional dynamic array, each element + // is initialized to an empty array. It actually does not hurt + // to re-use exactly the same empty array for all elements. Currently, + // a new one is created each time. + auto repeat = m_context.newTag(); + m_context << repeat; + pushZeroValue(*_type.baseType()); + storeInMemoryDynamic(*_type.baseType()); + m_context << Instruction::SWAP1 << u256(1) << Instruction::SWAP1; + m_context << Instruction::SUB << Instruction::SWAP1; + m_context << Instruction::DUP2; + m_context.appendConditionalJumpTo(repeat); + } m_context << Instruction::SWAP1 << Instruction::POP; } diff --git a/libsolidity/codegen/ExpressionCompiler.cpp b/libsolidity/codegen/ExpressionCompiler.cpp index 9e2d30d5..76aa6843 100644 --- a/libsolidity/codegen/ExpressionCompiler.cpp +++ b/libsolidity/codegen/ExpressionCompiler.cpp @@ -850,8 +850,6 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall) } case FunctionType::Kind::ObjectCreation: { - // Will allocate at the end of memory (MSIZE) and not write at all unless the base - // type is dynamically sized. ArrayType const& arrayType = dynamic_cast(*_functionCall.annotation().type); _functionCall.expression().accept(*this); solAssert(arguments.size() == 1, ""); @@ -861,15 +859,7 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall) utils().convertType(*arguments[0]->annotation().type, IntegerType(256)); // Stack: requested_length - // Allocate at max(MSIZE, freeMemoryPointer) utils().fetchFreeMemoryPointer(); - m_context << Instruction::DUP1 << Instruction::MSIZE; - m_context << Instruction::LT; - auto initialise = m_context.appendConditionalJump(); - // Free memory pointer does not point to empty memory, use MSIZE. - m_context << Instruction::POP; - m_context << Instruction::MSIZE; - m_context << initialise; // Stack: requested_length memptr m_context << Instruction::SWAP1; @@ -894,13 +884,10 @@ bool ExpressionCompiler::visit(FunctionCall const& _functionCall) // Check if length is zero m_context << Instruction::DUP1 << Instruction::ISZERO; auto skipInit = m_context.appendConditionalJump(); - - // We only have to initialise if the base type is a not a value type. - if (dynamic_cast(arrayType.baseType().get())) - { - m_context << Instruction::DUP2 << u256(32) << Instruction::ADD; - utils().zeroInitialiseMemoryArray(arrayType); - } + // Always initialize because the free memory pointer might point at + // a dirty memory area. + m_context << Instruction::DUP2 << u256(32) << Instruction::ADD; + utils().zeroInitialiseMemoryArray(arrayType); m_context << skipInit; m_context << Instruction::POP; break; -- cgit v1.2.3