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solidity/ArrayUtils.cpp
chriseth 2cde4f3404 Packing for arrays.
2015-03-17 18:13:28 +01:00

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/*
This file is part of cpp-ethereum.
cpp-ethereum is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
cpp-ethereum is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with cpp-ethereum. If not, see <http://www.gnu.org/licenses/>.
*/
/**
* @author Christian <c@ethdev.com>
* @date 2015
* Code generation utils that handle arrays.
*/
#include <libsolidity/ArrayUtils.h>
#include <libevmcore/Instruction.h>
#include <libsolidity/CompilerContext.h>
#include <libsolidity/CompilerUtils.h>
#include <libsolidity/Types.h>
#include <libsolidity/Utils.h>
#include <libsolidity/LValue.h>
using namespace std;
using namespace dev;
using namespace solidity;
void ArrayUtils::copyArrayToStorage(ArrayType const& _targetType, ArrayType const& _sourceType) const
{
// this copies source to target and also clears target if it was larger
// need to leave "target_ref target_byte_off" on the stack at the end
// stack layout: [source_ref] [source_byte_off] [source length] target_ref target_byte_off (top)
solAssert(_targetType.getLocation() == ArrayType::Location::Storage, "");
solAssert(
_sourceType.getLocation() == ArrayType::Location::CallData ||
_sourceType.getLocation() == ArrayType::Location::Storage,
"Given array location not implemented."
);
IntegerType uint256(256);
Type const* targetBaseType = _targetType.isByteArray() ? &uint256 : &(*_targetType.getBaseType());
Type const* sourceBaseType = _sourceType.isByteArray() ? &uint256 : &(*_sourceType.getBaseType());
// TODO unroll loop for small sizes
bool sourceIsStorage = _sourceType.getLocation() == ArrayType::Location::Storage;
bool directCopy = sourceIsStorage && sourceBaseType->isValueType() && *sourceBaseType == *targetBaseType;
bool haveByteOffsetSource = !directCopy && sourceIsStorage && sourceBaseType->getStorageBytes() <= 16;
bool haveByteOffsetTarget = !directCopy && targetBaseType->getStorageBytes() <= 16;
unsigned byteOffsetSize = (haveByteOffsetSource ? 1 : 0) + (haveByteOffsetTarget ? 1 : 0);
// stack: source_ref [source_byte_off] [source_length] target_ref target_byte_off
// store target_ref
// arrays always start at zero byte offset, pop offset
m_context << eth::Instruction::POP;
for (unsigned i = _sourceType.getSizeOnStack(); i > 0; --i)
m_context << eth::swapInstruction(i);
// stack: target_ref source_ref [source_byte_off] [source_length]
if (sourceIsStorage)
// arrays always start at zero byte offset, pop offset
m_context << eth::Instruction::POP;
// stack: target_ref source_ref [source_length]
// retrieve source length
if (_sourceType.getLocation() != ArrayType::Location::CallData || !_sourceType.isDynamicallySized())
retrieveLength(_sourceType); // otherwise, length is already there
// stack: target_ref source_ref source_length
m_context << eth::Instruction::DUP3;
// stack: target_ref source_ref source_length target_ref
retrieveLength(_targetType);
// stack: target_ref source_ref source_length target_ref target_length
if (_targetType.isDynamicallySized())
// store new target length
m_context << eth::Instruction::DUP3 << eth::Instruction::DUP3 << eth::Instruction::SSTORE;
if (sourceBaseType->getCategory() == Type::Category::Mapping)
{
solAssert(targetBaseType->getCategory() == Type::Category::Mapping, "");
solAssert(_sourceType.getLocation() == ArrayType::Location::Storage, "");
// nothing to copy
m_context
<< eth::Instruction::POP << eth::Instruction::POP
<< eth::Instruction::POP << eth::Instruction::POP;
m_context << u256(0);
return;
}
// compute hashes (data positions)
m_context << eth::Instruction::SWAP1;
if (_targetType.isDynamicallySized())
CompilerUtils(m_context).computeHashStatic();
// stack: target_ref source_ref source_length target_length target_data_pos
m_context << eth::Instruction::SWAP1;
convertLengthToSize(_targetType);
m_context << eth::Instruction::DUP2 << eth::Instruction::ADD;
// stack: target_ref source_ref source_length target_data_pos target_data_end
m_context << eth::Instruction::SWAP3;
// stack: target_ref target_data_end source_length target_data_pos source_ref
// skip copying if source length is zero
m_context << eth::Instruction::DUP3 << eth::Instruction::ISZERO;
eth::AssemblyItem copyLoopEndWithoutByteOffset = m_context.newTag();
m_context.appendConditionalJumpTo(copyLoopEndWithoutByteOffset);
if (_sourceType.getLocation() == ArrayType::Location::Storage && _sourceType.isDynamicallySized())
CompilerUtils(m_context).computeHashStatic();
// stack: target_ref target_data_end source_length target_data_pos source_data_pos
m_context << eth::Instruction::SWAP2;
convertLengthToSize(_sourceType);
m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end
if (haveByteOffsetTarget)
m_context << u256(0);
if (haveByteOffsetSource)
m_context << u256(0);
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset]
eth::AssemblyItem copyLoopStart = m_context.newTag();
m_context << copyLoopStart;
// check for loop condition
m_context
<< eth::dupInstruction(3 + byteOffsetSize) << eth::dupInstruction(2 + byteOffsetSize)
<< eth::Instruction::GT << eth::Instruction::ISZERO;
eth::AssemblyItem copyLoopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(copyLoopEnd);
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset]
// copy
if (sourceBaseType->getCategory() == Type::Category::Array)
{
solAssert(byteOffsetSize == 0, "Byte offset for array as base type.");
m_context << eth::Instruction::DUP3;
if (sourceIsStorage)
m_context << u256(0);
m_context << eth::dupInstruction(sourceIsStorage ? 4 : 3) << u256(0);
copyArrayToStorage(
dynamic_cast<ArrayType const&>(*targetBaseType),
dynamic_cast<ArrayType const&>(*sourceBaseType)
);
m_context << eth::Instruction::POP << eth::Instruction::POP;
}
else if (directCopy)
{
solAssert(byteOffsetSize == 0, "Byte offset for direct copy.");
m_context
<< eth::Instruction::DUP3 << eth::Instruction::SLOAD
<< eth::Instruction::DUP3 << eth::Instruction::SSTORE;
}
else
{
// Note that we have to copy each element on its own in case conversion is involved.
// We might copy too much if there is padding at the last element, but this way end
// checking is easier.
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset]
m_context << eth::dupInstruction(3 + byteOffsetSize);
if (_sourceType.getLocation() == ArrayType::Location::Storage)
{
if (haveByteOffsetSource)
m_context << eth::Instruction::DUP2;
else
m_context << u256(0);
StorageItem(m_context, *sourceBaseType).retrieveValue(SourceLocation(), true);
}
else if (sourceBaseType->isValueType())
CompilerUtils(m_context).loadFromMemoryDynamic(*sourceBaseType, true, true, false);
else
solAssert(false, "Copying of unknown type requested: " + sourceBaseType->toString());
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset] <source_value>...
solAssert(2 + byteOffsetSize + sourceBaseType->getSizeOnStack() <= 16, "Stack too deep.");
// fetch target storage reference
m_context << eth::dupInstruction(2 + byteOffsetSize + sourceBaseType->getSizeOnStack());
if (haveByteOffsetTarget)
m_context << eth::dupInstruction(1 + byteOffsetSize + sourceBaseType->getSizeOnStack());
else
m_context << u256(0);
StorageItem(m_context, *targetBaseType).storeValue(*sourceBaseType, SourceLocation(), true);
}
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset]
// increment source
if (haveByteOffsetSource)
incrementByteOffset(sourceBaseType->getStorageBytes(), 1, haveByteOffsetTarget ? 5 : 4);
else
m_context
<< eth::swapInstruction(2 + byteOffsetSize)
<< (sourceIsStorage ? sourceBaseType->getStorageSize() : sourceBaseType->getCalldataEncodedSize())
<< eth::Instruction::ADD
<< eth::swapInstruction(2 + byteOffsetSize);
// increment target
if (haveByteOffsetTarget)
incrementByteOffset(targetBaseType->getStorageBytes(), byteOffsetSize, byteOffsetSize + 2);
else
m_context
<< eth::swapInstruction(1 + byteOffsetSize)
<< targetBaseType->getStorageSize()
<< eth::Instruction::ADD
<< eth::swapInstruction(1 + byteOffsetSize);
m_context.appendJumpTo(copyLoopStart);
m_context << copyLoopEnd;
if (haveByteOffsetTarget)
{
// clear elements that might be left over in the current slot in target
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end target_byte_offset [source_byte_offset]
m_context << eth::dupInstruction(byteOffsetSize) << eth::Instruction::ISZERO;
eth::AssemblyItem copyCleanupLoopEnd = m_context.appendConditionalJump();
m_context << eth::dupInstruction(2 + byteOffsetSize) << eth::dupInstruction(1 + byteOffsetSize);
StorageItem(m_context, *targetBaseType).setToZero(SourceLocation(), true);
incrementByteOffset(targetBaseType->getStorageBytes(), byteOffsetSize, byteOffsetSize + 2);
m_context.appendJumpTo(copyLoopEnd);
m_context << copyCleanupLoopEnd;
m_context << eth::Instruction::POP; // might pop the source, but then target is popped next
}
if (haveByteOffsetSource)
m_context << eth::Instruction::POP;
m_context << copyLoopEndWithoutByteOffset;
// zero-out leftovers in target
// stack: target_ref target_data_end source_data_pos target_data_pos_updated source_data_end
m_context << eth::Instruction::POP << eth::Instruction::SWAP1 << eth::Instruction::POP;
// stack: target_ref target_data_end target_data_pos_updated
clearStorageLoop(*targetBaseType);
m_context << eth::Instruction::POP;
m_context << u256(0);
}
void ArrayUtils::clearArray(ArrayType const& _type) const
{
unsigned stackHeightStart = m_context.getStackHeight();
solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
if (_type.getBaseType()->getStorageBytes() < 32)
{
solAssert(_type.getBaseType()->isValueType(), "Invalid storage size for non-value type.");
solAssert(_type.getBaseType()->getStorageSize() <= 1, "Invalid storage size for type.");
}
if (_type.getBaseType()->isValueType())
solAssert(_type.getBaseType()->getStorageSize() <= 1, "Invalid size for value type.");
m_context << eth::Instruction::POP; // remove byte offset
if (_type.isDynamicallySized())
clearDynamicArray(_type);
else if (_type.getLength() == 0 || _type.getBaseType()->getCategory() == Type::Category::Mapping)
m_context << eth::Instruction::POP;
else if (_type.getBaseType()->isValueType() && _type.getStorageSize() <= 5)
{
// unroll loop for small arrays @todo choose a good value
// Note that we loop over storage slots here, not elements.
for (unsigned i = 1; i < _type.getStorageSize(); ++i)
m_context
<< u256(0) << eth::Instruction::DUP2 << eth::Instruction::SSTORE
<< u256(1) << eth::Instruction::ADD;
m_context << u256(0) << eth::Instruction::SWAP1 << eth::Instruction::SSTORE;
}
else if (!_type.getBaseType()->isValueType() && _type.getLength() <= 4)
{
// unroll loop for small arrays @todo choose a good value
solAssert(_type.getBaseType()->getStorageBytes() >= 32, "Invalid storage size.");
for (unsigned i = 1; i < _type.getLength(); ++i)
{
m_context << u256(0);
StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), false);
m_context
<< eth::Instruction::POP
<< u256(_type.getBaseType()->getStorageSize()) << eth::Instruction::ADD;
}
m_context << u256(0);
StorageItem(m_context, *_type.getBaseType()).setToZero(SourceLocation(), true);
}
else
{
m_context << eth::Instruction::DUP1 << _type.getLength();
convertLengthToSize(_type);
m_context << eth::Instruction::ADD << eth::Instruction::SWAP1;
if (_type.getBaseType()->getStorageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.getBaseType());
m_context << eth::Instruction::POP;
}
solAssert(m_context.getStackHeight() == stackHeightStart - 2, "");
}
void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
{
solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
solAssert(_type.isDynamicallySized(), "");
unsigned stackHeightStart = m_context.getStackHeight();
// fetch length
m_context << eth::Instruction::DUP1 << eth::Instruction::SLOAD;
// set length to zero
m_context << u256(0) << eth::Instruction::DUP3 << eth::Instruction::SSTORE;
// stack: ref old_length
convertLengthToSize(_type);
// compute data positions
m_context << eth::Instruction::SWAP1;
CompilerUtils(m_context).computeHashStatic();
// stack: len data_pos
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD
<< eth::Instruction::SWAP1;
// stack: data_pos_end data_pos
if (_type.isByteArray() || _type.getBaseType()->getStorageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.getBaseType());
// cleanup
m_context << eth::Instruction::POP;
solAssert(m_context.getStackHeight() == stackHeightStart - 1, "");
}
void ArrayUtils::resizeDynamicArray(const ArrayType& _type) const
{
solAssert(_type.getLocation() == ArrayType::Location::Storage, "");
solAssert(_type.isDynamicallySized(), "");
if (!_type.isByteArray() && _type.getBaseType()->getStorageBytes() < 32)
solAssert(_type.getBaseType()->isValueType(), "Invalid storage size for non-value type.");
unsigned stackHeightStart = m_context.getStackHeight();
eth::AssemblyItem resizeEnd = m_context.newTag();
// stack: ref new_length
// fetch old length
m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
// stack: ref new_length old_length
// store new length
m_context << eth::Instruction::DUP2 << eth::Instruction::DUP4 << eth::Instruction::SSTORE;
// skip if size is not reduced
m_context << eth::Instruction::DUP2 << eth::Instruction::DUP2
<< eth::Instruction::ISZERO << eth::Instruction::GT;
m_context.appendConditionalJumpTo(resizeEnd);
// size reduced, clear the end of the array
// stack: ref new_length old_length
convertLengthToSize(_type);
m_context << eth::Instruction::DUP2;
convertLengthToSize(_type);
// stack: ref new_length old_size new_size
// compute data positions
m_context << eth::Instruction::DUP4;
CompilerUtils(m_context).computeHashStatic();
// stack: ref new_length old_size new_size data_pos
m_context << eth::Instruction::SWAP2 << eth::Instruction::DUP3 << eth::Instruction::ADD;
// stack: ref new_length data_pos new_size delete_end
m_context << eth::Instruction::SWAP2 << eth::Instruction::ADD;
// stack: ref new_length delete_end delete_start
if (_type.isByteArray() || _type.getBaseType()->getStorageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.getBaseType());
m_context << resizeEnd;
// cleanup
m_context << eth::Instruction::POP << eth::Instruction::POP << eth::Instruction::POP;
solAssert(m_context.getStackHeight() == stackHeightStart - 2, "");
}
void ArrayUtils::clearStorageLoop(Type const& _type) const
{
unsigned stackHeightStart = m_context.getStackHeight();
if (_type.getCategory() == Type::Category::Mapping)
{
m_context << eth::Instruction::POP;
return;
}
// stack: end_pos pos
eth::AssemblyItem loopStart = m_context.newTag();
m_context << loopStart;
// check for loop condition
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3
<< eth::Instruction::GT << eth::Instruction::ISZERO;
eth::AssemblyItem zeroLoopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(zeroLoopEnd);
// delete
m_context << u256(0);
StorageItem(m_context, _type).setToZero(SourceLocation(), false);
m_context << eth::Instruction::POP;
// increment
m_context << u256(1) << eth::Instruction::ADD;
m_context.appendJumpTo(loopStart);
// cleanup
m_context << zeroLoopEnd;
m_context << eth::Instruction::POP;
solAssert(m_context.getStackHeight() == stackHeightStart - 1, "");
}
void ArrayUtils::convertLengthToSize(ArrayType const& _arrayType, bool _pad) const
{
if (_arrayType.getLocation() == ArrayType::Location::Storage)
{
if (_arrayType.isByteArray())
m_context << u256(31) << eth::Instruction::ADD
<< u256(32) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
else if (_arrayType.getBaseType()->getStorageSize() <= 1)
{
unsigned baseBytes = _arrayType.getBaseType()->getStorageBytes();
if (baseBytes == 0)
m_context << eth::Instruction::POP << u256(1);
else if (baseBytes <= 16)
{
unsigned itemsPerSlot = 32 / baseBytes;
m_context
<< u256(itemsPerSlot - 1) << eth::Instruction::ADD
<< u256(itemsPerSlot) << eth::Instruction::SWAP1 << eth::Instruction::DIV;
}
}
else
m_context << _arrayType.getBaseType()->getStorageSize() << eth::Instruction::MUL;
}
else
{
if (!_arrayType.isByteArray())
m_context << _arrayType.getBaseType()->getCalldataEncodedSize() << eth::Instruction::MUL;
else if (_pad)
m_context << u256(31) << eth::Instruction::ADD
<< u256(32) << eth::Instruction::DUP1
<< eth::Instruction::SWAP2 << eth::Instruction::DIV << eth::Instruction::MUL;
}
}
void ArrayUtils::retrieveLength(ArrayType const& _arrayType) const
{
if (!_arrayType.isDynamicallySized())
m_context << _arrayType.getLength();
else
{
m_context << eth::Instruction::DUP1;
switch (_arrayType.getLocation())
{
case ArrayType::Location::CallData:
// length is stored on the stack
break;
case ArrayType::Location::Memory:
m_context << eth::Instruction::MLOAD;
break;
case ArrayType::Location::Storage:
m_context << eth::Instruction::SLOAD;
break;
}
}
}
void ArrayUtils::incrementByteOffset(unsigned byteSize, unsigned byteOffsetPosition, unsigned storageOffsetPosition) const
{
solAssert(byteSize < 32, "");
// We do the following, but avoiding jumps:
// byteOffset += byteSize
// if (byteOffset + byteSize > 32)
// {
// storageOffset++;
// byteOffset = 0;
// }
if (byteOffsetPosition > 1)
m_context << eth::swapInstruction(byteOffsetPosition - 1);
m_context << u256(byteSize) << eth::Instruction::ADD;
if (byteOffsetPosition > 1)
m_context << eth::swapInstruction(byteOffsetPosition - 1);
// compute, X := (byteOffset + byteSize - 1) / 32, should be 1 iff byteOffset + bytesize > 32
m_context
<< u256(32) << eth::dupInstruction(1 + byteOffsetPosition) << u256(byteSize - 1)
<< eth::Instruction::ADD << eth::Instruction::DIV;
// increment storage offset if X == 1 (just add X to it)
// stack: X
m_context
<< eth::swapInstruction(storageOffsetPosition) << eth::dupInstruction(storageOffsetPosition + 1)
<< eth::Instruction::ADD << eth::swapInstruction(storageOffsetPosition);
// stack: X
// set source_byte_offset to zero if X == 1 (using source_byte_offset *= 1 - X)
m_context << u256(1) << eth::Instruction::SUB;
// stack: 1 - X
if (byteOffsetPosition == 1)
m_context << eth::Instruction::MUL;
else
m_context
<< eth::dupInstruction(byteOffsetPosition + 1) << eth::Instruction::MUL
<< eth::swapInstruction(byteOffsetPosition) << eth::Instruction::POP;
}
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