solidity/libsolidity/ArrayUtils.cpp
2015-09-08 13:12:00 +02:00

787 lines
31 KiB
C++

/*
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 length] target_ref (top)
solAssert(_targetType.location() == DataLocation::Storage, "");
IntegerType uint256(256);
Type const* targetBaseType = _targetType.isByteArray() ? &uint256 : &(*_targetType.baseType());
Type const* sourceBaseType = _sourceType.isByteArray() ? &uint256 : &(*_sourceType.baseType());
// TODO unroll loop for small sizes
bool sourceIsStorage = _sourceType.location() == DataLocation::Storage;
bool fromCalldata = _sourceType.location() == DataLocation::CallData;
bool directCopy = sourceIsStorage && sourceBaseType->isValueType() && *sourceBaseType == *targetBaseType;
bool haveByteOffsetSource = !directCopy && sourceIsStorage && sourceBaseType->storageBytes() <= 16;
bool haveByteOffsetTarget = !directCopy && targetBaseType->storageBytes() <= 16;
unsigned byteOffsetSize = (haveByteOffsetSource ? 1 : 0) + (haveByteOffsetTarget ? 1 : 0);
// stack: source_ref [source_length] target_ref
// store target_ref
for (unsigned i = _sourceType.sizeOnStack(); i > 0; --i)
m_context << eth::swapInstruction(i);
// stack: target_ref source_ref [source_length]
// stack: target_ref source_ref [source_length]
// retrieve source length
if (_sourceType.location() != DataLocation::CallData || !_sourceType.isDynamicallySized())
retrieveLength(_sourceType); // otherwise, length is already there
if (_sourceType.location() == DataLocation::Memory && _sourceType.isDynamicallySized())
{
// increment source pointer to point to data
m_context << eth::Instruction::SWAP1 << u256(0x20);
m_context << eth::Instruction::ADD << eth::Instruction::SWAP1;
}
// 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->category() == Type::Category::Mapping)
{
solAssert(targetBaseType->category() == Type::Category::Mapping, "");
solAssert(_sourceType.location() == DataLocation::Storage, "");
// nothing to copy
m_context
<< eth::Instruction::POP << eth::Instruction::POP
<< eth::Instruction::POP << eth::Instruction::POP;
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.location() == DataLocation::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->category() == Type::Category::Array)
{
solAssert(byteOffsetSize == 0, "Byte offset for array as base type.");
auto const& sourceBaseArrayType = dynamic_cast<ArrayType const&>(*sourceBaseType);
m_context << eth::Instruction::DUP3;
if (sourceBaseArrayType.location() == DataLocation::Memory)
m_context << eth::Instruction::MLOAD;
m_context << eth::Instruction::DUP3;
copyArrayToStorage(dynamic_cast<ArrayType const&>(*targetBaseType), sourceBaseArrayType);
m_context << 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.location() == DataLocation::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, fromCalldata, true, false);
else
solAssert(false, "Copying of type " + _sourceType.toString(false) + " to storage not yet supported.");
// 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->sizeOnStack() <= 16,
"Stack too deep, try removing local variables."
);
// fetch target storage reference
m_context << eth::dupInstruction(2 + byteOffsetSize + sourceBaseType->sizeOnStack());
if (haveByteOffsetTarget)
m_context << eth::dupInstruction(1 + byteOffsetSize + sourceBaseType->sizeOnStack());
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->storageBytes(), 1, haveByteOffsetTarget ? 5 : 4);
else
{
m_context << eth::swapInstruction(2 + byteOffsetSize);
if (sourceIsStorage)
m_context << sourceBaseType->storageSize();
else if (_sourceType.location() == DataLocation::Memory)
m_context << sourceBaseType->memoryHeadSize();
else
m_context << sourceBaseType->calldataEncodedSize(true);
m_context
<< eth::Instruction::ADD
<< eth::swapInstruction(2 + byteOffsetSize);
}
// increment target
if (haveByteOffsetTarget)
incrementByteOffset(targetBaseType->storageBytes(), byteOffsetSize, byteOffsetSize + 2);
else
m_context
<< eth::swapInstruction(1 + byteOffsetSize)
<< targetBaseType->storageSize()
<< 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->storageBytes(), 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;
}
void ArrayUtils::copyArrayToMemory(const ArrayType& _sourceType, bool _padToWordBoundaries) const
{
solAssert(
_sourceType.baseType()->calldataEncodedSize() > 0,
"Nested dynamic arrays not implemented here."
);
CompilerUtils utils(m_context);
unsigned baseSize = 1;
if (!_sourceType.isByteArray())
// We always pad the elements, regardless of _padToWordBoundaries.
baseSize = _sourceType.baseType()->calldataEncodedSize();
if (_sourceType.location() == DataLocation::CallData)
{
if (!_sourceType.isDynamicallySized())
m_context << _sourceType.length();
if (baseSize > 1)
m_context << u256(baseSize) << eth::Instruction::MUL;
// stack: target source_offset source_len
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3 << eth::Instruction::DUP5;
// stack: target source_offset source_len source_len source_offset target
m_context << eth::Instruction::CALLDATACOPY;
m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
m_context << eth::Instruction::SWAP2 << eth::Instruction::POP << eth::Instruction::POP;
}
else if (_sourceType.location() == DataLocation::Memory)
{
retrieveLength(_sourceType);
// stack: target source length
if (!_sourceType.baseType()->isValueType())
{
// copy using a loop
m_context << u256(0) << eth::Instruction::SWAP3;
// stack: counter source length target
auto repeat = m_context.newTag();
m_context << repeat;
m_context << eth::Instruction::DUP2 << eth::Instruction::DUP5;
m_context << eth::Instruction::LT << eth::Instruction::ISZERO;
auto loopEnd = m_context.appendConditionalJump();
m_context << eth::Instruction::DUP3 << eth::Instruction::DUP5;
accessIndex(_sourceType, false);
MemoryItem(m_context, *_sourceType.baseType(), true).retrieveValue(SourceLocation(), true);
if (auto baseArray = dynamic_cast<ArrayType const*>(_sourceType.baseType().get()))
copyArrayToMemory(*baseArray, _padToWordBoundaries);
else
utils.storeInMemoryDynamic(*_sourceType.baseType());
m_context << eth::Instruction::SWAP3 << u256(1) << eth::Instruction::ADD;
m_context << eth::Instruction::SWAP3;
m_context.appendJumpTo(repeat);
m_context << loopEnd;
m_context << eth::Instruction::SWAP3;
utils.popStackSlots(3);
// stack: updated_target_pos
return;
}
// memcpy using the built-in contract
if (_sourceType.isDynamicallySized())
{
// change pointer to data part
m_context << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD;
m_context << eth::Instruction::SWAP1;
}
// convert length to size
if (baseSize > 1)
m_context << u256(baseSize) << eth::Instruction::MUL;
// stack: <target> <source> <size>
//@TODO do not use ::CALL if less than 32 bytes?
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP4 << eth::Instruction::DUP4;
utils.memoryCopy();
m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
// stack: <target> <size>
bool paddingNeeded = false;
if (_sourceType.isDynamicallySized())
paddingNeeded = _padToWordBoundaries && ((baseSize % 32) != 0);
else
paddingNeeded = _padToWordBoundaries && (((_sourceType.length() * baseSize) % 32) != 0);
if (paddingNeeded)
{
// stack: <target> <size>
m_context << eth::Instruction::SWAP1 << eth::Instruction::DUP2 << eth::Instruction::ADD;
// stack: <length> <target + size>
m_context << eth::Instruction::SWAP1 << u256(31) << eth::Instruction::AND;
// stack: <target + size> <remainder = size % 32>
eth::AssemblyItem skip = m_context.newTag();
if (_sourceType.isDynamicallySized())
{
m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
m_context.appendConditionalJumpTo(skip);
}
// round off, load from there.
// stack <target + size> <remainder = size % 32>
m_context << eth::Instruction::DUP1 << eth::Instruction::DUP3;
m_context << eth::Instruction::SUB;
// stack: target+size remainder <target + size - remainder>
m_context << eth::Instruction::DUP1 << eth::Instruction::MLOAD;
// Now we AND it with ~(2**(8 * (32 - remainder)) - 1)
m_context << u256(1);
m_context << eth::Instruction::DUP4 << u256(32) << eth::Instruction::SUB;
// stack: ...<v> 1 <32 - remainder>
m_context << u256(0x100) << eth::Instruction::EXP << eth::Instruction::SUB;
m_context << eth::Instruction::NOT << eth::Instruction::AND;
// stack: target+size remainder target+size-remainder <v & ...>
m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
// stack: target+size remainder target+size-remainder
m_context << u256(32) << eth::Instruction::ADD;
// stack: target+size remainder <new_padded_end>
m_context << eth::Instruction::SWAP2 << eth::Instruction::POP;
if (_sourceType.isDynamicallySized())
m_context << skip.tag();
// stack <target + "size"> <remainder = size % 32>
m_context << eth::Instruction::POP;
}
else
// stack: <target> <size>
m_context << eth::Instruction::ADD;
}
else
{
solAssert(_sourceType.location() == DataLocation::Storage, "");
unsigned storageBytes = _sourceType.baseType()->storageBytes();
u256 storageSize = _sourceType.baseType()->storageSize();
solAssert(storageSize > 1 || (storageSize == 1 && storageBytes > 0), "");
retrieveLength(_sourceType);
// stack here: memory_offset storage_offset length
// jump to end if length is zero
m_context << eth::Instruction::DUP1 << eth::Instruction::ISZERO;
eth::AssemblyItem loopEnd = m_context.newTag();
m_context.appendConditionalJumpTo(loopEnd);
// compute memory end offset
if (baseSize > 1)
// convert length to memory size
m_context << u256(baseSize) << eth::Instruction::MUL;
m_context << eth::Instruction::DUP3 << eth::Instruction::ADD << eth::Instruction::SWAP2;
if (_sourceType.isDynamicallySized())
{
// actual array data is stored at SHA3(storage_offset)
m_context << eth::Instruction::SWAP1;
utils.computeHashStatic();
m_context << eth::Instruction::SWAP1;
}
// stack here: memory_end_offset storage_data_offset memory_offset
bool haveByteOffset = !_sourceType.isByteArray() && storageBytes <= 16;
if (haveByteOffset)
m_context << u256(0) << eth::Instruction::SWAP1;
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
eth::AssemblyItem loopStart = m_context.newTag();
m_context << loopStart;
// load and store
if (_sourceType.isByteArray())
{
// Packed both in storage and memory.
m_context << eth::Instruction::DUP2 << eth::Instruction::SLOAD;
m_context << eth::Instruction::DUP2 << eth::Instruction::MSTORE;
// increment storage_data_offset by 1
m_context << eth::Instruction::SWAP1 << u256(1) << eth::Instruction::ADD;
// increment memory offset by 32
m_context << eth::Instruction::SWAP1 << u256(32) << eth::Instruction::ADD;
}
else
{
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
if (haveByteOffset)
m_context << eth::Instruction::DUP3 << eth::Instruction::DUP3;
else
m_context << eth::Instruction::DUP2 << u256(0);
StorageItem(m_context, *_sourceType.baseType()).retrieveValue(SourceLocation(), true);
if (auto baseArray = dynamic_cast<ArrayType const*>(_sourceType.baseType().get()))
copyArrayToMemory(*baseArray, _padToWordBoundaries);
else
utils.storeInMemoryDynamic(*_sourceType.baseType());
// increment storage_data_offset and byte offset
if (haveByteOffset)
incrementByteOffset(storageBytes, 2, 3);
else
{
m_context << eth::Instruction::SWAP1;
m_context << storageSize << eth::Instruction::ADD;
m_context << eth::Instruction::SWAP1;
}
}
// check for loop condition
m_context << eth::Instruction::DUP1 << eth::dupInstruction(haveByteOffset ? 5 : 4);
m_context << eth::Instruction::GT;
m_context.appendConditionalJumpTo(loopStart);
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
if (haveByteOffset)
m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
if (_padToWordBoundaries && baseSize % 32 != 0)
{
// memory_end_offset - start is the actual length (we want to compute the ceil of).
// memory_offset - start is its next multiple of 32, but it might be off by 32.
// so we compute: memory_end_offset += (memory_offset - memory_end_offest) & 31
m_context << eth::Instruction::DUP3 << eth::Instruction::SWAP1 << eth::Instruction::SUB;
m_context << u256(31) << eth::Instruction::AND;
m_context << eth::Instruction::DUP3 << eth::Instruction::ADD;
m_context << eth::Instruction::SWAP2;
}
m_context << loopEnd << eth::Instruction::POP << eth::Instruction::POP;
}
}
void ArrayUtils::clearArray(ArrayType const& _type) const
{
unsigned stackHeightStart = m_context.stackHeight();
solAssert(_type.location() == DataLocation::Storage, "");
if (_type.baseType()->storageBytes() < 32)
{
solAssert(_type.baseType()->isValueType(), "Invalid storage size for non-value type.");
solAssert(_type.baseType()->storageSize() <= 1, "Invalid storage size for type.");
}
if (_type.baseType()->isValueType())
solAssert(_type.baseType()->storageSize() <= 1, "Invalid size for value type.");
m_context << eth::Instruction::POP; // remove byte offset
if (_type.isDynamicallySized())
clearDynamicArray(_type);
else if (_type.length() == 0 || _type.baseType()->category() == Type::Category::Mapping)
m_context << eth::Instruction::POP;
else if (_type.baseType()->isValueType() && _type.storageSize() <= 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.storageSize(); ++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.baseType()->isValueType() && _type.length() <= 4)
{
// unroll loop for small arrays @todo choose a good value
solAssert(_type.baseType()->storageBytes() >= 32, "Invalid storage size.");
for (unsigned i = 1; i < _type.length(); ++i)
{
m_context << u256(0);
StorageItem(m_context, *_type.baseType()).setToZero(SourceLocation(), false);
m_context
<< eth::Instruction::POP
<< u256(_type.baseType()->storageSize()) << eth::Instruction::ADD;
}
m_context << u256(0);
StorageItem(m_context, *_type.baseType()).setToZero(SourceLocation(), true);
}
else
{
m_context << eth::Instruction::DUP1 << _type.length();
convertLengthToSize(_type);
m_context << eth::Instruction::ADD << eth::Instruction::SWAP1;
if (_type.baseType()->storageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.baseType());
m_context << eth::Instruction::POP;
}
solAssert(m_context.stackHeight() == stackHeightStart - 2, "");
}
void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
{
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
unsigned stackHeightStart = m_context.stackHeight();
// 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.baseType()->storageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.baseType());
// cleanup
m_context << eth::Instruction::POP;
solAssert(m_context.stackHeight() == stackHeightStart - 1, "");
}
void ArrayUtils::resizeDynamicArray(const ArrayType& _type) const
{
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
if (!_type.isByteArray() && _type.baseType()->storageBytes() < 32)
solAssert(_type.baseType()->isValueType(), "Invalid storage size for non-value type.");
unsigned stackHeightStart = m_context.stackHeight();
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.baseType()->storageBytes() < 32)
clearStorageLoop(IntegerType(256));
else
clearStorageLoop(*_type.baseType());
m_context << resizeEnd;
// cleanup
m_context << eth::Instruction::POP << eth::Instruction::POP << eth::Instruction::POP;
solAssert(m_context.stackHeight() == stackHeightStart - 2, "");
}
void ArrayUtils::clearStorageLoop(Type const& _type) const
{
unsigned stackHeightStart = m_context.stackHeight();
if (_type.category() == Type::Category::Mapping)
{
m_context << eth::Instruction::POP;
return;
}
// stack: end_pos pos
// jump to and return from the loop to allow for duplicate code removal
eth::AssemblyItem returnTag = m_context.pushNewTag();
m_context << eth::Instruction::SWAP2 << eth::Instruction::SWAP1;
// stack: <return tag> end_pos pos
eth::AssemblyItem loopStart = m_context.appendJumpToNew();
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 << eth::Instruction::SWAP1;
// "return"
m_context << eth::Instruction::JUMP;
m_context << returnTag;
solAssert(m_context.stackHeight() == stackHeightStart - 1, "");
}
void ArrayUtils::convertLengthToSize(ArrayType const& _arrayType, bool _pad) const
{
if (_arrayType.location() == DataLocation::Storage)
{
if (_arrayType.baseType()->storageSize() <= 1)
{
unsigned baseBytes = _arrayType.baseType()->storageBytes();
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.baseType()->storageSize() << eth::Instruction::MUL;
}
else
{
if (!_arrayType.isByteArray())
{
if (_arrayType.location() == DataLocation::Memory)
m_context << _arrayType.baseType()->memoryHeadSize();
else
m_context << _arrayType.baseType()->calldataEncodedSize();
m_context << 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.length();
else
{
m_context << eth::Instruction::DUP1;
switch (_arrayType.location())
{
case DataLocation::CallData:
// length is stored on the stack
break;
case DataLocation::Memory:
m_context << eth::Instruction::MLOAD;
break;
case DataLocation::Storage:
m_context << eth::Instruction::SLOAD;
break;
}
}
}
void ArrayUtils::accessIndex(ArrayType const& _arrayType, bool _doBoundsCheck) const
{
DataLocation location = _arrayType.location();
eth::Instruction load =
location == DataLocation::Storage ? eth::Instruction::SLOAD :
location == DataLocation::Memory ? eth::Instruction::MLOAD :
eth::Instruction::CALLDATALOAD;
if (_doBoundsCheck)
{
// retrieve length
if (!_arrayType.isDynamicallySized())
m_context << _arrayType.length();
else if (location == DataLocation::CallData)
// length is stored on the stack
m_context << eth::Instruction::SWAP1;
else
m_context << eth::Instruction::DUP2 << load;
// stack: <base_ref> <index> <length>
// check out-of-bounds access
m_context << eth::Instruction::DUP2 << eth::Instruction::LT << eth::Instruction::ISZERO;
// out-of-bounds access throws exception
m_context.appendConditionalJumpTo(m_context.errorTag());
}
else if (location == DataLocation::CallData && _arrayType.isDynamicallySized())
// remove length if present
m_context << eth::Instruction::SWAP1 << eth::Instruction::POP;
// stack: <base_ref> <index>
m_context << eth::Instruction::SWAP1;
if (_arrayType.isDynamicallySized())
{
if (location == DataLocation::Storage)
CompilerUtils(m_context).computeHashStatic();
else if (location == DataLocation::Memory)
m_context << u256(32) << eth::Instruction::ADD;
}
// stack: <index> <data_ref>
switch (location)
{
case DataLocation::CallData:
case DataLocation::Memory:
if (!_arrayType.isByteArray())
{
m_context << eth::Instruction::SWAP1;
if (location == DataLocation::CallData)
m_context << _arrayType.baseType()->calldataEncodedSize();
else
m_context << u256(_arrayType.memoryHeadSize());
m_context << eth::Instruction::MUL;
}
m_context << eth::Instruction::ADD;
break;
case DataLocation::Storage:
m_context << eth::Instruction::SWAP1;
if (_arrayType.baseType()->storageBytes() <= 16)
{
// stack: <data_ref> <index>
// goal:
// <ref> <byte_number> = <base_ref + index / itemsPerSlot> <(index % itemsPerSlot) * byteSize>
unsigned byteSize = _arrayType.baseType()->storageBytes();
solAssert(byteSize != 0, "");
unsigned itemsPerSlot = 32 / byteSize;
m_context << u256(itemsPerSlot) << eth::Instruction::SWAP2;
// stack: itemsPerSlot index data_ref
m_context
<< eth::Instruction::DUP3 << eth::Instruction::DUP3
<< eth::Instruction::DIV << eth::Instruction::ADD
// stack: itemsPerSlot index (data_ref + index / itemsPerSlot)
<< eth::Instruction::SWAP2 << eth::Instruction::SWAP1
<< eth::Instruction::MOD;
if (byteSize != 1)
m_context << u256(byteSize) << eth::Instruction::MUL;
}
else
{
if (_arrayType.baseType()->storageSize() != 1)
m_context << _arrayType.baseType()->storageSize() << eth::Instruction::MUL;
m_context << eth::Instruction::ADD << u256(0);
}
break;
}
}
void ArrayUtils::incrementByteOffset(unsigned _byteSize, unsigned _byteOffsetPosition, unsigned _storageOffsetPosition) const
{
solAssert(_byteSize < 32, "");
solAssert(_byteSize != 0, "");
// 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;
}