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Copy pathArrayUtils.cpp
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ArrayUtils.cpp
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/*
This file is part of solidity.
solidity 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.
solidity 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 solidity. If not, see <http://www.gnu.org/licenses/>.
*/
// SPDX-License-Identifier: GPL-3.0
/**
* @author Christian <[email protected]>
* @date 2015
* Code generation utils that handle arrays.
*/
#include <libsolidity/codegen/ArrayUtils.h>
#include <libsolidity/ast/Types.h>
#include <libsolidity/ast/TypeProvider.h>
#include <libsolidity/codegen/CompilerContext.h>
#include <libsolidity/codegen/CompilerUtils.h>
#include <libsolidity/codegen/LValue.h>
#include <libsolutil/FunctionSelector.h>
#include <libsolutil/Whiskers.h>
#include <libsolutil/StackTooDeepString.h>
#include <libevmasm/Instruction.h>
#include <liblangutil/Exceptions.h>
using namespace solidity;
using namespace solidity::evmasm;
using namespace solidity::frontend;
using namespace solidity::langutil;
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, "");
Type const* targetBaseType = _targetType.baseType();
Type const* sourceBaseType = _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 ? 1u : 0u) + (haveByteOffsetTarget ? 1u : 0u);
// stack: source_ref [source_length] target_ref
// store target_ref
for (unsigned i = _sourceType.sizeOnStack(); i > 0; --i)
m_context << swapInstruction(i);
// stack: target_ref source_ref [source_length]
if (_targetType.isByteArrayOrString())
{
// stack: target_ref source_ref [source_length]
if (fromCalldata && _sourceType.isDynamicallySized())
{
// stack: target_ref source_ref source_length
m_context << Instruction::SWAP1;
// stack: target_ref source_length source_ref
m_context << Instruction::DUP3;
// stack: target_ref source_length source_ref target_ref
m_context.callYulFunction(
m_context.utilFunctions().copyByteArrayToStorageFunction(_sourceType, _targetType),
3,
0
);
}
else
{
// stack: target_ref source_ref
m_context << Instruction::DUP2;
// stack: target_ref source_ref target_ref
m_context.callYulFunction(
m_context.utilFunctions().copyByteArrayToStorageFunction(_sourceType, _targetType),
2,
0
);
}
// stack: target_ref
return;
}
// 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 << Instruction::SWAP1 << u256(0x20);
m_context << Instruction::ADD << Instruction::SWAP1;
}
// stack: target_ref source_ref source_length
Type const* targetType = &_targetType;
Type const* sourceType = &_sourceType;
m_context.callLowLevelFunction(
"$copyArrayToStorage_" + sourceType->identifier() + "_to_" + targetType->identifier(),
3,
1,
[=](CompilerContext& _context)
{
ArrayUtils utils(_context);
ArrayType const& _sourceType = dynamic_cast<ArrayType const&>(*sourceType);
ArrayType const& _targetType = dynamic_cast<ArrayType const&>(*targetType);
// stack: target_ref source_ref source_length
_context << Instruction::DUP3;
// stack: target_ref source_ref source_length target_ref
utils.retrieveLength(_targetType);
// stack: target_ref source_ref source_length target_ref target_length
if (_targetType.isDynamicallySized())
{
// store new target length
solAssert(!_targetType.isByteArrayOrString());
_context << Instruction::DUP3 << Instruction::DUP3 << Instruction::SSTORE;
}
if (sourceBaseType->category() == Type::Category::Mapping)
{
solAssert(targetBaseType->category() == Type::Category::Mapping, "");
solAssert(_sourceType.location() == DataLocation::Storage, "");
// nothing to copy
_context
<< Instruction::POP << Instruction::POP
<< Instruction::POP << Instruction::POP;
return;
}
// stack: target_ref source_ref source_length target_ref target_length
// compute hashes (data positions)
_context << Instruction::SWAP1;
if (_targetType.isDynamicallySized())
CompilerUtils(_context).computeHashStatic();
// stack: target_ref source_ref source_length target_length target_data_pos
_context << Instruction::SWAP1;
utils.convertLengthToSize(_targetType);
_context << Instruction::DUP2 << Instruction::ADD;
// stack: target_ref source_ref source_length target_data_pos target_data_end
_context << Instruction::SWAP3;
// stack: target_ref target_data_end source_length target_data_pos source_ref
evmasm::AssemblyItem copyLoopEndWithoutByteOffset = _context.newTag();
solAssert(!_targetType.isByteArrayOrString());
// skip copying if source length is zero
_context << Instruction::DUP3 << Instruction::ISZERO;
_context.appendConditionalJumpTo(copyLoopEndWithoutByteOffset);
if (_sourceType.location() == DataLocation::Storage && _sourceType.isDynamicallySized())
CompilerUtils(_context).computeHashStatic();
// stack: target_ref target_data_end source_length target_data_pos source_data_pos
_context << Instruction::SWAP2;
utils.convertLengthToSize(_sourceType);
_context << Instruction::DUP3 << Instruction::ADD;
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end
if (haveByteOffsetTarget)
_context << u256(0);
if (haveByteOffsetSource)
_context << u256(0);
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset]
evmasm::AssemblyItem copyLoopStart = _context.newTag();
_context << copyLoopStart;
// check for loop condition
_context
<< dupInstruction(3 + byteOffsetSize) << dupInstruction(2 + byteOffsetSize)
<< Instruction::GT << Instruction::ISZERO;
evmasm::AssemblyItem copyLoopEnd = _context.appendConditionalJump();
// 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);
solUnimplementedAssert(
_sourceType.location() != DataLocation::CallData ||
!_sourceType.isDynamicallyEncoded() ||
!sourceBaseArrayType.isDynamicallySized(),
"Copying nested calldata dynamic arrays to storage is not implemented in the old code generator."
);
_context << Instruction::DUP3;
if (sourceBaseArrayType.location() == DataLocation::Memory)
_context << Instruction::MLOAD;
_context << Instruction::DUP3;
utils.copyArrayToStorage(dynamic_cast<ArrayType const&>(*targetBaseType), sourceBaseArrayType);
_context << Instruction::POP;
}
else if (directCopy)
{
solAssert(byteOffsetSize == 0, "Byte offset for direct copy.");
_context
<< Instruction::DUP3 << Instruction::SLOAD
<< Instruction::DUP3 << 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]
_context << dupInstruction(3 + byteOffsetSize);
if (_sourceType.location() == DataLocation::Storage)
{
if (haveByteOffsetSource)
_context << Instruction::DUP2;
else
_context << u256(0);
StorageItem(_context, *sourceBaseType).retrieveValue(SourceLocation(), true);
}
else if (sourceBaseType->isValueType())
CompilerUtils(_context).loadFromMemoryDynamic(*sourceBaseType, fromCalldata, true, false);
else
solUnimplemented("Copying of type " + _sourceType.toString(false) + " to storage is not supported in legacy (only supported by the IR pipeline). Hint: try compiling with `--via-ir` (CLI) or the equivalent `viaIR: true` (Standard JSON)");
// stack: target_ref target_data_end source_data_pos target_data_pos source_data_end [target_byte_offset] [source_byte_offset] <source_value>...
assertThrow(
2 + byteOffsetSize + sourceBaseType->sizeOnStack() <= 16,
StackTooDeepError,
util::stackTooDeepString
);
// fetch target storage reference
_context << dupInstruction(2 + byteOffsetSize + sourceBaseType->sizeOnStack());
if (haveByteOffsetTarget)
_context << dupInstruction(1 + byteOffsetSize + sourceBaseType->sizeOnStack());
else
_context << u256(0);
StorageItem(_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)
utils.incrementByteOffset(sourceBaseType->storageBytes(), 1, haveByteOffsetTarget ? 5 : 4);
else
{
_context << swapInstruction(2 + byteOffsetSize);
if (sourceIsStorage)
_context << sourceBaseType->storageSize();
else if (_sourceType.location() == DataLocation::Memory)
_context << sourceBaseType->memoryHeadSize();
else
_context << sourceBaseType->calldataHeadSize();
_context
<< Instruction::ADD
<< swapInstruction(2 + byteOffsetSize);
}
// increment target
if (haveByteOffsetTarget)
utils.incrementByteOffset(targetBaseType->storageBytes(), byteOffsetSize, byteOffsetSize + 2);
else
_context
<< swapInstruction(1 + byteOffsetSize)
<< targetBaseType->storageSize()
<< Instruction::ADD
<< swapInstruction(1 + byteOffsetSize);
_context.appendJumpTo(copyLoopStart);
_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]
_context << dupInstruction(byteOffsetSize) << Instruction::ISZERO;
evmasm::AssemblyItem copyCleanupLoopEnd = _context.appendConditionalJump();
_context << dupInstruction(2 + byteOffsetSize) << dupInstruction(1 + byteOffsetSize);
StorageItem(_context, *targetBaseType).setToZero(SourceLocation(), true);
utils.incrementByteOffset(targetBaseType->storageBytes(), byteOffsetSize, byteOffsetSize + 2);
_context.appendJumpTo(copyLoopEnd);
_context << copyCleanupLoopEnd;
_context << Instruction::POP; // might pop the source, but then target is popped next
}
if (haveByteOffsetSource)
_context << Instruction::POP;
_context << copyLoopEndWithoutByteOffset;
// zero-out leftovers in target
// stack: target_ref target_data_end source_data_pos target_data_pos_updated source_data_end
_context << Instruction::POP << Instruction::SWAP1 << Instruction::POP;
// stack: target_ref target_data_end target_data_pos_updated
if (targetBaseType->storageBytes() < 32)
utils.clearStorageLoop(TypeProvider::uint256());
else
utils.clearStorageLoop(targetBaseType);
_context << Instruction::POP;
}
);
}
void ArrayUtils::copyArrayToMemory(ArrayType const& _sourceType, bool _padToWordBoundaries) const
{
solUnimplementedAssert(
!_sourceType.baseType()->isDynamicallySized(),
"Nested dynamic arrays not implemented here."
);
CompilerUtils utils(m_context);
if (_sourceType.location() == DataLocation::CallData)
{
if (!_sourceType.isDynamicallySized())
m_context << _sourceType.length();
if (!_sourceType.isByteArrayOrString())
convertLengthToSize(_sourceType);
std::string routine = "calldatacopy(target, source, len)\n";
if (_padToWordBoundaries)
routine += R"(
// Set padding suffix to zero
mstore(add(target, len), 0)
len := and(add(len, 0x1f), not(0x1f))
)";
routine += "target := add(target, len)\n";
m_context.appendInlineAssembly("{" + routine + "}", {"target", "source", "len"});
m_context << Instruction::POP << 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) << Instruction::SWAP3;
// stack: counter source length target
auto repeat = m_context.newTag();
m_context << repeat;
m_context << Instruction::DUP2 << Instruction::DUP5;
m_context << Instruction::LT << Instruction::ISZERO;
auto loopEnd = m_context.appendConditionalJump();
m_context << Instruction::DUP3 << Instruction::DUP5;
accessIndex(_sourceType, false);
MemoryItem(m_context, *_sourceType.baseType(), true).retrieveValue(SourceLocation(), true);
if (auto baseArray = dynamic_cast<ArrayType const*>(_sourceType.baseType()))
copyArrayToMemory(*baseArray, _padToWordBoundaries);
else
utils.storeInMemoryDynamic(*_sourceType.baseType());
m_context << Instruction::SWAP3 << u256(1) << Instruction::ADD;
m_context << Instruction::SWAP3;
m_context.appendJumpTo(repeat);
m_context << loopEnd;
m_context << 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 << Instruction::SWAP1 << u256(32) << Instruction::ADD;
m_context << Instruction::SWAP1;
}
if (!_sourceType.isByteArrayOrString())
convertLengthToSize(_sourceType);
// stack: <target> <source> <size>
m_context << Instruction::DUP1 << Instruction::DUP4 << Instruction::DUP4;
// We can resort to copying full 32 bytes only if
// - the length is known to be a multiple of 32 or
// - we will pad to full 32 bytes later anyway.
if (!_sourceType.isByteArrayOrString() || _padToWordBoundaries)
utils.memoryCopy32();
else
utils.memoryCopy();
m_context << Instruction::SWAP1 << Instruction::POP;
// stack: <target> <size>
bool paddingNeeded = _padToWordBoundaries && _sourceType.isByteArrayOrString();
if (paddingNeeded)
{
// stack: <target> <size>
m_context << Instruction::SWAP1 << Instruction::DUP2 << Instruction::ADD;
// stack: <length> <target + size>
m_context << Instruction::SWAP1 << u256(31) << Instruction::AND;
// stack: <target + size> <remainder = size % 32>
evmasm::AssemblyItem skip = m_context.newTag();
if (_sourceType.isDynamicallySized())
{
m_context << Instruction::DUP1 << Instruction::ISZERO;
m_context.appendConditionalJumpTo(skip);
}
// round off, load from there.
// stack <target + size> <remainder = size % 32>
m_context << Instruction::DUP1 << Instruction::DUP3;
m_context << Instruction::SUB;
// stack: target+size remainder <target + size - remainder>
m_context << Instruction::DUP1 << Instruction::MLOAD;
// Now we AND it with ~(2**(8 * (32 - remainder)) - 1)
m_context << u256(1);
m_context << Instruction::DUP4 << u256(32) << Instruction::SUB;
// stack: ...<v> 1 <32 - remainder>
m_context << u256(0x100) << Instruction::EXP << Instruction::SUB;
m_context << Instruction::NOT << Instruction::AND;
// stack: target+size remainder target+size-remainder <v & ...>
m_context << Instruction::DUP2 << Instruction::MSTORE;
// stack: target+size remainder target+size-remainder
m_context << u256(32) << Instruction::ADD;
// stack: target+size remainder <new_padded_end>
m_context << Instruction::SWAP2 << Instruction::POP;
if (_sourceType.isDynamicallySized())
m_context << skip.tag();
// stack <target + "size"> <remainder = size % 32>
m_context << Instruction::POP;
}
else
// stack: <target> <size>
m_context << 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 << Instruction::DUP1 << Instruction::ISZERO;
evmasm::AssemblyItem loopEnd = m_context.appendConditionalJump();
// Special case for tightly-stored byte arrays
if (_sourceType.isByteArrayOrString())
{
// stack here: memory_offset storage_offset length
m_context << Instruction::DUP1 << u256(31) << Instruction::LT;
evmasm::AssemblyItem longByteArray = m_context.appendConditionalJump();
// store the short byte array (discard lower-order byte)
m_context << u256(0x100) << Instruction::DUP1;
m_context << Instruction::DUP4 << Instruction::SLOAD;
m_context << Instruction::DIV << Instruction::MUL;
m_context << Instruction::DUP4 << Instruction::MSTORE;
// stack here: memory_offset storage_offset length
// add 32 or length to memory offset
m_context << Instruction::SWAP2;
if (_padToWordBoundaries)
m_context << u256(32);
else
m_context << Instruction::DUP3;
m_context << Instruction::ADD;
m_context << Instruction::SWAP2;
m_context.appendJumpTo(loopEnd);
m_context << longByteArray;
}
else
// convert length to memory size
m_context << _sourceType.baseType()->memoryHeadSize() << Instruction::MUL;
m_context << Instruction::DUP3 << Instruction::ADD << Instruction::SWAP2;
if (_sourceType.isDynamicallySized())
{
// actual array data is stored at KECCAK256(storage_offset)
m_context << Instruction::SWAP1;
utils.computeHashStatic();
m_context << Instruction::SWAP1;
}
// stack here: memory_end_offset storage_data_offset memory_offset
bool haveByteOffset = !_sourceType.isByteArrayOrString() && storageBytes <= 16;
if (haveByteOffset)
m_context << u256(0) << Instruction::SWAP1;
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
evmasm::AssemblyItem loopStart = m_context.newTag();
m_context << loopStart;
// load and store
if (_sourceType.isByteArrayOrString())
{
// Packed both in storage and memory.
m_context << Instruction::DUP2 << Instruction::SLOAD;
m_context << Instruction::DUP2 << Instruction::MSTORE;
// increment storage_data_offset by 1
m_context << Instruction::SWAP1 << u256(1) << Instruction::ADD;
// increment memory offset by 32
m_context << Instruction::SWAP1 << u256(32) << Instruction::ADD;
}
else
{
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
if (haveByteOffset)
m_context << Instruction::DUP3 << Instruction::DUP3;
else
m_context << Instruction::DUP2 << u256(0);
StorageItem(m_context, *_sourceType.baseType()).retrieveValue(SourceLocation(), true);
if (auto baseArray = dynamic_cast<ArrayType const*>(_sourceType.baseType()))
copyArrayToMemory(*baseArray, _padToWordBoundaries);
else
utils.storeInMemoryDynamic(*_sourceType.baseType());
// increment storage_data_offset and byte offset
if (haveByteOffset)
incrementByteOffset(storageBytes, 2, 3);
else
{
m_context << Instruction::SWAP1;
m_context << storageSize << Instruction::ADD;
m_context << Instruction::SWAP1;
}
}
// check for loop condition
m_context << Instruction::DUP1 << dupInstruction(haveByteOffset ? 5 : 4);
m_context << Instruction::GT;
m_context.appendConditionalJumpTo(loopStart);
// stack here: memory_end_offset storage_data_offset [storage_byte_offset] memory_offset
if (haveByteOffset)
m_context << Instruction::SWAP1 << Instruction::POP;
if (!_sourceType.isByteArrayOrString())
{
solAssert(_sourceType.calldataStride() % 32 == 0, "");
solAssert(_sourceType.memoryStride() % 32 == 0, "");
}
if (_padToWordBoundaries && _sourceType.isByteArrayOrString())
{
// 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_offset) & 31
m_context << Instruction::DUP3 << Instruction::SWAP1 << Instruction::SUB;
m_context << u256(31) << Instruction::AND;
m_context << Instruction::DUP3 << Instruction::ADD;
m_context << Instruction::SWAP2;
}
m_context << loopEnd << Instruction::POP << Instruction::POP;
}
}
void ArrayUtils::clearArray(ArrayType const& _typeIn) const
{
Type const* type = &_typeIn;
m_context.callLowLevelFunction(
"$clearArray_" + _typeIn.identifier(),
2,
0,
[type](CompilerContext& _context)
{
ArrayType const& _type = dynamic_cast<ArrayType const&>(*type);
unsigned stackHeightStart = _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.");
_context << Instruction::POP; // remove byte offset
if (_type.isDynamicallySized())
ArrayUtils(_context).clearDynamicArray(_type);
else if (_type.length() == 0 || _type.baseType()->category() == Type::Category::Mapping)
_context << 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)
_context
<< u256(0) << Instruction::DUP2 << Instruction::SSTORE
<< u256(1) << Instruction::ADD;
_context << u256(0) << Instruction::SWAP1 << 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)
{
_context << u256(0);
StorageItem(_context, *_type.baseType()).setToZero(SourceLocation(), false);
_context
<< Instruction::POP
<< u256(_type.baseType()->storageSize()) << Instruction::ADD;
}
_context << u256(0);
StorageItem(_context, *_type.baseType()).setToZero(SourceLocation(), true);
}
else
{
_context << Instruction::DUP1 << _type.length();
ArrayUtils(_context).convertLengthToSize(_type);
_context << Instruction::ADD << Instruction::SWAP1;
if (_type.baseType()->storageBytes() < 32)
ArrayUtils(_context).clearStorageLoop(TypeProvider::uint256());
else
ArrayUtils(_context).clearStorageLoop(_type.baseType());
_context << Instruction::POP;
}
solAssert(_context.stackHeight() == stackHeightStart - 2, "");
}
);
}
void ArrayUtils::clearDynamicArray(ArrayType const& _type) const
{
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
// fetch length
retrieveLength(_type);
// set length to zero
m_context << u256(0) << Instruction::DUP3 << Instruction::SSTORE;
// Special case: short byte arrays are stored togeher with their length
evmasm::AssemblyItem endTag = m_context.newTag();
if (_type.isByteArrayOrString())
{
// stack: ref old_length
m_context << Instruction::DUP1 << u256(31) << Instruction::LT;
evmasm::AssemblyItem longByteArray = m_context.appendConditionalJump();
m_context << Instruction::POP;
m_context.appendJumpTo(endTag);
m_context.adjustStackOffset(1); // needed because of jump
m_context << longByteArray;
}
// stack: ref old_length
convertLengthToSize(_type);
// compute data positions
m_context << Instruction::SWAP1;
CompilerUtils(m_context).computeHashStatic();
// stack: len data_pos
m_context << Instruction::SWAP1 << Instruction::DUP2 << Instruction::ADD
<< Instruction::SWAP1;
// stack: data_pos_end data_pos
if (_type.storageStride() < 32)
clearStorageLoop(TypeProvider::uint256());
else
clearStorageLoop(_type.baseType());
// cleanup
m_context << endTag;
m_context << Instruction::POP;
}
void ArrayUtils::resizeDynamicArray(ArrayType const& _typeIn) const
{
Type const* type = &_typeIn;
m_context.callLowLevelFunction(
"$resizeDynamicArray_" + _typeIn.identifier(),
2,
0,
[type](CompilerContext& _context)
{
ArrayType const& _type = dynamic_cast<ArrayType const&>(*type);
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
if (!_type.isByteArrayOrString() && _type.baseType()->storageBytes() < 32)
solAssert(_type.baseType()->isValueType(), "Invalid storage size for non-value type.");
unsigned stackHeightStart = _context.stackHeight();
evmasm::AssemblyItem resizeEnd = _context.newTag();
// stack: ref new_length
// fetch old length
ArrayUtils(_context).retrieveLength(_type, 1);
// stack: ref new_length old_length
solAssert(_context.stackHeight() - stackHeightStart == 3 - 2, "2");
// Special case for short byte arrays, they are stored together with their length
if (_type.isByteArrayOrString())
{
evmasm::AssemblyItem regularPath = _context.newTag();
// We start by a large case-distinction about the old and new length of the byte array.
_context << Instruction::DUP3 << Instruction::SLOAD;
// stack: ref new_length current_length ref_value
solAssert(_context.stackHeight() - stackHeightStart == 4 - 2, "3");
_context << Instruction::DUP2 << u256(31) << Instruction::LT;
evmasm::AssemblyItem currentIsLong = _context.appendConditionalJump();
_context << Instruction::DUP3 << u256(31) << Instruction::LT;
evmasm::AssemblyItem newIsLong = _context.appendConditionalJump();
// Here: short -> short
// Compute 1 << (256 - 8 * new_size)
evmasm::AssemblyItem shortToShort = _context.newTag();
_context << shortToShort;
_context << Instruction::DUP3 << u256(8) << Instruction::MUL;
_context << u256(0x100) << Instruction::SUB;
_context << u256(2) << Instruction::EXP;
// Divide and multiply by that value, clearing bits.
_context << Instruction::DUP1 << Instruction::SWAP2;
_context << Instruction::DIV << Instruction::MUL;
// Insert 2*length.
_context << Instruction::DUP3 << Instruction::DUP1 << Instruction::ADD;
_context << Instruction::OR;
// Store.
_context << Instruction::DUP4 << Instruction::SSTORE;
solAssert(_context.stackHeight() - stackHeightStart == 3 - 2, "3");
_context.appendJumpTo(resizeEnd);
_context.adjustStackOffset(1); // we have to do that because of the jumps
// Here: short -> long
_context << newIsLong;
// stack: ref new_length current_length ref_value
solAssert(_context.stackHeight() - stackHeightStart == 4 - 2, "3");
// Zero out lower-order byte.
_context << u256(0xff) << Instruction::NOT << Instruction::AND;
// Store at data location.
_context << Instruction::DUP4;
CompilerUtils(_context).computeHashStatic();
_context << Instruction::SSTORE;
// stack: ref new_length current_length
// Store new length: Compute 2*length + 1 and store it.
_context << Instruction::DUP2 << Instruction::DUP1 << Instruction::ADD;
_context << u256(1) << Instruction::ADD;
// stack: ref new_length current_length 2*new_length+1
_context << Instruction::DUP4 << Instruction::SSTORE;
solAssert(_context.stackHeight() - stackHeightStart == 3 - 2, "3");
_context.appendJumpTo(resizeEnd);
_context.adjustStackOffset(1); // we have to do that because of the jumps
_context << currentIsLong;
_context << Instruction::DUP3 << u256(31) << Instruction::LT;
_context.appendConditionalJumpTo(regularPath);
// Here: long -> short
// Read the first word of the data and store it on the stack. Clear the data location and
// then jump to the short -> short case.
// stack: ref new_length current_length ref_value
solAssert(_context.stackHeight() - stackHeightStart == 4 - 2, "3");
_context << Instruction::POP << Instruction::DUP3;
CompilerUtils(_context).computeHashStatic();
_context << Instruction::DUP1 << Instruction::SLOAD << Instruction::SWAP1;
// stack: ref new_length current_length first_word data_location
_context << Instruction::DUP3;
ArrayUtils(_context).convertLengthToSize(_type);
_context << Instruction::DUP2 << Instruction::ADD << Instruction::SWAP1;
// stack: ref new_length current_length first_word data_location_end data_location
ArrayUtils(_context).clearStorageLoop(TypeProvider::uint256());
_context << Instruction::POP;
// stack: ref new_length current_length first_word
solAssert(_context.stackHeight() - stackHeightStart == 4 - 2, "3");
_context.appendJumpTo(shortToShort);
_context << regularPath;
// stack: ref new_length current_length ref_value
_context << Instruction::POP;
}
// Change of length for a regular array (i.e. length at location, data at KECCAK256(location)).
// stack: ref new_length old_length
// store new length
_context << Instruction::DUP2;
if (_type.isByteArrayOrString())
// For a "long" byte array, store length as 2*length+1
_context << Instruction::DUP1 << Instruction::ADD << u256(1) << Instruction::ADD;
_context << Instruction::DUP4 << Instruction::SSTORE;
// skip if size is not reduced
_context << Instruction::DUP2 << Instruction::DUP2
<< Instruction::GT << Instruction::ISZERO;
_context.appendConditionalJumpTo(resizeEnd);
// size reduced, clear the end of the array
// stack: ref new_length old_length
ArrayUtils(_context).convertLengthToSize(_type);
_context << Instruction::DUP2;
ArrayUtils(_context).convertLengthToSize(_type);
// stack: ref new_length old_size new_size
// compute data positions
_context << Instruction::DUP4;
CompilerUtils(_context).computeHashStatic();
// stack: ref new_length old_size new_size data_pos
_context << Instruction::SWAP2 << Instruction::DUP3 << Instruction::ADD;
// stack: ref new_length data_pos new_size delete_end
_context << Instruction::SWAP2 << Instruction::ADD;
// stack: ref new_length delete_end delete_start
if (_type.storageStride() < 32)
ArrayUtils(_context).clearStorageLoop(TypeProvider::uint256());
else
ArrayUtils(_context).clearStorageLoop(_type.baseType());
_context << resizeEnd;
// cleanup
_context << Instruction::POP << Instruction::POP << Instruction::POP;
solAssert(_context.stackHeight() == stackHeightStart - 2, "");
}
);
}
void ArrayUtils::incrementDynamicArraySize(ArrayType const& _type) const
{
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
if (!_type.isByteArrayOrString() && _type.baseType()->storageBytes() < 32)
solAssert(_type.baseType()->isValueType(), "Invalid storage size for non-value type.");
if (_type.isByteArrayOrString())
{
// We almost always just add 2 (length of byte arrays is shifted left by one)
// except for the case where we transition from a short byte array
// to a long byte array, there we have to copy.
// This happens if the length is exactly 31, which means that the
// lowest-order byte (we actually use a mask with fewer bits) must
// be (31*2+0) = 62
m_context << Instruction::DUP1 << Instruction::SLOAD << Instruction::DUP1;
m_context.callYulFunction(m_context.utilFunctions().extractByteArrayLengthFunction(), 1, 1);
m_context.appendInlineAssembly(R"({
// We have to copy if length is exactly 31, because that marks
// the transition between in-place and out-of-place storage.
switch length
case 31
{
mstore(0, ref)
let data_area := keccak256(0, 0x20)
sstore(data_area, and(data, not(0xff)))
// Set old length in new format (31 * 2 + 1)
data := 63
}
sstore(ref, add(data, 2))
// return new length in ref
ref := add(length, 1)
})", {"ref", "data", "length"});
m_context << Instruction::POP << Instruction::POP;
}
else
m_context.appendInlineAssembly(R"({
let new_length := add(sload(ref), 1)
sstore(ref, new_length)
ref := new_length
})", {"ref"});
}
void ArrayUtils::popStorageArrayElement(ArrayType const& _type) const
{
solAssert(_type.location() == DataLocation::Storage, "");
solAssert(_type.isDynamicallySized(), "");
if (!_type.isByteArrayOrString() && _type.baseType()->storageBytes() < 32)
solAssert(_type.baseType()->isValueType(), "Invalid storage size for non-value type.");
if (_type.isByteArrayOrString())
{
m_context << Instruction::DUP1 << Instruction::SLOAD << Instruction::DUP1;
m_context.callYulFunction(m_context.utilFunctions().extractByteArrayLengthFunction(), 1, 1);
util::Whiskers code(R"({
if iszero(length) {
mstore(0, <panicSelector>)
mstore(4, <emptyArrayPop>)
revert(0, 0x24)
}
switch gt(length, 31)
case 0 {
// short byte array
// Zero-out the suffix including the least significant byte.
let mask := sub(exp(0x100, sub(33, length)), 1)
length := sub(length, 1)
slot_value := or(and(not(mask), slot_value), mul(length, 2))
}
case 1 {
// long byte array
mstore(0, ref)
let slot := keccak256(0, 0x20)
switch length
case 32
{
let data := sload(slot)
sstore(slot, 0)
data := and(data, not(0xff))
slot_value := or(data, 62)
}
default
{
let offset_inside_slot := and(sub(length, 1), 0x1f)
slot := add(slot, div(sub(length, 1), 32))
let data := sload(slot)
// Zero-out the suffix of the byte array by masking it.
// ((1<<(8 * (32 - offset))) - 1)
let mask := sub(exp(0x100, sub(32, offset_inside_slot)), 1)
data := and(not(mask), data)
sstore(slot, data)
// Reduce the length by 1
slot_value := sub(slot_value, 2)
}
}
sstore(ref, slot_value)
})");
code("panicSelector", util::selectorFromSignatureU256("Panic(uint256)").str());
code("emptyArrayPop", std::to_string(unsigned(util::PanicCode::EmptyArrayPop)));
m_context.appendInlineAssembly(code.render(), {"ref", "slot_value", "length"});
m_context << Instruction::POP << Instruction::POP << Instruction::POP;
}
else
{
// stack: ArrayReference
retrieveLength(_type);
// stack: ArrayReference oldLength
m_context << Instruction::DUP1;
// stack: ArrayReference oldLength oldLength
m_context << Instruction::ISZERO;
m_context.appendConditionalPanic(util::PanicCode::EmptyArrayPop);
// Stack: ArrayReference oldLength
m_context << u256(1) << Instruction::SWAP1 << Instruction::SUB;
// Stack ArrayReference newLength
if (_type.baseType()->category() != Type::Category::Mapping)
{
m_context << Instruction::DUP2 << Instruction::DUP2;
// Stack ArrayReference newLength ArrayReference newLength;
accessIndex(_type, false);
// Stack: ArrayReference newLength storage_slot byte_offset
StorageItem(m_context, *_type.baseType()).setToZero(SourceLocation(), true);
}
// Stack: ArrayReference newLength
m_context << Instruction::SWAP1 << Instruction::SSTORE;
}
}
void ArrayUtils::clearStorageLoop(Type const* _type) const
{
solAssert(_type->storageBytes() >= 32, "");
m_context.callLowLevelFunction(
"$clearStorageLoop_" + _type->identifier(),
2,
1,
[_type](CompilerContext& _context)
{
unsigned stackHeightStart = _context.stackHeight();
if (_type->category() == Type::Category::Mapping)
{
_context << Instruction::POP;
return;
}
// stack: end_pos pos
evmasm::AssemblyItem loopStart = _context.appendJumpToNew();
_context << loopStart;
// check for loop condition
_context <<
Instruction::DUP1 <<
Instruction::DUP3 <<
Instruction::GT <<
Instruction::ISZERO;
evmasm::AssemblyItem zeroLoopEnd = _context.newTag();
_context.appendConditionalJumpTo(zeroLoopEnd);
// delete
_context << u256(0);
StorageItem(_context, *_type).setToZero(SourceLocation(), false);
_context << Instruction::POP;
// increment
_context << _type->storageSize() << Instruction::ADD;
_context.appendJumpTo(loopStart);
// cleanup
_context << zeroLoopEnd;
_context << Instruction::POP;
solAssert(_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 << Instruction::POP << u256(1);
else if (baseBytes <= 16)
{
unsigned itemsPerSlot = 32 / baseBytes;
m_context
<< u256(itemsPerSlot - 1) << Instruction::ADD
<< u256(itemsPerSlot) << Instruction::SWAP1 << Instruction::DIV;
}
}
else
m_context << _arrayType.baseType()->storageSize() << Instruction::MUL;
}
else
{
if (!_arrayType.isByteArrayOrString())
{
if (_arrayType.location() == DataLocation::Memory)
m_context << _arrayType.memoryStride();
else
m_context << _arrayType.calldataStride();
m_context << Instruction::MUL;
}
else if (_pad)
m_context << u256(31) << Instruction::ADD
<< u256(32) << Instruction::DUP1
<< Instruction::SWAP2 << Instruction::DIV << Instruction::MUL;