/*

  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 <c@ethdev.com>

 * @date 2014

 * Routines used by both the compiler and the expression compiler.

 */

#pragma once

#include <libsolidity/ast/ASTForward.h>

#include <libsolidity/ast/TypeProvider.h>

#include <libsolidity/interface/DebugSettings.h>

#include <libsolidity/codegen/CompilerContext.h>

#include <libsolidity/codegen/CompilerContext.h>

namespace solidity::frontend

{

class Type; // forward

class CompilerUtils

{

public:

  explicit CompilerUtils(CompilerContext& _context): m_context(_context)

  {}

  /// Stores the initial value of the free-memory-pointer at its position;

  void initialiseFreeMemoryPointer();

  /// Copies the free memory pointer to the stack.

  /// Stack pre:

  /// Stack post: <mem_start>

  void fetchFreeMemoryPointer();

  /// Stores the free memory pointer from the stack.

  /// Stack pre: <mem_end>

  /// Stack post:

  void storeFreeMemoryPointer();

  /// Allocates a number of bytes in memory as given on the stack.

  /// Stack pre: <size>

  /// Stack post: <mem_start>

  void allocateMemory();

  /// Allocates a number of bytes in memory as given on the stack.

  /// Stack pre:

  /// Stack post: <mem_start>

  void allocateMemory(u256 const& size);

  /// Appends code that transforms memptr to (memptr - free_memptr) memptr

  /// Stack pre: <mem_end>

  /// Stack post: <size> <mem_start>

  void toSizeAfterFreeMemoryPointer();

  /// Appends code that performs a revert, providing the given string data.

  /// Will also append an error signature corresponding to Error(string).

  /// @param _argumentType the type of the string argument, will be converted to memory string.

  /// Stack pre: string data

  /// Stack post:

  void revertWithStringData(Type const& _argumentType);

  void revertWithError(

    std::string const& _errorName,

    std::vector<Type const*> const& _parameterTypes,

    std::vector<Type const*> const& _argumentTypes

  );

  /// Allocates a new array and copies the return data to it.

  /// If the EVM does not support return data, creates an empty array.

  void returnDataToArray();

  /// Computes the absolute calldata offset of a tail given a base reference and the (absolute)

  /// offset of the tail pointer. Performs bounds checks. If @a _type is a dynamically sized array it also

  /// returns the array length on the stack.

  /// Stack pre: base_ref tail_ptr

  /// Stack post: tail_ref [length]

  void accessCalldataTail(Type const& _type);

  /// Loads data from memory to the stack.

  /// @param _offset offset in memory (or calldata)

  /// @param _type data type to load

  /// @param _fromCalldata if true, load from calldata, not from memory

  /// @param _padToWords if true, assume the data is padded to full words (32 bytes)

  /// @returns the number of bytes consumed in memory.

  unsigned loadFromMemory(

    unsigned _offset,

    Type const& _type,

    bool _fromCalldata,

    bool _padToWords

  );

  /// Dynamic version of @see loadFromMemory, expects the memory offset on the stack.

  /// Stack pre: memory_offset

  /// Stack post: value... (memory_offset+length)

  void loadFromMemoryDynamic(

    Type const& _type,

    bool _fromCalldata = false,

    bool _padToWords = true,

    bool _keepUpdatedMemoryOffset = true

  );

  /// Stores a 256 bit integer from stack in memory.

  /// @param _offset offset in memory

  void storeInMemory(unsigned _offset);

  /// Dynamic version of @see storeInMemory, expects the memory offset below the value on the stack

  /// and also updates that. For reference types, only copies the data pointer. Fails for

  /// non-memory-references. For string literals no value is available on the stack.

  /// CAUTION: Even with @a _padToWords set to false, this may write a full 32-byte word and only

  /// advance the offset by the unpadded size, i.e., up to 31 bytes past the reported end of the

  /// stored value are overwritten.

  /// @param _padToWords if true, adds zeros to pad to multiple of 32 bytes. Array elements

  ///                    are always padded (except for byte arrays), regardless of this parameter.

  /// @param _cleanup if true, adds code to cleanup the value before storing it.

  /// Stack pre: memory_offset value...

  /// Stack post: (memory_offset+length)

  void storeInMemoryDynamic(Type const& _type, bool _padToWords = true, bool _cleanup = true);

  /// Creates code that unpacks the arguments according to their types specified by a vector of TypePointers.

  /// From memory if @a _fromMemory is true, otherwise from call data.

  /// Calls revert if the supplied size is shorter than the static data requirements

  /// or if dynamic data pointers reach outside of the area.

  /// Also has a hard cap of 0x100000000 for any given length/offset field.

  /// Stack pre: <source_offset> <length>

  /// Stack post: <value0> <value1> ... <valuen>

  void abiDecode(TypePointers const& _typeParameters, bool _fromMemory = false);

  /// Copies values (of types @a _givenTypes) given on the stack to a location in memory given

  /// at the stack top, encoding them according to the ABI as the given types @a _targetTypes.

  /// Removes the values from the stack and leaves the updated memory pointer.

  /// Stack pre: <v1> <v2> ... <vn> <memptr>

  /// Stack post: <memptr_updated>

  /// Does not touch the memory-free pointer.

  /// @param _padToWords if false, all values are concatenated without padding.

  /// @param _copyDynamicDataInPlace if true, dynamic types is stored (without length)

  /// together with fixed-length data.

  /// @param _encodeAsLibraryTypes if true, encodes for a library function, e.g. does not

  /// convert storage pointer types to memory types.

  /// @note the locations of target reference types are ignored, because it will always be

  /// memory.

  void encodeToMemory(

    TypePointers const& _givenTypes,

    TypePointers const& _targetTypes,

    bool _padToWords,

    bool _copyDynamicDataInPlace,

    bool _encodeAsLibraryTypes = false

  );

  /// Special case of @a encodeToMemory which assumes tight packing, e.g. no zero padding

  /// and dynamic data is encoded in-place.

  /// Stack pre: <value0> <value1> ... <valueN-1> <head_start>

  /// Stack post: <mem_ptr>

  void packedEncode(

    TypePointers const& _givenTypes,

    TypePointers const& _targetTypes,

    bool _encodeAsLibraryTypes = false

  )

  {

    encodeToMemory(_givenTypes, _targetTypes, false, true, _encodeAsLibraryTypes);

  }

  /// Special case of @a encodeToMemory which assumes that everything is padded to words

  /// and dynamic data is not copied in place (i.e. a proper ABI encoding).

  /// Stack pre: <value0> <value1> ... <valueN-1> <head_start>

  /// Stack post: <mem_ptr>

  void abiEncode(

    TypePointers const& _givenTypes,

    TypePointers const& _targetTypes,

    bool _encodeAsLibraryTypes = false

  )

  {

    encodeToMemory(_givenTypes, _targetTypes, true, false, _encodeAsLibraryTypes);

  }

  /// Special case of @a encodeToMemory which assumes that everything is padded to words

  /// and dynamic data is not copied in place (i.e. a proper ABI encoding).

  /// Uses a new, less tested encoder implementation.

  /// Stack pre: <value0> <value1> ... <valueN-1> <head_start>

  /// Stack post: <mem_ptr>

  void abiEncodeV2(

    TypePointers const& _givenTypes,

    TypePointers const& _targetTypes,

    bool _encodeAsLibraryTypes = false,

    bool _padToWordBoundaries = true

  );

  /// Decodes data from ABI encoding into internal encoding. If @a _fromMemory is set to true,

  /// the data is taken from memory instead of from calldata.

  /// Can allocate memory.

  /// Stack pre: <source_offset> <length>

  /// Stack post: <value0> <value1> ... <valuen>

  void abiDecodeV2(TypePointers const& _parameterTypes, bool _fromMemory = false);

  /// Zero-initialises (the data part of) an already allocated memory array.

  /// Length has to be nonzero!

  /// Stack pre: <length> <memptr>

  /// Stack post: <updated_memptr>

  void zeroInitialiseMemoryArray(ArrayType const& _type);

  /// Copies full 32 byte words in memory (regions cannot overlap), i.e. may copy more than length.

  /// Length can be zero, in this case, it copies nothing.

  /// Stack pre: <size> <target> <source>

  /// Stack post:

  void memoryCopy32();

  /// Copies data in memory (regions cannot overlap).

  /// Length can be zero, in this case, it copies nothing.

  /// Stack pre: <size> <target> <source>

  /// Stack post:

  void memoryCopy();

  /// Stores the given string in memory.

  /// Stack pre: mempos

  /// Stack post:

  void storeStringData(bytesConstRef _data);

  /// Converts the combined and left-aligned (right-aligned if @a _rightAligned is true)

  /// external function type <address><function identifier> into two stack slots:

  /// address (right aligned), function identifier (right aligned)

  void splitExternalFunctionType(bool _rightAligned);

  /// Performs the opposite operation of splitExternalFunctionType(_rightAligned)

  void combineExternalFunctionType(bool _rightAligned);

  /// Appends code that combines the construction-time (if available) and runtime function

  /// entry label of the given function into a single stack slot.

  /// Note: This might cause the compilation queue of the runtime context to be extended.

  /// If @a _runtimeOnly, the entry label will include the runtime assembly tag.

  void pushCombinedFunctionEntryLabel(Declaration const& _function, bool _runtimeOnly = true);

  /// Appends code for an implicit or explicit type conversion. This includes erasing higher

  /// order bits (@see appendHighBitCleanup) when widening integer but also copy to memory

  /// if a reference type is converted from calldata or storage to memory.

  /// If @a _cleanupNeeded, high order bits cleanup is also done if no type conversion would be

  /// necessary.

  /// If @a _chopSignBits, the function resets the signed bits out of the width of the signed integer.

  /// If @a _asPartOfArgumentDecoding is true, failed conversions are flagged via REVERT,

  /// otherwise they are flagged with INVALID.

  void convertType(

    Type const& _typeOnStack,

    Type const& _targetType,

    bool _cleanupNeeded = false,

    bool _chopSignBits = false,

    bool _asPartOfArgumentDecoding = false

  );

  /// Creates a zero-value for the given type and puts it onto the stack. This might allocate

  /// memory for memory references.

  void pushZeroValue(Type const& _type);

  /// Pushes a pointer to the stack that points to a (potentially shared) location in memory

  /// that always contains a zero. It is not allowed to write there.

  void pushZeroPointer();

  /// Moves the value that is at the top of the stack to a stack variable.

  void moveToStackVariable(VariableDeclaration const& _variable);

  /// Copies an item that occupies @a _itemSize stack slots from a stack depth of @a _stackDepth

  /// to the top of the stack.

  void copyToStackTop(unsigned _stackDepth, unsigned _itemSize);

  /// Moves an item that occupies @a _itemSize stack slots and has items occupying @a _stackDepth

  /// slots above it to the top of the stack.

  void moveToStackTop(unsigned _stackDepth, unsigned _itemSize = 1);

  /// Moves @a _itemSize elements past @a _stackDepth other stack elements

  void moveIntoStack(unsigned _stackDepth, unsigned _itemSize = 1);

  /// Rotates the topmost @a _items items on the stack, such that the previously topmost element

  /// is bottom-most.

  void rotateStackUp(unsigned _items);

  /// Rotates the topmost @a _items items on the stack, such that the previously bottom-most element

  /// is now topmost.

  void rotateStackDown(unsigned _items);

  /// Removes the current value from the top of the stack.

  void popStackElement(Type const& _type);

  /// Removes element from the top of the stack _amount times.

  void popStackSlots(size_t _amount);

  /// Pops slots from the stack such that its height is _toHeight.

  /// Adds jump to _jumpTo.

  /// Readjusts the stack offset to the original value.

  void popAndJump(unsigned _toHeight, evmasm::AssemblyItem const& _jumpTo);

  template <class T>

  static unsigned sizeOnStack(std::vector<T> const& _variables);

  static unsigned sizeOnStack(std::vector<Type const*> const& _variableTypes);

  /// Helper function to shift top value on the stack to the left.

  /// Stack pre: <value> <shift_by_bits>

  /// Stack post: <shifted_value>

  void leftShiftNumberOnStack(unsigned _bits);

  /// Helper function to shift top value on the stack to the right.

  /// Stack pre: <value> <shift_by_bits>

  /// Stack post: <shifted_value>

  void rightShiftNumberOnStack(unsigned _bits);

  /// Appends code that computes the Keccak-256 hash of the topmost stack element of 32 byte type.

  void computeHashStatic();

  /// Appends code that copies the code of the given contract to memory.

  /// Stack pre: Memory position

  /// Stack post: Updated memory position

  /// @param _creationCode if true, copies creation code, if false copies runtime code.

  /// @note the contract has to be compiled already, so beware of cyclic dependencies!

  void copyContractCodeToMemory(ContractDefinition const& contract, bool _creationCode);

  /// Bytes we need to the start of call data.

  ///  - The size in bytes of the function (hash) identifier.

  static unsigned const dataStartOffset;

  /// Position of the free-memory-pointer in memory;

  static size_t const freeMemoryPointer;

  /// Position of the memory slot that is always zero.

  static size_t const zeroPointer;

  /// Starting offset for memory available to the user (aka the contract).

  static size_t const generalPurposeMemoryStart;

private:

  /// Appends code that cleans higher-order bits for integer types.

  void cleanHigherOrderBits(IntegerType const& _typeOnStack);

  /// Prepares the given type for storing in memory by shifting it if necessary.

  /// @param _cleanup if true, also cleanup the value when preparing to store it in memory

  unsigned prepareMemoryStore(Type const& _type, bool _padToWords, bool _cleanup = true);

  /// Loads type from memory assuming memory offset is on stack top.

  unsigned loadFromMemoryHelper(Type const& _type, bool _fromCalldata, bool _padToWords);

  CompilerContext& m_context;

};

template <class T>

unsigned CompilerUtils::sizeOnStack(std::vector<T> const& _variables)

{

  unsigned size = 0;

  for (T const& variable: _variables)

    size += variable->annotation().type->sizeOnStack();

  return size;

}

}