Optimize like in PR #767

This commit is contained in:
Remco Bloemen
2018-06-23 18:03:49 +02:00
committed by Amir Bandeali
parent a2ff63daa5
commit 4df66a4802
3 changed files with 157 additions and 34 deletions

View File

@@ -43,35 +43,47 @@ contract MixinERC20Transfer is
{
// Decode asset data.
address token = assetData.readAddress(16);
// Transfer tokens.
// We do a raw call so we can check the success separate
// from the return data.
bool success = token.call(abi.encodeWithSelector(
IERC20Token(token).transferFrom.selector,
from,
to,
amount
));
require(
success,
TRANSFER_FAILED
);
// Check return data.
// If there is no return data, we assume the token incorrectly
// does not return a bool. In this case we expect it to revert
// on failure, which was handled above.
// If the token does return data, we require that it is a single
// value that evaluates to true.
bytes4 transferFromSelector = IERC20Token(token).transferFrom.selector;
bool success;
assembly {
if returndatasize {
success := 0
if eq(returndatasize, 32) {
// First 64 bytes of memory are reserved scratch space
returndatacopy(0, 0, 32)
success := mload(0)
/////// Setup State ///////
// `cdStart` is the start of the calldata for `token.transferFrom` (equal to free memory ptr).
let cdStart := mload(64)
// `cdEnd` is the end of the calldata for `token.transferFrom`.
let cdEnd := add(cdStart, 100)
/////// Setup Header Area ///////
// This area holds the 4-byte `transferFromSelector`.
mstore(cdStart, transferFromSelector)
/////// Setup Params Area ///////
// Each parameter is padded to 32-bytes. The entire Params Area is 96 bytes.
// A 20-byte mask is applied to addresses to zero-out the unused bytes.
mstore(add(cdStart, 4), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 36), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 68), amount)
/////// Call `token.transferFrom` using the constructed calldata ///////
success := call(
gas,
token,
0,
cdStart,
sub(cdEnd, cdStart),
cdStart,
32
)
if success {
if returndatasize {
success := 0
if eq(returndatasize, 32) {
// First 64 bytes of memory are reserved scratch space
returndatacopy(0, 0, 32)
success := mload(0)
}
}
}
}
require(

View File

@@ -27,7 +27,7 @@ contract MixinERC721Transfer is
LibTransferErrors
{
using LibBytes for bytes;
bytes4 constant SAFE_TRANSFER_FROM_SELECTOR = bytes4(keccak256("safeTransferFrom(address,address,uint256,bytes)"));
/// @dev Internal version of `transferFrom`.
/// @param assetData Encoded byte array.
/// @param from Address to transfer asset from.
@@ -54,11 +54,76 @@ contract MixinERC721Transfer is
bytes memory receiverData
) = decodeERC721AssetData(assetData);
ERC721Token(token).safeTransferFrom(
from,
to,
tokenId,
receiverData
// We construct calldata for the `token.safeTransferFrom` ABI.
// The layout of this calldata is in the table below.
//
// | Area | Offset | Length | Contents |
// | -------- |--------|---------|-------------------------------------------- |
// | Header | 0 | 4 | function selector |
// | Params | | 4 * 32 | function parameters: |
// | | 4 | | 1. from |
// | | 36 | | 2. to |
// | | 68 | | 3. tokenId |
// | | 100 | | 4. offset to receiverData (*) |
// | Data | | | receiverData: |
// | | 132 | 32 | receiverData Length |
// | | 164 | ** | receiverData Contents |
bytes4 safeTransferFromSelector = SAFE_TRANSFER_FROM_SELECTOR;
bool success;
assembly {
/////// Setup State ///////
// `cdStart` is the start of the calldata for `token.safeTransferFrom` (equal to free memory ptr).
let cdStart := mload(64)
// `dataAreaLength` is the total number of words needed to store `receiverData`
// As-per the ABI spec, this value is padded up to the nearest multiple of 32,
// and includes 32-bytes for length.
// It's calculated as folows:
// - Unpadded length in bytes = `mload(receiverData) + 32`
// - Add 31 to this value then divide by 32 to get the length in words.
// - Multiply this value by 32 to get the padded length in bytes.
let dataAreaLength := mul(div(add(mload(receiverData), 63), 32), 32)
// `cdEnd` is the end of the calldata for `token.safeTransferFrom`.
let cdEnd := add(cdStart, add(132, dataAreaLength))
/////// Setup Header Area ///////
// This area holds the 4-byte `transferFromSelector`.
mstore(cdStart, safeTransferFromSelector)
/////// Setup Params Area ///////
// Each parameter is padded to 32-bytes. The entire Params Area is 128 bytes.
// Notes:
// 1. A 20-byte mask is applied to addresses to zero-out the unused bytes.
// 2. The offset to `receiverData` is the length of the Params Area (128 bytes).
mstore(add(cdStart, 4), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 36), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 68), tokenId)
mstore(add(cdStart, 100), 128)
/////// Setup Data Area ///////
// This area holds `receiverData`.
let dataArea := add(cdStart, 132)
for {} lt(dataArea, cdEnd) {} {
mstore(dataArea, mload(receiverData))
dataArea := add(dataArea, 32)
receiverData := add(receiverData, 32)
}
/////// Call `token.safeTransferFrom` using the constructed calldata ///////
success := call(
gas,
token,
0,
cdStart,
sub(cdEnd, cdStart),
cdStart,
0
)
}
require(
success,
TRANSFER_FAILED
);
}

View File

@@ -100,21 +100,67 @@ contract MixinAssetProxyDispatcher is
{
// Do nothing if no amount should be transferred.
if (amount > 0) {
require(assetData.length >= 4, "ASSET_DATA_LENGTH");
// Lookup assetProxy
bytes4 assetProxyId = assetData.readBytes4(0);
bytes4 assetProxyId;
assembly {
assetProxyId := and(mload(add(assetData, 32)),
0xFFFFFFFF00000000000000000000000000000000000000000000000000000000
)
}
IAssetProxy assetProxy = assetProxies[assetProxyId];
// Ensure that assetProxy exists
require(
assetProxy != address(0),
ASSET_PROXY_DOES_NOT_EXIST
);
// transferFrom will either succeed or throw.
/*
assetProxy.transferFrom(
assetData,
from,
to,
amount
);
return;
*/
bytes4 transferFromSelector = IAssetProxy(assetProxy).transferFrom.selector;
bool success;
assembly {
let cdStart := mload(0x40)
let dataAreaLength := mul(div(add(mload(assetData), 63), 32), 32)
let cdEnd := add(cdStart, add(132, dataAreaLength))
mstore(cdStart, transferFromSelector)
mstore(add(cdStart, 4), 128)
mstore(add(cdStart, 36), and(from, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 68), and(to, 0xffffffffffffffffffffffffffffffffffffffff))
mstore(add(cdStart, 100), amount)
let dataArea := add(cdStart, 132)
for {} lt(dataArea, cdEnd) {} {
mstore(dataArea, mload(assetData))
dataArea := add(dataArea, 32)
assetData := add(assetData, 32)
}
success := call(
gas,
assetProxy,
0,
cdStart,
sub(cdEnd, cdStart),
cdStart,
0
)
}
require(
success,
"TRANSFER_FAILED"
);
}
}
}