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Release v5.3 cherrypick #2 (#5526)

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Signed-off-by: Hadrien Croubois <hadrien.croubois@gmail.com>
Co-authored-by: Ernesto García <ernestognw@gmail.com>
Co-authored-by: Arr00 <13561405+arr00@users.noreply.github.com>
Co-authored-by: Voronor <129545215+voronor@users.noreply.github.com>
Co-authored-by: StackOverflowExcept1on <109800286+StackOverflowExcept1on@users.noreply.github.com>
Co-authored-by: Michalis Kargakis <kargakis@protonmail.com>
This commit is contained in:
Hadrien Croubois
2025-03-03 15:51:41 +01:00
committed by GitHub
parent 77a459e987
commit 887697148d
34 changed files with 1641 additions and 262 deletions
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146
contracts/utils/math/Math.sol
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@ -17,14 +17,42 @@ library Math {
Expand // Away from zero
}
/**
* @dev Return the 512-bit addition of two uint256.
*
* The result is stored in two 256 variables such that sum = high * 2²⁵⁶ + low.
*/
function add512(uint256 a, uint256 b) internal pure returns (uint256 high, uint256 low) {
assembly ("memory-safe") {
low := add(a, b)
high := lt(low, a)
}
}
/**
* @dev Return the 512-bit multiplication of two uint256.
*
* The result is stored in two 256 variables such that product = high * 2²⁵⁶ + low.
*/
function mul512(uint256 a, uint256 b) internal pure returns (uint256 high, uint256 low) {
// 512-bit multiply [high low] = x * y. Compute the product mod 2²⁵⁶ and mod 2²⁵⁶ - 1, then use
// the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
// variables such that product = high * 2²⁵⁶ + low.
assembly ("memory-safe") {
let mm := mulmod(a, b, not(0))
low := mul(a, b)
high := sub(sub(mm, low), lt(mm, low))
}
}
/**
* @dev Returns the addition of two unsigned integers, with an success flag (no overflow).
*/
function tryAdd(uint256 a, uint256 b) internal pure returns (bool success, uint256 result) {
unchecked {
uint256 c = a + b;
if (c < a) return (false, 0);
return (true, c);
success = c >= a;
result = c * SafeCast.toUint(success);
}
}
@ -33,8 +61,9 @@ library Math {
*/
function trySub(uint256 a, uint256 b) internal pure returns (bool success, uint256 result) {
unchecked {
if (b > a) return (false, 0);
return (true, a - b);
uint256 c = a - b;
success = c <= a;
result = c * SafeCast.toUint(success);
}
}
@ -43,13 +72,14 @@ library Math {
*/
function tryMul(uint256 a, uint256 b) internal pure returns (bool success, uint256 result) {
unchecked {
// Gas optimization: this is cheaper than requiring 'a' not being zero, but the
// benefit is lost if 'b' is also tested.
// See: https://github.com/OpenZeppelin/openzeppelin-contracts/pull/522
if (a == 0) return (true, 0);
uint256 c = a * b;
if (c / a != b) return (false, 0);
return (true, c);
assembly ("memory-safe") {
// Only true when the multiplication doesn't overflow
// (c / a == b) || (a == 0)
success := or(eq(div(c, a), b), iszero(a))
}
// equivalent to: success ? c : 0
result = c * SafeCast.toUint(success);
}
}
@ -58,8 +88,11 @@ library Math {
*/
function tryDiv(uint256 a, uint256 b) internal pure returns (bool success, uint256 result) {
unchecked {
if (b == 0) return (false, 0);
return (true, a / b);
success = b > 0;
assembly ("memory-safe") {
// The `DIV` opcode returns zero when the denominator is 0.
result := div(a, b)
}
}
}
@ -68,11 +101,38 @@ library Math {
*/
function tryMod(uint256 a, uint256 b) internal pure returns (bool success, uint256 result) {
unchecked {
if (b == 0) return (false, 0);
return (true, a % b);
success = b > 0;
assembly ("memory-safe") {
// The `MOD` opcode returns zero when the denominator is 0.
result := mod(a, b)
}
}
}
/**
* @dev Unsigned saturating addition, bounds to `2²⁵⁶ - 1` instead of overflowing.
*/
function saturatingAdd(uint256 a, uint256 b) internal pure returns (uint256) {
(bool success, uint256 result) = tryAdd(a, b);
return ternary(success, result, type(uint256).max);
}
/**
* @dev Unsigned saturating subtraction, bounds to zero instead of overflowing.
*/
function saturatingSub(uint256 a, uint256 b) internal pure returns (uint256) {
(, uint256 result) = trySub(a, b);
return result;
}
/**
* @dev Unsigned saturating multiplication, bounds to `2²⁵⁶ - 1` instead of overflowing.
*/
function saturatingMul(uint256 a, uint256 b) internal pure returns (uint256) {
(bool success, uint256 result) = tryMul(a, b);
return ternary(success, result, type(uint256).max);
}
/**
* @dev Branchless ternary evaluation for `a ? b : c`. Gas costs are constant.
*
@ -143,26 +203,18 @@ library Math {
*/
function mulDiv(uint256 x, uint256 y, uint256 denominator) internal pure returns (uint256 result) {
unchecked {
// 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2²⁵⁶ and mod 2²⁵⁶ - 1, then use
// the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256
// variables such that product = prod1 * 2²⁵⁶ + prod0.
uint256 prod0 = x * y; // Least significant 256 bits of the product
uint256 prod1; // Most significant 256 bits of the product
assembly {
let mm := mulmod(x, y, not(0))
prod1 := sub(sub(mm, prod0), lt(mm, prod0))
}
(uint256 high, uint256 low) = mul512(x, y);
// Handle non-overflow cases, 256 by 256 division.
if (prod1 == 0) {
if (high == 0) {
// Solidity will revert if denominator == 0, unlike the div opcode on its own.
// The surrounding unchecked block does not change this fact.
// See https://docs.soliditylang.org/en/latest/control-structures.html#checked-or-unchecked-arithmetic.
return prod0 / denominator;
return low / denominator;
}
// Make sure the result is less than 2²⁵⁶. Also prevents denominator == 0.
if (denominator <= prod1) {
if (denominator <= high) {
Panic.panic(ternary(denominator == 0, Panic.DIVISION_BY_ZERO, Panic.UNDER_OVERFLOW));
}
@ -170,34 +222,34 @@ library Math {
// 512 by 256 division.
///////////////////////////////////////////////
// Make division exact by subtracting the remainder from [prod1 prod0].
// Make division exact by subtracting the remainder from [high low].
uint256 remainder;
assembly {
assembly ("memory-safe") {
// Compute remainder using mulmod.
remainder := mulmod(x, y, denominator)
// Subtract 256 bit number from 512 bit number.
prod1 := sub(prod1, gt(remainder, prod0))
prod0 := sub(prod0, remainder)
high := sub(high, gt(remainder, low))
low := sub(low, remainder)
}
// Factor powers of two out of denominator and compute largest power of two divisor of denominator.
// Always >= 1. See https://cs.stackexchange.com/q/138556/92363.
uint256 twos = denominator & (0 - denominator);
assembly {
assembly ("memory-safe") {
// Divide denominator by twos.
denominator := div(denominator, twos)
// Divide [prod1 prod0] by twos.
prod0 := div(prod0, twos)
// Divide [high low] by twos.
low := div(low, twos)
// Flip twos such that it is 2²⁵⁶ / twos. If twos is zero, then it becomes one.
twos := add(div(sub(0, twos), twos), 1)
}
// Shift in bits from prod1 into prod0.
prod0 |= prod1 * twos;
// Shift in bits from high into low.
low |= high * twos;
// Invert denominator mod 2²⁵⁶. Now that denominator is an odd number, it has an inverse modulo 2²⁵⁶ such
// that denominator * inv ≡ 1 mod 2²⁵⁶. Compute the inverse by starting with a seed that is correct for
@ -215,9 +267,9 @@ library Math {
// Because the division is now exact we can divide by multiplying with the modular inverse of denominator.
// This will give us the correct result modulo 2²⁵⁶. Since the preconditions guarantee that the outcome is
// less than 2²⁵⁶, this is the final result. We don't need to compute the high bits of the result and prod1
// less than 2²⁵⁶, this is the final result. We don't need to compute the high bits of the result and high
// is no longer required.
result = prod0 * inverse;
result = low * inverse;
return result;
}
}
@ -229,6 +281,26 @@ library Math {
return mulDiv(x, y, denominator) + SafeCast.toUint(unsignedRoundsUp(rounding) && mulmod(x, y, denominator) > 0);
}
/**
* @dev Calculates floor(x * y >> n) with full precision. Throws if result overflows a uint256.
*/
function mulShr(uint256 x, uint256 y, uint8 n) internal pure returns (uint256 result) {
unchecked {
(uint256 high, uint256 low) = mul512(x, y);
if (high >= 1 << n) {
Panic.panic(Panic.UNDER_OVERFLOW);
}
return (high << (256 - n)) | (low >> n);
}
}
/**
* @dev Calculates x * y >> n with full precision, following the selected rounding direction.
*/
function mulShr(uint256 x, uint256 y, uint8 n, Rounding rounding) internal pure returns (uint256) {
return mulShr(x, y, n) + SafeCast.toUint(unsignedRoundsUp(rounding) && mulmod(x, y, 1 << n) > 0);
}
/**
* @dev Calculate the modular multiplicative inverse of a number in Z/nZ.
*