From 48cc8a92f59b4a66ae1104c2383e2a04fcacd0c7 Mon Sep 17 00:00:00 2001 From: Vladislav Date: Tue, 1 Aug 2023 13:52:36 +0200 Subject: [PATCH] Optimize muldiv (#4494) Co-authored-by: Francisco --- .changeset/pink-suns-mix.md | 5 +++++ contracts/utils/math/Math.sol | 6 ++---- 2 files changed, 7 insertions(+), 4 deletions(-) create mode 100644 .changeset/pink-suns-mix.md diff --git a/.changeset/pink-suns-mix.md b/.changeset/pink-suns-mix.md new file mode 100644 index 00000000000..eb7aaac464b --- /dev/null +++ b/.changeset/pink-suns-mix.md @@ -0,0 +1,5 @@ +--- +'openzeppelin-solidity': patch +--- + +`Math`: Optimized stack operations in `mulDiv`. diff --git a/contracts/utils/math/Math.sol b/contracts/utils/math/Math.sol index 3e6f61bd1cd..17ce4c8aba1 100644 --- a/contracts/utils/math/Math.sol +++ b/contracts/utils/math/Math.sol @@ -124,11 +124,10 @@ library Math { // 512-bit multiply [prod1 prod0] = x * y. Compute the product mod 2^256 and mod 2^256 - 1, then use // use the Chinese Remainder Theorem to reconstruct the 512 bit result. The result is stored in two 256 // variables such that product = prod1 * 2^256 + prod0. - uint256 prod0; // Least significant 256 bits of the product + 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)) - prod0 := mul(x, y) prod1 := sub(sub(mm, prod0), lt(mm, prod0)) } @@ -163,8 +162,7 @@ library Math { // 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. - // Does not overflow because the denominator cannot be zero at this stage in the function. - uint256 twos = denominator & (~denominator + 1); + uint256 twos = denominator & (0 - denominator); assembly { // Divide denominator by twos. denominator := div(denominator, twos)