From 34e5863cd51149a592275dc79bc50b10082b2233 Mon Sep 17 00:00:00 2001
From: Tom French <15848336+TomAFrench@users.noreply.github.com>
Date: Wed, 5 Oct 2022 21:19:28 +0100
Subject: [PATCH] Reduce gas in `log256` (#3745)

---
 CHANGELOG.md                  | 1 +
 contracts/utils/math/Math.sol | 2 +-
 2 files changed, 2 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 2b8f0e56d0f..6b4a0b063da 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -35,6 +35,7 @@
  * `Math` and `SignedMath`: optimize function `max` by using `>` instead of `>=`. ([#3679](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3679))
  * `Math`: Add `log2`, `log10` and `log256`. ([#3670](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3670))
  * Arbitrum: Update the vendored arbitrum contracts to match the nitro upgrade. ([#3692](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3692))
+ * `Math`: optimize `log256` rounding check. ([#3745](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3745))
 
 ### Breaking changes
 
diff --git a/contracts/utils/math/Math.sol b/contracts/utils/math/Math.sol
index e7bb334040a..a521a9d0649 100644
--- a/contracts/utils/math/Math.sol
+++ b/contracts/utils/math/Math.sol
@@ -339,7 +339,7 @@ library Math {
     function log256(uint256 value, Rounding rounding) internal pure returns (uint256) {
         unchecked {
             uint256 result = log256(value);
-            return result + (rounding == Rounding.Up && 1 << (result * 8) < value ? 1 : 0);
+            return result + (rounding == Rounding.Up && 1 << (result << 3) < value ? 1 : 0);
         }
     }
 }