From 2ca08f0e89426468a4297be3dfa967ec90a814f3 Mon Sep 17 00:00:00 2001
From: Vectorized <webby1111@hotmail.com>
Date: Wed, 24 Aug 2022 17:25:52 +0800
Subject: [PATCH] Optimize Clones assembly (#3640)

---
 CHANGELOG.md               |  1 +
 contracts/proxy/Clones.sol | 36 +++++++++++++++++++-----------------
 2 files changed, 20 insertions(+), 17 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index e18691c7d60..29afc2a335d 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -19,6 +19,7 @@
  * `ECDSA`: Remove redundant check on the `v` value. ([#3591](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3591))
  * `VestingWallet`: add `releasable` getters. ([#3580](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3580))
  * `Create2`: optimize address computation by using assembly instead of `abi.encodePacked`. ([#3600](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3600))
+ * `Clones`: optimized the assembly to use only the scratch space during deployments, and optimized `predictDeterministicAddress` to use lesser operations. ([#3640](https://github.com/OpenZeppelin/openzeppelin-contracts/pull/3640))
 
 ### Deprecations
 
diff --git a/contracts/proxy/Clones.sol b/contracts/proxy/Clones.sol
index 8d8dc13173e..505fd613ad3 100644
--- a/contracts/proxy/Clones.sol
+++ b/contracts/proxy/Clones.sol
@@ -25,11 +25,12 @@ library Clones {
     function clone(address implementation) internal returns (address instance) {
         /// @solidity memory-safe-assembly
         assembly {
-            let ptr := mload(0x40)
-            mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
-            mstore(add(ptr, 0x14), shl(0x60, implementation))
-            mstore(add(ptr, 0x28), 0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000)
-            instance := create(0, ptr, 0x37)
+            // Cleans the upper 96 bits of the `implementation` word, then packs the first 3 bytes
+            // of the `implementation` address with the bytecode before the address.
+            mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))
+            // Packs the remaining 17 bytes of `implementation` with the bytecode after the address.
+            mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3))
+            instance := create(0, 0x09, 0x37)
         }
         require(instance != address(0), "ERC1167: create failed");
     }
@@ -44,11 +45,12 @@ library Clones {
     function cloneDeterministic(address implementation, bytes32 salt) internal returns (address instance) {
         /// @solidity memory-safe-assembly
         assembly {
-            let ptr := mload(0x40)
-            mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
-            mstore(add(ptr, 0x14), shl(0x60, implementation))
-            mstore(add(ptr, 0x28), 0x5af43d82803e903d91602b57fd5bf30000000000000000000000000000000000)
-            instance := create2(0, ptr, 0x37, salt)
+            // Cleans the upper 96 bits of the `implementation` word, then packs the first 3 bytes
+            // of the `implementation` address with the bytecode before the address.
+            mstore(0x00, or(shr(0xe8, shl(0x60, implementation)), 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000))
+            // Packs the remaining 17 bytes of `implementation` with the bytecode after the address.
+            mstore(0x20, or(shl(0x78, implementation), 0x5af43d82803e903d91602b57fd5bf3))
+            instance := create2(0, 0x09, 0x37, salt)
         }
         require(instance != address(0), "ERC1167: create2 failed");
     }
@@ -64,13 +66,13 @@ library Clones {
         /// @solidity memory-safe-assembly
         assembly {
             let ptr := mload(0x40)
-            mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73000000000000000000000000)
-            mstore(add(ptr, 0x14), shl(0x60, implementation))
-            mstore(add(ptr, 0x28), 0x5af43d82803e903d91602b57fd5bf3ff00000000000000000000000000000000)
-            mstore(add(ptr, 0x38), shl(0x60, deployer))
-            mstore(add(ptr, 0x4c), salt)
-            mstore(add(ptr, 0x6c), keccak256(ptr, 0x37))
-            predicted := keccak256(add(ptr, 0x37), 0x55)
+            mstore(add(ptr, 0x38), deployer)
+            mstore(add(ptr, 0x24), 0x5af43d82803e903d91602b57fd5bf3ff)
+            mstore(add(ptr, 0x14), implementation)
+            mstore(ptr, 0x3d602d80600a3d3981f3363d3d373d3d3d363d73)
+            mstore(add(ptr, 0x58), salt)
+            mstore(add(ptr, 0x78), keccak256(add(ptr, 0x0c), 0x37))
+            predicted := keccak256(add(ptr, 0x43), 0x55)
         }
     }