Update docs

contracts/utils/math/SignedMath.sol

@@ -1,24 +1,42 @@
 // SPDX-License-Identifier: MIT
-// OpenZeppelin Contracts (last updated v5.0.0) (utils/math/SignedMath.sol)
+// OpenZeppelin Contracts (last updated v5.1.0) (utils/math/SignedMath.sol)
 
 pragma solidity ^0.8.20;
 
+import {SafeCast} from "./SafeCast.sol";
+
 /**
  * @dev Standard signed math utilities missing in the Solidity language.
  */
 library SignedMath {
+    /**
+     * @dev Branchless ternary evaluation for `a ? b : c`. Gas costs are constant.
+     *
+     * IMPORTANT: This function may reduce bytecode size and consume less gas when used standalone.
+     * However, the compiler may optimize Solidity ternary operations (i.e. `a ? b : c`) to only compute
+     * one branch when needed, making this function more expensive.
+     */
+    function ternary(bool condition, int256 a, int256 b) internal pure returns (int256) {
+        unchecked {
+            // branchless ternary works because:
+            // b ^ (a ^ b) == a
+            // b ^ 0 == b
+            return b ^ ((a ^ b) * int256(SafeCast.toUint(condition)));
+        }
+    }
+
     /**
      * @dev Returns the largest of two signed numbers.
      */
     function max(int256 a, int256 b) internal pure returns (int256) {
-        return a > b ? a : b;
+        return ternary(a > b, a, b);
     }
 
     /**
      * @dev Returns the smallest of two signed numbers.
      */
     function min(int256 a, int256 b) internal pure returns (int256) {
-        return a < b ? a : b;
+        return ternary(a < b, a, b);
     }
 
     /**
@@ -36,8 +54,15 @@ library SignedMath {
      */
     function abs(int256 n) internal pure returns (uint256) {
         unchecked {
-            // must be unchecked in order to support `n = type(int256).min`
-            return uint256(n >= 0 ? n : -n);
+            // Formula from the "Bit Twiddling Hacks" by Sean Eron Anderson.
+            // Since `n` is a signed integer, the generated bytecode will use the SAR opcode to perform the right shift,
+            // taking advantage of the most significant (or "sign" bit) in two's complement representation.
+            // This opcode adds new most significant bits set to the value of the previous most significant bit. As a result,
+            // the mask will either be `bytes32(0)` (if n is positive) or `~bytes32(0)` (if n is negative).
+            int256 mask = n >> 255;
+
+            // A `bytes32(0)` mask leaves the input unchanged, while a `~bytes32(0)` mask complements it.
+            return uint256((n + mask) ^ mask);
         }
     }
 }