hrkrshnn

Compile solc locally after applying the below patch (solc.patch).Build instructions.

./solc example.sol --model-checker-engine bmc

Call to check. Solver state:
(declare-datatypes ((bytes_tuple 0)) (((bytes_tuple (bytes_tuple_accessor_array (Array Int Int)) (bytes_tuple_accessor_length Int)))))
(declare-datatypes ((tx_type 0)) (((tx_type (block.basefee Int) (block.chainid Int) (block.coinbase Int) (block.difficulty Int) (block.gaslimit Int) (block.number Int) (block.timestamp Int) (blockhash (Array Int Int)) (msg.data bytes_tuple) (msg.sender Int) (msg.sig Int) (msg.value Int) (tx.gasprice Int) (tx.origin Int)))))

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pragma solidity ^0.8.5;
contract C {
    function convert(bytes memory m) external pure returns (bytes4) {
        return bytes4(m);
    }
}

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// UNTESTED!
object "BribeContract" {
    code {
        let size := datasize("BribeRuntime")
        codecopy(0, dataoffset("BribeRuntime"), size)
        return(0, size)
    }
    object "BribeRuntime" {
        code {
            // Bribe by sending ETH. To try and claim, send a tx without ETH. Assumes that a tx with

hrkrshnn

Upgrade to at least 0.8.4

Using newer compiler versions and the optimizer gives gas optimizations and additional safety checks for free!

The advantages of versions 0.8.* over <0.8.0 are:

• Safemath by default from 0.8.0 (can be more gas efficient than some library based safemath).
• Low level inliner from 0.8.2, leads to cheaper runtime gas. Especially relevant when the contract has small functions. For

hrkrshnn

contract C {
    function f(uint[] calldata arr) external returns(uint) {
        return sum(arr);
    }
    function sum(uint[] calldata arr) internal returns(uint _sum) {
        for(uint i = 0; i < arr.length; i++) {
            _sum += arr[i];
        }
    }
}

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diff -u /tmp/old.yul /tmp/new.yul
--- /tmp/old.yul	2021-09-28 13:41:14.873051780 +0200
+++ /tmp/new.yul	2021-09-28 13:39:28.096229030 +0200
@@ -53,8 +53,8 @@
 
         }
 
-        function update_byte_slice_32_shift_0(value, toInsert) -> result {
-            let mask := 0xffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffffff
+        function update_byte_slice_1_shift_0(value, toInsert) -> result {

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Optimized IR:
/*=====================================================*
 *                       WARNING                       *
 *  Solidity to Yul compilation is still EXPERIMENTAL  *
 *       It can result in LOSS OF FUNDS or worse       *
 *                !USE AT YOUR OWN RISK!               *
 *=====================================================*/

/// @use-src 0:"/home/hari/s/4/test/libsolidity/semanticTests/userDefinedValueType/calldata.sol"
object "C_294" {

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modified   test/libsolidity/semanticTests/userDefinedValueType/erc20.sol
@@ -114,32 +114,32 @@ contract ERC20 {
 // constructor()
 // ~ emit Transfer(address,address,uint256): #0x00, #0x1212121212121212121212121212120000000012, 0x14
 // gas irOptimized: 460447
-// gas legacy: 833310
-// gas legacyOptimized: 416135
+// gas legacy: 855430
+// gas legacyOptimized: 420959
 // totalSupply() -> 20

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contract C
{
    constructor() payable {}
	function f(address payable a) public returns(bool) {
		require(1000 == address(this).balance);
		require(100 == a.balance);
		a.send(600);
		// a == this is not possible because address(this).balance == 1000
		// and a.balance == 100,
		// so this should hold in CHC, ignoring the transfer revert.

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pragma solidity ^0.8.7;

// User defined type name. Indicating a type with 18 decimals.
type UFixed18 is uint256;

library FixedMath
{
    function add(UFixed18 a, UFixed18 b) internal pure returns (UFixed18 c) {
        return UFixed18(uint(a) + uint(b));
    }