Questions tagged [opcode]
operation codes specify the instructions to be performed in machine languages
185
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Can evm make an EOA transaction during another transaction?
I want to deploy a smart contract that would do something like this:
transfer eth from the contract to account A
make a transaction to another smart contract from account A(given the nonce and the ...
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1
answer
23
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Can init code of a contract not return the deployed code?
As I understand, when deploying a new smart contract, the transaction has only the init code, which includes the code that will be actually deployed (the deployed code). The init code is executed and ...
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28
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why opcode create always returns zero address?
my 2 functions:
function func1(bytes memory code) public {
address addr;
assembly {
addr := create(callvalue(), add(code, 0x20), mload(code))
}
emit ...
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1
answer
42
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How OPCODES fees were defined?
When a function from a contract is executed the total cost, in weis, is calculated based on the OPCODES executed.
For example, this question shows how to calculate the gas cost for keccak, that is 30 ...
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31
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Can't supply assets to Compound via call Solidity
I have Smart Contract
I make two functions supplyLiquidity with call opcode and supplyLiquidity1 where using interface instead
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.19;
import {IERC20} ...
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1
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13
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What happens to opcodes during fork tests in foundry?
When you fork a chain in foundry, does it also copy the chain opcodes and the associated gas?
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62
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What's the difference between zkSync `system contracts` and EVM precompiles?
According to the zkSync docs
While most of the primitive EVM opcodes can be supported out of the box (i.e. zero-value calls, addition/multiplication/memory/storage management, etc), some of the ...
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can we send value as well as call smart contract function using CALL
CALL opcode consumes value of the stack (which is transferred to the account). It can also additionally consume stack items to pass input to the smart contract account function.
Can both happen ...
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what's the point of CODECOPY opcode
CODECOPY is used to copy the executing program's opcode onto the memory. I wonder what's the use of this though. Is there a deployed example where CODECOPY is useful?
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378
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Received `NotActivated` error when debugging my foundry test
I have hand-written a smart contract in opcodes. The first few opcodes are as such:
PUSH1 0x20
CALLDATALOAD
CALLER
PUSH0
SLOAD
ADD
However, all my tests for this contract keep breaking at PUSH0. When ...
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0
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10
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Why remaining gas increase after some opcodes
I use debug api of go ethereum to get traces of transactions. The api document shows that field gas represents the amount of gas remaining in the transaction at the current step of execution and field ...
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2
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Why does mload(0x40) result in 0x20?
I ran the code below and had a question.
function mloadTest1() public pure returns(bytes memory) {
bytes memory a;
assembly {
a :=mload(0x40)
}
return a;
}
mload(x) is a Yul ...
- 570
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0
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13
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Could someone please dumb down how the sign extend opcode works? [duplicate]
I was trying to understand how the sign extend opcode works via the playground of evm.codes, but I can't seem to wrap my head around it. Somebody please help me and explain how it works?
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How does opcode JUMP work in the EVM?
Could someone kindly explain how the program counter in the EVM knows where to jump to when the JUMP opcode is executed? I understand that a counter is supplied using PUSH (something) before the JUMP ...
- 59
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28
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How does the stack multiply a 32 byte number with a 1 byte number?
I was looking at an example of the multiply opcode(MUL) on the website www.evm.codes and noticed it multiplied:
0xFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF x 2
resulting in ...
- 59
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1
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36
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Solidity - Function Selector Loading onto the stack: why DIV instead of SHR?
I'm currently learning about how the function selector is loaded from calldata. The algorithm is like so:
PUSH4 ffffffff
PUSH29 0100000000000000000000000000000000000000000000000000000000000000
PUSH1 ...
- 89
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1
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29
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Reliably disassamble bytecode to opcodes across various evm versions
Is there a reliable way of disassembling bytecode into opcodes across different EVM versions, to make it agnostic to the EVM version used during compilation?
As the second best option - is there a ...
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1
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103
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Run optimizer on opcodes
According to documentation, one of the steps of solidity compilation is the optimization on opcodes level, with the following set of rules.
How can I apply optimization directly on opcodes?
Details
...
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1
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99
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How do old smart contracts that contain certain opcodes behave when those opcodes get deprecated/removed in hard fork upgrades?
For example say a contract with a compiler version of 0.7.5 (pragma solidity 0.7.5) contained selfdestruct(payable(address))
what happens to the contract when the self destruct opcode gets deprecated ...
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2
votes
1
answer
54
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Is there a way to stop wallet homomorph attacks without ditching the create2 opcode?
Losses from create2 wallets that look similar to recently active wallets has surpassed $60m:
https://gbhackers.com/create2-bypass-wallet-security-alerts/
Even today I made a transaction, and noticed ...
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225
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Invalid OpCode while deploying "HelloWorld"
I'm receiving the following error message trying to deploy a very simple contract to Ganache. How can I resolve this?
Contract:
pragma solidity ^0.8.21; // ^0.4.24;
contract HelloWorld {
string ...
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2
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1
answer
380
views
Beacon contract contructor seems to call address 0x02?
The Beacon (Eth 2.0 deposit) contract was once deployed using a certain (constructor) script, like every other contract on the EVM blockchain. While analyzing that constructor script, it seems that it ...
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2
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482
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What does FE stand for in "InvalidFEOpcode"?
I've seen the name InvalidFEOpcode used in client implementations, e.g. in REVM:
https://github.com/bluealloy/revm/blob/8206193e65ad199a1dde1e79e38bf9ffe38118c9/crates/interpreter/src/...
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381
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Can I edit in the msg.sender value for the called contract?
let's assume following solidity contracts:
contract EntryPointContract {
address one = '0x...';
address two = '0x...';
address delegateContract;
constructor(address ...
0
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1
answer
104
views
Determining if a smart contract is using delegatecall
Let's say that I have the bytecode of a smart contract deployed on ethereum (which I got with a call to eth_getCode).
How can I programmatically determine if this smart contract uses delegatecall ...
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2
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36
views
Where is the return data from an external call stored?
In ethervm.io, RETURNDATASIZE is described as follows.
RETURNDATASIZE : Byzantium hardfork, EIP-211: the size of the returned
data from the last external call, in bytes
The smart contract has 3 ...
- 570
2
votes
1
answer
47
views
Should all method hashes be found in a smart contract's opcodes?
I have a compiled/deployed solidity smart contract for which I have encoded all the functions signatures. (4-byte hashes)
With the deployed bytecode, I have parsed the pushdata into an array for all '...
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37
views
what does it mean "JUMPDEST occupies position 43"
I'm looking at the minimal proxy posted by OpenZeppelin(link). I don't know what the text below means.
The entire set of instructions for this EVM runtime code is made up of
45 bytes, and JUMPDEST ...
- 570
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1
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30
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EVM opcodes for Boolean AND operations
What opcodes does the EVM use in performing boolean AND (&&) operations
0
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1
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221
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Inline Assembly: RETURN opcode can't not work. Failed to decode output
I know that: return(p, s): end execution, return data mem[p…(p+s)).
I want to return something in memory but not a multiple of bytes32. For example, I want to return 1 byte:
pragma solidity 0.8.20;
...
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986
views
How does opcode PUSH0 work in EVM?
PUSH0 is a new opcode that appeared in solidity 0.8.20 to replace PUSH1 00.
Q1) Do PUSH0~32 need numbers(data) to be pushed next to it unconditionally?
example : PUSH1 00 || PUSH2 05
Q2) PUSH0 ...
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votes
5
answers
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invalid opcode: opcode 0x5f not defined
I'm new to Solidity and it's my first try to write a smart contract using Openzeppelin, Pancakeswap and BEP20 libraries basically to make a BEP-20 token.
When i try to deploy the smart contract, i get ...
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1
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251
views
When did each opcode get added to the EVM?
After the original set defined in the Ethereum yellow paper,
many new opcodes have been added.
I'm after a list of when each one was added (by fork).
- 245
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200
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How do the LT and GT opcodes differ from SLT and SGT respectively?
When reading the Opcodes for the EVM article, I saw that the LT and SLT opcodes are evaluated to the same expression (a < b), as well as the GT and SGT opcodes (a > b).
How do LT and GT differ ...
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2
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189
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Remix Assembly vs. Solidity Compiler Assembly
I am just diving into EVM assembly and am a little confused about the following.
I have the following simple contract:
pragma solidity >=0.8.1;
contract MyTest {}
When I compile it using Remix, I ...
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1
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103
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Question about a function implementation in Ethereum Account Abstraction
function numberMarker() internal view {
assembly {mstore(0, number())}
}
I'm studying about Account Abstraction, and exploring through the implementation code of EntryPoint.sol by Infinitism. ...
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vote
2
answers
64
views
Why don't specify add/sub/div/mul in the bytecode opcodes?
// SPDX-License-Identifier: MIT
pragma solidity ^0.8.10;
contract Test {
uint num = 2 * 2 + 10;
}
For example, when compiling the above code in Remix,
PUSH1 80 PUSH1 40 MSTORE PUSH1 0e PUSH1 00 ...
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1
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135
views
Is the deploying of the contract anonymous?
Is the deploying of the contract anonymous? is it possible to find the owner who posted the contract? Is the only mention of it a link to the wallet from which the smart contract was first replenished ...
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0
answers
36
views
Hardhat: setPrevRandao does not work
I'm trying to simulate prevrandao but it does not work out.
To check it, I've written a contract and a test.
contracts/AnotherContract.sol
// SPDX-License-Identifier: UNLICENSED
pragma solidity ^0.8.9;...
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0
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92
views
Which contract's storage does SLOAD/SSTORE use?
A given SSTORE and SLOAD instruction uses storage from a certain smart contract. How can we know which contract that is, and do we need any additional data than the raw struct/opcode traces to find ...
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50
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How do RETURN and MLOAD work for high offsets?
When trying to load the 32 bytes of memory that follow a high offset (say 0x12345678), the RETURN and MLOAD opcodes give an out of gas error. Why is that ?
Example
PUSH1 0x20
PUSH4 0x12345678
RETURN
...
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1
answer
310
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EOA transfer and OPCODEs
I'm doing some research on how the transactions are made in Ethereum.
I got reading the code of Geth and the Yellow Paper that a Smart Contract method call with a value on the payload will transfer ...
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1
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165
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How does the PUSH instruction get its input?
I'm trying to understand state storage, and by doing so (for the first time) looking at raw geth traces. I've hit a blocker, though, which is understanding where the arguments to PUSH instructions ...
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votes
3
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794
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OPCODES WHY DOES free memory pointer(0X40) use 0x80 as starting value?
The following opcodes 0x40 is "offset in the memory in bytes"
My question is why evm uses 0x80 as a "32-byte value to write in the memory."
PUSH1 0x80
PUSH1 0x40
MSTORE
Sincerely
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525
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OPCODES How is work "CODECOPY"?
Somebody could explain how CODECOPY works in practice ? There is only one sample in evm.playground but I dont understand above-mentioned sample. Could you give me another concrete sample (with ...
- 213
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Does the EVM revert if a call is attempted to an address that doesn't have code?
The following code would revert in high-level Solidity if the provided addr is an EOA or a contract that does not implement MyInterface:
interface MyInterface {
function myFunction() external;
}
...
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OPCODES How is work "CALLDATACOPY"?
I try to understand how CALLDATACOPY works.
destOffset: byte offset in the memory where the result will be copied.
offset: byte offset in the calldata to copy.
size: byte size to copy.
I try to ...
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1
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741
views
selfBalance() and address(this).balance gas cost
Yesterday I found out about the existence of selfbalance() and that it's cheaper than address(this).balance. I checked the EVM opcodes:
opcode 31 BALANCE - The static cost is 0. If the accessed ...
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36
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Invalid opcode when storing value in array part of a mapped struct
I have a public function that accepts some data from users and i basically want to store this data into a struct that is mapped to an address.
This is the definition of the Struct :
struct ...
1
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1
answer
90
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How to make submod in evm assembly?
I've been playing with huff language (assembly for EVM) and tried creating a macro for subtraction modulo n.
At first, I thought it would be easy since addmod(a,n-b,n) would do the job, but this isn't ...
