What's the difference between payable function and non-payable function in bytecode for solidity?

Question

Suppose I have two solidity functions:

function funcA()public{}

And

function funcB()public payable{}

What's the difference between their bytecode? if I call the funcA with some ether in the transaction, it will revert, and what happens in bytecode?

Answer 1

At the beginning a non-payable function will execute CALLVALUE and revert if it returns a non-zero value.

For example:

Assembly                 | Pseudocode
---------------------------------------------
  CALLVALUE              |
  DUP1                   |
  ISZERO                 |  if (msg.value == 0)
  PUSH2 label            |
  JUMPI                  |    goto label
  PUSH1 00               |
  DUP1                   |
  REVERT                 |  revert("")