Lifetime Management

[ControlCplusControlV]

Lifetime Management

[ControlCplusControlV]

Lifetime Management

• If a variable is not going to be used after a given expression, no need to save it to memory.
• If a variable is updated several times in a row, no need to save intermediate results to memory.

Test Cases

1. Input Yul

{
    let a := 700
    let b := 100
    let c := 200
    let d := add(a, c)
}

1. Assembly Output

// a gets pushed to the stack
// b gets pushed to the stack
// The stack is full, so the top value will attempt to save to memory
//Since b is the top value, the optimizer will check if b is used later
//if so, b gets saved to memory, if not, b gets dropped
//then c gets pushed to the stack
//a and c are added

2. Input Yul

let c = 1000
let b = 15
let a = 6
    
let d = mul(a, b)
let e = mul(d, a)

2. Assembly Output

// Assembly output should not put d back on the stack,
//  because it is immediately used after, since in 
//  multiplication the intermediate value 
//  must be stored in memory.