Slow Compilation Examples

Slow Compilation Examples.swift

// Code snippet 1

func test() {
	let f: Int = 5

	// Original:
	CGPoint(x: f + f * (f + f) + f * f, y: 1) // (1.5786 sec)

	// Faster:
	let x = f + f * (f + f) + f * f; let y = 1; CGPoint(x: x, y: y) // put in variables (0.0066 sec)
	CGPoint(x: f + f * (f + f) + f * f, y: CGFloat(1)) // hint to compiler to expect a CGFloat by casting the y parameter (0.0089 sec)
	CGPoint(x: f + f * (f + f) + f * f, y: f) // same as above but with variable (0.0063 sec)
	CGPoint(x: /*f + */f * (f + f) + f * f, y: 1) // get rid of one of the expressions (0.1 sec)
	CGPoint(x: f + 3 * f * f, y: 1) // (0.0245 sec)
	CGPoint(x: f + f * (f/* + f*/) + f * f, y: 1) // get rid of subexpression (0.3 sec)
	CGPoint(x: f * f * (f * f) * f * f, y: 1) // all multiplications (0.0304 sec)

	// Slower:
	CGPoint(x: f + f + (f + f) + f + f, y: 1) // all plusses (4.0897 sec)
	CGPoint(x: f + f * f + f * f + f * f, y: 1) // (4.2004 sec)
	CGPoint(x: 1 + 1 * (1 + 1) + 1 * 1, y: 1) // all literals (4.9021 sec)
}

// Code snippet 2

func test() -> Double { // 1502.4ms
	let a = 1.0
	let b = 3.0
	let c = 5.0
	let d = 6.0
	return a - b + c + ceil(d * 0.55) + 2.0
}

// Code snippet 3

func test() -> Double { // 0.7ms
	let a = 1.0
	let b = 3.0
	let c = 5.0
	let d = 6.0
	let e = ceil(d * 0.55)
	return a - b + c + e + 2.0
}