When should I use gcc's -Ofast optimization level?

Question

In xcode 5, the Optimization level introduce a new level named -Ofast (Fastest,Aggressive Optimizations). When and how should I use this level?

score 2 · Answer 1 · answered Sep 15 '13 at 02:46

2

In GCC, -Ofast means that the compiler is allowed to ignore finite precision of floating point numbers, and assume that they follow the same rules as real numbers. This enables many optimizations, but may cause changes in the answer due to rounding error.

I don't know if Xcode is different.

answered Sep 15 '13 at 02:46

Demi

3,535
5
29
45

Xcode just passes this compiler flag on to GCC or Clang. – Raptor007 Jan 10 '23 at 18:34

score 2 · Answer 2 · answered Nov 07 '13 at 21:52

2

-Ofast enables -O3, vectorization, strict aliasing and fast math.

answered Nov 07 '13 at 21:52

Davorin

1,160
15
31

When should I use gcc's -Ofast optimization level?

2 Answers2