| Option | Description |
|---|---|
| -O0 | Disables optimizations. |
| -O1 | Enables optimizations. Optimizes for speed. -O1 disables inline expansion of library functions. For Itanium® compiler, -O1 turns off software pipelining to reduce code size. |
| -O2 | Equivalent to option -O1. |
| -O3 | Builds on -O1 and -O2 by enabling high-level optimization. This level does not guarantee higher performance unless loop and memory access transformation take place. In conjunction with -axK/-xK, this switch causes the compiler to perform more aggressive data dependency analysis than for -O2. This may result in longer compilation times. |