optimize
#pragma optimize( "[optimization-list]", {on | off} )
Specifies optimizations to be performed on a function-by-function basis. The optimize pragma must appear outside a function and takes effect at the first function defined after the pragma is seen. The on and off arguments turn options specified in the optimization-list on or off.
The optimization-list can be zero or more of the parameters shown in Table 2.2.
Table 2.2 Parameters of the optimize Pragma
| Parameter(s) | Type of optimization |
|---|---|
| a | Assume no aliasing. |
| g | Enable global optimizations. |
| p | Improve floating-point consistency. |
| s or t | Specify short or fast sequences of machine code. |
| w | Assume that aliasing can occur across function calls (achieves the same effect as /Ow). |
| y | Generate frame pointers on the program stack. |
These are the same letters used with the /O compiler options. For example:
#pragma optimize( "atp", on )
Using the optimize pragma with the empty string ("") is a special form of the directive:
- When you use the off parameter, it turns the optimizations, listed in the table above, off.
- When you use the on parameter, it resets the optimizations to those that you specified with the /O compiler option.
#pragma optimize( "", off ) . . . #pragma optimize( "", on )