Optimization (Delphi)

Go Up to Delphi Compiler Directives (List) Index

Type	Switch
Syntax	{$O+} or {$O-} {$OPTIMIZATION ON} or {$OPTIMIZATION OFF}
Default	{$O+} {$OPTIMIZATION ON}
Scope	Local (except Global for DCCIOSARM64 compiler)

The $O directive controls code optimization. In the {$O+} state, the compiler performs a number of code optimizations, such as placing variables in CPU registers, eliminating common subexpressions, and generating induction variables. In the {$O-} state, all such optimizations are disabled.

Other than for certain debugging situations, you should never have a need to turn optimizations off. All optimizations performed by the Delphi compiler are guaranteed not to alter the meaning of a program. In other words, the compiler performs no "unsafe" optimizations that require special awareness by the programmer.

Note:

• The $O directive can only turn optimization on or off for an entire procedure or function. You cannot turn optimization on or off for a single line or group of lines within a routine.
• For iOS applications that target the 64-bit iOS Device (and thus use the DCCIOSARM64 compiler), the $O directive has global scope. The compiler does not generate any warning or hint messages, but the optimizer uses the last setting if multiple $O options exist in a single source code file.

See Also

• DCCIOSARM64.EXE, the Delphi Compiler for the 64-bit iOS Device