| register | Keyword

Keyword Index

Tells the compiler to store the variable being declared in a CPU register.

In standard C dialects, keyword `auto` uses the following syntax:

    register data-definition;

The `register` type modifier tells the compiler to store the variable being declared in a CPU register (if possible), to optimize access. For example,

    register int i;

Note that TIGCC will automatically store often used variables in CPU registers when the optimization is turned on, but the keyword `register` will force storing in registers even if the optimization is turned off. However, the request for storing data in registers may be denied, if the compiler concludes that there is not enough free registers for use at this place.
Note: The GNU C extends the usage of `register` keyword to allow explicitely choosing of used registers.