Atmel CAVR-4 Manual De Usuario

CAVR-4

Part 2. Compiler reference

The following keywords can be used with 

#pragma

 

object_attribute

 for a function 

or variable:

In the following example, the variable 

bar

 is placed in the non-initialized segment:

#pragma object_attribute=_ _no_init 

char bar; 

Unlike the directive 

#pragma

 

type_attribute

 that specifies the storing and accessing 

of a variable, it is not necessary to specify an object attribute in declarations. The 
following example declares 

bar

 without a 

#pragma

 

object_attribute

:

_ _no_init char bar;

#pragma optimize

#pragma optimize=token_1 token_2 token_3

where 

 is one of the following:

The 

#pragma

 

optimize

 directive is used for decreasing the optimization level, or for 

turning off some specific optimizations. This pragma directive only affects the function 
that follows immediately after the directive.

Note that it is not possible to optimize for speed and size at the same time. Only one of 
the 

s

 and 

z

 tokens can be used. It is also not possible to use macros embedded in this 

pragma directive. Any such macro will not get expanded by the preprocessor.

_ _root

Ensures that a function or data object is included in the linked 
application, even if it is not referenced.

_ _noreturn

Informs the compiler that the function will not return.

s

Optimizes for speed

z

Optimizes for size

2|none|3|low|6|medium|9|high

Specifies the level of optimization

no_code_motion

Turns off code motion

no_cse

Turns off common subexpression elimination

no_inline

Turns off function inlining

no_tbaa

Turns off type-based alias analysis