AVR GNU C compiler options

Table 4. AVR GNU C compiler options

OptionDescription
OptionDescription
General options

-mcall-prologues

Use subroutines for functions prologues and epilogues

-mno-interrupts

Change stack pointer without disabling interrupts

-funsigned-char

Default char type is unsigned

-funsigned-bitfield

Default bit field is unsigned

Preprocessor options

-nostdinc

Do not search system directories

-F

Preprocess only

Symbols options

There one can define (-D) or undefine (-U) a number of in-source symbols. New symbol declarations can be added, modified, or reordered, using the interface buttons below:

  • Add a new symbol. This and all following icons are reused with the same meaning in other parts of Atmel Studio interface

  • Remove a symbol.

  • Edit symbol

  • Move the symbol up in the parsing order

  • Move the symbol down in the parsing order

Include directories

Contains all the included header and definition directories, can be modified, using the same interface as symbols.

Optimization options

Optimization level (drop down menu): -O0, -O1, -O2, -O3, -Os

No optimization, optimize for speed (level 1 - 3), optimize for size

Other optimization flags (manual input form)

Here you should write optimization flags specific for the platform and your requirements

-ffunction-sections

Prepare functions for garbage collection, if a function is never used, its memory will be scrapped

-fpack-struct

Pack structure members together

-fshort-enums

Allocate only as many bytes needed by the enumerated types

-mshort-calls

Use rjmp/rcall limited range instructions on the >8K devices

Debug options

Debug level (drop down menu): none, -g1, -g2, -g3

Specifies the level of tracing and debugging code and headers left or inserted in the source code

Other debug options (form field)

Architecture specific debug options

Warning messages output options

-Wall

All warnings

-Werror

Escalate warnings to errors

-fsyntax-only

Check syntax only

-pedantic

Check conformity to GNU, raise warnings on non-standard programming practice

-pedantic-errors

Same as above, plus escalate warnings to errors

Miscelaneous options

Other flags (form field)

Input other project-specific flags

-v

Verbose

-ansi

Support ANSI programs

-save-temps

Do not delete temporary files