RealView Compilation Tools - ARM Information Center

Compiler-specific Features
Example
void Variable_Attributes_unused_0()
{
static int aStatic =0;
int aUnused __attribute__ ((unused));
int bUnused;
aStatic++;
}
In this example, the compiler warns that bUnused is declared but never referenced, but
does not warn about aUnused.
Note
The GNU compiler does not give any warning.
4.5.10 __attribute__((used))
This variable attribute informs the compiler that a static variable is to be retained in the
object file, even if it is unreferenced.
Static variables marked as used are emitted to a single section, in the order they are
declared. You can specify the section that variables are placed in using
__attribute__((section)).
Note
This variable attribute is a GNU compiler extension that is supported by the ARM
compiler.
Note
Static functions can also be marked as used using __attribute__((used)).
Usage
You can use __attribute__((used)) to build tables in the object.
Example
static int lose_this = 1;
static int keep_this __attribute__((used)) = 2; // retained in object file
static int keep_this_too __attribute__((used)) = 3; // retained in object file
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