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aligned |
Syntax: aligned [(alignment)]
This attribute specifies a minimum alignment for the variable or
structure field, measured in bytes. For example, the declaration:
int x __attribute__ ((aligned (4))) = 0;
causes the compiler to allocate the global variable x
on a
4-byte boundary.
You can also specify the alignment of structure fields. For example, to
create a 4-byte aligned int
pair, you could write:
struct foo { int x[2] __attribute__ ((aligned (4))); };
As in the preceding examples, you can explicitly specify the alignment
(in bytes) that you wish the compiler to use for a given variable or
structure field. Alternatively, you can leave out the alignment factor
and just ask the compiler to align a variable or field to the maximum
useful alignment for the target machine you are compiling for. For
example, you could write:
short array[3] __attribute__ ((aligned));
Whenever you leave out the alignment factor in an aligned
attribute
specification, the compiler automatically sets the alignment for the declared
variable or field to the largest alignment which is ever used for any data
type on the target machine you are compiling for (useless in TIGCC, since everything
is already aligned well enough with the default 2-byte alignment).
The aligned
attribute can only increase the alignment; but you
can decrease it by specifying packed
as well.