Next: Constant aggregates with an unconstrained nominal types, Up: Code generation for array aggregates
For the declarations:
type One_Dim is array (1..10) of integer; ar0 : constant One_Dim := ( 1, 2, 3, 4, 5, 6, 7, 8, 9, 0);
GNAT generates no executable code: the constant ar0 is placed in static memory. The same is true for constant aggregates with named associations:
Cr1 : constant One_Dim := (4 => 16, 2 => 4, 3 => 9, 1=> 1); Cr3 : constant One_Dim := (others => 7777);
The same is true for multidimensional constant arrays such as:
type two_dim is array (1..3, 1..3) of integer; Unit : constant two_dim := ( (1,0,0), (0,1,0), (0,0,1));
The same is true for arrays of one-dimensional arrays: the following are static:
type ar1b is array (1..3) of boolean; type ar_ar is array (1..3) of ar1b; None : constant ar1b := (others => false); -- fully static None2 : constant ar_ar := (1..3 => None); -- fully static
However, for multidimensional aggregates with named associations, GNAT will generate assignments and loops, even if all associations are static. The following two declarations generate a loop for the first dimension, and individual component assignments for the second dimension:
Zero1: constant two_dim := (1..3 => (1..3 => 0)); Zero2: constant two_dim := (others => (others => 0));