diff options
Diffstat (limited to 'gcc/ada/gnat_rm.texi')
| -rw-r--r-- | gcc/ada/gnat_rm.texi | 25 |
1 files changed, 25 insertions, 0 deletions
diff --git a/gcc/ada/gnat_rm.texi b/gcc/ada/gnat_rm.texi index 5166058..7680876 100644 --- a/gcc/ada/gnat_rm.texi +++ b/gcc/ada/gnat_rm.texi @@ -236,6 +236,7 @@ Implementation Defined Attributes * Compiler_Version:: * Code_Address:: * Default_Bit_Order:: +* Descriptor_Size:: * Elaborated:: * Elab_Body:: * Elab_Spec:: @@ -5718,6 +5719,7 @@ consideration, you should minimize the use of these attributes. * Compiler_Version:: * Code_Address:: * Default_Bit_Order:: +* Descriptor_Size:: * Elaborated:: * Elab_Body:: * Elab_Spec:: @@ -5932,6 +5934,29 @@ as a @code{Pos} value (0 for @code{High_Order_First}, 1 for @code{Low_Order_First}). This is used to construct the definition of @code{Default_Bit_Order} in package @code{System}. +@node Descriptor_Size +@unnumberedsec Descriptor_Size +@cindex Descriptor +@cindex Dope vector +@findex Descriptor_Size +@noindent +Attribute @code{Descriptor_Size} returns the size in bits of the descriptor +allocated for an unconstrained array type. An array descriptor contains bounds +information and is located immediately before the first element of the array. +The value of attribute @code{Descriptor_Size} is of type universal integer. + +@smallexample @c ada +type Unconstr_Array is array (Positive range <>) of Boolean; +Put_Line ("Descriptor size = " & Unconstr_Array'Descriptor_Size'Img); +@end smallexample + +@noindent +The attribute takes into account any additional padding due to type alignment. +In the example above, the descriptor contains two values of type +@code{Positive} representing the low and high bound. Since @code{Positive} has +a size of 31 bits and an alignment of 4, the descriptor size is @code{2 * +Positive'Size + 2} or 64 bits. + @node Elaborated @unnumberedsec Elaborated @findex Elaborated |