Module control directives

In this section:

Syntax

AAPCS [ modifier [...]]

END

PRESERVE8

REQUIRE8

RTMODEL key , value

Parameters

`key`	A text string specifying the key.
`modifier`	An AAPCS extension—possible values are `INTERWORK`, `VFP`, `VFP_COMPATIBLE`, `ROPI`, `RWPI`, `RWPI_COMPATIBLE`. Modifiers can be combined to specify AAPCS variants.
`value`	A text string specifying the value.

Description

Module control directives are used for marking the beginning and end of source program modules, and for assigning names and types to them. For information about the restrictions that apply when using a directive in an expression, see Expression restrictions.

Directive	Description	Expression restrictions
`END`	Ends the assembly of the module in a file.	Locally defined symbols plus offset or integer constants
`RTMODEL`	Declares runtime model attributes.	Not applicable

Table 146. Module control directives

Setting module attributes for AEABI compliance

In 32-bit mode, you can set specific attributes on a module to inform the linker that the exported functions in the module are compliant to certain parts of the AEABI standard.

Use AAPCS, optionally with modifiers, to indicate that a module is compliant with the AAPCS specification. Use PRESERVE8 if the module preserves an 8-byte aligned stack and REQUIRE8 if an 8-byte aligned stack is expected.

Note

It is up to you to verify that the module is compliant to these parts, as the assembler does not verify this. In 64-bit mode, these directives have no effect.

Declaring runtime model attributes

Use RTMODEL to enforce consistency between modules. All modules that are linked together and define the same runtime attribute key must have the same value for the corresponding key value, or the special value *. Using the special value * is equivalent to not defining the attribute at all. It can however be useful to explicitly state that the module can handle any runtime model.

A module can have several runtime model definitions.

Note

The compiler runtime model attributes start with double underscores. In order to avoid confusion, this style must not be used in the user-defined assembler attributes.

If you are writing assembler routines for use with C or C++ code, and you want to control the module consistency, refer to Runtime model attributes.

The following examples define three modules in one source file each, where:

MOD_1 and MOD_2 cannot be linked together since they have different values for runtime model CAN.
MOD_1 and MOD_3 can be linked together since they have the same definition of runtime model RTOS and no conflict in the definition of CAN.
MOD_2 and MOD_3 can be linked together since they have no runtime model conflicts. The value * matches any runtime model value.

Assembler source file f1.s:

            module  mod_1
            rtmodel "CAN",      "ISO11519"
            rtmodel "Platform", "M7"
            ; ...
            end

Assembler source file f2.s:

            module  mod_2
            rtmodel "CAN",      "ISO11898"
            rtmodel "Platform", "*"
            ; ...
            end

Assembler source file f3.s:

            module  mod_3
            rtmodel "Platform", "M7"
            ; ...
            end

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