Chapter 8. Assembler Directives

53

8.54.

.line line number

Change the logical line number.

line number

must be an absolute expression. The next line has that

logical line number. Therefore any other statements on the current line (after a statement separator

character) are reported as on logical line number

line number

  1. One day

as

will no longer support

this directive: it is recognized only for compatibility with existing assembler programs.

Warning: In the AMD29K configuration of as, this command is not available; use the synonym

.ln

in that context.

Even though this is a directive associated with the

a.out

or

b.out

object code formats,

as

still

recognizes it when producing COFF output, and treats

.line

as though it were the COFF

.ln

if it is

found outside a

.def

/

.endef

pair.

Inside a

.def

,

.line

is, instead, one of the directives used by compilers to generate auxiliary symbol

information for debugging.

8.55.

.linkonce [type]

Mark the current section so that the linker only includes a single copy of it. This may be used to

include the same section in several different object files, but ensure that the linker will only include it

once in the final output file. The

.linkonce

pseudo op must be used for each instance of the section.

Duplicate sections are detected based on the section name, so it should be unique.

This directive is only supported by a few object file formats; as of this writing, the only object file

format which supports it is the Portable Executable format used on Windows NT.

The

type

argument is optional. If specified, it must be one of the following strings. For example:

.linkonce same_size

Not all types may be supported on all object file formats.

discard

Silently discard duplicate sections. This is the default.

one_only

Warn if there are duplicate sections, but still keep only one copy.

same_size

Warn if any of the duplicates have different sizes.

same_contents

Warn if any of the duplicates do not have exactly the same contents.

8.56.

.ln line number

.ln

is a synonym for

.line

.

8.57.

.mri val

If

val

is non zero, this tells

as

to enter MRI mode. If

val

is zero, this tells

as

to exit MRI mode. This

change affects code assembled until the next

.mri

directive, or until the end of the file. MRI mode.