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Chapter 8. Assembler Directives

8.97.

.version "string"

This directive creates a

.note

section and places into it an ELF formatted note of type NT_VERSION.

The note's name is set to

string

.

8.98.

.vtable_entry table, offset

This directive finds or creates a symbol

table

and creates a

VTABLE_ENTRY

relocation for it with an

addend of

offset

.

8.99.

.vtable_inherit child, parent

This directive finds the symbol

child

and finds or creates the symbol

parent

and then creates a

VTABLE_INHERIT

relocation for the parent whose addend is the value of the child symbol. As a

special case the parent name of

0

is treated as refering the

*ABS*

section.

8.100.

.weak names

This directive sets the weak attribute on the comma separated list of symbol

names

. If the symbols do

not already exist, they will be created.

Weak symbols are supported in COFF as a GNU extension. This directive sets the weak attribute on

the comma separated list of symbol

names

. If the symbols do not already exist, they will be created.

.weak

name

[

= | ==

alternate

] [, ...]

On the PE target, weak aliases are supported natively. Weak aliases (usually called "weak externals"

in PE) are created when an alternate name is specified. When a weak symbol is linked and the symbol

is not defined, the weak symbol becomes an alias for the alternate symbol. If one equal sign is used,

the linker searches for defined symbols within other objects and libraries. This is the usual mode,

historically called "lazy externals." Otherwise, when two equal signs are used, the linker searches for

defined symbols only within other objects.

Non alias weak symbols are supported on PE as a GNU extension.

8.101.

.word expressions

This directive expects zero or more

expressions

, of any section, separated by commas.

The size of the number emitted, and its byte order, depend on what target computer the assembly is

for.

Warning: Special Treatment to support Compilers

Machines with a 32 bit address space, but that do less than 32 bit addressing, require the follow 

ing special treatment. If the machine of interest to you does 32 bit addressing (or doesn't require it;

Chapter 9 Machine Dependent Features), you can ignore this issue.

In order to assemble compiler output into something that works,

as

occasionally does strange things

to

.word

directives. Directives of the form

.word sym1 sym2

are often emitted by compilers as

part of jump tables. Therefore, when

as

assembles a directive of the form

.word sym1 sym2

, and

the difference between

sym1

and

sym2

does not fit in 16 bits,

as

creates a secondary jump table,