Chapter 8. Assembler Directives

65

.stabs string , type , other , desc , value

All five fields are specified.

8.87.

.string

"

str

"

Copy the characters in

str

to the object file. You may specify more than one string to copy, separated

by commas. Unless otherwise specified for a particular machine, the assembler marks the end of each

string with a 0 byte. You can use any of the escape sequences described in Section 4.6.1.1 Strings.

8.88.

.struct expression

Switch to the absolute section, and set the section offset to

expression

, which must be an absolute

expression. You might use this as follows:

.struct 0

field1:

.struct field1 + 4

field2:

.struct field2 + 4

field3:

This would define the symbol

field1

to have the value 0, the symbol

field2

to have the value 4,

and the symbol

field3

to have the value 8. Assembly would be left in the absolute section, and you

would need to use a

.section

directive of some sort to change to some other section before further

assembly.

8.89.

.subsection name

This is one of the ELF section stack manipulation directives. The others are

.section

(Section

8.78

.section name

),

.pushsection

(Section 8.73

.pushsection name, subsection

),

.popsection

(Section 8.68

.popsection

), and

.previous

(Section 8.67

.previous

).

This directive replaces the current subsection with

name

. The current section is not changed. The

replaced subsection is put onto the section stack in place of the then current top of stack subsection.

8.90.

.symver

Use the

.symver

directive to bind symbols to specific version nodes within a source file. This is only

supported on ELF platforms, and is typically used when assembling files to be linked into a shared

library. There are cases where it may make sense to use this in objects to be bound into an application

itself so as to override a versioned symbol from a shared library.

For ELF targets, the

.symver

directive can be used like this:

.symver name, name2@nodename

If the symbol

name

is defined within the file being assembled, the

.symver

directive effectively

creates a symbol alias with the name

name2@nodename

, and in fact the main reason that we just

don't try and create a regular alias is that the

@

character isn't permitted in symbol names. The

name2

part of the name is the actual name of the symbol by which it will be externally referenced. The name

name

itself is merely a name of convenience that is used so that it is possible to have definitions for

multiple versions of a function within a single source file, and so that the compiler can unambiguously

know which version of a function is being mentioned. The

nodename

portion of the alias should be