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Chapter 19. HPPA Dependent Features

.spnum secnam

Allocate four bytes of storage, and initialize them with the section number of the section named

secnam

. (You can define the section number with the HPPA

.space

directive.)

.string "str"

Copy the characters in the string

str

to the object file. Section 4.6.1.1 Strings, for information

on escape sequences you can use in

as

strings.

Warning! The HPPA version of

.string

differs from the usual

as

definition: it does not write a

zero byte after copying

str

.

.stringz "str"

Like

.string

, but appends a zero byte after copying

str

to object file.

.subspa name [ ,params ]

.nsubspa name [ ,params ]

Similar to

.space

, but selects a subsection

name

within the current section. You may only spec 

ify

params

when you create a subsection (in the first instance of

.subspa

for this

name

).

If specified, the list

params

declares attributes of the subsection, identified by keywords. The

keywords recognized are

quad=expr

("quadrant" for this subsection),

align=expr

(alignment

for beginning of this subsection; a power of two),

access=expr

(value for "access rights"

field),

sort=expr

(sorting order for this subspace in link),

code_only

(subsection contains only

code),

unloadable

(subsection cannot be loaded into memory),

comdat

(subsection is comdat),

common

(subsection is common block),

dup_comm

(subsection may have duplicate names), or

zero

(subsection is all zeros, do not write in object file).

.nsubspa

always creates a new subspace with the given name, even if one with the same name

already exists.

comdat

,

common

and

dup_comm

can be used to implement various flavors of one only support

when using the SOM linker. The SOM linker only supports specific combinations of these flags.

The details are not documented. A brief description is provided here.

comdat

provides a form of linkonce support. It is useful for both code and data subspaces. A

comdat

subspace has a key symbol marked by the

is_comdat

flag or

ST_COMDAT

. Only the

first subspace for any given key is selected. The key symbol becomes universal in shared links.

This is similar to the behavior of

secondary_def

symbols.

common

provides Fortran named common support. It is only useful for data subspaces. Symbols

with the flag

is_common

retain this flag in shared links. Referencing a

is_common

symbol in a

shared library from outside the library doesn't work. Thus,

is_common

symbols must be output

whenever they are needed.

common

and

dup_comm

together provide Cobol common support. The subspaces in this case

must all be the same length. Otherwise, this support is similar to the Fortran common support.

dup_comm

by itself provides a type of one only support for code. Only the first

dup_comm

sub 

space is selected. There is a rather complex algorithm to compare subspaces. Code symbols

marked with the

dup_common

flag are hidden. This support was intended for "C++ duplicate

inlines".

A simplified technique is used to mark the flags of symbols based on the flags of their subspace.

A symbol with the scope SS_UNIVERSAL and type ST_ENTRY, ST_CODE or ST_DATA is

marked with the corresponding settings of

comdat

,

common

and

dup_comm

from the subspace,

respectively. This avoids having to introduce additional directives to mark these symbols. The

HP assembler sets

is_common

from

common

. However, it doesn't set the

dup_common

from

dup_comm

. It doesn't have

comdat

support.