ld_pa.1 (2010 09)

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ld_pa(1) PA-RISC Systems Only
ld_pa(1)
On the initial incremental link, the linker processes the input object files and libraries in the same way as
the normal link. In addition to the normal linking process, the incremental linker saves information
about object files, global symbols, and relocations, and pads sections in the output file for expansion. On
subsequent incremental links, the linker uses timestamps and file sizes to determine which object files
have changed, and updates those modules.
Under certain conditions, the incremental linker cannot perform incremental links. When this occurs,
the incremental linker automatically performs an initial incremental link to restore the process. In the
following situations, the linker automatically performs an initial incremental link of the output file:
• Changed linker command line, where the linker command line does not match the command line
stored in the output file. (With the exceptions of the verbose and tracing options)
• Any of the padding spaces have been exhausted.
• Modules have been modified by the
ld -s or ld -x options or tools (for example, strip (1)). The
incremental linking requires the parts of the output load module which are stripped out with these
options.
• Incompatible incremental linker version, when you run a new version of the incremental linker on an
executable created by an older version.
• New working directory, where the incremental linker performs an initial incremental link if current
directory changes.
• Archive or shared libraries are added/removed to/from the linker command line.
• Objects are added/removed to/from the linker command line.
See the Online Linker and Libraries User’s Guide (
ld +help
) for more information.
Archive Library Processing
The incremental linker searches an archive library if there are unsatisfied symbols. It extracts all
archive members satisfying unsats and processes them as new object files. If an archive library is
modified, the linker replaces the modified archive library.
An object file extracted from an archive library in the previous link remains in the output load module
even if all references to symbols defined in the object file have been removed. The linker removes these
object files when it performs the next initial incremental link.
Shared Library Processing
In an initial incremental link, the linker scans shared library symbol tables and resolves unsats the same
way it would in a regular link. In incremental links, the linker does not process shared libraries and
their symbol tables at all and does not report shared library unsats. The dynamic loader detects them at
run time. If any of the shared libraries on the command line was modified, the linker reverts to an initial
incremental link.
Performance
Performance of the incremental linker may suffer greatly if you change a high percentage of object files.
The incremental linker may not link small programs much faster, and the relative increase in size of the
executable is greater than that for larger programs.
Generally, the linker needs to scan through all shared libraries on a link line in order to determine all
the unsats, even in incremental links. This process may slow down incremental links. The incremental
linker does not scan shared libraries and leaves detection of shared library unsats to the dynamic loader.
Do not use the incremental linker to create final production modules. Because it reserves additional pad-
ding space, modules created by the incremental linker are considerably larger than those created in regu-
lar links.
Notes
The HP WDB symbolic debugger only supports debugging of incrementally linked load modules that you
create with the
+objdebug compiler option enabled. (The HP DDE debugger does not support the
+ild option.
Any program that modifies an executable (for example, strip (1)), may affect the ability of
ld to perform
an incremental link. When this happens, the incremental linker issues a message and performs an initial
incremental link.
Third-party tools that work on object files may have unexpected results on modules produced by the
incremental linker.
18 Hewlett-Packard Company − 18 − HP-UX 11i Version 3: September 2010