According to XL C/C++ V9.0 documentation the default for -qpic/-qnopic
is platform-dependent. It won't hurt to add the option on platforms
where it is the default, so always add it when we want position
independent code.
Add a boolean target property NO_SONAME which may be used to disable
soname for the specified shared library or module even if the platform
supports it. This property should be useful for private shared
libraries or various plugins which live in private directories and have
not been designed to be found or loaded globally.
Replace references to <CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG> and
hard-coded -install_name flags with a conditional <SONAME_FLAG> which is
expanded to the value of the CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG
definition as long as soname supports is enabled for the target in
question. Keep expanding CMAKE_SHARED_LIBRARY_SONAME_${LANG}_FLAG in
rules in case third party projects still use it. Such projects would
not yet use NO_SONAME so the adjacent <TARGET_SONAME> will always be
expanded. Make <TARGET_INSTALLNAME_DIR> NO_SONAME aware as well. Since
-install_name is soname on OS X, this should not be a problem if this
variable is expanded only if soname is enabled.
The Ninja generator performs rule variable substitution only once
globally per rule to put its own placeholders. Final substitution is
performed by ninja at build time. Therefore we cannot conditionally
replace the soname placeholders on a per-target basis. Rather than
omitting $SONAME from rules.ninja, simply do not write its contents for
targets which have NO_SONAME. Since 3 variables are affected by
NO_SONAME ($SONAME, $SONAME_FLAG, $INSTALLNAME_DIR), set them only if
soname is enabled.
Linking broken on non-AIX machines when using XL compilers due to those
machines not using the CreateExportList tool. Made use of this tool
conditional on finding it.
The XL toolchain supports shared object files stored in archives. Since
CMake lists libraries on link lines by full path it is common for a
shared library link line to contain the path to an archive file.
When linking a shared library the compiler front-end by default runs
CreateExportList to construct the list of symbols to be exported.
Unfortunately it passes all files found on the command line to the tool
so archive and library files get processed along with the object files.
The tool returns a list of all symbols in all objects, archives, and
libraries on the command line. This causes the linker to copy every
object file out of every archive into the shared library whether they
are dependencies of the original object files or not.
Work around this problem by running CreateExportList ourselves with just
the original object files intended for inclusion in the shared library.
Then pass the list it produces on the link line to prevent the compiler
front-end from constructing its own. This tells the linker to export
only the symbols provided by the original source files of the shared
library.
Factor duplicate information out of Compiler/XL-<lang>.cmake modules
into a macro in a new Compiler/XL.cmake module. Invoke it from the
per-language files to produce the original settings.
Brad King
Modestas Vainius
Todd Gamblin