Platform-Specific Information for the Run-Time Libraries

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Appendix A Platform-Specific Information for the Run-Time Libraries

The GNAT run-time implementation may vary with respect to both the underlying threads library and the exception handling scheme. For threads support, one or more of the following are supplied:

native threads library, a binding to the thread package from the underlying operating system
pthreads library (Sparc Solaris only), a binding to the Solaris POSIX thread package

For exception handling, either or both of two models are supplied:

Zero-Cost Exceptions (“ZCX”),¹ which uses binder-generated tables that are interrogated at run time to locate a handler
setjmp / longjmp (“SJLJ”), which uses dynamically-set data to establish the set of handlers

This appendix summarizes which combinations of threads and exception support are supplied on various GNAT platforms. It then shows how to select a particular library either permanently or temporarily, explains the properties of (and tradeoffs among) the various threads libraries, and provides some additional information about several specific platforms.

Footnotes

[1] Most programs should experience a substantial speed improvement by being compiled with a ZCX run-time. This is especially true for tasking applications or applications with many exception handlers.