Hi John, On Thu, 2005-08-18 at 14:01 -0700, John M. Gabriele wrote: > What we've been discussing, and what you're talking about here, > is when, at runtime, a natively compiled app wants to load/use > an actual jar file. What in blazes does it matter whether or not > my app was natively compiled with -findirect-dispatch? Nobody's > trying to use ClassLoader.defineClass() to load my app's classes. Maybe it helps if you think about the non -findirect-dispatch case as doing direct-dispatch. In the old abi the code would try to Directly jump to the compiled code of the other class. In the new BC (-findirect-dispatch) abi case it jumps to the code of the other class Indirectly which means that (among other things) it first checks whether or not there is a native version of the class to jump to or if there is not it falls back on the interpreted version. People will probably cry about the above explanation, the real technical details can be found in ftp://gcc.gnu.org/pub/gcc/summit/2004/GCJ%20New% 20ABI.pdf (and are about making sure that certain kinds of binary compatibility rules are followed by native code with the above as nice side-effect) What Andrew tried to explain is that in the old case you could still call interpreted code "indirectly" if you didn't refer to the actual class names in your natively compiled source code. You could compile against interfaces, then load some jar dynamicly and call the interpreted classes through the interface methods (assuming those classes implemented them). Note that the interpreted code was always using "indirect-dispatch" meaning that interpreted code would automatically call either the byte code or native version depending on what was availble. One thing that is somewhat confusing is that .class files can both be seen as defining the API you are compiling agains, actual (byte) code that can be interpreted or as (byte code) source that can be compiled to native code. When using the --classpath=/path/to/mystuff.jar switch to gcj you are only using the jar as "header files" defining an api to compile against. But in the old case the native code would assume that those classes would be native at runtime. Hope this helps and isn't more confusing. Cheers, Mark
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