Re: More questions about the QPL for a compiler

[Edmund GRIMLEY EVANS <edmundo@rano.org>]

Brian Thomas Sniffen <bts@alum.mit.edu>:

> Yes, I understand that the runtime library and such are LGPL'd.  But
> the compiler, when it compiles a loop, for example, does it in a
> particular way.  The patterns of assembly code output by the compiler
> -- not the parts in the library linked in, but the part actually
> written out by the compiler -- are part of the compiler.  And they end
> up linked with my code.
> 
> It's hard for me to believe that the compiler doesn't write any
> creative bits into its output -- though maybe there really has been
> effort to put those all into the runtime.

Could you give an example of such a pattern in the binary output of
any compiler that you think might require a copyright licence?

I've seen some non-trivial patterns used for procedure prologues and
epilogues, for example, but it's not the sort of thing people usually
claim copyright for (they're not the expression of an idea), and
typically the same patterns are used by different compilers and also
by assembly-language programmers, so, if there is a problem, it's a
very general one. Perhaps someone will claim to own the copyright for
any code that stores the return address on a stack or uses a
particular set of callee-save registers or a frame pointer or finds
the lowest set bit in x by computing x & ~(x - 1) ...