68020-060 optimization mean "optimize for 68030, 68040 and 68060". I don't
looked at the compiler but I would assume this optimization avoid any
instruction usage that the 68060 don't have (the same for the 040).
Yes, normal instructions like movep or 64bit division aren't used. However, since m68020-60 means "compile for 68020 and FPU" it uses all 68881 instructions. And here it comes -- m68060 doesn't use emulated floating point instrucions what m68020-60 does.
Or are there special optimizations that are disabled for the 68020-060
compiler switch? What is the speed difference of the pure 68060
optimization against the 68020-60 optimization (I expect no speed
advantage).
Except the above things I assume it uses much wisely instruction and data caches, one can't optimize for 030 and 060 in the same time... For example, on 030 is unrolling always good option (as long as it fits into 256B cache), on 060 there's branch prediction so it doesn't matter very much. I think there's good chance gcc guys know about this :) But sure, except FPU stuff, the speed difference might be 10-20% max but -- in programs like zip or bash every speedup counts.
I just want to avoid an additional mintlib target. I think two are really
enough (one for 68000 and one for 68020-060; and don't forget the debug
and profiling targets). Btw. the same apply to the kernel too (too much
targets, one 68020-060 kernel is really enough I think).
I have no arguments here, I just like to have 060 software compiled with 060 libs. We can always disable it as default, I see no harm here. And about the kernel -- yes, maybe now, but for example when FreeMiNT will have FPSP package included, these switch will become handy (to include or not to include the package). But as I say, for me it's more matter of "good feeling" everything runs at max. possible speed than any serious reason. Look at gentoo guys -- everyone of them will tell you their system is "much, much faster", it's quite popular and even despite the fact there are many i686 distros where the performance loss is really minimal.