On Fri, Nov 04, 2011 at 11:31:30AM -0700, Jonathan Duke Leto wrote: > Since ARM has so many permutations, I am not quite sure how we should keep > track of it. Currently I am thinking a table for a few different versions of > the ARM spec (like v1, v5, v9, Cortex-x, Cortex-y) or something like that.
IIRC ARM v1 was only ever for prototypes, and not in released products. v2 has a 26 bit address bus, and stopped being used about 18 years ago. I think v3 is pretty dead, but I'm not sure. Their performance graph only shows v4 and later. IIRC around v4 one gets the half word (ie 16 bit) load/store instructions, sign extending load instructions, and the 64 bit multiply instructions. (And IIRC all are variants of v4, in that it was possible to have physical hardware with some but not others). These probably are useful for a JIT. After then, I'm not sure what the added instructions were for, but I suspect that they aren't going to be for things that JITs find useful. I'd suggest working out what ARM CPU architecture current Debian builds for, and doing that first. Then looking at what the later architectures offer, and only if they have something significantly useful that plugs a hole in the table, actually treating them differently. I'm not sure of the state of hardware floating point, as in, which chips have it (or means to do it), and how many different variations of it there are. Nicholas Clark _______________________________________________ http://lists.parrot.org/mailman/listinfo/parrot-dev
