MIPS opcodes patch: change move from andu to or
Mon Oct 25 10:39:00 GMT 1999
> Date: 25 Oct 1999 13:31:12 -0400
> From: Ian Lance Taylor <firstname.lastname@example.org>
> Date: Mon, 25 Oct 1999 11:19:28 -0400 (EDT)
> From: Gavin Romig-Koch <email@example.com>
> OK to commit?
> For opcodes:
> * mips-opc.c (move): Use "or" rather than "addu" or "daddu".
> We deliberately chose ``addu'' and ``daddu'' rather than ``or''
> because several MIPS chips have two pipelined addition units but only
> one pipelined logical unit. Those chips can move two pairs of
> registers around at once if we use ``addu'', but they can only move
> one pair if we use ``or''.
Aha! That's a *very* good reason. I'll add a comment, if that's OK
> Is there any reason we should use ``or''? Your comment mentions
> something about ``gcc -mips3 -gp32''; can't we fix gcc?
Yeah. The problem is that -mgp32 is supposed to generate 32-bit code,
but any move insns get converted into "dadd". I don't really think
that this is important, since the insns will have the same effect, but
it looks rather odd.
I suppose that we could change gcc to ouput "or" insns for 32-bit
moves, but that would degrade performance in the case that you
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