[patch] MIPS: Fix synthesized doubleword transfers (ping)

[cgd@broadcom.com]

At Thu, 24 Feb 2005 22:20:30 +0000, Richard Sandiford wrote:
> cgd@broadcom.com writes:
> > At Thu, 24 Feb 2005 21:05:49 +0000 (UTC), "Richard Sandiford" wrote:
> >> I suppose bad things could happen if you composed an aligned
> >> address from an unaligned symbol and an unaligned offset,
> >> but is that allowed?
> >
> > yes, at least as far as the ISA is concerned.
> 
> I don't follow.  The ISA has no concept of symbols vs. offsets.

right, but to some degree symbol + offset -> base reg + offset, since
the offsets in the base regs come directly from the relocs.

the offsets in the instructions are 16-bit sign-extended values only
-- no scale.

some MIPS ISA levels, MIPS IV IIRC, had requirements that base reg
must be properly aligned, and that offset must be properly aligned.
(But IIRC those weren't present before MIPS IV, and aren't present in
MIPS32/MIPS64.)


chris