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Re: RFA: enable LRA for rs6000 [patch for WRF]


On 13-04-22 12:35 AM, Alan Modra wrote:
On Fri, Apr 19, 2013 at 05:16:43PM -0400, Vladimir Makarov wrote:
   I don't understand what this check means and what comments ??? means too.
A lo_sum mem is only valid if you know it won't be offset (or that
offsetting will never cross a 64k+32k boundary).  If the access is
smaller than a word then the load or store can be done in one insn.
No offset required.  If the access is a DFmode *and* you are loading
or storing a floating point reg, then the access is also done in one
insn.  The ??? comment is referring to the fact that you don't know
for sure that the DFmode is in a floating point reg.  It usually is,
but may be in two general purpose regs.  Which then need an offset to
load/store the second reg.

Alan, thanks for the explanation. I'll search for another solution.


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