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Re: [PING] Move costs, allocno costs, and per-register costs


Bernd Schmidt wrote:
Vladimir Makarov wrote:
Richard Sandiford wrote:
In

http://gcc.gnu.org/ml/gcc-patches/2008-11/msg00325.html

you wrote

 In summary, I think ira-costs.c:record_reg_classes should not add
 ira_may_move_out_cost and ira_memory_cost for unused output operands.
 I'd like to test that at some point, but I've got a lot on my plate
 and probably won't find time.  (An agreement in principle might
 add a bit of incentive though.)

I think it would be interesting to see the results. Another would be
interesting code is to check dealing with equiv memory. The code
quality is very sensitive to changes in ira-costs.c.

Do you have something like the patch below in mind?
Yes, thanks.
  I tested this
against Richard's patches for a Blackfin target, with inconclusive
results.  It did seem to help with the testcase Richard found that had a
regression; other than that there weren't too many differences in code
quality that I could find.


I've just finished benchmarking it on x86 too. Two programs from SPECInt2000 has the same code. Other SPECInt2000 program has a bit better code (like 0.2% but it is in measurement error range even for my most stable machine which has a very small measurement range).


As for SPECFp2000 about half programs have the same code, the code quality of the rest are simply the same.

So I also see no cons or pros for the patch.


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