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From: "steven at gcc dot gnu.org" <gcc-bugzilla@gcc.gnu.org>
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Subject: [Bug rtl-optimization/56339] [4.8 Regression]: Suboptimal register allocation
Date: Fri, 15 Feb 2013 09:52:00 -0000
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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=56339

Steven Bosscher <steven at gcc dot gnu.org> changed:

           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |steven at gcc dot gnu.org

--- Comment #1 from Steven Bosscher <steven at gcc dot gnu.org> 2013-02-15 09:51:56 UTC ---
Confirmed.

Actually, it looks to me like IRA already makes this allocation:
Disposition:
    1:r64  l0    21    0:r67  l0    23
(21=>%xmm0, 23=>%xmm2)

=> .ira dump:

;; basic block 2
    2: r64:DF=xmm0:DF
    8: r67:DF=xmm2:DF
   12: r67:DF=r67:DF+r64:DF
   17: xmm0:DF=r67:DF
   20: use xmm0:DF

=> .reload (LRA) dump:

********** Local #1: **********
         Choosing alt 0 in insn 12:  (0) =x  (1) %0  (2) xm

;; basic block 2
    2: xmm0:DF=xmm0:DF
    8: xmm2:DF=xmm2:DF
   12: xmm2:DF=xmm2:DF+xmm0:DF
   17: xmm0:DF=xmm2:DF
   20: use xmm0:DF

So all LRA does, is follow IRA's recommended allocation.  That is IMHO
the right thing to do, too.