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[Bug target/38134] [4.6/4.7/4.8 Regression] speed regression with many loop invariants


http://gcc.gnu.org/bugzilla/show_bug.cgi?id=38134

Richard Biener <rguenth at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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             Status|NEW                         |ASSIGNED
         AssignedTo|unassigned at gcc dot       |rguenth at gcc dot gnu.org
                   |gnu.org                     |

--- Comment #19 from Richard Biener <rguenth at gcc dot gnu.org> 2013-01-15 15:20:01 UTC ---
It might be worth (in general) to "CSE" constants before RTL expansion again
and rely on IRA/LRA re-materializing them if there isn't an available register
(and/or there is just a single use).  Not sure if it would survive
combine / fwprop / ccp of course.  Certainly doable from within PRE/FRE
which should be able to compute good places for putting a shared constant
into a register (SSA name).  At least for "expensive" constants that might
be a good idea anyway (what is considered expensive the target can decide).

Let me take this for a while to experiment with the above.


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