[Bug target/54089] [SH] Refactor shift patterns

[amylaar at gcc dot gnu.org]

http://gcc.gnu.org/bugzilla/show_bug.cgi?id=54089

Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> changed:

           What    |Removed                     |Added
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                 CC|                            |amylaar at gcc dot gnu.org

--- Comment #22 from Jorn Wolfgang Rennecke <amylaar at gcc dot gnu.org> 2012-10-16 10:52:46 UTC ---
(In reply to comment #0)
> The code related to shift patterns in sh.c / sh.md maybe could use some
> improvements here and there.  In some places clobbers and scratch regs could be
> avoided.
> There is also a large part that deals with minimizing and-shift/shift-and
> sequences, but there are no test cases to verify that those actually work.
> It would also be interesting to see, whether some of the and-shift/shift-and
> combine code could be reduced due to improvements in the middle-end.

Be careful with removing 'useless' clobbers, as they might be needed to
facilitate instruction combinations into patterns that have these clobbers.