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Re: Proposed major change to combine
- To: amylaar at cambridge dot redhat dot com
- Subject: Re: Proposed major change to combine
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Date: Fri, 9 Mar 01 06:00:54 EST
- Cc: gcc at gcc dot gnu dot org
The SH port has a fake shift insn pattern that pretends to be able to
shift by amounts that the hardware doesn't actually support.
I'm not sure this is a good idea, for precisely these reasons: it messes up
the counting of instructions that combine does.
Why not do the expansion into smaller shifts at RTL generation time?
Heuristiucs for loops are also messed up by doing it the way it's
currently done.