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Re: CPROP and spec2000 slowdown in mid february
- To: jh at suse dot cz
- Subject: Re: CPROP and spec2000 slowdown in mid february
- From: kenner at vlsi1 dot ultra dot nyu dot edu (Richard Kenner)
- Date: Sun, 29 Apr 01 09:02:16 EDT
- Cc: gcc at gcc dot gnu dot org
In my previous experiments this turned out to be neccesary, since
certain backends require insns to be in non-canonical form. This may
be considered as bug in the backend tought.
Yes, they are.
The function recurses by calling simplify_gen_* familly of
fuctions. When it reach something that don't have such function, it
just stops recursing and doing substitutions. This does include the
MEM, SUBREG, SIGN_EXTEND and some other RTX constructs we would
probably want to handle.
Oh, that's just a matter of adding that code. What's there is most
definitely meant to be preliminary!
OK. I believed that you wanted to replace current way of doing
substituations on RTX stream by generating new RTX with modified
content, as current simplify_* functions does.
Yes, but that's only a very minor change in the way substitution is
done. Given how quickly we can nnow allocate an rtx, I think the
performance difference will be negligable and made up for by removing
the code that deals with the subst table.