This is the mail archive of the
mailing list for the GCC project.
Re: C++ compile-time regressions
- To: Richard Kenner <kenner at vlsi1 dot ultra dot nyu dot edu>
- Subject: Re: C++ compile-time regressions
- From: Daniel Berlin <dan at cgsoftware dot com>
- Date: Fri, 03 Aug 2001 13:20:26 -0400
- cc: gcc-patches at gcc dot gnu dot org, gcc at gcc dot gnu dot org
- References: <10108031358.AA07911@vlsi1.ultra.nyu.edu>
--On Friday, August 03, 2001 9:58 AM -0400 Richard Kenner
> I'm just completing some benchmark runs to see if our performance
> actually changes if i tell CSE to stop caring about memory (and run
> store motion after reload).
> As far as I know, CSE is the only pass which knows the precise
> semantics of when memory locations conflict. Remember that they aren't
> equivalence classes.
Both PRE and store motion know precisely when they conflict (I.E. they use
true_dependence), and when they aren't available/antic (I.E. Their register
It's faster because it doesn't require removing from a hash table, just
setting or resetting a bit in a bitvector.