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Re: [patch] Disable tree-ssa DSE for now




On Tue, 18 Jan 2005, Diego Novillo wrote:

Steven Bosscher wrote:

Thoughts?

Well, given your analysis, disabling it is not a bad idea. OTOH, DSE doesn't take a long time to run, does it? I don't think I've ever noticed it.


Also, just because a pass is fast doesn't mean we should keep it enabled :)
Down this path, slowness (because it's unnecessary work) lies.
We didn't get slower 30 or 40% a time, it was .7% or .3%


Jeff, maybe there's a couple of things we can do for 4.0? And then do a complete rewrite for 4.1.

The algorithm DSE is using could probably be replaced with a modified version of GVN-PRE (we need a kill set, but we need this for load PRE anyway), on the reverse flowgraph.


I'll look into it for 4.1.


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