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Re: [PATCH][3/n] Merge from match-and-simplify, first patterns and questions
- From: Richard Biener <rguenther at suse dot de>
- To: gcc-patches at gcc dot gnu dot org
- Date: Mon, 20 Oct 2014 13:43:45 +0200 (CEST)
- Subject: Re: [PATCH][3/n] Merge from match-and-simplify, first patterns and questions
- Authentication-results: sourceware.org; auth=none
- References: <alpine dot LSU dot 2 dot 11 dot 1410151340120 dot 20733 at zhemvz dot fhfr dot qr> <alpine dot DEB dot 2 dot 11 dot 1410191904550 dot 6698 at laptop-mg dot saclay dot inria dot fr>
On Sun, 19 Oct 2014, Marc Glisse wrote:
> looking though the patterns on the branch (not specifically the ones attached
> here), I am surprised to see so few calls to has_single_use. In RTL-land, we
> don't even valueize if there are several uses, so the question doesn't occur.
> In generic, we assume everything is single use (CSE could later disagree, but
> that's the user's fault for writing his code that way). In
> tree-ssa-forwprop.c, helpers like get_prop_source_stmt do test for single use.
> Since has_single_use is a bit painful to use in .pd files (separate test for
> generic and constants), it might deserve another helper function, or a special
But I don't think "has_single_use" is a good tool to disable transforms
on. It's also used very inconsistently in tree-ssa-forwprop.c.
See also my other mail.