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*From*: Prathamesh Kulkarni <bilbotheelffriend at gmail dot com>*To*: Richard Biener <richard dot guenther at gmail dot com>*Cc*: GCC Development <gcc at gcc dot gnu dot org>*Date*: Wed, 30 Jul 2014 17:55:27 +0530*Subject*: Re: writing patterns*Authentication-results*: sourceware.org; auth=none*References*: <CAJXstsDfsQbj4e-RVyGC0grF_UDx5J0pYh=M9H9w=VYA-HBY4w at mail dot gmail dot com> <CAFiYyc0mAyTVrn07+ZSzgRT3of=O90iKkM_HVo1MfTvZaJemvw at mail dot gmail dot com>

On Wed, Jul 30, 2014 at 4:41 PM, Richard Biener <richard.guenther@gmail.com> wrote: > On Wed, Jul 30, 2014 at 12:49 PM, Prathamesh Kulkarni > <bilbotheelffriend@gmail.com> wrote: >> Hi, >> Sorry to ask a stupid question, but I am having issues writing patterns >> involving casts. I am trying to write patterns from simplify_rotate. >> >> Could you show me how to write a patterns that involve >> casts ? >> for eg: >> ((T) ((T2) X << CNT1)) + ((T) ((T2) X >> CNT2)) iff CNT1 + CNT2 == B >> T -> some unsigned type with bitsize B, and some type T2 wider than T. >> How to express this in the pattern ? > > [copying gcc@ because of the syntax stuff] > > for example with (leaving captures as the appear in the pattern above) > > (match_and_simplify > (plus (convert@2 (lshift (convert@0 X) CNT1)) > (convert (rshift (convert@1 X) CNT2))) > /* Types T2 have to match */ > (if (types_compatible_p (TREE_TYPE (@0), TREE_TYPE (@1)) > /* Type T should be unsigned. */ > && TYPE_UNSIGNED (TREE_TYPE (@2)) > /* T2 should be wider than T. */ > && TYPE_PRECISION (TREE_TYPE (@0)) > TYPE_PRECISION (TREE_TYPE (@2)) > /* CNT1 + CNT2 == B */ > && wi::eq_p (TYPE_PRECISION (TREE_TYPE (@2)), > wi::add (CNT1, CNT2)))) > (lrotate CNT1)) > > which suggests that we may want to add some type capturing / matching > so we can maybe write > > (plus (convert@T (lshift (convert@T2 X) CNT1)) > (convert (rshift (convert@T2 X) CNT2))) > (if (/* T2s will be matched automagically */ > && TYPE_UNSIGNED (@T) > && TYPE_PRECISION (@T2) > TYPE_PRECISION (@T) > && wi::eq_p (TYPE_PRECISION (@T), wi::add (CNT1, CNT2)))) > Thanks. > which is less to type and supports requiring matching types. Maybe > require @T[0-9]+ here thus use @T0 and disallow plain @T. We could > then also use @T for the implicitely "captured" outermost type we > refer to as plain 'type' right now. What if we need to capture "value" as well as "type" ? for instance match type with another capture, and value with a different capture ? sth like: (bogus pattern): (match_and_simplify (plus (minus@T@2 @0 @1) (mult@T @2 @3)) transform) > I suggest to go ahead without a new syntax for now and see if it > gets unwieldingly ugly without first. > >> For this week, I have planned: >> a) writing patterns from simplify_rotate >> b) replacing op in c_expr >> c) writing more test-cases. >> >> If there's anything else you would like me to do, I would be happy >> to know. > > Just keep an eye open for things like above - easy ways to reduce > typing for patterns. > > Btw, I suggest to split up match.pd by code you converted from. Thus > for simplify_rotate add > > match-simplify-rotate.pd > > with the patterns and do a #include "match-simplify-rotate.pd" > in match.pd. That will make it easier to match the two later. Okay, should I correspondingly split bitwise patterns in match-simplify-bitwise.pd and the rest ? Thanks, Prathamesh > > Thanks, > Richard. > > >> Thanks, >> Prathamesh

**Follow-Ups**:**Re: writing patterns***From:*Prathamesh Kulkarni

**Re: writing patterns***From:*Richard Biener

**References**:**Re: writing patterns***From:*Richard Biener

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