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Re: [rfc] PR tree-optimization/52633 - ICE due to vectorizer pattern detection collision


Jakub Jelinek wrote:
> On Wed, Apr 25, 2012 at 10:29:36AM +0200, Richard Guenther wrote:
> > > Does this look reasonable?  Any comments or suggestions appreciated!
> > 
> > Yes, getting rid of this fragile interaction by doing more work in
> > vect_recog_widen_shift_pattern sounds like the correct thing to do.
> 
> Or give up when seeing already pattern recognized stmts when detecting
> different pattern, unless the current pattern recognizer is prepared to
> handle them (and in that case tweak everything as necessary).
> 
> E.g. several pattern recognizers already start with
>   if (STMT_VINFO_IN_PATTERN_P (stmt_vinfo))
>     return NULL;

Yes, we should do that, and it'll fix the ICE for sure, but -as I said
in the original mail- doing *only* this will cause regressions in some
cases because we no longer get the combined fix-over-widening-*and*-
use-widening-shift effect ...

Bye,
Ulrich

-- 
  Dr. Ulrich Weigand
  GNU Toolchain for Linux on System z and Cell BE
  Ulrich.Weigand@de.ibm.com


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