[Bug middle-end/43251] [4.4 Regression] Erroneous code with -ftree-vectorize

rguenth at gcc dot gnu dot org gcc-bugzilla@gcc.gnu.org
Fri Mar 19 09:56:00 GMT 2010



------- Comment #14 from rguenth at gcc dot gnu dot org  2010-03-19 09:56 -------
(In reply to comment #13)
> Hi!
> 
> I was wondering if this bug is likely to be fixed in the next GCC release; is
> this likely to be the case?

Unlikely.  Backporting the one-line change will cause massive performance
problems elsewhere (with scalar times complex multiplication).  There is
more to be backported.

The question is if the Fortran standard allows C*CX(IX) to be unconditionally
implemented as C * __real CX(IX) + _I * C * __imag CX(IX) or not.

It would be also interesting to know what vectorization makes for a difference
here, as it shouldn't change semantics.  Thus, did anyone analyze why
only the vectorized variant exhibits the problem?


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http://gcc.gnu.org/bugzilla/show_bug.cgi?id=43251



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