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Re: [Fortran-dev][Patch, Fortran] C_F_Pointer cleanup

From: Tobias Burnus <burnus at net-b dot de>
To: Mikael Morin <mikael dot morin at sfr dot fr>
Cc: gcc patches <gcc-patches at gcc dot gnu dot org>, gfortran <fortran at gcc dot gnu dot org>
Date: Fri, 20 Jul 2012 12:17:03 +0200
Subject: Re: [Fortran-dev][Patch, Fortran] C_F_Pointer cleanup
References: <500261E6.4070000@net-b.de> <50092A41.2020406@sfr.fr>

On 07/20/2012 11:52 AM, Mikael Morin wrote

OK.

Thanks for the review.

I guess the division will be dropped too (the middle-end does the
reverse multiplication implicitly in the pointer arithmetic).
I wonder which one is faster (the casts in the second version are
certainly not nice for the middle-end):

ptr + (offset_in_bytes / elt_size_in_bytes)
VS
(sometype *) (((char *)ptr) + offset_in_bytes)

As we have to support strides which aren't multiples of the element size, we have to use the second form. We currently do so for BT_CLASS but not for BT_TYPE. Actually, half of the remaining failures on the branch seem to be due to the wrong usage of stride- vs. byte-based offsets. For instance in SELECT TYPE .. TYPE IS, where one has a BT_TYPE and which fails.

I think the conversion to byte offsets will be the next step. Afterwards, we should get rid of the offset.

Tobias

Follow-Ups:
- Re: [Fortran-dev][Patch, Fortran] C_F_Pointer cleanup
  - From: Richard Guenther

References:
- [Fortran-dev][Patch, Fortran] C_F_Pointer cleanup
  - From: Tobias Burnus
- Re: [Fortran-dev][Patch, Fortran] C_F_Pointer cleanup
  - From: Mikael Morin

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