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Re: [Patch, fortran] PR37614 - Change position of padding for aligned COMMONs
Steve Kargl wrote:
> On Sat, Jan 17, 2009 at 09:47:17AM -0800, Jerry DeLisle wrote:
>
>> Seems we should maintain compatibility with g77 if it matters regarding
>> using g77 compiled libraries or .obj files working properly with gfortran
>> compiled libraries or .obj files.
>>
>> How about this: -fg77-common-align
Actually it goes beyond g77 compatibility - we change also the default
for gfortran. Thus we should have a new option and cannot recycle -ff2c.
While for the most common common blocks there is no problem (same
storage size of the elements), there are surely a couple of programs
which are affected. Having a new libgfortran version (ABI breakage)
actually helps here by forcing a recompilation. The advantage of the new
version is that ISO Fortran conforming programs such as:
common int4
[...]
common int4, int8
will work (with default options). With the current version the "int4" of
the first common and of the second common access different sections of
memory (with default options). Additionally, there is the advantage of
increased compatibility with other compiler's .o files. For the
disadvantage: See above.
Tobias