[patch, fortran] [4.6/4.7 Regression] Fix PR 48955

[Paul Richard Thomas]

Dear All,
>
> I have posted a simpler alternative on the PR that uses your
> suggestion that forward and backward dependences need to to be
> recorded to get this right.
>
> I believe that it's OK but have only now had the opportunity to put it
> on to regtest.
>

Following some comments from Thomas, the attached is the version that
I wound up with.  Tell us which one you prefer and Thomas and I will
do the honours.

Bootstrapped and regtested on FC9/x86_64  - OK for trunk and 4.6?

Paul

2011-05-24  Paul Thomas  <pault@gcc.gnu.org>
	    Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/48955
	* trans-expr.c (gfc_trans_assignment_1): GFC_REVERSE_NOT_SET
	changed to GFC_ENABLE_REVERSE.
	* trans-array.c (gfc_init_loopinfo): GFC_CANNOT_REVERSE changed
	to GFC_INHIBIT_REVERSE.
	* gfortran.h : Enum gfc_reverse is now GFC_ENABLE_REVERSE,
	GFC_FORWARD_SET, GFC_REVERSE_SET and GFC_INHIBIT_REVERSE.
	* dependency.c (gfc_dep_resolver): Change names for elements of
	gfc_reverse as necessary. Change the logic so that forward
	dependences are remembered as well as backward ones. When both
	have appeared, force a temporary.

2011-05-24  Thomas Koenig  <tkoenig@gcc.gnu.org>

	PR fortran/48955
	* gfortran.dg/dependency_40.f90 : New test.
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