isl_pw_multi_aff_from_map: detect easy floors directly from constraints
authorSven Verdoolaege <skimo@kotnet.org>
Tue, 11 Sep 2012 13:26:42 +0000 (15:26 +0200)
committerSven Verdoolaege <skimo@kotnet.org>
Tue, 18 Sep 2012 13:08:21 +0000 (15:08 +0200)
commit8f5dcdc677668e8fad8f48f68e7df2ac764842ab
treec0c4542372469f2220a56d6e037897206613bf1e
parent1809464782c47d4db42888e2556e897b41462277
isl_pw_multi_aff_from_map: detect easy floors directly from constraints

If the input map has constraints of the form

{ [i] -> [j] : i - 1 <= 2 j <= i }

then we can easily detect that j can be taken to be equal to floor(i / 2).
Detecting these conditions directly from the constraints saves us
from having to compute a minimum on this dimension
using parametric integer programming.  Not only can such an operation
be fairly costly, it can also lead to needless subdivisions if there
are any other constraints on the dimension to be minimized.

Signed-off-by: Sven Verdoolaege <skimo@kotnet.org>
isl_aff.c
isl_test.c