r243052 - /branches/ARM/sve-branch/gcc/tree-ssa...

[rsandifo at gcc dot gnu dot org]

Author: rsandifo
Date: Wed Nov 30 19:07:33 2016
New Revision: 243052

URL: https://gcc.gnu.org/viewcvs?rev=243052&root=gcc&view=rev
Log:
Tweak handling of zero address costs

[Branch only patch -- not intended for trunk in its current state]

If ivopts sees an address that needs no set-up and has a cost of 0, it
will change the cost to 1.  However, if that same address needs set-up,
ivopts will keep the address cost itself as 0 and just use the cost of
the set-up.  This seems to favour the second (non-native) address
slightly more than it should.

This patch makes sure that the address has a consistent cost
and that any set-up is added on top of that.

We should revisit this to see whether it's justifiable as a trunk
patch or whether it doesn't make that much difference.

Modified:
    branches/ARM/sve-branch/gcc/tree-ssa-loop-ivopts.c