r242383 - in /trunk/gcc: ChangeLog config/aarch...

[wilco at gcc dot gnu dot org]

Author: wilco
Date: Mon Nov 14 11:51:33 2016
New Revision: 242383

URL: https://gcc.gnu.org/viewcvs?rev=242383&root=gcc&view=rev
Log:
The existing vector costs stop some beneficial vectorization.  This is mostly
due to vector statement cost being set to 3 as well as vector loads having a
higher cost than scalar loads.  This means that even when we vectorize 4x, it
is possible that the cost of a vectorized loop is similar to the scalar
version, and we fail to vectorize.

Using a cost of 3 for a vector operation suggests they are 3 times as
expensive as scalar operations.  Since most vector operations have a 
similar throughput as scalar operations, this is not correct.

Using slightly lower values for these heuristics now allows this loop
and many others to be vectorized.  On a proprietary benchmark the gain
from vectorizing this loop is around 15-30% which shows vectorizing it is
indeed beneficial.

	* config/aarch64/aarch64.c (cortexa57_vector_cost):
	Change vec_stmt_cost, vec_align_load_cost and vec_unalign_load_cost.


Modified:
    trunk/gcc/ChangeLog
    trunk/gcc/config/aarch64/aarch64.c