r242171 - in /branches/ARM/sve-branch/gcc: call...

[rsandifo@gcc.gnu.org]

Author: rsandifo
Date: Fri Nov 11 17:12:36 2016
New Revision: 242171

URL: https://gcc.gnu.org/viewcvs?rev=242171&root=gcc&view=rev
Log:
Make more use of df_read_modify_subreg_p

This patch uses df_read_modify_subreg_p to check whether writing
to a subreg would preserve some of the existing contents.

This has the effect of putting more emphasis on the
REGMODE_NATURAL_SIZE-based definition of whether something can be
partially modified, instead of using UNITS_PER_WORD unconditionally.
This becomes important for SVE, where UNITS_PER_WORD has no
significance for subregs of multi-register LD2/ST2, LD3/ST3 and
LD4/ST4 tuples.

Modified:
    branches/ARM/sve-branch/gcc/caller-save.c
    branches/ARM/sve-branch/gcc/combine.c
    branches/ARM/sve-branch/gcc/df-scan.c
    branches/ARM/sve-branch/gcc/df.h
    branches/ARM/sve-branch/gcc/lra-constraints.c
    branches/ARM/sve-branch/gcc/lra.c
    branches/ARM/sve-branch/gcc/rtlanal.c