r242095 - /branches/ARM/sve-branch/gcc/cprop.c

[rsandifo@gcc.gnu.org]

Author: rsandifo
Date: Fri Nov 11 16:58:31 2016
New Revision: 242095

URL: https://gcc.gnu.org/viewcvs?rev=242095&root=gcc&view=rev
Log:
Use df_read_modify_subreg_p in cprop.c

local_cprop_find_used_regs punted on all multiword registers,
with the comment:

      /* Setting a subreg of a register larger than word_mode leaves
         the non-written words unchanged.  */

But this only applies if the outer mode is smaller than the
inner mode.  If they're the same size then writes to the subreg
are a normal full update.

This patch uses df_read_modify_subreg_p instead.  A later patch
adds more uses of the same routine, but this part had a (positive)
effect on code generation for the testsuite whereas the others
seemed to be simple clean-ups.

Modified:
    branches/ARM/sve-branch/gcc/cprop.c