target/9832: ARM: Arithmetic and move could be combined using liveness information

[rearnsha@gcc.gnu.org]

Synopsis: ARM: Arithmetic and move could be combined using liveness information

Responsible-Changed-From-To: unassigned->rearnsha
Responsible-Changed-By: rearnsha
Responsible-Changed-When: Mon Mar  3 14:14:27 2003
Responsible-Changed-Why:
    .
State-Changed-From-To: open->closed
State-Changed-By: rearnsha
State-Changed-When: Mon Mar  3 14:14:27 2003
State-Changed-Why:
    The analysis for the reasons behind this are mistaken.  GCC does get the liveness correct, but combine prevented from doing the combine into a hard register.  The current register allocator fails to spot that the move can be eliminated and thus generates sub-optimal code.  Compiling the same code with -fnew-ra shows that the new register allocator does a much better job in this area and eliminates the redundant move.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=9832