MachineRegisterInfo used to allow just one regalloc hint per virtual
register. This patch extends this to a vector of regalloc hints, which is
filled in by common code with sorted copy hints. Such hints will make for
more ID copies that can be removed.
NB! This improvement is currently (and hopefully temporarily) *disabled* by
default, except for SystemZ. The only reason for this is the big impact this
has on tests, which has unfortunately proven unmanageable. It was a long
while since all the tests were updated and just waiting for review (which
didn't happen), but now targets have to enable this themselves
instead. Several targets could get a head-start by downloading the tests
updates from the Phabricator review. Thanks to those who helped, and sorry
you now have to do this step yourselves.
This should be an improvement generally for any target!
The target may still create its own hint, in which case this has highest
priority and is stored first in the vector. If it has target-type, it will
not be recomputed, as per the previous behaviour.
The temporary hook enableMultipleCopyHints() will be removed as soon as all
targets return true.
Review: Quentin Colombet, Ulrich Weigand.
https://reviews.llvm.org/D38128
llvm-svn: 319754
The machine scheduler (before register allocation) is enabled by default for
SystemZ.
The SelectionDAG scheduling preference now becomes source order scheduling
(was regpressure).
Review: Ulrich Weigand
https://reviews.llvm.org/D37977
llvm-svn: 315063
This first cut is pretty conservative. The final argument register (R6)
is call-saved, so we would need to make sure that the R6 argument to a
sibling call is the same as the R6 argument to the calling function,
which seems worth keeping as a separate patch.
Saying that integer truncations are free means that we no longer
use the extending instructions LGF and LLGF for spills in int-conv-09.ll
and int-conv-10.ll. Instead we treat the registers as 64 bits wide and
truncate them to 32-bits where necessary. I think it's unlikely we'd
use LGF and LLGF for spills in other situations for the same reason,
so I'm removing the tests rather than replacing them. The associated
code is generic and applies to many more instructions than just
LGF and LLGF, so there is no corresponding code removal.
llvm-svn: 188669
Jonas Paulsson