There is no need to track dependencies for constant physregs, as they
don't change their value no matter in what order you read/write to them.
Differential Revision: https://reviews.llvm.org/D26221
llvm-svn: 286526
When copying to/from a constant register interferences can be ignored.
Also update the documentation for isConstantPhysReg() to make it more
obvious that this transformation is valid.
Differential Revision: https://reviews.llvm.org/D26106
llvm-svn: 286503
Go through implicit defs of CSMI and MI, and clear the kill flags on
their uses in all the instructions between CSMI and MI.
We might have made some of the kill flags redundant, consider:
subs ... %NZCV<imp-def> <- CSMI
csinc ... %NZCV<imp-use,kill> <- this kill flag isn't valid anymore
subs ... %NZCV<imp-def> <- MI, to be eliminated
csinc ... %NZCV<imp-use,kill>
Since we eliminated MI, and reused a register imp-def'd by CSMI
(here %NZCV), that register, if it was killed before MI, should have
that kill flag removed, because it's lifetime was extended.
Also, add an exhaustive testcase for the motivating example.
Reviewed by: Juergen Ributzka <juergen@apple.com>
llvm-svn: 223133
Matthias Braun