ppc64 --track-origins=yes failure because of bad cmov addHRegUse
For Pin_CMov getRegUsage_PPCInstr called addHRegUse for the dst
register with HRmWrite, but since this is a conditional move the
register could be both read and written (read + write = modify).
This matches the dst of Pin_FpCMov and Pin_AvCMov.
In a very rare case, and only with --track-origins=yes, this
could cause bad code generation.
This is slightly amazing, this code is from 2005 and as far as
I know we never seen an issue with --track-origins=yes on power
before. And I have been unable to come up simple reproducer.
https://bugs.kde.org/show_bug.cgi?id=449672