[Power9] Implement new altivec instructions: bcd* series
This patch implements the following altivec instructions:
- Decimal Convert From/to National/Zoned/Signed-QWord:
bcdcfn. bcdcfz. bcdctn. bcdctz. bcdcfsq. bcdctsq.
- Decimal Copy-Sign/Set-Sign:
bcdcpsgn. bcdsetsgn.
- Decimal Shift/Unsigned-Shift/Shift-and-Round:
bcds. bcdus. bcdsr.
- Decimal (Unsigned) Truncate:
bcdtrunc. bcdutrunc.
Total 13 instructions
Thanks Amehsan's advice! Thanks Kit's great help!
Reviewers: hal, nemanja, kbarton, tjablin, amehsan
http://reviews.llvm.org/D17838
llvm-svn: 264568