Changes

[lldb][NFC] Use raw_ostream instead of Stream in Baton::GetDescription
Removing raw_ostream here is getting us closer to removing LLDB's Stream 
class.

[lldb][NFC] Don't calculate member indices in
DWARFASTParserClang::ParseChildMembers
We keep counting members and then don't do anything with the computed
result.

[OpenCL] Fix address space for implicit conversion (PR43145)
Clang was creating a DerivedToBase ImplicitCastExpr that was also 
casting between address spaces as part of the second step in the 
standard conversion sequence.  Defer the address space conversion to the
third step in the sequence instead, such that we get a separate 
ImplicitCastExpr for the address space conversion.
Differential Revision: https://reviews.llvm.org/D70605

[InstCombine] fold copysign with constant sign argument to (fneg+)fabs
If the sign of the sign argument is known (this could be extended to use
ValueTracking), then we can use fneg+fabs to clear/set the sign bit of
the magnitude argument. 
http://llvm.org/docs/LangRef.html#llvm-copysign-intrinsic
This transform is already done in DAGCombiner, but we can do it sooner
in IR as suggested in PR44153: 
https://bugs.llvm.org/show_bug.cgi?id=44153
We have effectively no analysis for copysign in IR, so we are taking the
unusual step of increasing the number of IR instructions for the
negative constant case.
Differential Revision: https://reviews.llvm.org/D70792

[ARM][AArch64] Complex addition Neon intrinsics for Armv8.3-A
Summary: Add support for vcadd_* family of intrinsics. This set of
intrinsics is available in Armv8.3-A.
The fp16 versions require the FP16 extension, which has been available
(opt-in) since Armv8.2-A.
Reviewers: t.p.northover
Reviewed By: t.p.northover
Subscribers: t.p.northover, kristof.beyls, hiraditya, cfe-commits,
llvm-commits
Tags: #clang, #llvm
Differential Revision: https://reviews.llvm.org/D70862