Add isExtractSubreg property.

This patch adds a new property: isExtractSubreg and the related target hooks:
TargetIntrInfo::getExtractSubregInputs and
TargetInstrInfo::getExtractSubregLikeInputs to specify that a target specific
instruction is a (kind of) EXTRACT_SUBREG.

The approach is similar to r215394.

<rdar://problem/12702965>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216130 91177308-0d34-0410-b5e6-96231b3b80d8
Fix undefined behavior (left shift of negative value) in SystemZ backend.

This bug is reported by UBSan.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216131 91177308-0d34-0410-b5e6-96231b3b80d8
[ARM] Mark VMOVRRD with the ExtractSubreg property and implement the related
target hook.

This patch teaches the compiler that:
rX, rY = VMOVRRD dZ
is the same as:
rX = EXTRACT_SUBREG dZ, ssub_0
rY = EXTRACT_SUBREG dZ, ssub_1

<rdar://problem/12702965>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216132 91177308-0d34-0410-b5e6-96231b3b80d8
Don't allow MCStreamer::EmitIntValue to output 0-byte integers.
It makes no sense and can hide bugs. In particular, it lead
to left shift by 64 bits, which is an undefined behavior,
properly reported by UBSan.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@216134 91177308-0d34-0410-b5e6-96231b3b80d8