enabled and mthc1 and dmtc1 are not available (e.g. on MIPS32r1)
This prevents the upper 32-bits of a double precision value from being moved to
the FPU with mtc1 to an odd-numbered FPU register. This is necessary to ensure
that the code generated executes correctly regardless of the current FPU mode.
MIPS32r2 and above continues to use mtc1/mthc1, while MIPS-IV and above continue
to use dmtc1.
Differential Revision: http://reviews.llvm.org/D4465
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@212930 91177308-0d34-0410-b5e6-96231b3b80d8