[mips] Remove custom versions of CCState::AnalyzeReturn() and CCState::AnalyzeCallReturn().

Summary:
The N32/N64 ABI's return f128 values in $f0 and $f2 for hard-float and $v0 and
$a0 for soft-float. The registers used in the soft-float case differ from the
usual $v0, and $v1 specified for return values.

Both cases were previously handled by duplicating the CCState::AnalyzeReturn()
and CCState::AnalyzeCallReturn() functions and modifying them to delegate to
a different assignment function for f128 and further replace the register type
for the hard-float case. There is a simpler way to do both of these.

We now use the common functions and select an initial assignment function based
on whether the original type is f128 or not. We then handle the hard-float case
using CCBitConvertToType<>.

No functional change.

Reviewers: vmedic

Reviewed By: vmedic

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5269

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218036 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Add an SSSE3 run and check mode to the 128-bit v2 tests of the new
vector shuffle lowering. This will be needed for up-coming palignr
tests.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218037 91177308-0d34-0410-b5e6-96231b3b80d8
[x86] Use PALIGNR for v4i32 and v2i64 blends when appropriate.

There is no purpose in using it for single-input shuffles as
pshufd is just as fast and doesn't tie the two operands. This removes
a substantial amount of wrong-domain blend operations in SSSE3 mode. It
also completes the usage of PALIGNR for integer shuffles and addresses
one of the test cases Quentin hit with the new vector shuffle lowering.

There is still the question of whether and when to use this for floating
point shuffles. It is faster than shufps or shufpd but in the integer
domain. I don't yet really have a good heuristic here for when to use
this instruction for floating point vectors.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218038 91177308-0d34-0410-b5e6-96231b3b80d8