[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
Fix DWARFUnitSection::getUnitForOffset().

The current code is only able to return the right unit if the passed offset
is the exact offset of a section. Generalize the search function by comparing
againt the offset of the next unit instead and by switching the search
algorithm to upper_bound.

This way, the unit returned is the first unit with a getNextUnitOffset()
strictly greater than the searched offset, which is exactly what we want.
Note that there is no need for testing the range of the resulting unit as
the offsets of a DWARFUnitSection are in a single contiguous range from
0 inclusive to lastUnit->getNextUnitOffset() exclusive.

Reviewers: dblaikie samsonov

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5262

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218040 91177308-0d34-0410-b5e6-96231b3b80d8
Always emit DW_AT_declaration attribute when the variable isn't a definition.

Summary:
This doesn't show up today as we don't emit decalration only variables. This
will be tested when the followup patches implementing import of forward
declared entities lands in clang.

Reviewers: echristo, dblaikie, aprantl

Subscribers: llvm-commits

Differential Revision: http://reviews.llvm.org/D5382

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@218041 91177308-0d34-0410-b5e6-96231b3b80d8