[DAGCombiner] Slice a big load in two loads when the element are next to each
other in memory and the target has paired load and performs post-isel loads
combining.

E.g., this optimization will transform something like this:
 a = load i64* addr
 b = trunc i64 a to i32
 c = lshr i64 a, 32
 d = trunc i64 c to i32

into:
 b = load i32* addr1
 d = load i32* addr2
Where addr1 = addr2 +/- sizeof(i32), if the target supports paired load and
performs post-isel loads combining.

One should overload TargetLowering::hasPairedLoad to provide this information.
The default is false.

<rdar://problem/14477220>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192471 91177308-0d34-0410-b5e6-96231b3b80d8
Revert "Tests: Be less dependent on a specific schedule/regalloc"

This reverts r192454

Apparently FileCheck isn't as smart as I though and does not enforce a
topological order between variable defs+uses.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192472 91177308-0d34-0410-b5e6-96231b3b80d8
[DAGCombiner] Revert load slicing (r192471), until I figure out why it fails on ubuntu.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192474 91177308-0d34-0410-b5e6-96231b3b80d8
[DAGCombiner] Reapply load slicing (192471) with a test that explicitly set sse4.2 support.
This should fix the buildbots.

Original commit message:
[DAGCombiner] Slice a big load in two loads when the element are next to each
other in memory and the target has paired load and performs post-isel loads
combining.

E.g., this optimization will transform something like this:
a = load i64* addr
b = trunc i64 a to i32
c = lshr i64 a, 32
d = trunc i64 c to i32

into:
b = load i32* addr1
d = load i32* addr2
Where addr1 = addr2 +/- sizeof(i32), if the target supports paired load and
performs post-isel loads combining.

One should overload TargetLowering::hasPairedLoad to provide this information.
The default is false.

<rdar://problem/14477220>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192476 91177308-0d34-0410-b5e6-96231b3b80d8
Really fix CHECK-LABEL and CHECK-DAG interaction. This actually just restores the initial implementation that was in r186162 but got lost in some subsequent refactoring. More explicit variable names and comments are present now to hopefully prevent repeat regression, as well as another test.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192477 91177308-0d34-0410-b5e6-96231b3b80d8
Debug Info Testing Case: check for the name of a structure.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192478 91177308-0d34-0410-b5e6-96231b3b80d8
Add warning about CHECK-DAG with variable definition

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192479 91177308-0d34-0410-b5e6-96231b3b80d8
[DAGCombiner] Load slicing test case: attempt to really fix the buildbots (used sse4.2 instead of avx!).

<rdar://problem/14477220>


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@192480 91177308-0d34-0410-b5e6-96231b3b80d8