InstCombine: variations on 0xffffffff - x >= 4

The following transforms are valid if -C is a power of 2:
(icmp ugt (xor X, C), ~C) -> (icmp ult X, C)
(icmp ult (xor X, C), -C) -> (icmp uge X, C)

These are nice, they get rid of the xor.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185915 91177308-0d34-0410-b5e6-96231b3b80d8
InstCombine: Fix typo in comment for visitICmpInstWithInstAndIntCst


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185916 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Use "STC;MVC" for memset

Use "STC;MVC" for memsets that are too big for two STCs or MV...Is yet
small enough for a single MVC.  As with memcpy, I'm leaving longer cases
till later.

The number of tests might seem excessive, but f33 & f34 from memset-04.ll
failed the first cut because I'd not added the "?:" on the calculation
of Size1.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185918 91177308-0d34-0410-b5e6-96231b3b80d8
[SystemZ] Use MVC for simple load/store pairs

Look for patterns of the form (store (load ...), ...) in which the two
locations are known not to partially overlap.  (Identical locations are OK.)
These sequences are better implemented by MVC unless either the load or
the store could use RELATIVE LONG instructions.

The testcase showed that we weren't using LHRL and LGHRL for extload16,
only sextloadi16.  The patch fixes that too.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@185919 91177308-0d34-0410-b5e6-96231b3b80d8