GlobalISel: support overflow arithmetic intrinsics.
Unsigned addition and subtraction can reuse the instructions created to
legalize large width operations (i.e. both produce and consume a carry flag).
Signed operations and multiplies get a dedicated op-with-overflow instruction.
Once this is produced the two values are combined into a struct register (which
will almost always be merged with a corresponding G_EXTRACT as part of
legalization).
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@279278
91177308-0d34-0410-b5e6-
96231b3b80d8
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