[TableGen][DAGISel] Dedup predicates with same code to run. NFCI.
[TableGen][DAGISel] Dedup predicates with same code to run. NFCI.

I locally hit the 255 limit, but a lot of these are redundant: each
predicate coming from a different record was allocated a new number,
even when we already emitted the same code for another predicate.

Instead, re-use numbers and emit the predicate code only once.
This reduces the total text size of *DAGISel.cpp.o by ~1%.


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@246208 91177308-0d34-0410-b5e6-96231b3b80d8

apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,apple/swift-llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,apple/swift-llvm,apple/swift-llvm,GPUOpen-Drivers/llvm,GPUOpen-Drivers/llvm,llvm-mirror/llvm