[ARM] ARMExpandPseudoInsts: add debug messages
[ARM] ARMExpandPseudoInsts: add debug messages

This pass wasn't printing any messages at all, which I find really inconvenient
while debugging/tracing things. It now dumps the before and after of expanded
instructions. It doesn't do this yet for all instructions, but this is a good
start I guess.

Differential Revision: https://reviews.llvm.org/D62297


git-svn-id: 0ff597fd157e6f4fc38580e8d64ab130330d2411@361604 91177308-0d34-0410-b5e6-96231b3b80d8

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