[TableGen] In AsmWriterEmitter unique command search, rather than storing a mapping from instruction to unique command, instead store a list of which instructions each unique command corresponds to.

This simplifies the complexity of the code that tries to find further operands to merge into the unique command.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@258656 91177308-0d34-0410-b5e6-96231b3b80d8
1 file changed