[RISCV] Replace AddiPair ComplexPattern with a PatLeaf. NFC (details)
[RISCV] Replace AddiPair ComplexPattern with a PatLeaf. NFC
The ComplexPattern is looking for an immediate in a certain range that has a single use. This can be handled with a PatLeaf since we aren't matching multiple patterns or checking any complicated relationships between nodes.
This shrinks the isel table a little bit since tablegen no longer has to generate patterns with commuted operands. With the PatLeaf, tablegen can see we're matching an immediate which should always be on the right hand side of add.