[llvm] [RISCV][GISEL] Add legalizer for G_BSWAP (PR #70226)

[Michael Maitland via llvm-commits]

================
@@ -68,77 +68,32 @@ body:             |
     ; CHECK-NEXT: {{  $}}
     ; CHECK-NEXT: [[COPY:%[0-9]+]]:_(s32) = COPY $x10
     ; CHECK-NEXT: [[COPY1:%[0-9]+]]:_(s32) = COPY $x11
----------------
michaelmaitland wrote:

@topperc does this look okay to you for bswap.i64 on rv32? Is there a way to compare against existing SDAG codegen so I can answer this question myself?

https://github.com/llvm/llvm-project/pull/70226