[llvm] [RISCV] add more generic macrofusions (PR #151140)

[Daniel Henrique Barboza via llvm-commits]

================
@@ -91,3 +91,94 @@ def TuneLDADDFusion
                    CheckIsImmOperand<2>,
                    CheckImmOperand<2, 0>
                  ]>>;
+
+// Fuse add with lw:
+//   add rd, rs1, rs2
+//   lw rd, 0(rd)
----------------
danielhb wrote:

Oh, I believe I forgot add+lh/add+lb because they barely appear in the benchmarks I've run. The bulk of fusions are add+ld and add+lw and LLVM already has add+ld.

I'll add add+lh and add+lb to complete the add + load macrofusion support. Should I add an aggregate add+ld/lw/lh/lb macrofusion like I did with shNadd? 

https://github.com/llvm/llvm-project/pull/151140