[RISCV][GISel] Add atomic load/store test. Add additional atomic load/store isel patterns."

Author: topperc

llvm/lib/Target/RISCV/RISCVGISel.td

@@ -177,6 +177,19 @@ def : StPat<store, SH, GPR, i16>;
 def : LdPat<extloadi8, LBU, i16>; // Prefer unsigned due to no c.lb in Zcb.
 def : StPat<truncstorei8, SB, GPR, i16>;
 
+let Predicates = [HasAtomicLdSt] in {
+  def : LdPat<atomic_load_8,  LB, i16>;
+  def : LdPat<atomic_load_16, LH, i16>;
+
+  def : StPat<atomic_store_8,  SB, GPR, i16>;
+  def : StPat<atomic_store_16, SH, GPR, i16>;
+}
+
+let Predicates = [HasAtomicLdSt, IsRV64] in {
+  def : LdPat<atomic_load_32, LW, i32>;
+  def : StPat<atomic_store_32, SW, GPR, i32>;
+}
+
 //===----------------------------------------------------------------------===//
 // RV64 i32 patterns not used by SelectionDAG
 //===----------------------------------------------------------------------===//