add m68k isel support for non-ARI atomic loads/stores

Author: knickish

llvm/lib/Target/M68k/M68kISelDAGToDAG.cpp

@@ -772,6 +772,19 @@ static bool isAddressBase(const SDValue &N) {
   }
 }
 
+static bool AllowARIIWithZeroDisp(SDNode *Parent) {
+  if (!Parent) return false;
+  switch (Parent->getOpcode()) {
+    case ISD::LOAD:
+    case ISD::STORE:
+    case ISD::ATOMIC_LOAD:
+    case ISD::ATOMIC_STORE:
+      return true;
+    default:
+      return false;
+  }
+}
+
 bool M68kDAGToDAGISel::SelectARII(SDNode *Parent, SDValue N, SDValue &Disp,
                                   SDValue &Base, SDValue &Index) {
   M68kISelAddressMode AM(M68kISelAddressMode::AddrType::ARII);
@@ -811,8 +824,7 @@ bool M68kDAGToDAGISel::SelectARII(SDNode *Parent, SDValue N, SDValue &Disp,
   // The idea here is that we want to use AddrType::ARII without displacement
   // only if necessary like memory operations, otherwise this must be lowered
   // into addition
-  if (AM.Disp == 0 && (!Parent || (Parent->getOpcode() != ISD::LOAD &&
-                                   Parent->getOpcode() != ISD::STORE))) {
+  if (AM.Disp == 0 && !AllowARIIWithZeroDisp(Parent)) {
     LLVM_DEBUG(dbgs() << "REJECT: Displacement is Zero\n");
     return false;
   }

llvm/lib/Target/M68k/M68kInstrAtomics.td

@@ -10,9 +10,16 @@ foreach size = [8, 16, 32] in {
   def : Pat<(!cast<SDPatternOperator>("atomic_load_"#size) MxCP_ARI:$ptr),
             (!cast<MxInst>("MOV"#size#"dj") !cast<MxMemOp>("MxARI"#size):$ptr)>;
 
+  def : Pat<(!cast<SDPatternOperator>("atomic_load_"#size) MxCP_ARII:$ptr),
+            (!cast<MxInst>("MOV"#size#"df") !cast<MxMemOp>("MxARII"#size):$ptr)>;
+
   def : Pat<(!cast<SDPatternOperator>("atomic_store_"#size) !cast<MxRegOp>("MxDRD"#size):$val, MxCP_ARI:$ptr),
             (!cast<MxInst>("MOV"#size#"jd") !cast<MxMemOp>("MxARI"#size):$ptr,
                                             !cast<MxRegOp>("MxDRD"#size):$val)>;
+
+  def : Pat<(!cast<SDPatternOperator>("atomic_store_"#size) !cast<MxRegOp>("MxDRD"#size):$val, MxCP_ARII:$ptr),
+            (!cast<MxInst>("MOV"#size#"fd") !cast<MxMemOp>("MxARII"#size):$ptr,
+                                            !cast<MxRegOp>("MxDRD"#size):$val)>;
 }
 
 let Predicates = [AtLeastM68020] in {