S390: [Atomics] Remove Atomics code stubs; use TF ops

src/compiler/s390/instruction-selector-s390.cc

Index: src/compiler/s390/instruction-selector-s390.cc
diff --git a/src/compiler/s390/instruction-selector-s390.cc b/src/compiler/s390/instruction-selector-s390.cc
index 8a4af5e65c5caeff7e12e4390401cb7192cc412a..e96b7e76c5bf542bd2483530c0396f5a3b93c45f 100644
--- a/src/compiler/s390/instruction-selector-s390.cc
+++ b/src/compiler/s390/instruction-selector-s390.cc
@@ -1750,6 +1750,30 @@ void InstructionSelector::VisitFloat64InsertHighWord32(Node* node) {
        g.UseRegister(left), g.UseRegister(right));
 }
 
+void InstructionSelector::VisitAtomicLoad(Node* node) {
+  LoadRepresentation load_rep = LoadRepresentationOf(node->op());
+  S390OperandGenerator g(this);
+  Node* base = node->InputAt(0);
+  Node* index = node->InputAt(1);
+  ArchOpcode opcode = kArchNop;
+  switch (load_rep.representation()) {
+    case MachineRepresentation::kWord8:
+      opcode = load_rep.IsSigned() ? kAtomicLoadInt8 : kAtomicLoadUint8;
+      break;
+    case MachineRepresentation::kWord16:
+      opcode = load_rep.IsSigned() ? kAtomicLoadInt16 : kAtomicLoadUint16;
+      break;
+    case MachineRepresentation::kWord32:
+      opcode = kAtomicLoadWord32;
+      break;
+    default:
+      UNREACHABLE();
+      return;
+  }
+  Emit(opcode | AddressingModeField::encode(kMode_MRR),
+       g.DefineAsRegister(node), g.UseRegister(base), g.UseRegister(index));
+}
+
 // static
 MachineOperatorBuilder::Flags
 InstructionSelector::SupportedMachineOperatorFlags() {