[Atomics] Make Atomics.exchange a builtin using TF

src/compiler/arm64/code-generator-arm64.cc

Index: src/compiler/arm64/code-generator-arm64.cc
diff --git a/src/compiler/arm64/code-generator-arm64.cc b/src/compiler/arm64/code-generator-arm64.cc
index 1cdedb0f9e6c6f508efd4c1a6f11d053ac5bd5ad..46b2dbdf469600a01ce54a344f9a3e932d0c7c27 100644
--- a/src/compiler/arm64/code-generator-arm64.cc
+++ b/src/compiler/arm64/code-generator-arm64.cc
@@ -99,6 +99,8 @@ class Arm64OperandConverter final : public InstructionOperandConverter {
 
   Register OutputRegister32() { return ToRegister(instr_->Output()).W(); }
 
+  Register TempRegister32() { return ToRegister(instr_->TempAt(0)).W(); }
+
   Operand InputOperand2_32(size_t index) {
     switch (AddressingModeField::decode(instr_->opcode())) {
       case kMode_None:
@@ -527,6 +529,17 @@ Condition FlagsConditionToCondition(FlagsCondition condition) {
     __ Dmb(InnerShareable, BarrierAll);                               \
   } while (0)
 
+#define ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(load_instr, store_instr)      \
+  do {                                                                 \
+    Label exchange;                                                    \
+    __ bind(&exchange);                                                \
+    __ Add(i.TempRegister(0), i.InputRegister(0), i.InputRegister(1)); \
+    __ load_instr(i.OutputRegister32(), i.TempRegister(0));            \
+    __ store_instr(i.TempRegister32(), i.InputRegister32(2),           \
+                   i.TempRegister(0));                                 \
+    __ cbnz(i.TempRegister32(), &exchange);                            \
+  } while (0)
+
 #define ASSEMBLE_IEEE754_BINOP(name)                                          \
   do {                                                                        \
     FrameScope scope(masm(), StackFrame::MANUAL);                             \
@@ -1631,6 +1644,25 @@ CodeGenerator::CodeGenResult CodeGenerator::AssembleArchInstruction(
              MemOperand(i.InputRegister(0), i.InputRegister(1)));
       __ Dmb(InnerShareable, BarrierAll);
       break;
+    case kAtomicExchangeInt8:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldaxrb, stlxrb);
+      __ Sxtb(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeUint8:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldaxrb, stlxrb);
+      __ Uxtb(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeInt16:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldaxrh, stlxrh);
+      __ Sxth(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeUint16:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldaxrh, stlxrh);
+      __ Uxth(i.OutputRegister(0), i.OutputRegister(0));
+      break;
+    case kAtomicExchangeWord32:
+      ASSEMBLE_ATOMIC_EXCHANGE_INTEGER(ldaxr, stlxr);
+      break;
   }
   return kSuccess;
 }  // NOLINT(readability/fn_size)