diff --git a/js/src/jit/MacroAssembler.h b/js/src/jit/MacroAssembler.h
index ec57ddca14ac..e7ce3cca52f9 100644
--- a/js/src/jit/MacroAssembler.h
+++ b/js/src/jit/MacroAssembler.h
@@ -3666,11 +3666,13 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void compareExchange64(const Synchronization& sync, const Address& mem,
                          Register64 expected, Register64 replacement,
-                         Register64 output) DEFINED_ON(arm, arm64, x64, x86);
+                         Register64 output)
+      DEFINED_ON(arm, arm64, x64, x86, mips64);
 
   void compareExchange64(const Synchronization& sync, const BaseIndex& mem,
                          Register64 expected, Register64 replacement,
-                         Register64 output) DEFINED_ON(arm, arm64, x64, x86);
+                         Register64 output)
+      DEFINED_ON(arm, arm64, x64, x86, mips64);
 
   // Exchange with memory.  Return the value initially in memory.
   // MIPS: `valueTemp`, `offsetTemp` and `maskTemp` must be defined for 8-bit
@@ -3700,11 +3702,11 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void atomicExchange64(const Synchronization& sync, const Address& mem,
                         Register64 value, Register64 output)
-      DEFINED_ON(arm, arm64, x64, x86);
+      DEFINED_ON(arm, arm64, x64, x86, mips64);
 
   void atomicExchange64(const Synchronization& sync, const BaseIndex& mem,
                         Register64 value, Register64 output)
-      DEFINED_ON(arm, arm64, x64, x86);
+      DEFINED_ON(arm, arm64, x64, x86, mips64);
 
   // Read-modify-write with memory.  Return the value in memory before the
   // operation.
@@ -3759,7 +3761,7 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void atomicFetchOp64(const Synchronization& sync, AtomicOp op,
                        Register64 value, const Address& mem, Register64 temp,
-                       Register64 output) DEFINED_ON(arm, arm64, x64);
+                       Register64 output) DEFINED_ON(arm, arm64, x64, mips64);
 
   void atomicFetchOp64(const Synchronization& sync, AtomicOp op,
                        const Address& value, const Address& mem,
@@ -3767,7 +3769,7 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void atomicFetchOp64(const Synchronization& sync, AtomicOp op,
                        Register64 value, const BaseIndex& mem, Register64 temp,
-                       Register64 output) DEFINED_ON(arm, arm64, x64);
+                       Register64 output) DEFINED_ON(arm, arm64, x64, mips64);
 
   void atomicFetchOp64(const Synchronization& sync, AtomicOp op,
                        const Address& value, const BaseIndex& mem,
@@ -3785,14 +3787,14 @@ class MacroAssembler : public MacroAssemblerSpecific {
 
   void atomicEffectOp64(const Synchronization& sync, AtomicOp op,
                         Register64 value, const Address& mem, Register64 temp)
-      DEFINED_ON(arm, arm64);
+      DEFINED_ON(arm, arm64, mips64);
 
   void atomicEffectOp64(const Synchronization& sync, AtomicOp op,
                         Register64 value, const BaseIndex& mem) DEFINED_ON(x64);
 
   void atomicEffectOp64(const Synchronization& sync, AtomicOp op,
                         Register64 value, const BaseIndex& mem, Register64 temp)
-      DEFINED_ON(arm, arm64);
+      DEFINED_ON(arm, arm64, mips64);
 
   // 64-bit atomic load. On 64-bit systems, use regular load with
   // Synchronization::Load, not this method.
diff --git a/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp b/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
index 8e48c2c0e389..5c55bf0742f3 100644
--- a/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
+++ b/js/src/jit/mips-shared/CodeGenerator-mips-shared.cpp
@@ -2168,30 +2168,113 @@ void CodeGenerator::visitAtomicExchangeTypedArrayElement(
   }
 }
 
-void CodeGenerator::visitAtomicLoad64(LAtomicLoad64* lir) { MOZ_CRASH("NYI"); }
-
-void CodeGenerator::visitAtomicStore64(LAtomicStore64* lir) {
-  MOZ_CRASH("NYI");
-}
-
 void CodeGenerator::visitCompareExchangeTypedArrayElement64(
     LCompareExchangeTypedArrayElement64* lir) {
-  MOZ_CRASH("NYI");
+  Register elements = ToRegister(lir->elements());
+  Register oldval = ToRegister(lir->oldval());
+  Register newval = ToRegister(lir->newval());
+  Register64 temp1 = ToRegister64(lir->temp1());
+  Register64 temp2 = ToRegister64(lir->temp2());
+  Register out = ToRegister(lir->output());
+  Register64 tempOut(out);
+
+  Scalar::Type arrayType = lir->mir()->arrayType();
+
+  masm.loadBigInt64(oldval, temp1);
+  masm.loadBigInt64(newval, tempOut);
+
+  if (lir->index()->isConstant()) {
+    Address dest = ToAddress(elements, lir->index(), arrayType);
+    masm.compareExchange64(Synchronization::Full(), dest, temp1, tempOut,
+                           temp2);
+  } else {
+    BaseIndex dest(elements, ToRegister(lir->index()),
+                   ScaleFromScalarType(arrayType));
+    masm.compareExchange64(Synchronization::Full(), dest, temp1, tempOut,
+                           temp2);
+  }
+
+  emitCreateBigInt(lir, arrayType, temp2, out, temp1.scratchReg());
 }
 
 void CodeGenerator::visitAtomicExchangeTypedArrayElement64(
     LAtomicExchangeTypedArrayElement64* lir) {
-  MOZ_CRASH("NYI");
+  Register elements = ToRegister(lir->elements());
+  Register value = ToRegister(lir->value());
+  Register64 temp1 = ToRegister64(lir->temp1());
+  Register64 temp2 = Register64(ToRegister(lir->temp2()));
+  Register out = ToRegister(lir->output());
+
+  Scalar::Type arrayType = lir->mir()->arrayType();
+
+  masm.loadBigInt64(value, temp1);
+
+  if (lir->index()->isConstant()) {
+    Address dest = ToAddress(elements, lir->index(), arrayType);
+    masm.atomicExchange64(Synchronization::Full(), dest, temp1, temp2);
+  } else {
+    BaseIndex dest(elements, ToRegister(lir->index()),
+                   ScaleFromScalarType(arrayType));
+    masm.atomicExchange64(Synchronization::Full(), dest, temp1, temp2);
+  }
+
+  emitCreateBigInt(lir, arrayType, temp2, out, temp1.scratchReg());
 }
 
 void CodeGenerator::visitAtomicTypedArrayElementBinop64(
     LAtomicTypedArrayElementBinop64* lir) {
-  MOZ_CRASH("NYI");
+  MOZ_ASSERT(lir->mir()->hasUses());
+
+  Register elements = ToRegister(lir->elements());
+  Register value = ToRegister(lir->value());
+  Register64 temp1 = ToRegister64(lir->temp1());
+  Register64 temp2 = ToRegister64(lir->temp2());
+  Register out = ToRegister(lir->output());
+  Register64 tempOut = Register64(out);
+
+  Scalar::Type arrayType = lir->mir()->arrayType();
+  AtomicOp atomicOp = lir->mir()->operation();
+
+  masm.loadBigInt64(value, temp1);
+
+  if (lir->index()->isConstant()) {
+    Address dest = ToAddress(elements, lir->index(), arrayType);
+    masm.atomicFetchOp64(Synchronization::Full(), atomicOp, temp1, dest,
+                         tempOut, temp2);
+  } else {
+    BaseIndex dest(elements, ToRegister(lir->index()),
+                   ScaleFromScalarType(arrayType));
+    masm.atomicFetchOp64(Synchronization::Full(), atomicOp, temp1, dest,
+                         tempOut, temp2);
+  }
+
+  emitCreateBigInt(lir, arrayType, temp2, out, temp1.scratchReg());
 }
 
 void CodeGenerator::visitAtomicTypedArrayElementBinopForEffect64(
     LAtomicTypedArrayElementBinopForEffect64* lir) {
-  MOZ_CRASH("NYI");
+  MOZ_ASSERT(!lir->mir()->hasUses());
+
+  Register elements = ToRegister(lir->elements());
+  Register value = ToRegister(lir->value());
+  Register64 temp1 = ToRegister64(lir->temp1());
+  Register64 temp2 = ToRegister64(lir->temp2());
+
+  Scalar::Type arrayType = lir->mir()->arrayType();
+  AtomicOp atomicOp = lir->mir()->operation();
+
+  masm.loadBigInt64(value, temp1);
+
+  if (lir->index()->isConstant()) {
+    Address dest = ToAddress(elements, lir->index(), arrayType);
+    masm.atomicEffectOp64(Synchronization::Full(), atomicOp, temp1, dest,
+                          temp2);
+  } else {
+    BaseIndex dest(elements, ToRegister(lir->index()),
+                   ScaleFromScalarType(arrayType));
+    masm.atomicEffectOp64(Synchronization::Full(), atomicOp, temp1, dest,
+                          temp2);
+  }
 }
 
 void CodeGenerator::visitWasmCompareExchangeI64(LWasmCompareExchangeI64* lir) {
diff --git a/js/src/jit/mips-shared/Lowering-mips-shared.cpp b/js/src/jit/mips-shared/Lowering-mips-shared.cpp
index 9d11b4349b16..e9ce0a4b0f77 100644
--- a/js/src/jit/mips-shared/Lowering-mips-shared.cpp
+++ b/js/src/jit/mips-shared/Lowering-mips-shared.cpp
@@ -602,16 +602,23 @@ void LIRGenerator::visitCompareExchangeTypedArrayElement(
   const LAllocation index =
       useRegisterOrIndexConstant(ins->index(), ins->arrayType());
 
+  const LAllocation newval = useRegister(ins->newval());
+  const LAllocation oldval = useRegister(ins->oldval());
+
   if (Scalar::isBigIntType(ins->arrayType())) {
-    MOZ_CRASH("NYI");
+    LInt64Definition temp1 = tempInt64();
+    LInt64Definition temp2 = tempInt64();
+
+    auto* lir = new (alloc()) LCompareExchangeTypedArrayElement64(
+        elements, index, oldval, newval, temp1, temp2);
+    define(lir, ins);
+    assignSafepoint(lir, ins);
+    return;
   }
 
   // If the target is a floating register then we need a temp at the
   // CodeGenerator level for creating the result.
 
-  const LAllocation newval = useRegister(ins->newval());
-  const LAllocation oldval = useRegister(ins->oldval());
-
   LDefinition outTemp = LDefinition::BogusTemp();
   LDefinition valueTemp = LDefinition::BogusTemp();
   LDefinition offsetTemp = LDefinition::BogusTemp();
@@ -637,8 +644,6 @@ void LIRGenerator::visitCompareExchangeTypedArrayElement(
 
 void LIRGenerator::visitAtomicExchangeTypedArrayElement(
     MAtomicExchangeTypedArrayElement* ins) {
-  MOZ_ASSERT(ins->arrayType() <= Scalar::Uint32);
-
   MOZ_ASSERT(ins->elements()->type() == MIRType::Elements);
   MOZ_ASSERT(ins->index()->type() == MIRType::IntPtr);
 
@@ -646,14 +651,24 @@ void LIRGenerator::visitAtomicExchangeTypedArrayElement(
   const LAllocation index =
       useRegisterOrIndexConstant(ins->index(), ins->arrayType());
 
+  const LAllocation value = useRegister(ins->value());
+
   if (Scalar::isBigIntType(ins->arrayType())) {
-    MOZ_CRASH("NYI");
+    LInt64Definition temp1 = tempInt64();
+    LDefinition temp2 = temp();
+
+    auto* lir = new (alloc()) LAtomicExchangeTypedArrayElement64(
+        elements, index, value, temp1, temp2);
+    define(lir, ins);
+    assignSafepoint(lir, ins);
+    return;
   }
 
   // If the target is a floating register then we need a temp at the
   // CodeGenerator level for creating the result.
 
-  const LAllocation value = useRegister(ins->value());
+  MOZ_ASSERT(ins->arrayType() <= Scalar::Uint32);
+
   LDefinition outTemp = LDefinition::BogusTemp();
   LDefinition valueTemp = LDefinition::BogusTemp();
   LDefinition offsetTemp = LDefinition::BogusTemp();
@@ -677,14 +692,6 @@ void LIRGenerator::visitAtomicExchangeTypedArrayElement(
   define(lir, ins);
 }
 
-void LIRGeneratorMIPSShared::lowerAtomicLoad64(MLoadUnboxedScalar* ins) {
-  MOZ_CRASH("NYI");
-}
-
-void LIRGeneratorMIPSShared::lowerAtomicStore64(MStoreUnboxedScalar* ins) {
-  MOZ_CRASH("NYI");
-}
-
 void LIRGenerator::visitWasmCompareExchangeHeap(MWasmCompareExchangeHeap* ins) {
   MOZ_ASSERT(ins->base()->type() == MIRType::Int32);
 
@@ -794,7 +801,27 @@ void LIRGenerator::visitAtomicTypedArrayElementBinop(
   const LAllocation value = useRegister(ins->value());
 
   if (Scalar::isBigIntType(ins->arrayType())) {
-    MOZ_CRASH("NYI");
+    LInt64Definition temp1 = tempInt64();
+    LInt64Definition temp2 = tempInt64();
+
+    // Case 1: the result of the operation is not used.
+    //
+    // We can omit allocating the result BigInt.
+
+    if (ins->isForEffect()) {
+      auto* lir = new (alloc()) LAtomicTypedArrayElementBinopForEffect64(
+          elements, index, value, temp1, temp2);
+      add(lir, ins);
+      return;
+    }
+
+    // Case 2: the result of the operation is used.
+
+    auto* lir = new (alloc())
+        LAtomicTypedArrayElementBinop64(elements, index, value, temp1, temp2);
+    define(lir, ins);
+    assignSafepoint(lir, ins);
+    return;
   }
 
   LDefinition valueTemp = LDefinition::BogusTemp();
diff --git a/js/src/jit/mips-shared/Lowering-mips-shared.h b/js/src/jit/mips-shared/Lowering-mips-shared.h
index f99aaa95dd33..ba6dde774fa1 100644
--- a/js/src/jit/mips-shared/Lowering-mips-shared.h
+++ b/js/src/jit/mips-shared/Lowering-mips-shared.h
@@ -69,9 +69,6 @@ class LIRGeneratorMIPSShared : public LIRGeneratorShared {
   void lowerBigIntLsh(MBigIntLsh* ins);
   void lowerBigIntRsh(MBigIntRsh* ins);
 
-  void lowerAtomicLoad64(MLoadUnboxedScalar* ins);
-  void lowerAtomicStore64(MStoreUnboxedScalar* ins);
-
   LTableSwitch* newLTableSwitch(const LAllocation& in,
                                 const LDefinition& inputCopy,
                                 MTableSwitch* ins);
diff --git a/js/src/jit/mips64/CodeGenerator-mips64.cpp b/js/src/jit/mips64/CodeGenerator-mips64.cpp
index ff09b39598a5..6b53e2bd27c0 100644
--- a/js/src/jit/mips64/CodeGenerator-mips64.cpp
+++ b/js/src/jit/mips64/CodeGenerator-mips64.cpp
@@ -514,3 +514,48 @@ void CodeGenerator::visitTestI64AndBranch(LTestI64AndBranch* lir) {
 
   emitBranch(input.reg, Imm32(0), Assembler::NonZero, ifTrue, ifFalse);
 }
+
+void CodeGenerator::visitAtomicLoad64(LAtomicLoad64* lir) {
+  Register elements = ToRegister(lir->elements());
+  Register temp = ToRegister(lir->temp());
+  Register64 temp64 = ToRegister64(lir->temp64());
+  Register out = ToRegister(lir->output());
+  const MLoadUnboxedScalar* mir = lir->mir();
+
+  Scalar::Type storageType = mir->storageType();
+
+  auto sync = Synchronization::Load();
+  masm.memoryBarrierBefore(sync);
+  if (lir->index()->isConstant()) {
+    Address source =
+        ToAddress(elements, lir->index(), storageType, mir->offsetAdjustment());
+    masm.load64(source, temp64);
+  } else {
+    BaseIndex source(elements, ToRegister(lir->index()),
+                     ScaleFromScalarType(storageType), mir->offsetAdjustment());
+    masm.load64(source, temp64);
+  }
+  masm.memoryBarrierAfter(sync);
+  emitCreateBigInt(lir, storageType, temp64, out, temp);
+}
+
+void CodeGenerator::visitAtomicStore64(LAtomicStore64* lir) {
+  Register elements = ToRegister(lir->elements());
+  Register value = ToRegister(lir->value());
+  Register64 temp1 = ToRegister64(lir->temp1());
+
+  Scalar::Type writeType = lir->mir()->writeType();
+
+  masm.loadBigInt64(value, temp1);
+  auto sync = Synchronization::Store();
+  masm.memoryBarrierBefore(sync);
+  if (lir->index()->isConstant()) {
+    Address dest = ToAddress(elements, lir->index(), writeType);
+    masm.store64(temp1, dest);
+  } else {
+    BaseIndex dest(elements, ToRegister(lir->index()),
+                   ScaleFromScalarType(writeType));
+    masm.store64(temp1, dest);
+  }
+  masm.memoryBarrierAfter(sync);
+}
diff --git a/js/src/jit/mips64/Lowering-mips64.cpp b/js/src/jit/mips64/Lowering-mips64.cpp
index 3c557e8ad1df..e9cda9299c40 100644
--- a/js/src/jit/mips64/Lowering-mips64.cpp
+++ b/js/src/jit/mips64/Lowering-mips64.cpp
@@ -88,6 +88,25 @@ void LIRGeneratorMIPS64::lowerBigIntMod(MBigIntMod* ins) {
   assignSafepoint(lir, ins);
 }
 
+void LIRGeneratorMIPS64::lowerAtomicLoad64(MLoadUnboxedScalar* ins) {
+  const LUse elements = useRegister(ins->elements());
+  const LAllocation index =
+      useRegisterOrIndexConstant(ins->index(), ins->storageType());
+
+  auto* lir = new (alloc()) LAtomicLoad64(elements, index, temp(), tempInt64());
+  define(lir, ins);
+  assignSafepoint(lir, ins);
+}
+
+void LIRGeneratorMIPS64::lowerAtomicStore64(MStoreUnboxedScalar* ins) {
+  LUse elements = useRegister(ins->elements());
+  LAllocation index =
+      useRegisterOrIndexConstant(ins->index(), ins->writeType());
+  LAllocation value = useRegister(ins->value());
+
+  add(new (alloc()) LAtomicStore64(elements, index, value, tempInt64()), ins);
+}
+
 void LIRGenerator::visitBox(MBox* box) {
   MDefinition* opd = box->getOperand(0);
 
diff --git a/js/src/jit/mips64/Lowering-mips64.h b/js/src/jit/mips64/Lowering-mips64.h
index 67a444f5e253..b8543de6d2d5 100644
--- a/js/src/jit/mips64/Lowering-mips64.h
+++ b/js/src/jit/mips64/Lowering-mips64.h
@@ -43,6 +43,9 @@ class LIRGeneratorMIPS64 : public LIRGeneratorMIPSShared {
 
   void lowerBigIntDiv(MBigIntDiv* ins);
   void lowerBigIntMod(MBigIntMod* ins);
+
+  void lowerAtomicLoad64(MLoadUnboxedScalar* ins);
+  void lowerAtomicStore64(MStoreUnboxedScalar* ins);
 };
 
 typedef LIRGeneratorMIPS64 LIRGeneratorSpecific;
diff --git a/js/src/jit/mips64/MacroAssembler-mips64.cpp b/js/src/jit/mips64/MacroAssembler-mips64.cpp
index 92a55afa79a4..2102b06bb03d 100644
--- a/js/src/jit/mips64/MacroAssembler-mips64.cpp
+++ b/js/src/jit/mips64/MacroAssembler-mips64.cpp
@@ -2561,20 +2561,24 @@ void MacroAssemblerMIPS64Compat::wasmStoreI64Impl(
 }
 
 template <typename T>
-static void WasmCompareExchange64(MacroAssembler& masm,
-                                  const wasm::MemoryAccessDesc& access,
-                                  const T& mem, Register64 expect,
-                                  Register64 replace, Register64 output) {
+static void CompareExchange64(MacroAssembler& masm,
+                              const wasm::MemoryAccessDesc* access,
+                              const Synchronization& sync, const T& mem,
+                              Register64 expect, Register64 replace,
+                              Register64 output) {
+  MOZ_ASSERT(oldval != output && newval != output);
   masm.computeEffectiveAddress(mem, SecondScratchReg);
 
   Label tryAgain;
   Label exit;
 
-  masm.memoryBarrierBefore(access.sync());
+  masm.memoryBarrierBefore(sync);
 
   masm.bind(&tryAgain);
 
-  masm.append(access, masm.size());
+  if (access) {
+    masm.append(*access, masm.size());
+  }
   masm.as_lld(output.reg, SecondScratchReg, 0);
 
   masm.ma_b(output.reg, expect.reg, &exit, Assembler::NotEqual, ShortJump);
@@ -2583,7 +2587,7 @@ static void WasmCompareExchange64(MacroAssembler& masm,
   masm.ma_b(ScratchRegister, ScratchRegister, &tryAgain, Assembler::Zero,
             ShortJump);
 
-  masm.memoryBarrierAfter(access.sync());
+  masm.memoryBarrierAfter(sync);
 
   masm.bind(&exit);
 }
@@ -2593,7 +2597,8 @@ void MacroAssembler::wasmCompareExchange64(const wasm::MemoryAccessDesc& access,
                                            Register64 expect,
                                            Register64 replace,
                                            Register64 output) {
-  WasmCompareExchange64(*this, access, mem, expect, replace, output);
+  CompareExchange64(*this, &access, access.sync(), mem, expect, replace,
+                    output);
 }
 
 void MacroAssembler::wasmCompareExchange64(const wasm::MemoryAccessDesc& access,
@@ -2601,58 +2606,100 @@ void MacroAssembler::wasmCompareExchange64(const wasm::MemoryAccessDesc& access,
                                            Register64 expect,
                                            Register64 replace,
                                            Register64 output) {
-  WasmCompareExchange64(*this, access, mem, expect, replace, output);
+  CompareExchange64(*this, &access, access.sync(), mem, expect, replace,
+                    output);
+}
+
+void MacroAssembler::compareExchange64(const Synchronization& sync,
+                                       const Address& mem, Register64 expect,
+                                       Register64 replace, Register64 output) {
+  CompareExchange64(*this, nullptr, sync, mem, expect, replace, output);
+}
+
+void MacroAssembler::compareExchange64(const Synchronization& sync,
+                                       const BaseIndex& mem, Register64 expect,
+                                       Register64 replace, Register64 output) {
+  CompareExchange64(*this, nullptr, sync, mem, expect, replace, output);
 }
 
 template <typename T>
 static void AtomicExchange64(MacroAssembler& masm,
-                             const wasm::MemoryAccessDesc& access, const T& mem,
-                             Register64 src, Register64 output) {
+                             const wasm::MemoryAccessDesc* access,
+                             const Synchronization& sync, const T& mem,
+                             Register64 value, Register64 output) {
+  MOZ_ASSERT(value != output);
   masm.computeEffectiveAddress(mem, SecondScratchReg);
 
   Label tryAgain;
 
-  masm.memoryBarrierBefore(access.sync());
+  masm.memoryBarrierBefore(sync);
 
   masm.bind(&tryAgain);
 
-  masm.append(access, masm.size());
-  masm.as_lld(output.reg, SecondScratchReg, 0);
+  if (access) {
+    masm.append(*access, masm.size());
+  }
 
-  masm.movePtr(src.reg, ScratchRegister);
+  masm.as_lld(output.reg, SecondScratchReg, 0);
+  masm.movePtr(value.reg, ScratchRegister);
   masm.as_scd(ScratchRegister, SecondScratchReg, 0);
   masm.ma_b(ScratchRegister, ScratchRegister, &tryAgain, Assembler::Zero,
             ShortJump);
 
-  masm.memoryBarrierAfter(access.sync());
+  masm.memoryBarrierAfter(sync);
+}
+
+template <typename T>
+static void WasmAtomicExchange64(MacroAssembler& masm,
+                                 const wasm::MemoryAccessDesc& access,
+                                 const T& mem, Register64 value,
+                                 Register64 output) {
+  AtomicExchange64(masm, &access, access.sync(), mem, value, output);
 }
 
 void MacroAssembler::wasmAtomicExchange64(const wasm::MemoryAccessDesc& access,
                                           const Address& mem, Register64 src,
                                           Register64 output) {
-  AtomicExchange64(*this, access, mem, src, output);
+  WasmAtomicExchange64(*this, access, mem, src, output);
 }
 
 void MacroAssembler::wasmAtomicExchange64(const wasm::MemoryAccessDesc& access,
                                           const BaseIndex& mem, Register64 src,
                                           Register64 output) {
-  AtomicExchange64(*this, access, mem, src, output);
+  WasmAtomicExchange64(*this, access, mem, src, output);
+}
+
+void MacroAssembler::atomicExchange64(const Synchronization& sync,
+                                      const Address& mem, Register64 value,
+                                      Register64 output) {
+  AtomicExchange64(*this, nullptr, sync, mem, value, output);
+}
+
+void MacroAssembler::atomicExchange64(const Synchronization& sync,
+                                      const BaseIndex& mem, Register64 value,
+                                      Register64 output) {
+  AtomicExchange64(*this, nullptr, sync, mem, value, output);
 }
 
 template <typename T>
 static void AtomicFetchOp64(MacroAssembler& masm,
-                            const wasm::MemoryAccessDesc& access, AtomicOp op,
+                            const wasm::MemoryAccessDesc* access,
+                            const Synchronization& sync, AtomicOp op,
                             Register64 value, const T& mem, Register64 temp,
                             Register64 output) {
+  MOZ_ASSERT(value != output);
+  MOZ_ASSERT(value != temp);
   masm.computeEffectiveAddress(mem, SecondScratchReg);
 
   Label tryAgain;
 
-  masm.memoryBarrierBefore(access.sync());
+  masm.memoryBarrierBefore(sync);
 
   masm.bind(&tryAgain);
+  if (access) {
+    masm.append(*access, masm.size());
+  }
 
-  masm.append(access, masm.size());
   masm.as_lld(output.reg, SecondScratchReg, 0);
 
   switch (op) {
@@ -2678,21 +2725,45 @@ static void AtomicFetchOp64(MacroAssembler& masm,
   masm.as_scd(temp.reg, SecondScratchReg, 0);
   masm.ma_b(temp.reg, temp.reg, &tryAgain, Assembler::Zero, ShortJump);
 
-  masm.memoryBarrierAfter(access.sync());
+  masm.memoryBarrierAfter(sync);
 }
 
 void MacroAssembler::wasmAtomicFetchOp64(const wasm::MemoryAccessDesc& access,
                                          AtomicOp op, Register64 value,
                                          const Address& mem, Register64 temp,
                                          Register64 output) {
-  AtomicFetchOp64(*this, access, op, value, mem, temp, output);
+  AtomicFetchOp64(*this, &access, access.sync(), op, value, mem, temp, output);
 }
 
 void MacroAssembler::wasmAtomicFetchOp64(const wasm::MemoryAccessDesc& access,
                                          AtomicOp op, Register64 value,
                                          const BaseIndex& mem, Register64 temp,
                                          Register64 output) {
-  AtomicFetchOp64(*this, access, op, value, mem, temp, output);
+  AtomicFetchOp64(*this, &access, access.sync(), op, value, mem, temp, output);
+}
+
+void MacroAssembler::atomicFetchOp64(const Synchronization& sync, AtomicOp op,
+                                     Register64 value, const Address& mem,
+                                     Register64 temp, Register64 output) {
+  AtomicFetchOp64(*this, nullptr, sync, op, value, mem, temp, output);
+}
+
+void MacroAssembler::atomicFetchOp64(const Synchronization& sync, AtomicOp op,
+                                     Register64 value, const BaseIndex& mem,
+                                     Register64 temp, Register64 output) {
+  AtomicFetchOp64(*this, nullptr, sync, op, value, mem, temp, output);
+}
+
+void MacroAssembler::atomicEffectOp64(const Synchronization& sync, AtomicOp op,
+                                      Register64 value, const Address& mem,
+                                      Register64 temp) {
+  AtomicFetchOp64(*this, nullptr, sync, op, value, mem, temp, temp);
+}
+
+void MacroAssembler::atomicEffectOp64(const Synchronization& sync, AtomicOp op,
+                                      Register64 value, const BaseIndex& mem,
+                                      Register64 temp) {
+  AtomicFetchOp64(*this, nullptr, sync, op, value, mem, temp, temp);
 }
 
 // ========================================================================