--- a/js/src/irregexp/NativeRegExpMacroAssembler.cpp
+++ b/js/src/irregexp/NativeRegExpMacroAssembler.cpp
@@ -117,18 +117,17 @@ NativeRegExpMacroAssembler::GenerateCode
     Label return_temp0;
 
     // Finalize code - write the entry point code now we know how many
     // registers we need.
     masm.bind(&entry_label_);
 
 #ifdef JS_CODEGEN_ARM64
     // ARM64 communicates stack address via sp, but uses a pseudo-sp for addressing.
-    MOZ_ASSERT(!masm.GetStackPointer64().Is(sp));
-    masm.Mov(masm.GetStackPointer64(), sp);
+    masm.initStackPtr();
 #endif
 
     // Push non-volatile registers which might be modified by jitcode.
     size_t pushedNonVolatileRegisters = 0;
     for (GeneralRegisterForwardIterator iter(savedNonVolatileRegisters); iter.more(); ++iter) {
         masm.Push(*iter);
         pushedNonVolatileRegisters++;
     }

--- a/js/src/vm/UnboxedObject.cpp
+++ b/js/src/vm/UnboxedObject.cpp
@@ -100,16 +100,21 @@ UnboxedLayout::makeConstructorCode(JSCon
     newKindReg = ecx;
     masm.loadPtr(Address(masm.getStackPointer(), sizeof(void*)), propertiesReg);
     masm.loadPtr(Address(masm.getStackPointer(), 2 * sizeof(void*)), newKindReg);
 #else
     propertiesReg = IntArgReg0;
     newKindReg = IntArgReg1;
 #endif
 
+#ifdef JS_CODEGEN_ARM64
+    // ARM64 communicates stack address via sp, but uses a pseudo-sp for addressing.
+    masm.initStackPtr();
+#endif
+
     MOZ_ASSERT(propertiesReg.volatile_());
     MOZ_ASSERT(newKindReg.volatile_());
 
     AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
     regs.take(propertiesReg);
     regs.take(newKindReg);
     Register object = regs.takeAny(), scratch1 = regs.takeAny(), scratch2 = regs.takeAny();