Uses assembler macro for dart SP setup on arm64.

runtime/vm/stub_code_arm64.cc

 // Copyright (c) 2014, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "vm/globals.h"
 #if defined(TARGET_ARCH_ARM64)
 
 #include "vm/assembler.h"
 #include "vm/code_generator.h"
 #include "vm/compiler.h"
@@ skipping 757 matching lines @@
 
 // Called when invoking Dart code from C++ (VM code).
 // Input parameters:
 //   LR : points to return address.
 //   R0 : entrypoint of the Dart function to call.
 //   R1 : arguments descriptor array.
 //   R2 : arguments array.
 //   R3 : new context containing the current isolate pointer.
 void StubCode::GenerateInvokeDartCodeStub(Assembler* assembler) {
   __ Comment("InvokeDartCodeStub");
-  // Copy the C stack pointer (R31) into the stack pointer we'll actually use
-  // to access the stack.
-  __ mov(SP, CSP);
-  __ EnterFrame(0);
-
   // The new context, saved vm tag, the top exit frame, and the old context.
   const intptr_t kNewContextOffsetFromFp =
       -(1 + kAbiPreservedCpuRegCount + kAbiPreservedFpuRegCount) * kWordSize;
 
+  // Amount of space to reserve with the system stack pointer before setting it
+  // to the stack limit.
+  const intptr_t kRegSaveSpace = Utils::RoundUp(-kNewContextOffsetFromFp, 16);
+
+  // Copy the C stack pointer (R31) into the stack pointer we'll actually use
+  // to access the stack.
+  __ SetupDartSP(kRegSaveSpace);
+  __ EnterFrame(0);
+
   // Save the callee-saved registers.
   for (int i = kAbiFirstPreservedCpuReg; i <= kAbiLastPreservedCpuReg; i++) {
     const Register r = static_cast<Register>(i);
     // We use str instead of the Push macro because we will be pushing the PP
     // register when it is not holding a pool-pointer since we are coming from
     // C++ code.
     __ str(r, Address(SP, -1 * kWordSize, Address::PreIndex));
   }
 
   // Save the bottom 64-bits of callee-saved V registers.
@@ skipping 1166 matching lines @@
   const Register right = R0;
   __ LoadFromOffset(left, SP, 1 * kWordSize, kNoPP);
   __ LoadFromOffset(right, SP, 0 * kWordSize, kNoPP);
   GenerateIdenticalWithNumberCheckStub(assembler, left, right, temp);
   __ ret();
 }
 
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64