[Interpreter] Add ForInPrepare runtime function which returns a ObjectTriple.

src/arm64/code-stubs-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
 #include "src/ic/handler-compiler.h"
@@ skipping 1086 matching lines @@
   // Derive argv from the stack pointer so that it points to the first argument
   // (arg[argc-2]), or just below the receiver in case there are no arguments.
   //  - Adjust for the arg[] array.
   Register temp_argv = x11;
   if (!argv_in_register()) {
     __ Add(temp_argv, jssp, Operand(x0, LSL, kPointerSizeLog2));
     //  - Adjust for the receiver.
     __ Sub(temp_argv, temp_argv, 1 * kPointerSize);
   }
 
-  // Enter the exit frame. Reserve three slots to preserve x21-x23 callee-saved
-  // registers.
+  // Reserve three slots to preserve x21-x23 callee-saved registers. If the
+  // result size is too large to be returned in registers then also reserve
+  // space for the return value.
+  int extra_stack_space = 3 + (result_size() <= 2 ? 0 : result_size());
+  // Enter the exit frame.
   FrameScope scope(masm, StackFrame::MANUAL);
-  __ EnterExitFrame(save_doubles(), x10, 3);
+  __ EnterExitFrame(save_doubles(), x10, extra_stack_space);
   DCHECK(csp.Is(__ StackPointer()));
 
   // Poke callee-saved registers into reserved space.
   __ Poke(argv, 1 * kPointerSize);
   __ Poke(argc, 2 * kPointerSize);
   __ Poke(target, 3 * kPointerSize);
 
+  if (result_size() > 2) {
+    // Save the location of the return value into x8 for call.
+    __ Add(x8, __ StackPointer(), Operand(4 * kPointerSize));
+  }
+
   // We normally only keep tagged values in callee-saved registers, as they
   // could be pushed onto the stack by called stubs and functions, and on the
   // stack they can confuse the GC. However, we're only calling C functions
   // which can push arbitrary data onto the stack anyway, and so the GC won't
   // examine that part of the stack.
   __ Mov(argc, argc_input);
   __ Mov(target, target_input);
   __ Mov(argv, temp_argv);
 
   // x21 : argv
@@ skipping 49 matching lines @@
     __ Ldr(temp, MemOperand(fp, ExitFrameConstants::kSPOffset));
     __ Ldr(temp, MemOperand(temp, -static_cast<int64_t>(kXRegSize)));
     __ Cmp(temp, x12);
     __ Check(eq, kReturnAddressNotFoundInFrame);
   }
 
   // Call the builtin.
   __ Blr(target);
   __ Bind(&return_location);
 
-  //  x0    result      The return code from the call.
+  if (result_size() > 2) {
+    DCHECK_EQ(3, result_size());
+    // Read result values stored on stack.
+    __ Ldr(x0, MemOperand(__ StackPointer(), 4 * kPointerSize));
+    __ Ldr(x1, MemOperand(__ StackPointer(), 5 * kPointerSize));
+    __ Ldr(x2, MemOperand(__ StackPointer(), 6 * kPointerSize));
+  }
+  // Result returned in x0, x1:x0 or x2:x1:x0 - do not destroy these registers!
+
+  //  x0    result0      The return code from the call.
+  //  x1    result1      For calls which return ObjectPair or ObjectTriple.
+  //  x2    result2      For calls which return ObjectTriple.
   //  x21   argv
   //  x22   argc
   //  x23   target
   const Register& result = x0;
 
   // Check result for exception sentinel.
   Label exception_returned;
   __ CompareRoot(result, Heap::kExceptionRootIndex);
   __ B(eq, &exception_returned);
 
@@ skipping 4637 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64