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

src/arm/code-stubs-arm.cc

 // Copyright 2012 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_ARM
 
 #include "src/base/bits.h"
 #include "src/bootstrapper.h"
 #include "src/code-stubs.h"
 #include "src/codegen.h"
@@ skipping 981 matching lines @@
   FrameScope scope(masm, StackFrame::MANUAL);
   __ EnterExitFrame(save_doubles());
 
   // Store a copy of argc in callee-saved registers for later.
   __ mov(r4, Operand(r0));
 
   // r0, r4: number of arguments including receiver  (C callee-saved)
   // r1: pointer to the first argument (C callee-saved)
   // r5: pointer to builtin function  (C callee-saved)
 
-  // Result returned in r0 or r0+r1 by default.
-
-#if V8_HOST_ARCH_ARM
   int frame_alignment = MacroAssembler::ActivationFrameAlignment();
   int frame_alignment_mask = frame_alignment - 1;
+#if V8_HOST_ARCH_ARM
   if (FLAG_debug_code) {
     if (frame_alignment > kPointerSize) {
       Label alignment_as_expected;
       DCHECK(base::bits::IsPowerOfTwo32(frame_alignment));
       __ tst(sp, Operand(frame_alignment_mask));
       __ b(eq, &alignment_as_expected);
       // Don't use Check here, as it will call Runtime_Abort re-entering here.
       __ stop("Unexpected alignment");
       __ bind(&alignment_as_expected);
     }
   }
 #endif
 
   // Call C built-in.
-  // r0 = argc, r1 = argv
-  __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));
+  int result_stack_size;
+  if (result_size() <= 2) {
+    // r0 = argc, r1 = argv, r2 = isolate
+    __ mov(r2, Operand(ExternalReference::isolate_address(isolate())));
+    result_stack_size = 0;
+  } else {
+    DCHECK_EQ(3, result_size());
+    // Allocate additional space for the result.
+    result_stack_size =
+        ((result_size() * kPointerSize) + frame_alignment_mask) &
+        ~frame_alignment_mask;
+    __ sub(sp, sp, Operand(result_stack_size));
+
+    // r0 = hidden result argument, r1 = argc, r2 = argv, r3 = isolate.
+    __ mov(r3, Operand(ExternalReference::isolate_address(isolate())));
+    __ mov(r2, Operand(r1));
+    __ mov(r1, Operand(r0));
+    __ mov(r0, Operand(sp));
+  }
 
   // To let the GC traverse the return address of the exit frames, we need to
   // know where the return address is. The CEntryStub is unmovable, so
   // we can store the address on the stack to be able to find it again and
   // we never have to restore it, because it will not change.
   // Compute the return address in lr to return to after the jump below. Pc is
   // already at '+ 8' from the current instruction but return is after three
   // instructions so add another 4 to pc to get the return address.
   {
     // Prevent literal pool emission before return address.
     Assembler::BlockConstPoolScope block_const_pool(masm);
     __ add(lr, pc, Operand(4));
-    __ str(lr, MemOperand(sp, 0));
+    __ str(lr, MemOperand(sp, result_stack_size));
     __ Call(r5);
   }
+  if (result_size() > 2) {
+    DCHECK_EQ(3, result_size());
+    // Read result values stored on stack.
+    __ ldr(r2, MemOperand(r0, 2 * kPointerSize));
+    __ ldr(r1, MemOperand(r0, 1 * kPointerSize));
+    __ ldr(r0, MemOperand(r0, 0 * kPointerSize));
+  }
+  // Result returned in r0, r1:r0 or r2:r1:r0 - do not destroy these registers!
 
-  __ VFPEnsureFPSCRState(r2);
+  __ VFPEnsureFPSCRState(r3);
 
   // Check result for exception sentinel.
   Label exception_returned;
   __ CompareRoot(r0, Heap::kExceptionRootIndex);
   __ b(eq, &exception_returned);
 
   // Check that there is no pending exception, otherwise we
   // should have returned the exception sentinel.
   if (FLAG_debug_code) {
     Label okay;
     ExternalReference pending_exception_address(
         Isolate::kPendingExceptionAddress, isolate());
-    __ mov(r2, Operand(pending_exception_address));
-    __ ldr(r2, MemOperand(r2));
-    __ CompareRoot(r2, Heap::kTheHoleValueRootIndex);
+    __ mov(r3, Operand(pending_exception_address));
+    __ ldr(r3, MemOperand(r3));
+    __ CompareRoot(r3, Heap::kTheHoleValueRootIndex);
     // Cannot use check here as it attempts to generate call into runtime.
     __ b(eq, &okay);
     __ stop("Unexpected pending exception");
     __ bind(&okay);
   }
 
   // Exit C frame and return.
   // r0:r1: result
   // sp: stack pointer
   // fp: frame pointer
@@ skipping 4319 matching lines @@
                            MemOperand(fp, 6 * kPointerSize), NULL);
 }
 
 
 #undef __
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM