Refactor and improve inlined double-aligned allocations

src/arm/macro-assembler-arm.cc

Index: src/arm/macro-assembler-arm.cc
diff --git a/src/arm/macro-assembler-arm.cc b/src/arm/macro-assembler-arm.cc
index 33b557e43cdd702d1e364a6564151cd63166b476..77ee36eae0b1d25a55bc930a416889c4c0401728 100644
--- a/src/arm/macro-assembler-arm.cc
+++ b/src/arm/macro-assembler-arm.cc
@@ -1617,6 +1617,18 @@ void MacroAssembler::AllocateInNewSpace(int object_size,
     ldr(ip, MemOperand(topaddr, limit - top));
   }
 
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    // Align the next allocation. Storing the filler map without checking top is
+    // always safe because the limit of the heap is always aligned.
+    ASSERT(kPointerAlignment * 2 == kDoubleAlignment);
+    and_(scratch2, result, Operand(kDoubleAlignmentMask), SetCC);
+    Label aligned;
+    b(eq, &aligned);
+    mov(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    str(scratch2, MemOperand(result, kDoubleSize / 2, PostIndex));
+    bind(&aligned);
+  }
+
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top.
   if (obj_size_operand.is_single_instruction(this)) {
@@ -1702,6 +1714,18 @@ void MacroAssembler::AllocateInNewSpace(Register object_size,
     ldr(ip, MemOperand(topaddr, limit - top));
   }
 
+  if ((flags & DOUBLE_ALIGNMENT) != 0) {
+    // Align the next allocation. Storing the filler map without checking top is
+    // always safe because the limit of the heap is always aligned.
+    ASSERT(kPointerAlignment * 2 == kDoubleAlignment);
+    and_(scratch2, result, Operand(kDoubleAlignmentMask), SetCC);
+    Label aligned;
+    b(eq, &aligned);
+    mov(scratch2, Operand(isolate()->factory()->one_pointer_filler_map()));
+    str(scratch2, MemOperand(result, kDoubleSize / 2, PostIndex));
+    bind(&aligned);
+  }
+
   // Calculate new top and bail out if new space is exhausted. Use result
   // to calculate the new top. Object size may be in words so a shift is
   // required to get the number of bytes.