[turbofan] Add alignment parameter to StackSlot operator

src/compiler/frame.h

 // Copyright 2014 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.
 
 #ifndef V8_COMPILER_FRAME_H_
 #define V8_COMPILER_FRAME_H_
 
 #include "src/bit-vector.h"
 #include "src/frames.h"
 
@@ skipping 93 matching lines @@
     if (delta != alignment_slots) {
       frame_slot_count_ += delta;
     }
     spill_slot_count_ += delta;
   }
 
   void AllocateSavedCalleeRegisterSlots(int count) {
     frame_slot_count_ += count;
   }
 
-  int AllocateSpillSlot(int width) {
+  int AllocateSpillSlot(int width, int alignment = 0) {
     int frame_slot_count_before = frame_slot_count_;
-    AllocateAlignedFrameSlots(width);
+    if (alignment <= kPointerSize) {
+      AllocateAlignedFrameSlots(width);
+    } else {
+      // We need to allocate more place for spill slot
+      // in case we need an aligned spill slot to be
+      // able to properly align start of spill slot
+      // and still have enough place to hold all the
+      // data
+      AllocateAlignedFrameSlots(width + alignment - kPointerSize);
+    }
     spill_slot_count_ += frame_slot_count_ - frame_slot_count_before;
     return frame_slot_count_ - 1;
   }
 
   int AlignFrame(int alignment = kDoubleSize);
 
   int ReserveSpillSlots(size_t slot_count) {
     DCHECK_EQ(0, spill_slot_count_);
     spill_slot_count_ += static_cast<int>(slot_count);
     frame_slot_count_ += static_cast<int>(slot_count);
@@ skipping 96 matching lines @@
   const Frame* const frame_;
   bool access_frame_with_fp_;
   int sp_delta_;
   bool has_frame_;
 };
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_COMPILER_FRAME_H_