[turbofan] Reland of `Add alignment parameter to StackSlot operator`

src/compiler/mips64/instruction-selector-mips64.cc

 // 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.
 
 #include "src/base/adapters.h"
 #include "src/base/bits.h"
 #include "src/compiler/instruction-selector-impl.h"
 #include "src/compiler/node-matchers.h"
 #include "src/compiler/node-properties.h"
 
@@ skipping 334 matching lines @@
 static void VisitBinop(InstructionSelector* selector, Node* node,
                        InstructionCode opcode, FlagsContinuation* cont) {
   VisitBinop(selector, node, opcode, false, kArchNop, cont);
 }
 
 static void VisitBinop(InstructionSelector* selector, Node* node,
                        InstructionCode opcode) {
   VisitBinop(selector, node, opcode, false, kArchNop);
 }
 
+void InstructionSelector::VisitStackSlot(Node* node) {
+  StackSlotRepresentation rep = StackSlotRepresentationOf(node->op());
+  int alignment = rep.alignment();
+  int slot = frame_->AllocateSpillSlot(rep.size(), alignment);
+  OperandGenerator g(this);
+
+  Emit(kArchStackSlot, g.DefineAsRegister(node),
+       sequence()->AddImmediate(Constant(slot)),
+       sequence()->AddImmediate(Constant(alignment)), 0, nullptr);
+}
+
 void EmitLoad(InstructionSelector* selector, Node* node, InstructionCode opcode,
               Node* output = nullptr) {
   Mips64OperandGenerator g(selector);
   Node* base = node->InputAt(0);
   Node* index = node->InputAt(1);
 
   if (g.CanBeImmediate(index, opcode)) {
     selector->Emit(opcode | AddressingModeField::encode(kMode_MRI),
                    g.DefineAsRegister(output == nullptr ? node : output),
                    g.UseRegister(base), g.UseImmediate(index));
@@ skipping 2577 matching lines @@
   } else {
     DCHECK(kArchVariant == kMips64r2);
     return MachineOperatorBuilder::AlignmentRequirements::
         NoUnalignedAccessSupport();
   }
 }
 
 }  // namespace compiler
 }  // namespace internal
 }  // namespace v8