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

src/compiler/x87/instruction-selector-x87.cc

Index: src/compiler/x87/instruction-selector-x87.cc
diff --git a/src/compiler/x87/instruction-selector-x87.cc b/src/compiler/x87/instruction-selector-x87.cc
index c11ac287d0d25fb2c5f58d1bfd49d5f553e452db..b5594b8894e658d462a4ae85e629b9e57fe788e3 100644
--- a/src/compiler/x87/instruction-selector-x87.cc
+++ b/src/compiler/x87/instruction-selector-x87.cc
@@ -168,6 +168,14 @@ class X87OperandGenerator final : public OperandGenerator {
   }
 };
 
+void InstructionSelector::VisitStackSlot(Node* node) {
+  StackSlotRepresentation rep = StackSlotRepresentationOf(node->op());
+  int slot = frame_->AllocateSpillSlot(rep.size());
+  OperandGenerator g(this);
+
+  Emit(kArchStackSlot, g.DefineAsRegister(node),
+       sequence()->AddImmediate(Constant(slot)), 0, nullptr);
+}
 
 void InstructionSelector::VisitLoad(Node* node) {
   LoadRepresentation load_rep = LoadRepresentationOf(node->op());