[turbofan] Add the StackSlot operator to turbofan.

src/compiler/x87/code-generator-x87.cc

Index: src/compiler/x87/code-generator-x87.cc
diff --git a/src/compiler/x87/code-generator-x87.cc b/src/compiler/x87/code-generator-x87.cc
index 0ac411e431ecc002bed904c2b637f6cde2eea909..86859edf0e646a3d9c1d7add1da9a78d9c3bf1da 100644
--- a/src/compiler/x87/code-generator-x87.cc
+++ b/src/compiler/x87/code-generator-x87.cc
@@ -587,6 +587,18 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ bind(ool->exit());
       break;
     }
+    case kArchStackSlot: {
+      FrameOffset offset =
+          frame_access_state()->GetFrameOffset(i.InputInt32(0));
+      Register base;
+      if (offset.from_stack_pointer()) {
+        base = esp;
+      } else {
+        base = ebp;
+      }
+      __ lea(i.OutputRegister(), Operand(base, offset.offset()));
+      break;
+    }
     case kX87Add:
       if (HasImmediateInput(instr, 1)) {
         __ add(i.InputOperand(0), i.InputImmediate(1));