[turbofan] Add the StackSlot operator to turbofan.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index b52146b4d24a2c08d970a56951df08947d123ff4..0d51913868e7a24de0b88f99526f91e8896c818b 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -499,6 +499,18 @@ 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 kIA32Add:
       if (HasImmediateInput(instr, 1)) {
         __ add(i.InputOperand(0), i.InputImmediate(1));