| // Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file |
| // for details. All rights reserved. Use of this source code is governed by a |
| // BSD-style license that can be found in the LICENSE file. |
| package com.android.tools.r8.ir.code; |
| |
| /** |
| * Instruction representing the SSA value for an uninitialized local. |
| * |
| * This instruction allows the local information to not necessarily be properly block structured. |
| * For example, Javac will emit local-end labels in blocks that are not dominated by the |
| * introduction of the same local, causing our SSA graph to attempt to reference a local value that |
| * does not exist in all predecessors (eg, for a local declared in an unscoped switch-case). |
| * By emitting this "uninitialized" value in the method prelude, such a reference will instead |
| * become a phi of the uninitialized value and the local. |
| * |
| * This instruction may (and almost always will) be considered dead code and removed. |
| */ |
| public class DebugLocalUninitialized extends ConstNumber { |
| |
| public DebugLocalUninitialized(Value value) { |
| super(value, 0); |
| } |
| |
| @Override |
| public <T> T accept(InstructionVisitor<T> visitor) { |
| return visitor.visit(this); |
| } |
| |
| @Override |
| public boolean isDebugLocalUninitialized() { |
| return true; |
| } |
| |
| @Override |
| public DebugLocalUninitialized asDebugLocalUninitialized() { |
| return this; |
| } |
| |
| @Override |
| public boolean isAllowedAfterThrowingInstruction() { |
| return true; |
| } |
| } |