content: /*
   * Copyright (C) 2007 The Android Open Source Project
   *
   * Licensed under the Apache License, Version 2.0 (the "License");
   * you may not use this file except in compliance with the License.
   * You may obtain a copy of the License at
   *
   *      http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software
   * distributed under the License is distributed on an "AS IS" BASIS,
   * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
   * See the License for the specific language governing permissions and
   * limitations under the License.
   */
  
  package com.taobao.android.dx.rop.code;
  
  import com.taobao.android.dx.rop.cst.Constant;
  import com.taobao.android.dx.rop.cst.CstInteger;
  import com.taobao.android.dx.rop.type.StdTypeList;
  import com.taobao.android.dx.rop.type.Type;
  import com.taobao.android.dx.rop.type.TypeBearer;
  import com.taobao.android.dx.rop.type.TypeList;
  
  /**
   * Plain instruction, which has no embedded data and which cannot possibly
   * throw an exception.
   */
  public final class PlainInsn
          extends Insn {
      /**
       * Constructs an instance.
       *
       * @param opcode {@code non-null;} the opcode
       * @param position {@code non-null;} source position
       * @param result {@code null-ok;} spec for the result, if any
       * @param sources {@code non-null;} specs for all the sources
       */
      public PlainInsn(Rop opcode, SourcePosition position,
                       RegisterSpec result, RegisterSpecList sources) {
          super(opcode, position, result, sources);
  
          switch (opcode.getBranchingness()) {
              case Rop.BRANCH_SWITCH:
              case Rop.BRANCH_THROW: {
                  throw new IllegalArgumentException("bogus branchingness");
              }
          }
  
          if (result != null && opcode.getBranchingness() != Rop.BRANCH_NONE) {
              // move-result-pseudo is required here
              throw new IllegalArgumentException
                      ("can't mix branchingness with result");
          }
      }
  
      /**
       * Constructs a single-source instance.
       *
       * @param opcode {@code non-null;} the opcode
       * @param position {@code non-null;} source position
       * @param result {@code null-ok;} spec for the result, if any
       * @param source {@code non-null;} spec for the source
       */
      public PlainInsn(Rop opcode, SourcePosition position, RegisterSpec result,
                       RegisterSpec source) {
          this(opcode, position, result, RegisterSpecList.make(source));
      }
  
      /** {@inheritDoc} */
      @Override
      public TypeList getCatches() {
          return StdTypeList.EMPTY;
      }
  
      /** {@inheritDoc} */
      @Override
      public void accept(Visitor visitor) {
          visitor.visitPlainInsn(this);
      }
  
      /** {@inheritDoc} */
      @Override
      public Insn withAddedCatch(Type type) {
          throw new UnsupportedOperationException("unsupported");
      }
  
      /** {@inheritDoc} */
      @Override
      public Insn withRegisterOffset(int delta) {
          return new PlainInsn(getOpcode(), getPosition(),
                               getResult().withOffset(delta),
                               getSources().withOffset(delta));
      }
  
      /** {@inheritDoc} */
      @Override
      public Insn withSourceLiteral() {
          RegisterSpecList sources = getSources();
          int szSources = sources.size();
  
          if (szSources == 0) {
              return this;
          }
  
          TypeBearer lastType = sources.get(szSources - 1).getTypeBearer();
  
          if (!lastType.isConstant()) {
              // Check for reverse subtraction, where first source is constant
              TypeBearer firstType = sources.get(0).getTypeBearer();
              if (szSources == 2 && firstType.isConstant()) {
                  Constant cst = (Constant) firstType;
                  RegisterSpecList newSources = sources.withoutFirst();
                  Rop newRop = Rops.ropFor(getOpcode().getOpcode(), getResult(),
                                               newSources, cst);
                  return new PlainCstInsn(newRop, getPosition(), getResult(),
                                              newSources, cst);
              }
              return this;
          } else {
  
              Constant cst = (Constant) lastType;
  
              RegisterSpecList newSources = sources.withoutLast();
  
              Rop newRop;
              try {
                  // Check for constant subtraction and flip it to be addition
                  int opcode = getOpcode().getOpcode();
                  if (opcode == RegOps.SUB && cst instanceof CstInteger) {
                      opcode = RegOps.ADD;
                      cst = CstInteger.make(-((CstInteger)cst).getValue());
                  }
                  newRop = Rops.ropFor(opcode, getResult(), newSources, cst);
              } catch (IllegalArgumentException ex) {
                  // There's no rop for this case
                  return this;
              }
  
              return new PlainCstInsn(newRop, getPosition(),
                      getResult(), newSources, cst);
          }
      }
  
  
      /** {@inheritDoc} */
      @Override
      public Insn withNewRegisters(RegisterSpec result,
              RegisterSpecList sources) {
  
          return new PlainInsn(getOpcode(), getPosition(),
                               result,
                               sources);
  
      }
  }
  