/*
 * Copyright 2009 Google Inc.
 *
 * 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.google.gwt.dev.jjs.impl.gflow;

import com.google.gwt.core.ext.TreeLogger;
import com.google.gwt.dev.jjs.ast.JMethod;
import com.google.gwt.dev.jjs.ast.JProgram;
import com.google.gwt.dev.jjs.impl.DeadCodeElimination;
import com.google.gwt.dev.jjs.impl.FullOptimizerContext;
import com.google.gwt.dev.jjs.impl.MethodInliner;
import com.google.gwt.dev.jjs.impl.OptimizerTestBase;

/**
 * Tests for {@link DataflowOptimizer}
 */
public class DataflowOptimizerTest extends OptimizerTestBase {
  @Override
  protected void setUp() throws Exception {
    super.setUp();

    /*
     * TODO: Each of these snippets shouldn't be setup for every test, and thus should be moved
     * to the individual test cases they are needed for (or to shared methods if needed).
     */
    addSnippetClassDecl("static void foo(int i) { }");
    addSnippetClassDecl("static boolean bar() { return true; }");
    addSnippetClassDecl("static void baz(boolean b) {  }");
    addSnippetClassDecl("static int genInt() { return 1; }");
    addSnippetClassDecl("static int multiply(int i, int j) { return i * j; }");

    addSnippetClassDecl("static class CheckedException extends Exception {}");
    addSnippetClassDecl("static class UncheckedException1 extends RuntimeException {}");
    addSnippetClassDecl("static class UncheckedException2 extends RuntimeException {}");

    addSnippetClassDecl("static void throwUncheckedException1() " +
        "throws UncheckedException1 {}");
    addSnippetClassDecl("static void throwCheckedException() " +
        "throws CheckedException {}");
    addSnippetClassDecl("static void throwSeveralExceptions() " +
        "throws CheckedException, UncheckedException1 {}");

    addSnippetClassDecl("static class Foo { int i; int j; int k; }");
    addSnippetClassDecl("static Foo createFoo() {return null;}");
    addSnippetClassDecl("static Foo staticFooInstance;");

    runMethodInliner = false;
    runDCE = false;
  }

  public void testLinearStatements1() throws Exception {
    optimize("int", "int i = 1; int j = i; return i;").into(
        "int i; int j; return 1;");
  }

  public void testLinearStatements2() throws Exception {
    optimize("int", "int i = 1; int j = i; return j;").into(
        "int i; int j; return 1;");
  }

  public void testLinearStatements3() throws Exception {
    optimize("void", "int i = 1; int j = 1; foo(j);").into(
        "int i; int j; foo(1);");
  }

  /**
   * Test case for issue 8115 (http://code.google.com/p/google-web-toolkit/issues/detail?id=8115)
   * @throws Exception
   */
  public void testCatchThrowExceptionFinally() throws Exception {
    addSnippetClassDecl("static boolean b;");
    addSnippetClassDecl("static int i;");
    addSnippetClassDecl("static int j;");

    optimize("void", ""
        + "Object o = null;"
        + "try {"
        + "  if (b) throw new UncheckedException1();"
        + "} catch (UncheckedException1 e) {"
        + "  o = e;"
        + "  throw e;"
        + "} finally {"
        + "  if (o == null)"
        + "    j++;"
        + "}").into(""

        + "Object o = null;"
        + "try {"
        + "  if (b) throw new UncheckedException1();"
        + "} catch (UncheckedException1 e) {"
        + "  o = e;"
        + "  throw e;"
        + "} finally {"
        + "  if (o == null)"   // the bug would cause this if to be optimized away as always true.
        + "    j++;"
        + "}");
  }

  public void testDeadIfBranch1() throws Exception {
    optimize("void",
        "int i = 1; if (i == 1) { int j = 2; } else { int j = 3; }").into(
        "int i; { int j; } ");
  }

  public void testDeadIfBranch2() throws Exception {
    optimize("void",
        "int i = 1; if (i != 1) { int j = 2; } else { int j = 3; }").into(
        "int i; { int j; } ");
  }

  public void testDeadIfBranch3() throws Exception {
    optimize("int",
        "int i = 1; int j = 0; if (i != 1) { j = 2; } else { j = 3; } return j;").into(
        "int i; int j; return 3; ");
  }

  public void testDeadIfBranch4() throws Exception {
    addSnippetClassDecl("static Object f = null;");
    optimize("void",
        "Object e = null;" +
        "if (e == null && f == null) {" +
        "  return;" +
        "}" +
        "boolean b = e == null;").into(
        "Object e; if (EntryPoint.f == null) { return; } boolean b;"
        );
  }

  public void testDeadWhile() throws Exception {
    optimize("void",
    "int j = 0; while (j > 0) { }").into(
    "int j;");
  }

  // Various complex stuff
  public void testComplexCode1() throws Exception {
    optimize("int",
        "int i = 1; int j = 0; while (j > 0) { if (i != 1) { i++; j++; } } return i;").into(
        "int i; int j; return 1;");
  }

  public void testComplexCode2() throws Exception {
    optimize("void",
        "boolean b = bar(); if (b) { baz(b); return; }").into(
        "boolean b = bar(); if (b) { baz(true); return; }");
  }

  public void testAssert() throws Exception {
    optimize("void",
        "boolean b = true;",
        "assert b;").into(
        "boolean b;");
  }

  public void testDebuggerStatement() throws Exception {
    addSnippetImport("com.google.gwt.core.shared.GWT");
    optimize("void", "GWT.debugger();").noChange();
  }

  public void testDeadCodeRemovalNearDebuggerStatement() throws Exception {
    addSnippetImport("com.google.gwt.core.shared.GWT");
    optimize("void",
        "int i = 1; if (i==1) { GWT.debugger(); } else { GWT.debugger(); }").into(
        "int i; GWT.debugger();"
    );
  }

  public void testNoChange() throws Exception {
    optimize("void",
        "try {",
        "  foo(1);",
        "} catch (RuntimeException e) { }").noChange();
  }

  public void testAssignToField() throws Exception {
    optimize("void",
        "Foo foo = createFoo();",
        "foo.i = 1;"
        ).noChange();
  }

  public void testSwapValues() throws Exception {
    optimize("int",
        "int i = genInt(); int j = genInt(); int t;",
        "if (i > j) { t = i; i = j; j = t; }",
        "return multiply(i, j);"
        ).into(
            "int i = genInt(); int j = genInt(); int t;",
            "if (i > j) { t = i; i = j; j = t; }",
            "return multiply(i, j);"
         );
  }

  public void testSwapValuesMethodParameter() throws Exception {
    addSnippetClassDecl("int calculate(int i, int j) {" +
        "int t;" +
        "if (i > j) { t = i; i = j; j = t; }" +
        "return multiply(i, j);" +
        "}");

    optimizeMethod("calculate", "int", "return 1;"
        ).intoString(
            "int t;",
            "if (i > j) {",
            "  t = i;",
            "  i = j;",
            "  j = t;",
            "}",
            "return EntryPoint.multiply(i, j);"
            );
  }

  public void testComplexCode3() throws Exception {
    addSnippetClassDecl("static final int SPLIT_LOOKING_FOR_COMMA = 0;");
    addSnippetClassDecl("static final int SPLIT_IN_STRING = 1;");
    addSnippetClassDecl("static final int SPLIT_IN_ESCAPE = 2;");
    addSnippetClassDecl("static String getCsvString() { return null; }");

    addSnippetClassDecl(
        "static class JsArrayString {" +
        "  static JsArrayString createArray() { return null; }" +
        "  JsArrayString cast() { return this; }" +
        "  void push(String s) { }" +
        "}");

    addSnippetClassDecl(
        "static class StringBuilder {" +
        "  void append(char c) { }" +
        "}");

    optimize("JsArrayString",
       "int state;",
       "String csvString = getCsvString();",
       "JsArrayString results = JsArrayString.createArray().cast();",
       "int index = 0;",
       "StringBuilder field = new StringBuilder();",
       "state = SPLIT_LOOKING_FOR_COMMA;",
       "while (index < csvString.length()) {",
       "  char nextCharacter = csvString.charAt(index);",
       "  switch (state) {",
       "    case SPLIT_LOOKING_FOR_COMMA:",
       "      switch (nextCharacter) {",
       "        case ',':",
       "          results.push(field.toString());",
       "          field = new StringBuilder();",
       "          break;",
       "        case '\"':",
       "          state = SPLIT_IN_STRING;",
       "          break;",
       "        default:",
       "          field.append(nextCharacter);",
       "      }",
       "      break;",
       "    case SPLIT_IN_STRING:",
       "      switch (nextCharacter) {",
       "        case '\"':",
       "          state = SPLIT_LOOKING_FOR_COMMA;",
       "          break;",
       "        case '\\\\':",
       "          state = SPLIT_IN_ESCAPE;",
       "          field.append(nextCharacter);",
       "          break;",
       "        default:",
       "          field.append(nextCharacter);",
       "      }",
       "      break;",
       "    case SPLIT_IN_ESCAPE:",
       "      state = SPLIT_IN_STRING;",
       "      field.append(nextCharacter);",
       "      break;",
       "    default:",
       "      field.append(nextCharacter);",
       "  }",
       "  index++;",
       "}",
       "results.push(field.toString());",
       "return results;"
   ).into(
       "int state;",
       "String csvString = getCsvString();",
       "JsArrayString results = JsArrayString.createArray().cast();",
       "int index = 0;",
       "StringBuilder field = new StringBuilder();",
       "state = 0;",
       "while (index < csvString.length()) {",
       "  char nextCharacter = csvString.charAt(index);",
       "  switch (state) {",
       "    case 0:",
       "      switch (nextCharacter) {",
       "        case ',':",
       "          results.push(field.toString());",
       "          field = new StringBuilder();",
       "          break;",
       "        case '\"':",
       "          state = 1;",
       "          break;",
       "        default:",
       "          field.append(nextCharacter);",
       "      }",
       "      break;",
       "    case 1:",
       "      switch (nextCharacter) {",
       "        case '\"':",
       "          state = 0;",
       "          break;",
       "        case '\\\\':",
       "          state = 2;",
       "          field.append('\\\\');",
       "          break;",
       "        default:",
       "          field.append(nextCharacter);",
       "      }",
       "      break;",
       "    case 2:",
       "      state = 1;",
       "      field.append(nextCharacter);",
       "      break;",
       "    default:",
       "      field.append(nextCharacter);",
       "  }",
       "  ++index;",
       "}",
       "results.push(field.toString());",
       "return results;"
       );
  }

  public void testComplexCode4() throws Exception {
    addSnippetClassDecl("static boolean confirm() { return true; }");

    optimize("int",
       "int n = 0;",
       "for (; ; ) {",
       "  if (confirm()) {",
       "    break;",
       "  } else {",
       "    for (int i = 0; i < 2; i++) {",
       "      n = i;",
       "    }",
       "  }",
       "}",
       "return n;"
   ).into(
       "int n = 0;",
       "for (; ; ) {",
       "  if (confirm()) {",
       "    break;",
       "  } else {",
       "    for (int i = 0; i < 2; i++) {",
       "      n = i;",
       "    }",
       "  }",
       "}",
      "return n;"
      );
  }

  /**
   * Test fix for http://code.google.com/p/google-web-toolkit/issues/detail?id=5739
   */
  public void testExceptionInitializerFlow() throws Exception {
    addSnippetClassDecl("static int foo() { return 0; }");
    optimize("boolean", " int size = -1;\n" +
            "  try {\n" +
            "    size = ((Object[]) (Object)\"aaa\").length;\n" +
            "  } catch (final Exception ex) {\n" +
            "  }\n" +
            "  if (size < 0) {\n" +
            "    try {\n" +
            "      size = 3;\n" +
            "    } catch (final Exception ex) {\n" +
            "    }\n" +
            "  }\n" +
            "  return size > 0;").into("int size = -1;\n" +
            "  try {\n" +
            "    size = ((Object[]) (Object)\"aaa\").length;\n" +
            "  } catch (final Exception ex) {\n" +
            "  }\n" +
            "  if (size < 0) {\n" +
            "    try {\n" +
            "      size = 3;\n" +
            "    } catch (final Exception ex) {\n" +
            "    }\n" +
            "  } return size > 0;");
  }

  public void testImplicitConversion() throws Exception {
    optimize("long",
        "int bar = 0x12345678;",
        "bar = bar * 1234;",
        "long lng = bar;",
        "long lng8 = lng << 8;",
        "return lng8;"
        ).into(
            "  int bar;",
            "  long lng = -1068970384;",
            "  long lng8 = lng << 8;",
            "  return lng8;");
  }

  /*
   * This test is a regression for an issue where inlined multiexpressions were getting removed
   * by the ConstantsTransformationFunction, based on the constant value of the multi-expression,
   * despite there being side-effects of the multi-expression.  So, we want to test that inlining
   * proceeds, but not further constant transformation.
   *
   * TODO(rluble): This test may need to evolve over time, as the specifics of the
   * optimizers change.
   */
  public void testInlinedConstantExpressionWithSideEffects() throws Exception {

    runDCE = true;
    runMethodInliner = true;

    addSnippetClassDecl("static void fail() {" +
                        "  throw new RuntimeException();" +
                        "}");
    addSnippetClassDecl("static Integer x;");
    addSnippetClassDecl("static boolean copy(Number n) {" +
                        "  x = (Integer) n;" +
                        "  return true;" +
                        "}");

    optimize("int",
              "Integer n = new Integer(1);",
              "if (!copy(n)) {",
              "  fail();",
              "}",
              "return x;")
        .into("Integer n = new Integer(1);",
               "x = n;",
               "return x;");
  }

  private boolean runDCE;
  private boolean runMethodInliner;

  @Override
  protected boolean doOptimizeMethod(TreeLogger logger, JProgram program, JMethod method) {
    boolean didChange = false;
    boolean optimizeChange;

    // Run optimizations in a loop to make the tests more robusts to unrelated
    // changes.
    do {
      optimizeChange = false;
      if (runDCE) {
        optimizeChange = DeadCodeElimination.exec(program, new FullOptimizerContext(program)) > 0 || optimizeChange;
      }

      if (runMethodInliner) {
        optimizeChange = MethodInliner.exec(program) > 0 || optimizeChange;
      }
      didChange = didChange || optimizeChange;
    } while (optimizeChange);

    didChange = DataflowOptimizer.exec(program, method) > 0 || didChange;
    return didChange;
  }
}
