Exemple #1
0
    private void computeOutgoingEdges() {
      if (DEBUG) {
        System.err.println("Block " + this + ": computeOutgoingEdges()");
      }

      IInstruction last = getInstructions()[getLastInstructionIndex()];
      int[] targets = last.getBranchTargets();
      for (int i = 0; i < targets.length; i++) {
        BasicBlock b = getBlockForInstruction(targets[i]);
        addNormalEdgeTo(b);
      }
      addExceptionalEdges(last);
      if (last.isFallThrough()) {
        BasicBlock next = getNode(getNumber() + 1);
        addNormalEdgeTo(next);
      }
      if (last instanceof ReturnInstruction) {
        // link each return instruction to the exit block.
        BasicBlock exit = exit();
        addNormalEdgeTo(exit);
      }
    }
Exemple #2
0
    /**
     * Add any exceptional edges generated by the last instruction in a basic block.
     *
     * @param last the last instruction in a basic block.
     */
    protected void addExceptionalEdges(IInstruction last) {
      IClassHierarchy cha = getMethod().getClassHierarchy();
      if (last.isPEI()) {
        Collection<TypeReference> exceptionTypes = null;
        boolean goToAllHandlers = false;

        ExceptionHandler[] hs = getExceptionHandlers();
        if (last instanceof ThrowInstruction) {
          // this class does not have the type information needed
          // to determine what the athrow throws. So, add an
          // edge to all reachable handlers. Better information can
          // be obtained later with SSA type propagation.
          // TODO: consider pruning to only the exception types that
          // this method either catches or allocates, since these are
          // the only types that can flow to an athrow.
          goToAllHandlers = true;
        } else {
          if (hs != null && hs.length > 0) {
            IClassLoader loader = getMethod().getDeclaringClass().getClassLoader();
            BytecodeLanguage l = (BytecodeLanguage) loader.getLanguage();
            exceptionTypes = l.getImplicitExceptionTypes(last);
            if (last instanceof IInvokeInstruction) {
              IInvokeInstruction call = (IInvokeInstruction) last;
              exceptionTypes = HashSetFactory.make(exceptionTypes);
              MethodReference target =
                  MethodReference.findOrCreate(
                      l,
                      loader.getReference(),
                      call.getClassType(),
                      call.getMethodName(),
                      call.getMethodSignature());
              try {
                exceptionTypes.addAll(l.inferInvokeExceptions(target, cha));
              } catch (InvalidClassFileException e) {
                e.printStackTrace();
                Assertions.UNREACHABLE();
              }
            }
          }
        }

        if (hs != null && hs.length > 0) {
          // found a handler for this PEI

          // create a mutable copy
          if (!goToAllHandlers) {
            exceptionTypes = HashSetFactory.make(exceptionTypes);
          }

          // this var gets set to false if goToAllHandlers is true but some enclosing exception
          // handler catches all
          // exceptions.  in such a case, we need not add an exceptional edge to the method exit
          boolean needEdgeToExitForAllHandlers = true;
          for (int j = 0; j < hs.length; j++) {
            if (DEBUG) {
              System.err.println(" handler " + hs[j]);
            }
            BasicBlock b = getBlockForInstruction(hs[j].getHandler());
            if (DEBUG) {
              System.err.println(" target " + b);
            }
            if (goToAllHandlers) {
              // add an edge to the catch block.
              if (DEBUG) {
                System.err.println(" gotoAllHandlers " + b);
              }
              addExceptionalEdgeTo(b);
              // if the handler catches all exceptions, we don't need to add an edge to the exit or
              // any other handlers
              if (hs[j].getCatchClass() == null) {
                needEdgeToExitForAllHandlers = false;
                break;
              }
            } else {
              TypeReference caughtException = null;
              if (hs[j].getCatchClass() != null) {
                ClassLoaderReference loader =
                    ShrikeCFG.this.getMethod().getDeclaringClass().getReference().getClassLoader();
                caughtException = ShrikeUtil.makeTypeReference(loader, hs[j].getCatchClass());
                if (DEBUG) {
                  System.err.println(" caughtException " + caughtException);
                }
                IClass caughtClass = cha.lookupClass(caughtException);
                if (caughtClass == null) {
                  // conservatively add the edge, and raise a warning
                  addExceptionalEdgeTo(b);
                  Warnings.add(FailedExceptionResolutionWarning.create(caughtException));
                  // null out caughtException, to avoid attempting to process it
                  caughtException = null;
                }
              } else {
                if (DEBUG) {
                  System.err.println(" catchClass() == null");
                }
                // hs[j].getCatchClass() == null.
                // this means that the handler catches all exceptions.
                // add the edge and null out all types
                if (!exceptionTypes.isEmpty()) {
                  addExceptionalEdgeTo(b);
                  exceptionTypes.clear();
                  caughtException = null;
                }
              }
              if (caughtException != null) {
                IClass caughtClass = cha.lookupClass(caughtException);
                // the set "caught" should be the set of exceptions that MUST
                // have been caught by the handlers in scope
                ArrayList<TypeReference> caught =
                    new ArrayList<TypeReference>(exceptionTypes.size());
                // check if we should add an edge to the catch block.
                for (TypeReference t : exceptionTypes) {
                  if (t != null) {
                    IClass klass = cha.lookupClass(t);
                    if (klass == null) {
                      Warnings.add(FailedExceptionResolutionWarning.create(caughtException));
                      // conservatively add an edge
                      addExceptionalEdgeTo(b);
                    } else {
                      boolean subtype1 = cha.isSubclassOf(klass, caughtClass);
                      if (subtype1 || cha.isSubclassOf(caughtClass, klass)) {
                        // add the edge and null out the type from the array
                        addExceptionalEdgeTo(b);
                        if (subtype1) {
                          caught.add(t);
                        }
                      }
                    }
                  }
                }
                exceptionTypes.removeAll(caught);
              }
            }
          }
          // if needed, add an edge to the exit block.
          if ((exceptionTypes == null && needEdgeToExitForAllHandlers)
              || (exceptionTypes != null && !exceptionTypes.isEmpty())) {
            BasicBlock exit = exit();
            addExceptionalEdgeTo(exit);
          }
        } else {
          // found no handler for this PEI ... link to the exit block.
          BasicBlock exit = exit();
          addExceptionalEdgeTo(exit);
        }
      }
    }