Exemplo n.º 1
0
//
// For a given BasicBlock, compute which variables are used.
//
Assignments DataFlowUtil::uses(const BasicBlock& block) {
  Assignments useSet;
  for (BasicBlock::const_reverse_iterator it = block.rbegin(); it != block.rend(); ++it) {
    const Instruction& instr = *it;
    const User* user = &instr;
    // iterate through all operands
    User::const_op_iterator OI, OE;
    for(OI = user->op_begin(), OE = user->op_end(); OI != OE; ++OI) {
      Value* val = *OI;
      // check if the operand is used
      if ((isa<Instruction>(val) || isa<Argument>(val)) && (!isa<PHINode>(val))) {
        useSet.insert(Assignment(val));
      }
    }
    useSet.erase(Assignment(&instr));
  }
  return useSet;
}
Exemplo n.º 2
0
//
// The following functions perform basic set operations in O(n*log(m)) time,
// where m and n are the sizes of the sets. For our purposes, this is fast
// enough.
//
// The result of these operations is stored back into the 1st argument.
//
void DataFlowUtil::setSubtract(Assignments& dest, const Assignments& src) {
  for (Assignments::const_iterator i = src.begin(); i != src.end(); ++i) {
    const Assignment& sub = *i;
    dest.erase(sub);
  }
}