C++ (Cpp) ICmpInst::operand_values Exemples

Exemple #1

// Look for control dependencies on a read.
bool branchesOn(BasicBlock *bb, Value *load,
                ICmpInst **icmpOut, int *outIdx) {
  // XXX: make this platform configured; on some platforms maybe an
  // atomic cmpxchg does /not/ behave like it branches on the old value
  if (isa<AtomicCmpXchgInst>(load) || isa<AtomicRMWInst>(load)) {
    if (icmpOut) *icmpOut = nullptr;
    if (outIdx) *outIdx = 0;
    return true;
  }

  // TODO: we should be able to follow values through phi nodes,
  // since we are path dependent anyways.
  BranchInst *br = dyn_cast<BranchInst>(bb->getTerminator());
  if (!br || !br->isConditional()) return false;
  // TODO: We only check one level of things. Check deeper?

  // We pretty heavily restrict what operations we handle here.
  // Some would just be wrong (like call), but really icmp is
  // the main one, so. Probably we should be able to also
  // pick through casts and wideness changes.
  ICmpInst *icmp = dyn_cast<ICmpInst>(br->getCondition());
  if (!icmp) return false;
  int idx = 0;
  for (auto v : icmp->operand_values()) {
    if (getRealValue(v) == load) {
      if (icmpOut) *icmpOut = icmp;
      if (outIdx) *outIdx = idx;
      return true;
    }
    ++idx;
  }

  return false;
}