[SOLVED] Does java have a divmod instruction?

Does java have a divmod instruction?

Besides divmod being a native instruction on many chipsets, it also is a lot easier on the eyes when subdividing a number in multiple different denominations

(which happens with e.g. milliseconds -> datetime conversion, or cents -> coin denomination conversion).

So is there a divmod that returns both the result of the division and of the remainder at the same time?

Solution

The HotSpot JIT compiler will replace division and modulo operations against the same arguments with a single divmod operation, if supported. So while this may not address the readability concerns, you don't need to worry about performance.

From the OpenJDK 9 source code:

case Op_ModI:
  if (UseDivMod) {
    // Check if a%b and a/b both exist
    Node* d = n->find_similar(Op_DivI);
    if (d) {
      // Replace them with a fused divmod if supported
      if (Matcher::has_match_rule(Op_DivModI)) {
        DivModINode* divmod = DivModINode::make(n);
        d->subsume_by(divmod->div_proj(), this);
        n->subsume_by(divmod->mod_proj(), this);
      } else {
        // replace a%b with a-((a/b)*b)
        Node* mult = new MulINode(d, d->in(2));
        Node* sub  = new SubINode(d->in(1), mult);
        n->subsume_by(sub, this);
      }
    }
  }
  break;

By using diagnostic options to print the generated JIT instructions, I was able to see that a method that used both idiv and irem instructions at the C1 optimization level used only a single idiv instruction at the C2 level.