RFR(S): 8214862: assert(proj != __null) at compile.cpp:3251

[Roland Westrelin]

> Do you hit next bailout (with fix)?:
>
> http://hg.openjdk.java.net/jdk/jdk/file/24525070d934/src/hotspot/share/opto/compile.cpp#l3669

yes.

> Is fall-through path eliminated because it is not reachable from Root because of infinite loop?

yes.

> I think we should detect infinite loop very early, after first PhaseRemoveUseless. Or may be just before or during 
> PhaseRemoveUseless when we still have path.

Isn't there a chance that the path that leads to the infinite loop can
be optimized out during optimizations so bailing out early could cause a
valid method to never be compiled?

> What happens if a method has *only* infinite loop? In which phase we detect it and bailout?

This:

private static void test() {
    while (true);
}

bails out in:

bool Compile::final_graph_reshaping() {
  // an infinite loop may have been eliminated by the optimizer,
  // in which case the graph will be empty.
  if (root()->req() == 1) {
    record_method_not_compilable("trivial infinite loop");
    return true;
  }


Roland.