1.1 --- a/src/share/vm/opto/node.cpp Thu Apr 10 15:49:29 2008 -0400
1.2 +++ b/src/share/vm/opto/node.cpp Tue Apr 15 10:49:32 2008 -0700
1.3 @@ -1017,6 +1017,101 @@
1.4 return false;
1.5 };
1.6
1.7 +//--------------------------find_exact_control---------------------------------
1.8 +// Skip Proj and CatchProj nodes chains. Check for Null and Top.
1.9 +Node* Node::find_exact_control(Node* ctrl) {
1.10 + if (ctrl == NULL && this->is_Region())
1.11 + ctrl = this->as_Region()->is_copy();
1.12 +
1.13 + if (ctrl != NULL && ctrl->is_CatchProj()) {
1.14 + if (ctrl->as_CatchProj()->_con == CatchProjNode::fall_through_index)
1.15 + ctrl = ctrl->in(0);
1.16 + if (ctrl != NULL && !ctrl->is_top())
1.17 + ctrl = ctrl->in(0);
1.18 + }
1.19 +
1.20 + if (ctrl != NULL && ctrl->is_Proj())
1.21 + ctrl = ctrl->in(0);
1.22 +
1.23 + return ctrl;
1.24 +}
1.25 +
1.26 +//--------------------------dominates------------------------------------------
1.27 +// Helper function for MemNode::all_controls_dominate().
1.28 +// Check if 'this' control node dominates or equal to 'sub' control node.
1.29 +bool Node::dominates(Node* sub, Node_List &nlist) {
1.30 + assert(this->is_CFG(), "expecting control");
1.31 + assert(sub != NULL && sub->is_CFG(), "expecting control");
1.32 +
1.33 + Node* orig_sub = sub;
1.34 + nlist.clear();
1.35 + bool this_dominates = false;
1.36 + uint region_input = 0;
1.37 + while (sub != NULL) { // walk 'sub' up the chain to 'this'
1.38 + if (sub == this) {
1.39 + if (nlist.size() == 0) {
1.40 + // No Region nodes except loops were visited before and the EntryControl
1.41 + // path was taken for loops: it did not walk in a cycle.
1.42 + return true;
1.43 + } else if (!this_dominates) {
1.44 + // Region nodes were visited. Continue walk up to Start or Root
1.45 + // to make sure that it did not walk in a cycle.
1.46 + this_dominates = true; // first time meet
1.47 + } else {
1.48 + return false; // already met before: walk in a cycle
1.49 + }
1.50 + }
1.51 + if (sub->is_Start() || sub->is_Root())
1.52 + return this_dominates;
1.53 +
1.54 + Node* up = sub->find_exact_control(sub->in(0));
1.55 + if (up == NULL || up->is_top())
1.56 + return false; // Conservative answer for dead code
1.57 +
1.58 + if (sub == up && sub->is_Loop()) {
1.59 + up = sub->in(0); // in(LoopNode::EntryControl);
1.60 + } else if (sub == up && sub->is_Region()) {
1.61 + uint i = 1;
1.62 + if (nlist.size() == 0) {
1.63 + // No Region nodes (except Loops) were visited before.
1.64 + // Take first valid path on the way up to 'this'.
1.65 + } else if (nlist.at(nlist.size() - 1) == sub) {
1.66 + // This Region node was just visited. Take other path.
1.67 + i = region_input + 1;
1.68 + nlist.pop();
1.69 + } else {
1.70 + // Was this Region node visited before?
1.71 + uint size = nlist.size();
1.72 + for (uint j = 0; j < size; j++) {
1.73 + if (nlist.at(j) == sub) {
1.74 + return false; // The Region node was visited before. Give up.
1.75 + }
1.76 + }
1.77 + // The Region node was not visited before.
1.78 + // Take first valid path on the way up to 'this'.
1.79 + }
1.80 + for (; i < sub->req(); i++) {
1.81 + Node* in = sub->in(i);
1.82 + if (in != NULL && !in->is_top() && in != sub) {
1.83 + break;
1.84 + }
1.85 + }
1.86 + if (i < sub->req()) {
1.87 + nlist.push(sub);
1.88 + up = sub->in(i);
1.89 + region_input = i;
1.90 + }
1.91 + }
1.92 + if (sub == up)
1.93 + return false; // some kind of tight cycle
1.94 + if (orig_sub == up)
1.95 + return false; // walk in a cycle
1.96 +
1.97 + sub = up;
1.98 + }
1.99 + return false;
1.100 +}
1.101 +
1.102 //------------------------------remove_dead_region-----------------------------
1.103 // This control node is dead. Follow the subgraph below it making everything
1.104 // using it dead as well. This will happen normally via the usual IterGVN
