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6701887: JDK7 server VM in endless loop in Node::dominates

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The method Node::dominates loops in the dead code which does not have a Region node.

Reviewed-by: jrose, never
This commit is contained in:
Vladimir Kozlov 2008-05-15 22:43:11 -07:00
parent 9bcba384cb
commit 60c74ba115
3 changed files with 23 additions and 15 deletions
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20
hotspot/src/share/vm/opto/node.cpp
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@ -1043,6 +1043,9 @@ bool Node::dominates(Node* sub, Node_List &nlist) {
assert(this->is_CFG(), "expecting control");
assert(sub != NULL && sub->is_CFG(), "expecting control");
// detect dead cycle without regions
int iterations_without_region_limit = DominatorSearchLimit;
Node* orig_sub = sub;
nlist.clear();
bool this_dominates = false;
@ -1057,6 +1060,7 @@ bool Node::dominates(Node* sub, Node_List &nlist) {
// Region nodes were visited. Continue walk up to Start or Root
// to make sure that it did not walk in a cycle.
this_dominates = true; // first time meet
iterations_without_region_limit = DominatorSearchLimit; // Reset
} else {
return false; // already met before: walk in a cycle
}
@ -1069,19 +1073,20 @@ bool Node::dominates(Node* sub, Node_List &nlist) {
return false; // Conservative answer for dead code
if (sub == up && sub->is_Loop()) {
up = sub->in(0); // in(LoopNode::EntryControl);
} else if (sub == up && sub->is_Region()) {
up = sub->in(1); // in(LoopNode::EntryControl);
} else if (sub == up && sub->is_Region() && sub->req() == 3) {
iterations_without_region_limit = DominatorSearchLimit; // Reset
uint i = 1;
if (nlist.size() == 0) {
uint size = nlist.size();
if (size == 0) {
// No Region nodes (except Loops) were visited before.
// Take first valid path on the way up to 'this'.
} else if (nlist.at(nlist.size() - 1) == sub) {
} else if (nlist.at(size - 1) == sub) {
// This Region node was just visited. Take other path.
i = region_input + 1;
nlist.pop();
} else {
// Was this Region node visited before?
uint size = nlist.size();
for (uint j = 0; j < size; j++) {
if (nlist.at(j) == sub) {
return false; // The Region node was visited before. Give up.
@ -1104,8 +1109,9 @@ bool Node::dominates(Node* sub, Node_List &nlist) {
}
if (sub == up)
return false; // some kind of tight cycle
if (orig_sub == up)
return false; // walk in a cycle
if (--iterations_without_region_limit < 0)
return false; // dead cycle
sub = up;
}