1.1 --- a/src/share/vm/opto/loopnode.cpp Sat Oct 24 16:18:50 2020 +0800
1.2 +++ b/src/share/vm/opto/loopnode.cpp Sat Oct 24 16:43:47 2020 +0800
1.3 @@ -3282,6 +3282,41 @@
1.4 return LCA;
1.5 }
1.6
1.7 +// Check the shape of the graph at the loop entry. In some cases,
1.8 +// the shape of the graph does not match the shape outlined below.
1.9 +// That is caused by the Opaque1 node "protecting" the shape of
1.10 +// the graph being removed by, for example, the IGVN performed
1.11 +// in PhaseIdealLoop::build_and_optimize().
1.12 +//
1.13 +// After the Opaque1 node has been removed, optimizations (e.g., split-if,
1.14 +// loop unswitching, and IGVN, or a combination of them) can freely change
1.15 +// the graph's shape. As a result, the graph shape outlined below cannot
1.16 +// be guaranteed anymore.
1.17 +bool PhaseIdealLoop::is_canonical_main_loop_entry(CountedLoopNode* cl) {
1.18 + assert(cl->is_main_loop(), "check should be applied to main loops");
1.19 + Node* ctrl = cl->in(LoopNode::EntryControl);
1.20 + if (ctrl == NULL || (!ctrl->is_IfTrue() && !ctrl->is_IfFalse())) {
1.21 + return false;
1.22 + }
1.23 + Node* iffm = ctrl->in(0);
1.24 + if (iffm == NULL || !iffm->is_If()) {
1.25 + return false;
1.26 + }
1.27 + Node* bolzm = iffm->in(1);
1.28 + if (bolzm == NULL || !bolzm->is_Bool()) {
1.29 + return false;
1.30 + }
1.31 + Node* cmpzm = bolzm->in(1);
1.32 + if (cmpzm == NULL || !cmpzm->is_Cmp()) {
1.33 + return false;
1.34 + }
1.35 + Node* opqzm = cmpzm->in(2);
1.36 + if (opqzm == NULL || opqzm->Opcode() != Op_Opaque1) {
1.37 + return false;
1.38 + }
1.39 + return true;
1.40 +}
1.41 +
1.42 //------------------------------get_late_ctrl----------------------------------
1.43 // Compute latest legal control.
1.44 Node *PhaseIdealLoop::get_late_ctrl( Node *n, Node *early ) {
