6854812: 6.0_14-b08 crashes with a SIGSEGV

Reviewed-by: kvn, twisti

src/share/vm/ci/ciMethod.cpp

@@ -325,10 +325,10 @@ ciTypeFlow* ciMethod::get_osr_flow_analysis(int osr_bci) {
 }
 
 // ------------------------------------------------------------------
-// ciMethod::liveness_at_bci
+// ciMethod::raw_liveness_at_bci
 //
 // Which local variables are live at a specific bci?
-MethodLivenessResult ciMethod::liveness_at_bci(int bci) {
+MethodLivenessResult ciMethod::raw_liveness_at_bci(int bci) {
   check_is_loaded();
   if (_liveness == NULL) {
     // Create the liveness analyzer.
@@ -336,7 +336,17 @@ MethodLivenessResult ciMethod::liveness_at_bci(int bci) {
     _liveness = new (arena) MethodLiveness(arena, this);
     _liveness->compute_liveness();
   }
-  MethodLivenessResult result = _liveness->get_liveness_at(bci);
+  return _liveness->get_liveness_at(bci);
+}
+
+// ------------------------------------------------------------------
+// ciMethod::liveness_at_bci
+//
+// Which local variables are live at a specific bci?  When debugging
+// will return true for all locals in some cases to improve debug
+// information.
+MethodLivenessResult ciMethod::liveness_at_bci(int bci) {
+  MethodLivenessResult result = raw_liveness_at_bci(bci);
   if (CURRENT_ENV->jvmti_can_access_local_variables() || DeoptimizeALot || CompileTheWorld) {
     // Keep all locals live for the user's edification and amusement.
     result.at_put_range(0, result.size(), true);

src/share/vm/ci/ciMethod.hpp

@@ -149,6 +149,12 @@ class ciMethod : public ciObject {
   bool          has_monitor_bytecodes() const    { return _uses_monitors; }
   bool          has_balanced_monitors();
 
+  // Returns a bitmap indicating which locals are required to be
+  // maintained as live for deopt.  raw_liveness_at_bci is always the
+  // direct output of the liveness computation while liveness_at_bci
+  // may mark all locals as live to improve support for debugging Java
+  // code by maintaining the state of as many locals as possible.
+  MethodLivenessResult raw_liveness_at_bci(int bci);
   MethodLivenessResult liveness_at_bci(int bci);
 
   // Get the interpreters viewpoint on oop liveness.  MethodLiveness is

src/share/vm/ci/ciTypeFlow.cpp

@@ -2486,8 +2486,13 @@ void ciTypeFlow::build_loop_tree(Block* blk) {
         // Assume irreducible entries need more data flow
         add_to_work_list(succ);
       }
-      lp = lp->parent();
-      assert(lp != NULL, "nested loop must have parent by now");
+      Loop* plp = lp->parent();
+      if (plp == NULL) {
+        // This only happens for some irreducible cases.  The parent
+        // will be updated during a later pass.
+        break;
+      }
+      lp = plp;
     }
 
     // Merge loop tree branch for all successors.

src/share/vm/opto/parse1.cpp

@@ -229,7 +229,9 @@ void Parse::load_interpreter_state(Node* osr_buf) {
     }
   }
 
-  MethodLivenessResult live_locals = method()->liveness_at_bci(osr_bci());
+  // Use the raw liveness computation to make sure that unexpected
+  // values don't propagate into the OSR frame.
+  MethodLivenessResult live_locals = method()->raw_liveness_at_bci(osr_bci());
   if (!live_locals.is_valid()) {
     // Degenerate or breakpointed method.
     C->record_method_not_compilable("OSR in empty or breakpointed method");