--- a/hotspot/src/share/vm/c1/c1_Canonicalizer.cpp	Tue Feb 14 15:43:56 2012 -0800
+++ b/hotspot/src/share/vm/c1/c1_Canonicalizer.cpp	Wed Feb 15 09:43:16 2012 +0100
@@ -594,6 +594,13 @@
   return false;
 }
 
+static bool is_safepoint(BlockEnd* x, BlockBegin* sux) {
+  // An Instruction with multiple successors, x, is replaced by a Goto
+  // to a single successor, sux. Is a safepoint check needed = was the
+  // instruction being replaced a safepoint and the single remaining
+  // successor a back branch?
+  return x->is_safepoint() && (sux->bci() < x->state_before()->bci());
+}
 
 void Canonicalizer::do_If(If* x) {
   // move const to right
@@ -614,7 +621,7 @@
     case If::geq: sux = x->sux_for(true);  break;
     }
     // If is a safepoint then the debug information should come from the state_before of the If.
-    set_canonical(new Goto(sux, x->state_before(), x->is_safepoint()));
+    set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
     return;
   }
 
@@ -626,7 +633,7 @@
                                                        x->sux_for(false));
       if (sux != NULL) {
         // If is a safepoint then the debug information should come from the state_before of the If.
-        set_canonical(new Goto(sux, x->state_before(), x->is_safepoint()));
+        set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
       }
     }
   } else if (rt->as_IntConstant() != NULL) {
@@ -694,10 +701,12 @@
     }
   } else if (rt == objectNull && (l->as_NewInstance() || l->as_NewArray())) {
     if (x->cond() == Instruction::eql) {
-      set_canonical(new Goto(x->fsux(), x->state_before(), x->is_safepoint()));
+      BlockBegin* sux = x->fsux();
+      set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
     } else {
       assert(x->cond() == Instruction::neq, "only other valid case");
-      set_canonical(new Goto(x->tsux(), x->state_before(), x->is_safepoint()));
+      BlockBegin* sux = x->tsux();
+      set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
     }
   }
 }
@@ -710,7 +719,7 @@
     if (v >= x->lo_key() && v <= x->hi_key()) {
       sux = x->sux_at(v - x->lo_key());
     }
-    set_canonical(new Goto(sux, x->state_before(), x->is_safepoint()));
+    set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
   } else if (x->number_of_sux() == 1) {
     // NOTE: Code permanently disabled for now since the switch statement's
     //       tag expression may produce side-effects in which case it must
@@ -741,7 +750,7 @@
         sux = x->sux_at(i);
       }
     }
-    set_canonical(new Goto(sux, x->state_before(), x->is_safepoint()));
+    set_canonical(new Goto(sux, x->state_before(), is_safepoint(x, sux)));
   } else if (x->number_of_sux() == 1) {
     // NOTE: Code permanently disabled for now since the switch statement's
     //       tag expression may produce side-effects in which case it must

--- a/hotspot/src/share/vm/c1/c1_GraphBuilder.cpp	Tue Feb 14 15:43:56 2012 -0800
+++ b/hotspot/src/share/vm/c1/c1_GraphBuilder.cpp	Wed Feb 15 09:43:16 2012 +0100
@@ -1181,6 +1181,11 @@
   bool is_bb = tsux->bci() < stream()->cur_bci() || fsux->bci() < stream()->cur_bci();
   Instruction *i = append(new If(x, cond, false, y, tsux, fsux, is_bb ? state_before : NULL, is_bb));
 
+  assert(i->as_Goto() == NULL ||
+         (i->as_Goto()->sux_at(0) == tsux  && i->as_Goto()->is_safepoint() == tsux->bci() < stream()->cur_bci()) ||
+         (i->as_Goto()->sux_at(0) == fsux  && i->as_Goto()->is_safepoint() == fsux->bci() < stream()->cur_bci()),
+         "safepoint state of Goto returned by canonicalizer incorrect");
+
   if (is_profiling()) {
     If* if_node = i->as_If();
     if (if_node != NULL) {
@@ -1303,7 +1308,16 @@
     // add default successor
     sux->at_put(i, block_at(bci() + sw.default_offset()));
     ValueStack* state_before = has_bb ? copy_state_before() : NULL;
-    append(new TableSwitch(ipop(), sux, sw.low_key(), state_before, has_bb));
+    Instruction* res = append(new TableSwitch(ipop(), sux, sw.low_key(), state_before, has_bb));
+#ifdef ASSERT
+    if (res->as_Goto()) {
+      for (i = 0; i < l; i++) {
+        if (sux->at(i) == res->as_Goto()->sux_at(0)) {
+          assert(res->as_Goto()->is_safepoint() == sw.dest_offset_at(i) < 0, "safepoint state of Goto returned by canonicalizer incorrect");
+        }
+      }
+    }
+#endif
   }
 }
 
@@ -1338,7 +1352,16 @@
     // add default successor
     sux->at_put(i, block_at(bci() + sw.default_offset()));
     ValueStack* state_before = has_bb ? copy_state_before() : NULL;
-    append(new LookupSwitch(ipop(), sux, keys, state_before, has_bb));
+    Instruction* res = append(new LookupSwitch(ipop(), sux, keys, state_before, has_bb));
+#ifdef ASSERT
+    if (res->as_Goto()) {
+      for (i = 0; i < l; i++) {
+        if (sux->at(i) == res->as_Goto()->sux_at(0)) {
+          assert(res->as_Goto()->is_safepoint() == sw.pair_at(i).offset() < 0, "safepoint state of Goto returned by canonicalizer incorrect");
+        }
+      }
+    }
+#endif
   }
 }