src/hotspot/share/gc/shenandoah/c2/shenandoahBarrierSetC2.cpp

rev 59252 : 8244813: [BACKOUT] 8244523: Shenandoah: Remove null-handling in LRB expansion

@@ -479,20 +479,20 @@
   const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+0, fields);
 
   return TypeFunc::make(domain, range);
 }
 
-const TypeFunc* ShenandoahBarrierSetC2::shenandoah_load_reference_barrier_Type(const Type* value_type) {
+const TypeFunc* ShenandoahBarrierSetC2::shenandoah_load_reference_barrier_Type() {
   const Type **fields = TypeTuple::fields(2);
-  fields[TypeFunc::Parms+0] = value_type;           // original field value
+  fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL; // original field value
   fields[TypeFunc::Parms+1] = TypeRawPtr::BOTTOM;   // original load address
 
   const TypeTuple *domain = TypeTuple::make(TypeFunc::Parms+2, fields);
 
   // create result type (range)
   fields = TypeTuple::fields(1);
-  fields[TypeFunc::Parms+0] = value_type;
+  fields[TypeFunc::Parms+0] = TypeInstPtr::NOTNULL;
   const TypeTuple *range = TypeTuple::make(TypeFunc::Parms+1, fields);
 
   return TypeFunc::make(domain, range);
 }
 

@@ -1057,11 +1057,38 @@
         }
         return n;
       }
     }
   }
-  if (can_reshape &&
+  if (n->Opcode() == Op_CmpP) {
+    Node* in1 = n->in(1);
+    Node* in2 = n->in(2);
+    if (in1->bottom_type() == TypePtr::NULL_PTR) {
+      in2 = step_over_gc_barrier(in2);
+    }
+    if (in2->bottom_type() == TypePtr::NULL_PTR) {
+      in1 = step_over_gc_barrier(in1);
+    }
+    PhaseIterGVN* igvn = phase->is_IterGVN();
+    if (in1 != n->in(1)) {
+      if (igvn != NULL) {
+        n->set_req_X(1, in1, igvn);
+      } else {
+        n->set_req(1, in1);
+      }
+      assert(in2 == n->in(2), "only one change");
+      return n;
+    }
+    if (in2 != n->in(2)) {
+      if (igvn != NULL) {
+        n->set_req_X(2, in2, igvn);
+      } else {
+        n->set_req(2, in2);
+      }
+      return n;
+    }
+  } else if (can_reshape &&
       n->Opcode() == Op_If &&
       ShenandoahBarrierC2Support::is_heap_stable_test(n) &&
       n->in(0) != NULL) {
     Node* dom = n->in(0);
     Node* prev_dom = n;