8077504: Unsafe load can loose control dependency and cause crash

Summary: Node::depends_only_on_test() should return false for Unsafe loads
Reviewed-by: kvn, adinn

src/share/vm/opto/graphKit.cpp

@@ -1452,18 +1452,18 @@ void GraphKit::set_all_memory_call(Node* call, bool separate_io_proj) {
 // factory methods in "int adr_idx"
 Node* GraphKit::make_load(Node* ctl, Node* adr, const Type* t, BasicType bt,
                           int adr_idx,
-                          MemNode::MemOrd mo, bool require_atomic_access) {
+                          MemNode::MemOrd mo, LoadNode::ControlDependency control_dependency, bool require_atomic_access) {
   assert(adr_idx != Compile::AliasIdxTop, "use other make_load factory" );
   const TypePtr* adr_type = NULL; // debug-mode-only argument
   debug_only(adr_type = C->get_adr_type(adr_idx));
   Node* mem = memory(adr_idx);
   Node* ld;
   if (require_atomic_access && bt == T_LONG) {
-    ld = LoadLNode::make_atomic(C, ctl, mem, adr, adr_type, t, mo);
+    ld = LoadLNode::make_atomic(C, ctl, mem, adr, adr_type, t, mo, control_dependency);
   } else if (require_atomic_access && bt == T_DOUBLE) {
-    ld = LoadDNode::make_atomic(C, ctl, mem, adr, adr_type, t, mo);
+    ld = LoadDNode::make_atomic(C, ctl, mem, adr, adr_type, t, mo, control_dependency);
   } else {
-    ld = LoadNode::make(_gvn, ctl, mem, adr, adr_type, t, bt, mo);
+    ld = LoadNode::make(_gvn, ctl, mem, adr, adr_type, t, bt, mo, control_dependency);
   }
   ld = _gvn.transform(ld);
   if ((bt == T_OBJECT) && C->do_escape_analysis() || C->eliminate_boxing()) {

src/share/vm/opto/graphKit.hpp

@@ -516,21 +516,24 @@ class GraphKit : public Phase {
   // adapted the `do_put_xxx' and `do_get_xxx' procedures for the case
   // of volatile fields.
   Node* make_load(Node* ctl, Node* adr, const Type* t, BasicType bt,
-                  MemNode::MemOrd mo, bool require_atomic_access = false) {
+                  MemNode::MemOrd mo, LoadNode::ControlDependency control_dependency = LoadNode::DependsOnlyOnTest,
+                  bool require_atomic_access = false) {
     // This version computes alias_index from bottom_type
     return make_load(ctl, adr, t, bt, adr->bottom_type()->is_ptr(),
-                     mo, require_atomic_access);
+                     mo, control_dependency, require_atomic_access);
   }
   Node* make_load(Node* ctl, Node* adr, const Type* t, BasicType bt, const TypePtr* adr_type,
-                  MemNode::MemOrd mo, bool require_atomic_access = false) {
+                  MemNode::MemOrd mo, LoadNode::ControlDependency control_dependency = LoadNode::DependsOnlyOnTest,
+                  bool require_atomic_access = false) {
     // This version computes alias_index from an address type
     assert(adr_type != NULL, "use other make_load factory");
     return make_load(ctl, adr, t, bt, C->get_alias_index(adr_type),
-                     mo, require_atomic_access);
+                     mo, control_dependency, require_atomic_access);
   }
   // This is the base version which is given an alias index.
   Node* make_load(Node* ctl, Node* adr, const Type* t, BasicType bt, int adr_idx,
-                  MemNode::MemOrd mo, bool require_atomic_access = false);
+                  MemNode::MemOrd mo, LoadNode::ControlDependency control_dependency = LoadNode::DependsOnlyOnTest,
+                  bool require_atomic_access = false);
 
   // Create & transform a StoreNode and store the effect into the
   // parser's memory state.

src/share/vm/opto/library_call.cpp

@@ -2669,7 +2669,9 @@ bool LibraryCallKit::inline_unsafe_access(bool is_native_ptr, bool is_store, Bas
 
   if (!is_store) {
     MemNode::MemOrd mo = is_volatile ? MemNode::acquire : MemNode::unordered;
-    Node* p = make_load(control(), adr, value_type, type, adr_type, mo, is_volatile);
+    // To be valid, unsafe loads may depend on other conditions than
+    // the one that guards them: pin the Load node
+    Node* p = make_load(control(), adr, value_type, type, adr_type, mo, LoadNode::Pinned, is_volatile);
     // load value
     switch (type) {
     case T_BOOLEAN:
@@ -6038,7 +6040,7 @@ Node * LibraryCallKit::load_field_from_object(Node * fromObj, const char * field
   }
   // Build the load.
   MemNode::MemOrd mo = is_vol ? MemNode::acquire : MemNode::unordered;
-  Node* loadedField = make_load(NULL, adr, type, bt, adr_type, mo, is_vol);
+  Node* loadedField = make_load(NULL, adr, type, bt, adr_type, mo, LoadNode::DependsOnlyOnTest, is_vol);
   // If reference is volatile, prevent following memory ops from
   // floating up past the volatile read.  Also prevents commoning
   // another volatile read.

src/share/vm/opto/loopPredicate.cpp

@@ -438,7 +438,13 @@ class Invariance : public StackObj {
           }
         }
         if (all_inputs_invariant) {
-          _invariant.set(n->_idx); // I am a invariant too
+          // If n's control is a predicate that was moved out of the
+          // loop, it was marked invariant but n is only invariant if
+          // it depends only on that test. Otherwise, unless that test
+          // is out of the loop, it's not invariant.
+          if (n->is_CFG() || n->depends_only_on_test() || n->in(0) == NULL || !_phase->is_member(_lpt, n->in(0))) {
+            _invariant.set(n->_idx); // I am a invariant too
+          }
         }
       } else { // process next input
         _stack.set_index(idx + 1);

src/share/vm/opto/matcher.cpp

@@ -840,7 +840,7 @@ void Matcher::init_spill_mask( Node *ret ) {
   MachNode *spillCP = match_tree(new (C) LoadNNode(NULL,mem,fp,atp,TypeInstPtr::BOTTOM,MemNode::unordered));
 #endif
   MachNode *spillI  = match_tree(new (C) LoadINode(NULL,mem,fp,atp,TypeInt::INT,MemNode::unordered));
-  MachNode *spillL  = match_tree(new (C) LoadLNode(NULL,mem,fp,atp,TypeLong::LONG,MemNode::unordered,false));
+  MachNode *spillL  = match_tree(new (C) LoadLNode(NULL,mem,fp,atp,TypeLong::LONG,MemNode::unordered, LoadNode::DependsOnlyOnTest,false));
   MachNode *spillF  = match_tree(new (C) LoadFNode(NULL,mem,fp,atp,Type::FLOAT,MemNode::unordered));
   MachNode *spillD  = match_tree(new (C) LoadDNode(NULL,mem,fp,atp,Type::DOUBLE,MemNode::unordered));
   MachNode *spillP  = match_tree(new (C) LoadPNode(NULL,mem,fp,atp,TypeInstPtr::BOTTOM,MemNode::unordered));

src/share/vm/opto/memnode.cpp

@@ -878,6 +878,9 @@ void LoadNode::dump_spec(outputStream *st) const {
     // standard dump does this in Verbose and WizardMode
     st->print(" #"); _type->dump_on(st);
   }
+  if (!_depends_only_on_test) {
+    st->print(" (does not depend only on test)");
+  }
 }
 #endif
 
@@ -894,7 +897,7 @@ bool LoadNode::is_immutable_value(Node* adr) {
 
 //----------------------------LoadNode::make-----------------------------------
 // Polymorphic factory method:
-Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo) {
+Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypePtr* adr_type, const Type *rt, BasicType bt, MemOrd mo, ControlDependency control_dependency) {
   Compile* C = gvn.C;
 
   // sanity check the alias category against the created node type
@@ -910,39 +913,39 @@ Node *LoadNode::make(PhaseGVN& gvn, Node *ctl, Node *mem, Node *adr, const TypeP
           rt->isa_oopptr() || is_immutable_value(adr),
           "raw memory operations should have control edge");
   switch (bt) {
-  case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo);
-  case T_BYTE:    return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo);
-  case T_INT:     return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo);
-  case T_CHAR:    return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo);
-  case T_SHORT:   return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo);
-  case T_LONG:    return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo);
-  case T_FLOAT:   return new (C) LoadFNode (ctl, mem, adr, adr_type, rt,            mo);
-  case T_DOUBLE:  return new (C) LoadDNode (ctl, mem, adr, adr_type, rt,            mo);
-  case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo);
+  case T_BOOLEAN: return new (C) LoadUBNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency);
+  case T_BYTE:    return new (C) LoadBNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency);
+  case T_INT:     return new (C) LoadINode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency);
+  case T_CHAR:    return new (C) LoadUSNode(ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency);
+  case T_SHORT:   return new (C) LoadSNode (ctl, mem, adr, adr_type, rt->is_int(),  mo, control_dependency);
+  case T_LONG:    return new (C) LoadLNode (ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency);
+  case T_FLOAT:   return new (C) LoadFNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency);
+  case T_DOUBLE:  return new (C) LoadDNode (ctl, mem, adr, adr_type, rt,            mo, control_dependency);
+  case T_ADDRESS: return new (C) LoadPNode (ctl, mem, adr, adr_type, rt->is_ptr(),  mo, control_dependency);
   case T_OBJECT:
 #ifdef _LP64
     if (adr->bottom_type()->is_ptr_to_narrowoop()) {
-      Node* load  = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo));
+      Node* load  = gvn.transform(new (C) LoadNNode(ctl, mem, adr, adr_type, rt->make_narrowoop(), mo, control_dependency));
       return new (C) DecodeNNode(load, load->bottom_type()->make_ptr());
     } else
 #endif
     {
       assert(!adr->bottom_type()->is_ptr_to_narrowoop() && !adr->bottom_type()->is_ptr_to_narrowklass(), "should have got back a narrow oop");
-      return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo);
+      return new (C) LoadPNode(ctl, mem, adr, adr_type, rt->is_oopptr(), mo, control_dependency);
     }
   }
   ShouldNotReachHere();
   return (LoadNode*)NULL;
 }
 
-LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
+LoadLNode* LoadLNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
   bool require_atomic = true;
-  return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, require_atomic);
+  return new (C) LoadLNode(ctl, mem, adr, adr_type, rt->is_long(), mo, control_dependency, require_atomic);
 }
 
-LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo) {
+LoadDNode* LoadDNode::make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type, const Type* rt, MemOrd mo, ControlDependency control_dependency) {
   bool require_atomic = true;
-  return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, require_atomic);
+  return new (C) LoadDNode(ctl, mem, adr, adr_type, rt, mo, control_dependency, require_atomic);
 }
 
 

src/share/vm/opto/memnode.hpp

@@ -138,7 +138,33 @@ public:
 //------------------------------LoadNode---------------------------------------
 // Load value; requires Memory and Address
 class LoadNode : public MemNode {
+public:
+  // Some loads (from unsafe) should be pinned: they don't depend only
+  // on the dominating test.  The boolean field _depends_only_on_test
+  // below records whether that node depends only on the dominating
+  // test.
+  // Methods used to build LoadNodes pass an argument of type enum
+  // ControlDependency instead of a boolean because those methods
+  // typically have multiple boolean parameters with default values:
+  // passing the wrong boolean to one of these parameters by mistake
+  // goes easily unnoticed. Using an enum, the compiler can check that
+  // the type of a value and the type of the parameter match.
+  enum ControlDependency {
+    Pinned,
+    DependsOnlyOnTest
+  };
 private:
+  // LoadNode::hash() doesn't take the _depends_only_on_test field
+  // into account: If the graph already has a non-pinned LoadNode and
+  // we add a pinned LoadNode with the same inputs, it's safe for GVN
+  // to replace the pinned LoadNode with the non-pinned LoadNode,
+  // otherwise it wouldn't be safe to have a non pinned LoadNode with
+  // those inputs in the first place. If the graph already has a
+  // pinned LoadNode and we add a non pinned LoadNode with the same
+  // inputs, it's safe (but suboptimal) for GVN to replace the
+  // non-pinned LoadNode by the pinned LoadNode.
+  bool _depends_only_on_test;
+
   // On platforms with weak memory ordering (e.g., PPC, Ia64) we distinguish
   // loads that can be reordered, and such requiring acquire semantics to
   // adhere to the Java specification.  The required behaviour is stored in
@@ -153,8 +179,8 @@ protected:
   const Type* const _type;      // What kind of value is loaded?
 public:
 
-  LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo)
-    : MemNode(c,mem,adr,at), _type(rt), _mo(mo) {
+  LoadNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *rt, MemOrd mo, ControlDependency control_dependency)
+    : MemNode(c,mem,adr,at), _type(rt), _mo(mo), _depends_only_on_test(control_dependency == DependsOnlyOnTest) {
     init_class_id(Class_Load);
   }
   inline bool is_unordered() const { return !is_acquire(); }
@@ -165,7 +191,8 @@ public:
 
   // Polymorphic factory method:
    static Node* make(PhaseGVN& gvn, Node *c, Node *mem, Node *adr,
-                     const TypePtr* at, const Type *rt, BasicType bt, MemOrd mo);
+                     const TypePtr* at, const Type *rt, BasicType bt,
+                     MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
 
   virtual uint hash()   const;  // Check the type
 
@@ -233,16 +260,15 @@ protected:
   // which produce results (new raw memory state) inside of loops preventing all
   // manner of other optimizations).  Basically, it's ugly but so is the alternative.
   // See comment in macro.cpp, around line 125 expand_allocate_common().
-  virtual bool depends_only_on_test() const { return adr_type() != TypeRawPtr::BOTTOM; }
-
+  virtual bool depends_only_on_test() const { return adr_type() != TypeRawPtr::BOTTOM && _depends_only_on_test; }
 };
 
 //------------------------------LoadBNode--------------------------------------
 // Load a byte (8bits signed) from memory
 class LoadBNode : public LoadNode {
 public:
-  LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo)
-    : LoadNode(c, mem, adr, at, ti, mo) {}
+  LoadBNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
@@ -255,8 +281,8 @@ public:
 // Load a unsigned byte (8bits unsigned) from memory
 class LoadUBNode : public LoadNode {
 public:
-  LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo)
-    : LoadNode(c, mem, adr, at, ti, mo) {}
+  LoadUBNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeInt* ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node* Ideal(PhaseGVN *phase, bool can_reshape);
@@ -269,8 +295,8 @@ public:
 // Load an unsigned short/char (16bits unsigned) from memory
 class LoadUSNode : public LoadNode {
 public:
-  LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo)
-    : LoadNode(c, mem, adr, at, ti, mo) {}
+  LoadUSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
@@ -283,8 +309,8 @@ public:
 // Load a short (16bits signed) from memory
 class LoadSNode : public LoadNode {
 public:
-  LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo)
-    : LoadNode(c, mem, adr, at, ti, mo) {}
+  LoadSNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual Node *Ideal(PhaseGVN *phase, bool can_reshape);
@@ -297,8 +323,8 @@ public:
 // Load an integer from memory
 class LoadINode : public LoadNode {
 public:
-  LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo)
-    : LoadNode(c, mem, adr, at, ti, mo) {}
+  LoadINode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeInt *ti, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, ti, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegI; }
   virtual int store_Opcode() const { return Op_StoreI; }
@@ -330,15 +356,15 @@ class LoadLNode : public LoadNode {
 
 public:
   LoadLNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const TypeLong *tl,
-            MemOrd mo, bool require_atomic_access = false)
-    : LoadNode(c, mem, adr, at, tl, mo), _require_atomic_access(require_atomic_access) {}
+            MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
+    : LoadNode(c, mem, adr, at, tl, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegL; }
   virtual int store_Opcode() const { return Op_StoreL; }
   virtual BasicType memory_type() const { return T_LONG; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static LoadLNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
-                                const Type* rt, MemOrd mo);
+                                const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     LoadNode::dump_spec(st);
@@ -351,8 +377,8 @@ public:
 // Load a long from unaligned memory
 class LoadL_unalignedNode : public LoadLNode {
 public:
-  LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo)
-    : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo) {}
+  LoadL_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadLNode(c, mem, adr, at, TypeLong::LONG, mo, control_dependency) {}
   virtual int Opcode() const;
 };
 
@@ -360,8 +386,8 @@ public:
 // Load a float (64 bits) from memory
 class LoadFNode : public LoadNode {
 public:
-  LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo)
-    : LoadNode(c, mem, adr, at, t, mo) {}
+  LoadFNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegF; }
   virtual int store_Opcode() const { return Op_StoreF; }
@@ -381,15 +407,15 @@ class LoadDNode : public LoadNode {
 
 public:
   LoadDNode(Node *c, Node *mem, Node *adr, const TypePtr* at, const Type *t,
-            MemOrd mo, bool require_atomic_access = false)
-    : LoadNode(c, mem, adr, at, t, mo), _require_atomic_access(require_atomic_access) {}
+            MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest, bool require_atomic_access = false)
+    : LoadNode(c, mem, adr, at, t, mo, control_dependency), _require_atomic_access(require_atomic_access) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegD; }
   virtual int store_Opcode() const { return Op_StoreD; }
   virtual BasicType memory_type() const { return T_DOUBLE; }
   bool require_atomic_access() const { return _require_atomic_access; }
   static LoadDNode* make_atomic(Compile *C, Node* ctl, Node* mem, Node* adr, const TypePtr* adr_type,
-                                const Type* rt, MemOrd mo);
+                                const Type* rt, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest);
 #ifndef PRODUCT
   virtual void dump_spec(outputStream *st) const {
     LoadNode::dump_spec(st);
@@ -402,8 +428,8 @@ public:
 // Load a double from unaligned memory
 class LoadD_unalignedNode : public LoadDNode {
 public:
-  LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo)
-    : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo) {}
+  LoadD_unalignedNode(Node *c, Node *mem, Node *adr, const TypePtr* at, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadDNode(c, mem, adr, at, Type::DOUBLE, mo, control_dependency) {}
   virtual int Opcode() const;
 };
 
@@ -411,8 +437,8 @@ public:
 // Load a pointer from memory (either object or array)
 class LoadPNode : public LoadNode {
 public:
-  LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo)
-    : LoadNode(c, mem, adr, at, t, mo) {}
+  LoadPNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const TypePtr* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegP; }
   virtual int store_Opcode() const { return Op_StoreP; }
@@ -424,8 +450,8 @@ public:
 // Load a narrow oop from memory (either object or array)
 class LoadNNode : public LoadNode {
 public:
-  LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo)
-    : LoadNode(c, mem, adr, at, t, mo) {}
+  LoadNNode(Node *c, Node *mem, Node *adr, const TypePtr *at, const Type* t, MemOrd mo, ControlDependency control_dependency = DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, t, mo, control_dependency) {}
   virtual int Opcode() const;
   virtual uint ideal_reg() const { return Op_RegN; }
   virtual int store_Opcode() const { return Op_StoreN; }

src/share/vm/opto/parse3.cpp

@@ -233,7 +233,7 @@ void Parse::do_get_xxx(Node* obj, ciField* field, bool is_field) {
   // Build the load.
   //
   MemNode::MemOrd mo = is_vol ? MemNode::acquire : MemNode::unordered;
-  Node* ld = make_load(NULL, adr, type, bt, adr_type, mo, is_vol);
+  Node* ld = make_load(NULL, adr, type, bt, adr_type, mo, LoadNode::DependsOnlyOnTest, is_vol);
 
   // Adjust Java stack
   if (type2size[bt] == 1)

src/share/vm/opto/superword.cpp

@@ -1431,7 +1431,7 @@ void SuperWord::output() {
         }
         Node* adr = low_adr->in(MemNode::Address);
         const TypePtr* atyp = n->adr_type();
-        vn = LoadVectorNode::make(C, opc, ctl, mem, adr, atyp, vlen, velt_basic_type(n));
+        vn = LoadVectorNode::make(C, opc, ctl, mem, adr, atyp, vlen, velt_basic_type(n), control_dependency(p));
         vlen_in_bytes = vn->as_LoadVector()->memory_size();
       } else if (n->is_Store()) {
         // Promote value to be stored to vector
@@ -2029,6 +2029,19 @@ Node* SuperWord::executed_last(Node_List* p) {
   return n;
 }
 
+LoadNode::ControlDependency SuperWord::control_dependency(Node_List* p) {
+  LoadNode::ControlDependency dep = LoadNode::DependsOnlyOnTest;
+  for (uint i = 0; i < p->size(); i++) {
+    Node* n = p->at(i);
+    assert(n->is_Load(), "only meaningful for loads");
+    if (!n->depends_only_on_test()) {
+      dep = LoadNode::Pinned;
+    }
+  }
+  return dep;
+}
+
+
 //----------------------------align_initial_loop_index---------------------------
 // Adjust pre-loop limit so that in main loop, a load/store reference
 // to align_to_ref will be a position zero in the vector.

src/share/vm/opto/superword.hpp

@@ -399,6 +399,7 @@ class SuperWord : public ResourceObj {
   Node* executed_first(Node_List* p);
   // Return the node executed last in pack p.
   Node* executed_last(Node_List* p);
+  static LoadNode::ControlDependency control_dependency(Node_List* p);
   // Alignment within a vector memory reference
   int memory_alignment(MemNode* s, int iv_adjust);
   // (Start, end] half-open range defining which operands are vector

src/share/vm/opto/vectornode.cpp

@@ -403,9 +403,10 @@ PackNode* PackNode::binary_tree_pack(Compile* C, int lo, int hi) {
 
 // Return the vector version of a scalar load node.
 LoadVectorNode* LoadVectorNode::make(Compile* C, int opc, Node* ctl, Node* mem,
-                                     Node* adr, const TypePtr* atyp, uint vlen, BasicType bt) {
+                                     Node* adr, const TypePtr* atyp, uint vlen, BasicType bt,
+                                     ControlDependency control_dependency) {
   const TypeVect* vt = TypeVect::make(bt, vlen);
-  return new (C) LoadVectorNode(ctl, mem, adr, atyp, vt);
+  return new (C) LoadVectorNode(ctl, mem, adr, atyp, vt, control_dependency);
 }
 
 // Return the vector version of a scalar store node.

src/share/vm/opto/vectornode.hpp

@@ -355,8 +355,8 @@ class XorVNode : public VectorNode {
 // Load Vector from memory
 class LoadVectorNode : public LoadNode {
  public:
-  LoadVectorNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeVect* vt)
-    : LoadNode(c, mem, adr, at, vt, MemNode::unordered) {
+  LoadVectorNode(Node* c, Node* mem, Node* adr, const TypePtr* at, const TypeVect* vt, ControlDependency control_dependency = LoadNode::DependsOnlyOnTest)
+    : LoadNode(c, mem, adr, at, vt, MemNode::unordered, control_dependency) {
     init_class_id(Class_LoadVector);
   }
 
@@ -372,7 +372,8 @@ class LoadVectorNode : public LoadNode {
   virtual int store_Opcode() const { return Op_StoreVector; }
 
   static LoadVectorNode* make(Compile* C, int opc, Node* ctl, Node* mem,
-                              Node* adr, const TypePtr* atyp, uint vlen, BasicType bt);
+                              Node* adr, const TypePtr* atyp, uint vlen, BasicType bt,
+                              ControlDependency control_dependency = LoadNode::DependsOnlyOnTest);
 };
 
 //------------------------------StoreVectorNode--------------------------------

test/compiler/unsafe/TestUnsafeLoadControl.java

+/*
+ * Copyright (c) 2015, Oracle and/or its affiliates. All rights reserved.
+ * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ */
+
+/*
+ * @test
+ * @bug 8077504
+ * @summary Unsafe load can loose control dependency and cause crash
+ * @run main/othervm -XX:-BackgroundCompilation -XX:-UseOnStackReplacement TestUnsafeLoadControl
+ *
+ */
+
+import java.lang.reflect.Field;
+import sun.misc.Unsafe;
+
+public class TestUnsafeLoadControl {
+
+    private static final Unsafe UNSAFE;
+
+    static {
+        try {
+            Field unsafeField = Unsafe.class.getDeclaredField("theUnsafe");
+            unsafeField.setAccessible(true);
+            UNSAFE = (Unsafe) unsafeField.get(null);
+        } catch(Exception e) {
+            throw new RuntimeException(e);
+        }
+    }
+
+    static int val;
+    static void test1(int[] a, boolean[] flags, boolean flag, long j) {
+        for (int i = 0; i < 10; i++) {
+            if (flags[i]) {
+                if (flag) {
+                    long address = (j << 2) + UNSAFE.ARRAY_INT_BASE_OFFSET;
+                    int v = UNSAFE.getInt(a, address);
+                    val = v;
+                }
+            }
+        }
+    }
+
+    static int test2(int[] a, boolean[] flags, boolean flag, long j) {
+        int sum = 0;
+        for (int i = 0; i < 10; i++) {
+            if (flags[i]) {
+                if (flag) {
+                    long address = (j << 2) + UNSAFE.ARRAY_INT_BASE_OFFSET;
+                    int v = UNSAFE.getInt(a, address);
+                    if (v == 0) {
+                        sum++;
+                    }
+                }
+            }
+        }
+        return sum;
+    }
+
+    static public void main(String[] args) {
+        boolean[] flags = new boolean[10];
+        for (int i = 0; i < flags.length; i++) {
+            flags[i] = true;
+        }
+        int[] array = new int[10];
+        for (int i = 0; i < 20000; i++) {
+            test1(array, flags, true, 0);
+        }
+        for (int i = 0; i < flags.length; i++) {
+            flags[i] = false;
+        }
+        test1(array, flags, true, Long.MAX_VALUE/4);
+
+        for (int i = 0; i < flags.length; i++) {
+            flags[i] = true;
+        }
+        for (int i = 0; i < 20000; i++) {
+            test2(array, flags, true, 0);
+        }
+        for (int i = 0; i < flags.length; i++) {
+            flags[i] = false;
+        }
+        test2(array, flags, true, Long.MAX_VALUE/4);
+    }
+}