1 /*
   2  * Copyright (c) 2018, Oracle and/or its affiliates. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
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  23  */
  24 
  25 #ifndef SHARE_GC_SHARED_C2_BARRIERSETC2_HPP
  26 #define SHARE_GC_SHARED_C2_BARRIERSETC2_HPP
  27 
  28 #include "memory/allocation.hpp"
  29 #include "oops/accessDecorators.hpp"
  30 #include "opto/loopnode.hpp"
  31 #include "opto/memnode.hpp"
  32 #include "utilities/globalDefinitions.hpp"
  33 
  34 // This means the access is mismatched. This means the value of an access
  35 // is not equivalent to the value pointed to by the address.
  36 const DecoratorSet C2_MISMATCHED             = DECORATOR_LAST << 1;
  37 // The access may not be aligned to its natural size.
  38 const DecoratorSet C2_UNALIGNED              = DECORATOR_LAST << 2;
  39 // The atomic cmpxchg is weak, meaning that spurious false negatives are allowed,
  40 // but never false positives.
  41 const DecoratorSet C2_WEAK_CMPXCHG           = DECORATOR_LAST << 3;
  42 // This denotes that a load has control dependency.
  43 const DecoratorSet C2_CONTROL_DEPENDENT_LOAD = DECORATOR_LAST << 4;
  44 // This denotes that a load that must be pinned.
  45 const DecoratorSet C2_PINNED_LOAD            = DECORATOR_LAST << 5;
  46 // This denotes that the access is produced from the sun.misc.Unsafe intrinsics.
  47 const DecoratorSet C2_UNSAFE_ACCESS          = DECORATOR_LAST << 6;
  48 // This denotes that the access mutates state.
  49 const DecoratorSet C2_WRITE_ACCESS           = DECORATOR_LAST << 7;
  50 // This denotes that the access reads state.
  51 const DecoratorSet C2_READ_ACCESS            = DECORATOR_LAST << 8;
  52 
  53 class GraphKit;
  54 class IdealKit;
  55 class Node;
  56 class Type;
  57 class TypePtr;
  58 class PhaseMacroExpand;
  59 
  60 // This class wraps a node and a type.
  61 class C2AccessValue: public StackObj {
  62 protected:
  63   Node* _node;
  64   const Type* _type;
  65 
  66 public:
  67   C2AccessValue(Node* node, const Type* type) :
  68     _node(node),
  69     _type(type) {}
  70 
  71   Node* node() const        { return _node; }
  72   const Type* type() const  { return _type; }
  73 
  74   void set_node(Node* node) { _node = node; }
  75 };
  76 
  77 // This class wraps a node and a pointer type.
  78 class C2AccessValuePtr: public C2AccessValue {
  79 
  80 public:
  81   C2AccessValuePtr(Node* node, const TypePtr* type) :
  82     C2AccessValue(node, reinterpret_cast<const Type*>(type)) {}
  83 
  84   const TypePtr* type() const { return reinterpret_cast<const TypePtr*>(_type); }
  85 };
  86 
  87 // This class wraps a bunch of context parameters thare are passed around in the
  88 // BarrierSetC2 backend hierarchy, for loads and stores, to reduce boiler plate.
  89 class C2Access: public StackObj {
  90 protected:
  91   GraphKit*         _kit;
  92   DecoratorSet      _decorators;
  93   BasicType         _type;
  94   Node*             _base;
  95   C2AccessValuePtr& _addr;
  96   Node*             _raw_access;
  97 
  98   void fixup_decorators();
  99   void* barrier_set_state() const;
 100 
 101 public:
 102   C2Access(GraphKit* kit, DecoratorSet decorators,
 103            BasicType type, Node* base, C2AccessValuePtr& addr) :
 104     _kit(kit),
 105     _decorators(decorators),
 106     _type(type),
 107     _base(base),
 108     _addr(addr),
 109     _raw_access(NULL)
 110   {
 111     fixup_decorators();
 112   }
 113 
 114   GraphKit* kit() const           { return _kit; }
 115   DecoratorSet decorators() const { return _decorators; }
 116   Node* base() const              { return _base; }
 117   C2AccessValuePtr& addr() const  { return _addr; }
 118   BasicType type() const          { return _type; }
 119   bool is_oop() const             { return _type == T_OBJECT || _type == T_ARRAY; }
 120   bool is_raw() const             { return (_decorators & AS_RAW) != 0; }
 121   Node* raw_access() const        { return _raw_access; }
 122 
 123   void set_raw_access(Node* raw_access) { _raw_access = raw_access; }
 124   virtual void set_memory() {} // no-op for normal accesses, but not for atomic accesses.
 125 
 126   MemNode::MemOrd mem_node_mo() const;
 127   bool needs_cpu_membar() const;
 128 
 129   template <typename T>
 130   T barrier_set_state_as() const {
 131     return reinterpret_cast<T>(barrier_set_state());
 132   }
 133 };
 134 
 135 // This class wraps a bunch of context parameters thare are passed around in the
 136 // BarrierSetC2 backend hierarchy, for atomic accesses, to reduce boiler plate.
 137 class C2AtomicAccess: public C2Access {
 138   Node* _memory;
 139   uint  _alias_idx;
 140   bool  _needs_pinning;
 141 
 142 public:
 143   C2AtomicAccess(GraphKit* kit, DecoratorSet decorators, BasicType type,
 144                  Node* base, C2AccessValuePtr& addr, uint alias_idx) :
 145     C2Access(kit, decorators, type, base, addr),
 146     _memory(NULL),
 147     _alias_idx(alias_idx),
 148     _needs_pinning(true) {}
 149 
 150   // Set the memory node based on the current memory slice.
 151   virtual void set_memory();
 152 
 153   Node* memory() const       { return _memory; }
 154   uint alias_idx() const     { return _alias_idx; }
 155   bool needs_pinning() const { return _needs_pinning; }
 156 
 157   void set_needs_pinning(bool value)    { _needs_pinning = value; }
 158 };
 159 
 160 // This is the top-level class for the backend of the Access API in C2.
 161 // The top-level class is responsible for performing raw accesses. The
 162 // various GC barrier sets inherit from the BarrierSetC2 class to sprinkle
 163 // barriers into the accesses.
 164 class BarrierSetC2: public CHeapObj<mtGC> {
 165 protected:
 166   virtual void resolve_address(C2Access& access) const;
 167   virtual Node* store_at_resolved(C2Access& access, C2AccessValue& val) const;
 168   virtual Node* load_at_resolved(C2Access& access, const Type* val_type) const;
 169 
 170   virtual Node* atomic_cmpxchg_val_at_resolved(C2AtomicAccess& access, Node* expected_val,
 171                                                Node* new_val, const Type* val_type) const;
 172   virtual Node* atomic_cmpxchg_bool_at_resolved(C2AtomicAccess& access, Node* expected_val,
 173                                                 Node* new_val, const Type* value_type) const;
 174   virtual Node* atomic_xchg_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* val_type) const;
 175   virtual Node* atomic_add_at_resolved(C2AtomicAccess& access, Node* new_val, const Type* val_type) const;
 176   void pin_atomic_op(C2AtomicAccess& access) const;
 177 
 178 public:
 179   // This is the entry-point for the backend to perform accesses through the Access API.
 180   virtual Node* store_at(C2Access& access, C2AccessValue& val) const;
 181   virtual Node* load_at(C2Access& access, const Type* val_type) const;
 182 
 183   virtual Node* atomic_cmpxchg_val_at(C2AtomicAccess& access, Node* expected_val,
 184                                       Node* new_val, const Type* val_type) const;
 185   virtual Node* atomic_cmpxchg_bool_at(C2AtomicAccess& access, Node* expected_val,
 186                                        Node* new_val, const Type* val_type) const;
 187   virtual Node* atomic_xchg_at(C2AtomicAccess& access, Node* new_val, const Type* value_type) const;
 188   virtual Node* atomic_add_at(C2AtomicAccess& access, Node* new_val, const Type* value_type) const;
 189 
 190   virtual void clone(GraphKit* kit, Node* src, Node* dst, Node* size, bool is_array) const;
 191 
 192   virtual Node* resolve(GraphKit* kit, Node* n, DecoratorSet decorators) const { return n; }
 193 
 194   virtual Node* obj_allocate(PhaseMacroExpand* macro, Node* ctrl, Node* mem, Node* toobig_false, Node* size_in_bytes,
 195                              Node*& i_o, Node*& needgc_ctrl,
 196                              Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
 197                              intx prefetch_lines) const;
 198 
 199   // These are general helper methods used by C2
 200   enum ArrayCopyPhase {
 201     Parsing,
 202     Optimization,
 203     Expansion
 204   };
 205   virtual bool array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, ArrayCopyPhase phase) const { return false; }
 206 
 207   // Support for GC barriers emitted during parsing
 208   virtual bool has_load_barriers() const { return false; }
 209   virtual bool is_gc_barrier_node(Node* node) const { return false; }
 210   virtual Node* step_over_gc_barrier(Node* c) const { return c; }
 211 
 212   // Support for macro expanded GC barriers
 213   virtual void register_potential_barrier_node(Node* node) const { }
 214   virtual void unregister_potential_barrier_node(Node* node) const { }
 215   virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
 216   virtual void enqueue_useful_gc_barrier(Unique_Node_List &worklist, Node* node) const {}
 217   virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful) const {}
 218   virtual void add_users_to_worklist(Unique_Node_List* worklist) const {}
 219 
 220   // Allow barrier sets to have shared state that is preserved across a compilation unit.
 221   // This could for example comprise macro nodes to be expanded during macro expansion.
 222   virtual void* create_barrier_state(Arena* comp_arena) const { return NULL; }
 223   // If the BarrierSetC2 state has kept macro nodes in its compilation unit state to be
 224   // expanded later, then now is the time to do so.
 225   virtual bool expand_macro_nodes(PhaseMacroExpand* macro) const { return false; }
 226   virtual void verify_gc_barriers(bool post_parse) const {}
 227 };
 228 
 229 #endif // SHARE_GC_SHARED_C2_BARRIERSETC2_HPP