304                              Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
305                              intx prefetch_lines) const;
306 
307   virtual Node* ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const { return nullptr; }
308 
309   // These are general helper methods used by C2
310   enum ArrayCopyPhase {
311     Parsing,
312     Optimization,
313     Expansion
314   };
315 
316   virtual bool array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, bool is_clone_instance, ArrayCopyPhase phase) const { return false; }
317   virtual void clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const;
318 
319   // Support for GC barriers emitted during parsing
320   virtual bool has_load_barrier_nodes() const { return false; }
321   virtual bool is_gc_pre_barrier_node(Node* node) const { return false; }
322   virtual bool is_gc_barrier_node(Node* node) const { return false; }
323   virtual Node* step_over_gc_barrier(Node* c) const { return c; }

324 
325   // Support for macro expanded GC barriers
326   virtual void register_potential_barrier_node(Node* node) const { }
327   virtual void unregister_potential_barrier_node(Node* node) const { }
328   virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
329   virtual void eliminate_gc_barrier_data(Node* node) const { }
330   virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
331   virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {}
332 
333   // Allow barrier sets to have shared state that is preserved across a compilation unit.
334   // This could for example comprise macro nodes to be expanded during macro expansion.
335   virtual void* create_barrier_state(Arena* comp_arena) const { return nullptr; }
336   // If the BarrierSetC2 state has barrier nodes in its compilation
337   // unit state to be expanded later, then now is the time to do so.
338   virtual bool expand_barriers(Compile* C, PhaseIterGVN& igvn) const { return false; }
339   virtual bool optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const { return false; }
340   virtual bool strip_mined_loops_expanded(LoopOptsMode mode) const { return false; }
341   virtual bool is_gc_specific_loop_opts_pass(LoopOptsMode mode) const { return false; }
342   // Estimated size of the node barrier in number of C2 Ideal nodes.
343   // This is used to guide heuristics in C2, e.g. whether to unroll a loop.

304                              Node*& fast_oop_ctrl, Node*& fast_oop_rawmem,
305                              intx prefetch_lines) const;
306 
307   virtual Node* ideal_node(PhaseGVN* phase, Node* n, bool can_reshape) const { return nullptr; }
308 
309   // These are general helper methods used by C2
310   enum ArrayCopyPhase {
311     Parsing,
312     Optimization,
313     Expansion
314   };
315 
316   virtual bool array_copy_requires_gc_barriers(bool tightly_coupled_alloc, BasicType type, bool is_clone, bool is_clone_instance, ArrayCopyPhase phase) const { return false; }
317   virtual void clone_at_expansion(PhaseMacroExpand* phase, ArrayCopyNode* ac) const;
318 
319   // Support for GC barriers emitted during parsing
320   virtual bool has_load_barrier_nodes() const { return false; }
321   virtual bool is_gc_pre_barrier_node(Node* node) const { return false; }
322   virtual bool is_gc_barrier_node(Node* node) const { return false; }
323   virtual Node* step_over_gc_barrier(Node* c) const { return c; }
324   virtual int reserved_slots() const { return 0; }
325 
326   // Support for macro expanded GC barriers
327   virtual void register_potential_barrier_node(Node* node) const { }
328   virtual void unregister_potential_barrier_node(Node* node) const { }
329   virtual void eliminate_gc_barrier(PhaseMacroExpand* macro, Node* node) const { }
330   virtual void eliminate_gc_barrier_data(Node* node) const { }
331   virtual void enqueue_useful_gc_barrier(PhaseIterGVN* igvn, Node* node) const {}
332   virtual void eliminate_useless_gc_barriers(Unique_Node_List &useful, Compile* C) const {}
333 
334   // Allow barrier sets to have shared state that is preserved across a compilation unit.
335   // This could for example comprise macro nodes to be expanded during macro expansion.
336   virtual void* create_barrier_state(Arena* comp_arena) const { return nullptr; }
337   // If the BarrierSetC2 state has barrier nodes in its compilation
338   // unit state to be expanded later, then now is the time to do so.
339   virtual bool expand_barriers(Compile* C, PhaseIterGVN& igvn) const { return false; }
340   virtual bool optimize_loops(PhaseIdealLoop* phase, LoopOptsMode mode, VectorSet& visited, Node_Stack& nstack, Node_List& worklist) const { return false; }
341   virtual bool strip_mined_loops_expanded(LoopOptsMode mode) const { return false; }
342   virtual bool is_gc_specific_loop_opts_pass(LoopOptsMode mode) const { return false; }
343   // Estimated size of the node barrier in number of C2 Ideal nodes.
344   // This is used to guide heuristics in C2, e.g. whether to unroll a loop.