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*/
// Base class for range check elimination class RangeCheckElimination : AllStatic { public: staticvoid eliminate(IR *ir);
};
// Implementation class RangeCheckEliminator { private: int _number_of_instructions; bool _optimistic; // Insert predicates and deoptimize when they fail
IR *_ir;
public: // Bounds for an instruction in the form x + c which c integer // constant and x another instruction class Bound : public CompilationResourceObj { private: int _upper;
Value _upper_instr; int _lower;
Value _lower_instr;
public:
Bound();
Bound(Value v);
Bound(Instruction::Condition cond, Value v, int constant = 0);
Bound(int lower, Value lower_instr, int upper, Value upper_instr);
~Bound();
#ifdef ASSERT void add_assertion(Instruction *instruction, Instruction *position, int i, Value instr, Instruction::Condition cond); #endif int upper();
Value upper_instr(); int lower();
Value lower_instr(); void print(); bool check_no_overflow(int const_value); void or_op(Bound *b); void and_op(Bound *b); bool has_upper(); bool has_lower(); void set_upper(int upper, Value upper_instr); void set_lower(int lower, Value lower_instr); bool is_smaller(Bound *b); void remove_upper(); void remove_lower(); void add_constant(int value);
Bound *copy();
};
class Visitor : public InstructionVisitor { private:
Bound *_bound;
RangeCheckEliminator *_rce;
class AccessIndexedInfo : public CompilationResourceObj { public:
AccessIndexedList *_list; int _min; int _max;
};
typedef GrowableArray<AccessIndexedInfo*> AccessIndexedInfoArray;
BoundMap _bounds; // Mapping from Instruction's id to current bound
AccessIndexedInfoArray _access_indexed_info; // Mapping from Instruction's id to AccessIndexedInfo for in block motion
Visitor _visitor;
public:
RangeCheckEliminator(IR *ir);
IR *ir() const { return _ir; }
// Pass over the dominator tree to identify blocks where there's an oppportunity for optimization bool set_process_block_flags(BlockBegin *block); // The core of the optimization work: pass over the dominator tree // to propagate bound information, insert predicate out of loops, // eliminate bound checks when possible and perform in block motion void calc_bounds(BlockBegin *block, BlockBegin *loop_header); // reorder bound checks within a block in order to eliminate some of them void in_block_motion(BlockBegin *block, AccessIndexedList &accessIndexed, InstructionList &arrays);
// update/access current bound void update_bound(IntegerStack &pushed, Value v, Instruction::Condition cond, Value value, int constant); void update_bound(IntegerStack &pushed, Value v, Bound *bound);
Bound *get_bound(Value v);
bool loop_invariant(BlockBegin *loop_header, Instruction *instruction); // check for loop invariance void add_access_indexed_info(InstructionList &indices, int i, Value instruction, AccessIndexed *ai); // record indexed access for in block motion void remove_range_check(AccessIndexed *ai); // Mark this instructions as not needing a range check void add_if_condition(IntegerStack &pushed, Value x, Value y, Instruction::Condition condition); // Update bound for an If bool in_array_bound(Bound *bound, Value array); // Check whether bound is known to fall within array
// helper functions to work with predicates
Instruction* insert_after(Instruction* insert_position, Instruction* instr, int bci);
Instruction* predicate(Instruction* left, Instruction::Condition cond, Instruction* right, ValueStack* state, Instruction *insert_position, int bci=-1);
Instruction* predicate_cmp_with_const(Instruction* instr, Instruction::Condition cond, int constant, ValueStack* state, Instruction *insert_position, int bci=1);
Instruction* predicate_add(Instruction* left, int left_const, Instruction::Condition cond, Instruction* right, ValueStack* state, Instruction *insert_position, int bci=-1);
Instruction* predicate_add_cmp_with_const(Instruction* left, int left_const, Instruction::Condition cond, int constant, ValueStack* state, Instruction *insert_position, int bci=-1);
void insert_deoptimization(ValueStack *state, Instruction *insert_position, Instruction *array_instr, // Add predicate
Instruction *length_instruction, Instruction *lower_instr, int lower,
Instruction *upper_instr, int upper, AccessIndexed *ai); bool is_ok_for_deoptimization(Instruction *insert_position, Instruction *array_instr, // Can we safely add a predicate?
Instruction *length_instr, Instruction *lower_instr, int lower, Instruction *upper_instr, int upper); void process_if(IntegerStack &pushed, BlockBegin *block, If *cond); // process If Instruction void process_access_indexed(BlockBegin *loop_header, BlockBegin *block, AccessIndexed *ai); // process indexed access
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