src/share/vm/c1/c1_ValueMap.cpp

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rev 4136 : 7153771: array bound check elimination for c1
Summary: when possible optimize out array bound checks, inserting predicates when needed.
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*** 24,36 **** #include "precompiled.hpp" #include "c1/c1_Canonicalizer.hpp" #include "c1/c1_IR.hpp" #include "c1/c1_ValueMap.hpp" #include "utilities/bitMap.inline.hpp" - #ifndef PRODUCT int ValueMap::_number_of_finds = 0; int ValueMap::_number_of_hits = 0; int ValueMap::_number_of_kills = 0; --- 24,36 ---- #include "precompiled.hpp" #include "c1/c1_Canonicalizer.hpp" #include "c1/c1_IR.hpp" #include "c1/c1_ValueMap.hpp" + #include "c1/c1_ValueStack.hpp" #include "utilities/bitMap.inline.hpp" #ifndef PRODUCT int ValueMap::_number_of_finds = 0; int ValueMap::_number_of_hits = 0; int ValueMap::_number_of_kills = 0;
*** 190,203 **** LoadField* lf = value->as_LoadField(); \ bool must_kill = lf != NULL \ && lf->field()->holder() == field->holder() \ && (all_offsets || lf->field()->offset() == field->offset()); - #define MUST_KILL_EXCEPTION(must_kill, entry, value) \ - assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \ - bool must_kill = (entry->nesting() == nesting() - 1); - void ValueMap::kill_memory() { GENERIC_KILL_VALUE(MUST_KILL_MEMORY); } --- 190,199 ----
*** 207,221 **** void ValueMap::kill_field(ciField* field, bool all_offsets) { GENERIC_KILL_VALUE(MUST_KILL_FIELD); } - void ValueMap::kill_exception() { - GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION); - } - - void ValueMap::kill_map(ValueMap* map) { assert(is_global_value_numbering(), "only for global value numbering"); _killed_values.set_union(&map->_killed_values); } --- 203,212 ----
*** 272,302 **** class ShortLoopOptimizer : public ValueNumberingVisitor { private: GlobalValueNumbering* _gvn; BlockList _loop_blocks; bool _too_complicated_loop; // simplified access to methods of GlobalValueNumbering ValueMap* current_map() { return _gvn->current_map(); } ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); } // implementation for abstract methods of ValueNumberingVisitor void kill_memory() { _too_complicated_loop = true; } ! void kill_field(ciField* field, bool all_offsets) { current_map()->kill_field(field, all_offsets); }; ! void kill_array(ValueType* type) { current_map()->kill_array(type); }; public: ShortLoopOptimizer(GlobalValueNumbering* gvn) : _gvn(gvn) , _loop_blocks(ValueMapMaxLoopSize) , _too_complicated_loop(false) { } bool process(BlockBegin* loop_header); }; bool ShortLoopOptimizer::process(BlockBegin* loop_header) { TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block")); _too_complicated_loop = false; --- 263,445 ---- class ShortLoopOptimizer : public ValueNumberingVisitor { private: GlobalValueNumbering* _gvn; BlockList _loop_blocks; bool _too_complicated_loop; + bool _has_field_store[T_ARRAY + 1]; + bool _has_indexed_store[T_ARRAY + 1]; // simplified access to methods of GlobalValueNumbering ValueMap* current_map() { return _gvn->current_map(); } ValueMap* value_map_of(BlockBegin* block) { return _gvn->value_map_of(block); } // implementation for abstract methods of ValueNumberingVisitor void kill_memory() { _too_complicated_loop = true; } ! void kill_field(ciField* field, bool all_offsets) { ! current_map()->kill_field(field, all_offsets); ! assert(field->type()->basic_type() >= 0 && field->type()->basic_type() <= T_ARRAY, "Invalid type"); ! _has_field_store[field->type()->basic_type()] = true; ! } ! void kill_array(ValueType* type) { ! current_map()->kill_array(type); ! BasicType basic_type = as_BasicType(type); assert(basic_type >= 0 && basic_type <= T_ARRAY, "Invalid type"); ! _has_indexed_store[basic_type] = true; ! } public: ShortLoopOptimizer(GlobalValueNumbering* gvn) : _gvn(gvn) , _loop_blocks(ValueMapMaxLoopSize) , _too_complicated_loop(false) { + for (int i=0; i<= T_ARRAY; i++){ + _has_field_store[i] = false; + _has_indexed_store[i] = false; + } + } + + bool has_field_store(BasicType type) { + assert(type >= 0 && type <= T_ARRAY, "Invalid type"); + return _has_field_store[type]; + } + + bool has_indexed_store(BasicType type) { + assert(type >= 0 && type <= T_ARRAY, "Invalid type"); + return _has_indexed_store[type]; } bool process(BlockBegin* loop_header); }; + class LoopInvariantCodeMotion : public StackObj { + private: + GlobalValueNumbering* _gvn; + ShortLoopOptimizer* _short_loop_optimizer; + Instruction* _insertion_point; + ValueStack * _state; + + void set_invariant(Value v) const { _gvn->set_processed(v); } + bool is_invariant(Value v) const { return _gvn->is_processed(v); } + + void process_block(BlockBegin* block); + + public: + LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks); + }; + + LoopInvariantCodeMotion::LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks) + : _gvn(gvn), _short_loop_optimizer(slo) + { + + TRACE_VALUE_NUMBERING(tty->print_cr("using loop invariant code motion loop_header = %d", loop_header->block_id())); + TRACE_VALUE_NUMBERING(tty->print_cr("** loop invariant code motion for short loop B%d", loop_header->block_id())); + + BlockBegin* insertion_block = loop_header->dominator(); + if (insertion_block->number_of_preds() == 0) { + return; // only the entry block does not have a predecessor + } + + assert(insertion_block->end()->as_Base() == NULL, "cannot insert into entry block"); + _insertion_point = insertion_block->end()->prev(); + + BlockEnd *block_end = insertion_block->end(); + _state = block_end->state_before(); + + if (!_state) { + // If, TableSwitch and LookupSwitch always have state_before when + // loop invariant code motion happens.. + assert(block_end->as_Goto(), "Block has to be goto"); + _state = block_end->state(); + } + + // the loop_blocks are filled by going backward from the loop header, so this processing order is best + assert(loop_blocks->at(0) == loop_header, "loop header must be first loop block"); + process_block(loop_header); + for (int i = loop_blocks->length() - 1; i >= 1; i--) { + process_block(loop_blocks->at(i)); + } + } + + void LoopInvariantCodeMotion::process_block(BlockBegin* block) { + + TRACE_VALUE_NUMBERING(tty->print_cr("processing block B%d", block->block_id())); + + Instruction* prev = block; + Instruction* cur = block->next(); + + while (cur != NULL) { + + // determine if cur instruction is loop invariant + // only selected instruction types are processed here + bool cur_invariant = false; + + if (cur->as_Constant() != NULL) { + + cur_invariant = !cur->can_trap(); + + } else if (cur->as_ArithmeticOp() != NULL || cur->as_LogicOp() != NULL || cur->as_ShiftOp() != NULL) { + + assert(cur->as_Op2() != NULL, "must be Op2"); + Op2* op2 = (Op2*)cur; + cur_invariant = !op2->can_trap() && is_invariant(op2->x()) && is_invariant(op2->y()); + + } else if (cur->as_LoadField() != NULL) { + + LoadField* lf = (LoadField*)cur; + + // deoptimizes on NullPointerException + cur_invariant = !lf->needs_patching() && !lf->field()->is_volatile() && !_short_loop_optimizer->has_field_store(lf->field()->type()->basic_type()) && is_invariant(lf->obj()); + } else if (cur->as_ArrayLength() != NULL) { + + ArrayLength *length = cur->as_ArrayLength(); + cur_invariant = is_invariant(length->array()); + } else if (cur->as_LoadIndexed() != NULL) { + + LoadIndexed *li = (LoadIndexed *)cur->as_LoadIndexed(); + cur_invariant = (!_short_loop_optimizer->has_indexed_store(li->elt_type())) && (is_invariant(li->array()) && is_invariant(li->index())); + } + + if (cur_invariant) { + + // perform value numbering and mark instruction as loop-invariant + _gvn->substitute(cur); + + if (cur->as_Constant() == NULL) { + // ensure that code for non-constant instructions is always generated + cur->pin(); + } + + // remove cur instruction from loop block and append it to block before loop + Instruction* next = cur->next(); + + Instruction* in = _insertion_point->next(); + _insertion_point = _insertion_point->set_next(cur); + cur->set_next(in); + + // Deoptimize on exception + cur->set_flag(Instruction::DeoptimizeOnException, true); + + // Clear exception handlers + cur->set_exception_handlers(NULL); + + TRACE_VALUE_NUMBERING(tty->print_cr("Instruction %c%d is loop invariant", cur->type()->tchar(), cur->id())); + + if (cur->state_before() != NULL) { + cur->set_state_before(_state->copy()); + } + if (cur->exception_state() != NULL) { + cur->set_exception_state(_state->copy()); + } + + cur = prev->set_next(next); + + } else { + prev = cur; + cur = cur->next(); + } + } + } bool ShortLoopOptimizer::process(BlockBegin* loop_header) { TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block")); _too_complicated_loop = false;
*** 314,323 **** --- 457,470 ---- // add predecessors to worklist for (int j = block->number_of_preds() - 1; j >= 0; j--) { BlockBegin* pred = block->pred_at(j); + if (pred->is_set(BlockBegin::osr_entry_flag)) { + return false; + } + ValueMap* pred_map = value_map_of(pred); if (pred_map != NULL) { current_map()->kill_map(pred_map); } else if (!_loop_blocks.contains(pred)) { if (_loop_blocks.length() >= ValueMapMaxLoopSize) {
*** 334,364 **** return false; } } } TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized")); return true; } GlobalValueNumbering::GlobalValueNumbering(IR* ir) : _current_map(NULL) , _value_maps(ir->linear_scan_order()->length(), NULL) { TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering")); ShortLoopOptimizer short_loop_optimizer(this); - int subst_count = 0; BlockList* blocks = ir->linear_scan_order(); int num_blocks = blocks->length(); BlockBegin* start_block = blocks->at(0); assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block"); assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions"); // initial, empty value map with nesting 0 set_value_map_of(start_block, new ValueMap()); for (int i = 1; i < num_blocks; i++) { BlockBegin* block = blocks->at(i); --- 481,523 ---- return false; } } } + bool optimistic = this->_gvn->compilation()->is_optimistic(); + + if (UseLoopInvariantCodeMotion && optimistic) { + LoopInvariantCodeMotion code_motion(this, _gvn, loop_header, &_loop_blocks); + } + TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized")); return true; } GlobalValueNumbering::GlobalValueNumbering(IR* ir) : _current_map(NULL) , _value_maps(ir->linear_scan_order()->length(), NULL) + , _compilation(ir->compilation()) { TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering")); ShortLoopOptimizer short_loop_optimizer(this); BlockList* blocks = ir->linear_scan_order(); int num_blocks = blocks->length(); BlockBegin* start_block = blocks->at(0); assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block"); assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions"); + // method parameters are not linked in instructions list, so process them separateley + for_each_state_value(start_block->state(), value, + assert(value->as_Local() != NULL, "only method parameters allowed"); + set_processed(value); + ); + // initial, empty value map with nesting 0 set_value_map_of(start_block, new ValueMap()); for (int i = 1; i < num_blocks; i++) { BlockBegin* block = blocks->at(i);
*** 372,382 **** assert(value_map_of(dominator) != NULL, "value map of dominator must exist"); // create new value map with increased nesting _current_map = new ValueMap(value_map_of(dominator)); ! if (num_preds == 1) { assert(dominator == block->pred_at(0), "dominator must be equal to predecessor"); // nothing to do here } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) { // block has incoming backward branches -> try to optimize short loops --- 531,541 ---- assert(value_map_of(dominator) != NULL, "value map of dominator must exist"); // create new value map with increased nesting _current_map = new ValueMap(value_map_of(dominator)); ! if (num_preds == 1 && !block->is_set(BlockBegin::exception_entry_flag)) { assert(dominator == block->pred_at(0), "dominator must be equal to predecessor"); // nothing to do here } else if (block->is_set(BlockBegin::linear_scan_loop_header_flag)) { // block has incoming backward branches -> try to optimize short loops
*** 401,438 **** current_map()->kill_memory(); } } } ! if (block->is_set(BlockBegin::exception_entry_flag)) { ! current_map()->kill_exception(); ! } TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print()); // visit all instructions of this block for (Value instr = block->next(); instr != NULL; instr = instr->next()) { - assert(!instr->has_subst(), "substitution already set"); - // check if instruction kills any values instr->visit(this); ! ! if (instr->hash() != 0) { ! Value f = current_map()->find_insert(instr); ! if (f != instr) { ! assert(!f->has_subst(), "can't have a substitution"); ! instr->set_subst(f); ! subst_count++; ! } ! } } // remember value map for successors set_value_map_of(block, current_map()); } ! if (subst_count != 0) { SubstitutionResolver resolver(ir); } TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics()); } --- 560,602 ---- current_map()->kill_memory(); } } } ! // phi functions are not linked in instructions list, so process them separateley ! for_each_phi_fun(block, phi, ! set_processed(phi); ! ); TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print()); // visit all instructions of this block for (Value instr = block->next(); instr != NULL; instr = instr->next()) { // check if instruction kills any values instr->visit(this); ! // perform actual value numbering ! substitute(instr); } // remember value map for successors set_value_map_of(block, current_map()); } ! if (_has_substitutions) { SubstitutionResolver resolver(ir); } TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics()); } + + void GlobalValueNumbering::substitute(Instruction* instr) { + assert(!instr->has_subst(), "substitution already set"); + Value subst = current_map()->find_insert(instr); + if (subst != instr) { + assert(!subst->has_subst(), "can't have a substitution"); + + TRACE_VALUE_NUMBERING(tty->print_cr("substitution for %d set to %d", instr->id(), subst->id())); + instr->set_subst(subst); + _has_substitutions = true; + } + set_processed(instr); + }