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7153771: array bound check elimination for c1
When possible optimize out array bound checks, inserting predicates when needed. Reviewed-by: never, kvn, twisti
This commit is contained in:
Thomas Wuerthinger
Roland Westrelin
parent
2f4ecb86a2
commit
06ef4cddf7
40 changed files with 2861 additions and 153 deletions
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@ -26,9 +26,9 @@
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#include "c1/c1_Canonicalizer.hpp"
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#include "c1/c1_IR.hpp"
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#include "c1/c1_ValueMap.hpp"
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#include "c1/c1_ValueStack.hpp"
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#include "utilities/bitMap.inline.hpp"
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#ifndef PRODUCT
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int ValueMap::_number_of_finds = 0;
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@ -192,10 +192,6 @@ Value ValueMap::find_insert(Value x) {
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&& lf->field()->holder() == field->holder() \
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&& (all_offsets || lf->field()->offset() == field->offset());
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#define MUST_KILL_EXCEPTION(must_kill, entry, value) \
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assert(entry->nesting() < nesting(), "must not find bigger nesting than current"); \
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bool must_kill = (entry->nesting() == nesting() - 1);
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void ValueMap::kill_memory() {
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GENERIC_KILL_VALUE(MUST_KILL_MEMORY);
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@ -209,11 +205,6 @@ void ValueMap::kill_field(ciField* field, bool all_offsets) {
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GENERIC_KILL_VALUE(MUST_KILL_FIELD);
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}
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void ValueMap::kill_exception() {
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GENERIC_KILL_VALUE(MUST_KILL_EXCEPTION);
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}
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void ValueMap::kill_map(ValueMap* map) {
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assert(is_global_value_numbering(), "only for global value numbering");
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_killed_values.set_union(&map->_killed_values);
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@ -274,6 +265,8 @@ class ShortLoopOptimizer : public ValueNumberingVisitor {
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GlobalValueNumbering* _gvn;
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BlockList _loop_blocks;
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bool _too_complicated_loop;
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bool _has_field_store[T_ARRAY + 1];
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bool _has_indexed_store[T_ARRAY + 1];
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// simplified access to methods of GlobalValueNumbering
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ValueMap* current_map() { return _gvn->current_map(); }
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@ -281,8 +274,16 @@ class ShortLoopOptimizer : public ValueNumberingVisitor {
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// implementation for abstract methods of ValueNumberingVisitor
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void kill_memory() { _too_complicated_loop = true; }
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void kill_field(ciField* field, bool all_offsets) { current_map()->kill_field(field, all_offsets); };
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void kill_array(ValueType* type) { current_map()->kill_array(type); };
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void kill_field(ciField* field, bool all_offsets) {
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current_map()->kill_field(field, all_offsets);
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assert(field->type()->basic_type() >= 0 && field->type()->basic_type() <= T_ARRAY, "Invalid type");
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_has_field_store[field->type()->basic_type()] = true;
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}
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void kill_array(ValueType* type) {
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current_map()->kill_array(type);
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BasicType basic_type = as_BasicType(type); assert(basic_type >= 0 && basic_type <= T_ARRAY, "Invalid type");
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_has_indexed_store[basic_type] = true;
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}
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public:
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ShortLoopOptimizer(GlobalValueNumbering* gvn)
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@ -290,11 +291,141 @@ class ShortLoopOptimizer : public ValueNumberingVisitor {
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, _loop_blocks(ValueMapMaxLoopSize)
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, _too_complicated_loop(false)
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{
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for (int i=0; i<= T_ARRAY; i++){
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_has_field_store[i] = false;
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_has_indexed_store[i] = false;
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}
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}
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bool has_field_store(BasicType type) {
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assert(type >= 0 && type <= T_ARRAY, "Invalid type");
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return _has_field_store[type];
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}
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bool has_indexed_store(BasicType type) {
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assert(type >= 0 && type <= T_ARRAY, "Invalid type");
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return _has_indexed_store[type];
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}
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bool process(BlockBegin* loop_header);
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};
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class LoopInvariantCodeMotion : public StackObj {
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private:
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GlobalValueNumbering* _gvn;
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ShortLoopOptimizer* _short_loop_optimizer;
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Instruction* _insertion_point;
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ValueStack * _state;
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void set_invariant(Value v) const { _gvn->set_processed(v); }
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bool is_invariant(Value v) const { return _gvn->is_processed(v); }
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void process_block(BlockBegin* block);
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public:
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LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks);
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};
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LoopInvariantCodeMotion::LoopInvariantCodeMotion(ShortLoopOptimizer *slo, GlobalValueNumbering* gvn, BlockBegin* loop_header, BlockList* loop_blocks)
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: _gvn(gvn), _short_loop_optimizer(slo) {
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TRACE_VALUE_NUMBERING(tty->print_cr("using loop invariant code motion loop_header = %d", loop_header->block_id()));
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TRACE_VALUE_NUMBERING(tty->print_cr("** loop invariant code motion for short loop B%d", loop_header->block_id()));
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BlockBegin* insertion_block = loop_header->dominator();
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if (insertion_block->number_of_preds() == 0) {
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return; // only the entry block does not have a predecessor
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}
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assert(insertion_block->end()->as_Base() == NULL, "cannot insert into entry block");
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_insertion_point = insertion_block->end()->prev();
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BlockEnd *block_end = insertion_block->end();
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_state = block_end->state_before();
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if (!_state) {
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// If, TableSwitch and LookupSwitch always have state_before when
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// loop invariant code motion happens..
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assert(block_end->as_Goto(), "Block has to be goto");
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_state = block_end->state();
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}
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// the loop_blocks are filled by going backward from the loop header, so this processing order is best
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assert(loop_blocks->at(0) == loop_header, "loop header must be first loop block");
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process_block(loop_header);
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for (int i = loop_blocks->length() - 1; i >= 1; i--) {
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process_block(loop_blocks->at(i));
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}
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}
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void LoopInvariantCodeMotion::process_block(BlockBegin* block) {
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TRACE_VALUE_NUMBERING(tty->print_cr("processing block B%d", block->block_id()));
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Instruction* prev = block;
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Instruction* cur = block->next();
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while (cur != NULL) {
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// determine if cur instruction is loop invariant
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// only selected instruction types are processed here
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bool cur_invariant = false;
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if (cur->as_Constant() != NULL) {
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cur_invariant = !cur->can_trap();
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} else if (cur->as_ArithmeticOp() != NULL || cur->as_LogicOp() != NULL || cur->as_ShiftOp() != NULL) {
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assert(cur->as_Op2() != NULL, "must be Op2");
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Op2* op2 = (Op2*)cur;
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cur_invariant = !op2->can_trap() && is_invariant(op2->x()) && is_invariant(op2->y());
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} else if (cur->as_LoadField() != NULL) {
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LoadField* lf = (LoadField*)cur;
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// deoptimizes on NullPointerException
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cur_invariant = !lf->needs_patching() && !lf->field()->is_volatile() && !_short_loop_optimizer->has_field_store(lf->field()->type()->basic_type()) && is_invariant(lf->obj());
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} else if (cur->as_ArrayLength() != NULL) {
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ArrayLength *length = cur->as_ArrayLength();
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cur_invariant = is_invariant(length->array());
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} else if (cur->as_LoadIndexed() != NULL) {
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LoadIndexed *li = (LoadIndexed *)cur->as_LoadIndexed();
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cur_invariant = !_short_loop_optimizer->has_indexed_store(as_BasicType(cur->type())) && is_invariant(li->array()) && is_invariant(li->index());
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}
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if (cur_invariant) {
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// perform value numbering and mark instruction as loop-invariant
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_gvn->substitute(cur);
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if (cur->as_Constant() == NULL) {
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// ensure that code for non-constant instructions is always generated
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cur->pin();
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}
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// remove cur instruction from loop block and append it to block before loop
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Instruction* next = cur->next();
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Instruction* in = _insertion_point->next();
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_insertion_point = _insertion_point->set_next(cur);
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cur->set_next(in);
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// Deoptimize on exception
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cur->set_flag(Instruction::DeoptimizeOnException, true);
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// Clear exception handlers
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cur->set_exception_handlers(NULL);
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TRACE_VALUE_NUMBERING(tty->print_cr("Instruction %c%d is loop invariant", cur->type()->tchar(), cur->id()));
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if (cur->state_before() != NULL) {
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cur->set_state_before(_state->copy());
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}
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if (cur->exception_state() != NULL) {
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cur->set_exception_state(_state->copy());
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}
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cur = prev->set_next(next);
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} else {
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prev = cur;
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cur = cur->next();
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}
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}
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}
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bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
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TRACE_VALUE_NUMBERING(tty->print_cr("** loop header block"));
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@ -316,6 +447,10 @@ bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
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for (int j = block->number_of_preds() - 1; j >= 0; j--) {
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BlockBegin* pred = block->pred_at(j);
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if (pred->is_set(BlockBegin::osr_entry_flag)) {
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return false;
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}
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ValueMap* pred_map = value_map_of(pred);
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if (pred_map != NULL) {
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current_map()->kill_map(pred_map);
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@ -336,6 +471,12 @@ bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
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}
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}
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bool optimistic = this->_gvn->compilation()->is_optimistic();
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if (UseLoopInvariantCodeMotion && optimistic) {
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LoopInvariantCodeMotion code_motion(this, _gvn, loop_header, &_loop_blocks);
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}
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TRACE_VALUE_NUMBERING(tty->print_cr("** loop successfully optimized"));
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return true;
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}
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@ -344,11 +485,11 @@ bool ShortLoopOptimizer::process(BlockBegin* loop_header) {
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GlobalValueNumbering::GlobalValueNumbering(IR* ir)
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: _current_map(NULL)
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, _value_maps(ir->linear_scan_order()->length(), NULL)
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, _compilation(ir->compilation())
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{
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TRACE_VALUE_NUMBERING(tty->print_cr("****** start of global value numbering"));
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ShortLoopOptimizer short_loop_optimizer(this);
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int subst_count = 0;
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BlockList* blocks = ir->linear_scan_order();
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int num_blocks = blocks->length();
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@ -357,6 +498,12 @@ GlobalValueNumbering::GlobalValueNumbering(IR* ir)
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assert(start_block == ir->start() && start_block->number_of_preds() == 0 && start_block->dominator() == NULL, "must be start block");
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assert(start_block->next()->as_Base() != NULL && start_block->next()->next() == NULL, "start block must not have instructions");
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// method parameters are not linked in instructions list, so process them separateley
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for_each_state_value(start_block->state(), value,
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assert(value->as_Local() != NULL, "only method parameters allowed");
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set_processed(value);
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);
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// initial, empty value map with nesting 0
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set_value_map_of(start_block, new ValueMap());
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@ -374,7 +521,7 @@ GlobalValueNumbering::GlobalValueNumbering(IR* ir)
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// create new value map with increased nesting
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_current_map = new ValueMap(value_map_of(dominator));
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if (num_preds == 1) {
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if (num_preds == 1 && !block->is_set(BlockBegin::exception_entry_flag)) {
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assert(dominator == block->pred_at(0), "dominator must be equal to predecessor");
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// nothing to do here
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@ -403,36 +550,41 @@ GlobalValueNumbering::GlobalValueNumbering(IR* ir)
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}
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}
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if (block->is_set(BlockBegin::exception_entry_flag)) {
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current_map()->kill_exception();
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}
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// phi functions are not linked in instructions list, so process them separateley
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for_each_phi_fun(block, phi,
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set_processed(phi);
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);
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TRACE_VALUE_NUMBERING(tty->print("value map before processing block: "); current_map()->print());
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// visit all instructions of this block
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for (Value instr = block->next(); instr != NULL; instr = instr->next()) {
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assert(!instr->has_subst(), "substitution already set");
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// check if instruction kills any values
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instr->visit(this);
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if (instr->hash() != 0) {
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Value f = current_map()->find_insert(instr);
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if (f != instr) {
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assert(!f->has_subst(), "can't have a substitution");
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instr->set_subst(f);
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subst_count++;
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}
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}
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// perform actual value numbering
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substitute(instr);
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}
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// remember value map for successors
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set_value_map_of(block, current_map());
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}
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if (subst_count != 0) {
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if (_has_substitutions) {
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SubstitutionResolver resolver(ir);
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}
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TRACE_VALUE_NUMBERING(tty->print("****** end of global value numbering. "); ValueMap::print_statistics());
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}
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void GlobalValueNumbering::substitute(Instruction* instr) {
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assert(!instr->has_subst(), "substitution already set");
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Value subst = current_map()->find_insert(instr);
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if (subst != instr) {
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assert(!subst->has_subst(), "can't have a substitution");
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TRACE_VALUE_NUMBERING(tty->print_cr("substitution for %d set to %d", instr->id(), subst->id()));
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instr->set_subst(subst);
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_has_substitutions = true;
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}
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set_processed(instr);
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}
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