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comparison src/share/vm/opto/chaitin.hpp @ 14496:99fc8c086679

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8032894: Remove dead code in Pressure::lower Summary: Remove dead code in Pressure::lower Reviewed-by: kvn, roland
author adlertz
date Tue, 25 Feb 2014 10:26:21 +0100
parents c84312468f5c
children 04e7587c97dc
comparison
equal deleted inserted replaced
14495:cd5d10655495 14496:99fc8c086679
499 499
500 // Build the interference graph using virtual registers only. 500 // Build the interference graph using virtual registers only.
501 // Used for aggressive coalescing. 501 // Used for aggressive coalescing.
502 void build_ifg_virtual( ); 502 void build_ifg_virtual( );
503 503
504 // used when computing the register pressure for each block in the CFG. This
505 // is done during IFG creation.
504 class Pressure { 506 class Pressure {
505 public:
506 // keeps track of the register pressure at the current 507 // keeps track of the register pressure at the current
507 // instruction (used when stepping backwards in the block) 508 // instruction (used when stepping backwards in the block)
508 uint _current_pressure; 509 uint _current_pressure;
509 510
510 // keeps track of the instruction index of the first low to high register pressure 511 // keeps track of the instruction index of the first low to high register pressure
516 // stores the highest pressure we find 517 // stores the highest pressure we find
517 uint _final_pressure; 518 uint _final_pressure;
518 519
519 // number of live ranges that constitute high register pressure 520 // number of live ranges that constitute high register pressure
520 const uint _high_pressure_limit; 521 const uint _high_pressure_limit;
522 public:
521 523
522 // lower the register pressure and look for a low to high pressure 524 // lower the register pressure and look for a low to high pressure
523 // transition 525 // transition
524 void lower(LRG& lrg, uint& location) { 526 void lower(LRG& lrg, uint& location) {
525 _current_pressure -= lrg.reg_pressure(); 527 _current_pressure -= lrg.reg_pressure();
526 if (_current_pressure == _high_pressure_limit) { 528 if (_current_pressure == _high_pressure_limit) {
527 _high_pressure_index = location; 529 _high_pressure_index = location;
528 if (_current_pressure > _final_pressure) {
529 _final_pressure = _current_pressure + 1;
530 }
531 } 530 }
532 } 531 }
533 532
534 // raise the pressure and store the pressure if it's the biggest 533 // raise the pressure and store the pressure if it's the biggest
535 // pressure so far 534 // pressure so far
536 void raise(LRG &lrg) { 535 void raise(LRG &lrg) {
537 _current_pressure += lrg.reg_pressure(); 536 _current_pressure += lrg.reg_pressure();
538 if (_current_pressure > _final_pressure) { 537 if (_current_pressure > _final_pressure) {
539 _final_pressure = _current_pressure; 538 _final_pressure = _current_pressure;
539 }
540 }
541
542 uint high_pressure_index() const {
543 return _high_pressure_index;
544 }
545
546 uint final_pressure() const {
547 return _final_pressure;
548 }
549
550 uint current_pressure() const {
551 return _current_pressure;
552 }
553
554 uint high_pressure_limit() const {
555 return _high_pressure_limit;
556 }
557
558 void lower_high_pressure_index() {
559 _high_pressure_index--;
560 }
561
562 void set_high_pressure_index_to_block_start() {
563 _high_pressure_index = 0;
564 }
565
566 void check_pressure_at_fatproj(uint fatproj_location, RegMask& fatproj_mask) {
567 // this pressure is only valid at this instruction, i.e. we don't need to lower
568 // the register pressure since the fat proj was never live before (going backwards)
569 uint new_pressure = current_pressure() + fatproj_mask.Size();
570 if (new_pressure > final_pressure()) {
571 _final_pressure = new_pressure;
572 }
573
574 // if we were at a low pressure and now and the fat proj is at high pressure, record the fat proj location
575 // as coming from a low to high (to low again)
576 if (current_pressure() <= high_pressure_limit() && new_pressure > high_pressure_limit()) {
577 _high_pressure_index = fatproj_location;
540 } 578 }
541 } 579 }
542 580
543 Pressure(uint high_pressure_index, uint high_pressure_limit) 581 Pressure(uint high_pressure_index, uint high_pressure_limit)
544 : _current_pressure(0) 582 : _current_pressure(0)