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comparison src/share/vm/opto/loopTransform.cpp @ 2412:f9424955eb18

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7029152: Ideal nodes for String intrinsics miss memory edge optimization Summary: In Ideal() method of String intrinsics nodes look for TypeAryPtr::CHARS memory slice if memory is MergeMem. Do not unroll a loop with String intrinsics code. Reviewed-by: never
author kvn
date Wed, 30 Mar 2011 12:08:49 -0700
parents 1927db75dd85
children cb162b348743
comparison
equal deleted inserted replaced
2411:63997f575155 2412:f9424955eb18
394 394
395 //------------------------------policy_maximally_unroll------------------------ 395 //------------------------------policy_maximally_unroll------------------------
396 // Return exact loop trip count, or 0 if not maximally unrolling 396 // Return exact loop trip count, or 0 if not maximally unrolling
397 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const { 397 bool IdealLoopTree::policy_maximally_unroll( PhaseIdealLoop *phase ) const {
398 CountedLoopNode *cl = _head->as_CountedLoop(); 398 CountedLoopNode *cl = _head->as_CountedLoop();
399 assert( cl->is_normal_loop(), "" ); 399 assert(cl->is_normal_loop(), "");
400 400
401 Node *init_n = cl->init_trip(); 401 Node *init_n = cl->init_trip();
402 Node *limit_n = cl->limit(); 402 Node *limit_n = cl->limit();
403 403
404 // Non-constant bounds 404 // Non-constant bounds
405 if( init_n == NULL || !init_n->is_Con() || 405 if (init_n == NULL || !init_n->is_Con() ||
406 limit_n == NULL || !limit_n->is_Con() || 406 limit_n == NULL || !limit_n->is_Con() ||
407 // protect against stride not being a constant 407 // protect against stride not being a constant
408 !cl->stride_is_con() ) { 408 !cl->stride_is_con()) {
409 return false; 409 return false;
410 } 410 }
411 int init = init_n->get_int(); 411 int init = init_n->get_int();
412 int limit = limit_n->get_int(); 412 int limit = limit_n->get_int();
413 int span = limit - init; 413 int span = limit - init;
426 // size. After all, it will no longer be a loop. 426 // size. After all, it will no longer be a loop.
427 uint body_size = _body.size(); 427 uint body_size = _body.size();
428 uint unroll_limit = (uint)LoopUnrollLimit * 4; 428 uint unroll_limit = (uint)LoopUnrollLimit * 4;
429 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits"); 429 assert( (intx)unroll_limit == LoopUnrollLimit * 4, "LoopUnrollLimit must fit in 32bits");
430 cl->set_trip_count(trip_count); 430 cl->set_trip_count(trip_count);
431 if( trip_count <= unroll_limit && body_size <= unroll_limit ) { 431 if (trip_count > unroll_limit || body_size > unroll_limit) {
432 return false;
433 }
434
435 // Do not unroll a loop with String intrinsics code.
436 // String intrinsics are large and have loops.
437 for (uint k = 0; k < _body.size(); k++) {
438 Node* n = _body.at(k);
439 switch (n->Opcode()) {
440 case Op_StrComp:
441 case Op_StrEquals:
442 case Op_StrIndexOf:
443 case Op_AryEq: {
444 return false;
445 }
446 } // switch
447 }
448
449 if (body_size <= unroll_limit) {
432 uint new_body_size = body_size * trip_count; 450 uint new_body_size = body_size * trip_count;
433 if (new_body_size <= unroll_limit && 451 if (new_body_size <= unroll_limit &&
434 body_size == new_body_size / trip_count && 452 body_size == new_body_size / trip_count &&
435 // Unrolling can result in a large amount of node construction 453 // Unrolling can result in a large amount of node construction
436 new_body_size < MaxNodeLimit - phase->C->unique()) { 454 new_body_size < MaxNodeLimit - phase->C->unique()) {
446 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if 464 // Return TRUE or FALSE if the loop should be unrolled or not. Unroll if
447 // the loop is a CountedLoop and the body is small enough. 465 // the loop is a CountedLoop and the body is small enough.
448 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const { 466 bool IdealLoopTree::policy_unroll( PhaseIdealLoop *phase ) const {
449 467
450 CountedLoopNode *cl = _head->as_CountedLoop(); 468 CountedLoopNode *cl = _head->as_CountedLoop();
451 assert( cl->is_normal_loop() || cl->is_main_loop(), "" ); 469 assert(cl->is_normal_loop() || cl->is_main_loop(), "");
452 470
453 // protect against stride not being a constant 471 // protect against stride not being a constant
454 if( !cl->stride_is_con() ) return false; 472 if (!cl->stride_is_con()) return false;
455 473
456 // protect against over-unrolling 474 // protect against over-unrolling
457 if( cl->trip_count() <= 1 ) return false; 475 if (cl->trip_count() <= 1) return false;
458 476
459 int future_unroll_ct = cl->unrolled_count() * 2; 477 int future_unroll_ct = cl->unrolled_count() * 2;
460 478
461 // Don't unroll if the next round of unrolling would push us 479 // Don't unroll if the next round of unrolling would push us
462 // over the expected trip count of the loop. One is subtracted 480 // over the expected trip count of the loop. One is subtracted
483 Node *init_n = cl->init_trip(); 501 Node *init_n = cl->init_trip();
484 Node *limit_n = cl->limit(); 502 Node *limit_n = cl->limit();
485 // Non-constant bounds. 503 // Non-constant bounds.
486 // Protect against over-unrolling when init or/and limit are not constant 504 // Protect against over-unrolling when init or/and limit are not constant
487 // (so that trip_count's init value is maxint) but iv range is known. 505 // (so that trip_count's init value is maxint) but iv range is known.
488 if( init_n == NULL || !init_n->is_Con() || 506 if (init_n == NULL || !init_n->is_Con() ||
489 limit_n == NULL || !limit_n->is_Con() ) { 507 limit_n == NULL || !limit_n->is_Con()) {
490 Node* phi = cl->phi(); 508 Node* phi = cl->phi();
491 if( phi != NULL ) { 509 if (phi != NULL) {
492 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi."); 510 assert(phi->is_Phi() && phi->in(0) == _head, "Counted loop should have iv phi.");
493 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int(); 511 const TypeInt* iv_type = phase->_igvn.type(phi)->is_int();
494 int next_stride = cl->stride_con() * 2; // stride after this unroll 512 int next_stride = cl->stride_con() * 2; // stride after this unroll
495 if( next_stride > 0 ) { 513 if (next_stride > 0) {
496 if( iv_type->_lo + next_stride <= iv_type->_lo || // overflow 514 if (iv_type->_lo + next_stride <= iv_type->_lo || // overflow
497 iv_type->_lo + next_stride > iv_type->_hi ) { 515 iv_type->_lo + next_stride > iv_type->_hi) {
498 return false; // over-unrolling 516 return false; // over-unrolling
499 } 517 }
500 } else if( next_stride < 0 ) { 518 } else if (next_stride < 0) {
501 if( iv_type->_hi + next_stride >= iv_type->_hi || // overflow 519 if (iv_type->_hi + next_stride >= iv_type->_hi || // overflow
502 iv_type->_hi + next_stride < iv_type->_lo ) { 520 iv_type->_hi + next_stride < iv_type->_lo) {
503 return false; // over-unrolling 521 return false; // over-unrolling
504 } 522 }
505 } 523 }
506 } 524 }
507 } 525 }
509 // Adjust body_size to determine if we unroll or not 527 // Adjust body_size to determine if we unroll or not
510 uint body_size = _body.size(); 528 uint body_size = _body.size();
511 // Key test to unroll CaffeineMark's Logic test 529 // Key test to unroll CaffeineMark's Logic test
512 int xors_in_loop = 0; 530 int xors_in_loop = 0;
513 // Also count ModL, DivL and MulL which expand mightly 531 // Also count ModL, DivL and MulL which expand mightly
514 for( uint k = 0; k < _body.size(); k++ ) { 532 for (uint k = 0; k < _body.size(); k++) {
515 switch( _body.at(k)->Opcode() ) { 533 Node* n = _body.at(k);
516 case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test 534 switch (n->Opcode()) {
517 case Op_ModL: body_size += 30; break; 535 case Op_XorI: xors_in_loop++; break; // CaffeineMark's Logic test
518 case Op_DivL: body_size += 30; break; 536 case Op_ModL: body_size += 30; break;
519 case Op_MulL: body_size += 10; break; 537 case Op_DivL: body_size += 30; break;
520 } 538 case Op_MulL: body_size += 10; break;
539 case Op_StrComp:
540 case Op_StrEquals:
541 case Op_StrIndexOf:
542 case Op_AryEq: {
543 // Do not unroll a loop with String intrinsics code.
544 // String intrinsics are large and have loops.
545 return false;
546 }
547 } // switch
521 } 548 }
522 549
523 // Check for being too big 550 // Check for being too big
524 if( body_size > (uint)LoopUnrollLimit ) { 551 if (body_size > (uint)LoopUnrollLimit) {
525 if( xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true; 552 if (xors_in_loop >= 4 && body_size < (uint)LoopUnrollLimit*4) return true;
526 // Normal case: loop too big 553 // Normal case: loop too big
527 return false; 554 return false;
528 } 555 }
529 556
530 // Check for stride being a small enough constant 557 // Check for stride being a small enough constant
531 if( abs(cl->stride_con()) > (1<<3) ) return false; 558 if (abs(cl->stride_con()) > (1<<3)) return false;
532 559
533 // Unroll once! (Each trip will soon do double iterations) 560 // Unroll once! (Each trip will soon do double iterations)
534 return true; 561 return true;
535 } 562 }
536 563