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) { |
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432 return false; |
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433 } |
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434 |
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435 // Do not unroll a loop with String intrinsics code. |
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436 // String intrinsics are large and have loops. |
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437 for (uint k = 0; k < _body.size(); k++) { |
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438 Node* n = _body.at(k); |
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439 switch (n->Opcode()) { |
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440 case Op_StrComp: |
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441 case Op_StrEquals: |
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442 case Op_StrIndexOf: |
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443 case Op_AryEq: { |
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444 return false; |
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445 } |
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446 } // switch |
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447 } |
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448 |
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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; |
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539 case Op_StrComp: |
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540 case Op_StrEquals: |
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541 case Op_StrIndexOf: |
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542 case Op_AryEq: { |
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543 // Do not unroll a loop with String intrinsics code. |
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544 // String intrinsics are large and have loops. |
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545 return false; |
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546 } |
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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 |