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comparison src/share/vm/opto/compile.cpp @ 8883:b9a918201d47

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Merge with hsx25
author Gilles Duboscq <duboscq@ssw.jku.at>
date Sat, 06 Apr 2013 20:04:06 +0200
parents b7c2c5b2572c
children cc32ccaaf47f
comparison
equal deleted inserted replaced
8660:d47b52b0ff68 8883:b9a918201d47
890 bool save_arg_registers, 890 bool save_arg_registers,
891 bool return_pc ) 891 bool return_pc )
892 : Phase(Compiler), 892 : Phase(Compiler),
893 _env(ci_env), 893 _env(ci_env),
894 _log(ci_env->log()), 894 _log(ci_env->log()),
895 _compile_id(-1), 895 _compile_id(0),
896 _save_argument_registers(save_arg_registers), 896 _save_argument_registers(save_arg_registers),
897 _method(NULL), 897 _method(NULL),
898 _stub_name(stub_name), 898 _stub_name(stub_name),
899 _stub_function(stub_function), 899 _stub_function(stub_function),
900 _stub_entry_point(NULL), 900 _stub_entry_point(NULL),
2897 if (in2->outcnt() == 0) { // Remove dead node 2897 if (in2->outcnt() == 0) { // Remove dead node
2898 in2->disconnect_inputs(NULL, this); 2898 in2->disconnect_inputs(NULL, this);
2899 } 2899 }
2900 } 2900 }
2901 break; 2901 break;
2902 case Op_MemBarStoreStore:
2903 // Break the link with AllocateNode: it is no longer useful and
2904 // confuses register allocation.
2905 if (n->req() > MemBarNode::Precedent) {
2906 n->set_req(MemBarNode::Precedent, top());
2907 }
2908 break;
2902 default: 2909 default:
2903 assert( !n->is_Call(), "" ); 2910 assert( !n->is_Call(), "" );
2904 assert( !n->is_Mem(), "" ); 2911 assert( !n->is_Mem(), "" );
2905 break; 2912 break;
2906 } 2913 }
3667 // Clear control input and let IGVN optimize expensive nodes if 3674 // Clear control input and let IGVN optimize expensive nodes if
3668 // OptimizeExpensiveOps is off. 3675 // OptimizeExpensiveOps is off.
3669 n->set_req(0, NULL); 3676 n->set_req(0, NULL);
3670 } 3677 }
3671 } 3678 }
3679
3680 // Auxiliary method to support randomized stressing/fuzzing.
3681 //
3682 // This method can be called the arbitrary number of times, with current count
3683 // as the argument. The logic allows selecting a single candidate from the
3684 // running list of candidates as follows:
3685 // int count = 0;
3686 // Cand* selected = null;
3687 // while(cand = cand->next()) {
3688 // if (randomized_select(++count)) {
3689 // selected = cand;
3690 // }
3691 // }
3692 //
3693 // Including count equalizes the chances any candidate is "selected".
3694 // This is useful when we don't have the complete list of candidates to choose
3695 // from uniformly. In this case, we need to adjust the randomicity of the
3696 // selection, or else we will end up biasing the selection towards the latter
3697 // candidates.
3698 //
3699 // Quick back-envelope calculation shows that for the list of n candidates
3700 // the equal probability for the candidate to persist as "best" can be
3701 // achieved by replacing it with "next" k-th candidate with the probability
3702 // of 1/k. It can be easily shown that by the end of the run, the
3703 // probability for any candidate is converged to 1/n, thus giving the
3704 // uniform distribution among all the candidates.
3705 //
3706 // We don't care about the domain size as long as (RANDOMIZED_DOMAIN / count) is large.
3707 #define RANDOMIZED_DOMAIN_POW 29
3708 #define RANDOMIZED_DOMAIN (1 << RANDOMIZED_DOMAIN_POW)
3709 #define RANDOMIZED_DOMAIN_MASK ((1 << (RANDOMIZED_DOMAIN_POW + 1)) - 1)
3710 bool Compile::randomized_select(int count) {
3711 assert(count > 0, "only positive");
3712 return (os::random() & RANDOMIZED_DOMAIN_MASK) < (RANDOMIZED_DOMAIN / count);
3713 }