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comparison src/share/vm/opto/node.cpp @ 163:885ed790ecf0

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6695810: null oop passed to encode_heap_oop_not_null Summary: fix several problems in C2 related to Escape Analysis and Compressed Oops. Reviewed-by: never, jrose
author kvn
date Wed, 21 May 2008 10:45:07 -0700
parents 723be81c1212
children 44a553b2809d
comparison
equal deleted inserted replaced
162:8aa010f60e0f 163:885ed790ecf0
1047 int iterations_without_region_limit = DominatorSearchLimit; 1047 int iterations_without_region_limit = DominatorSearchLimit;
1048 1048
1049 Node* orig_sub = sub; 1049 Node* orig_sub = sub;
1050 nlist.clear(); 1050 nlist.clear();
1051 bool this_dominates = false; 1051 bool this_dominates = false;
1052 uint region_input = 0; 1052 bool result = false; // Conservative answer
1053
1053 while (sub != NULL) { // walk 'sub' up the chain to 'this' 1054 while (sub != NULL) { // walk 'sub' up the chain to 'this'
1054 if (sub == this) { 1055 if (sub == this) {
1055 if (nlist.size() == 0) { 1056 if (nlist.size() == 0) {
1056 // No Region nodes except loops were visited before and the EntryControl 1057 // No Region nodes except loops were visited before and the EntryControl
1057 // path was taken for loops: it did not walk in a cycle. 1058 // path was taken for loops: it did not walk in a cycle.
1058 return true; 1059 result = true;
1059 } else if (!this_dominates) { 1060 break;
1061 } else if (this_dominates) {
1062 result = false; // already met before: walk in a cycle
1063 break;
1064 } else {
1060 // Region nodes were visited. Continue walk up to Start or Root 1065 // Region nodes were visited. Continue walk up to Start or Root
1061 // to make sure that it did not walk in a cycle. 1066 // to make sure that it did not walk in a cycle.
1062 this_dominates = true; // first time meet 1067 this_dominates = true; // first time meet
1063 iterations_without_region_limit = DominatorSearchLimit; // Reset 1068 iterations_without_region_limit = DominatorSearchLimit; // Reset
1064 } else { 1069 }
1065 return false; // already met before: walk in a cycle 1070 }
1066 } 1071 if (sub->is_Start() || sub->is_Root()) {
1067 } 1072 result = this_dominates;
1068 if (sub->is_Start() || sub->is_Root()) 1073 break;
1069 return this_dominates; 1074 }
1070
1071 Node* up = sub->find_exact_control(sub->in(0)); 1075 Node* up = sub->find_exact_control(sub->in(0));
1072 if (up == NULL || up->is_top()) 1076 if (up == NULL || up->is_top()) {
1073 return false; // Conservative answer for dead code 1077 result = false; // Conservative answer for dead code
1074 1078 break;
1075 if (sub == up && sub->is_Loop()) { 1079 }
1080 if (sub == up && (sub->is_Loop() || sub->is_Region() && sub->req() != 3)) {
1081 // Take first valid path on the way up to 'this'.
1076 up = sub->in(1); // in(LoopNode::EntryControl); 1082 up = sub->in(1); // in(LoopNode::EntryControl);
1077 } else if (sub == up && sub->is_Region() && sub->req() == 3) { 1083 } else if (sub == up && sub->is_Region()) {
1084 assert(sub->req() == 3, "sanity");
1078 iterations_without_region_limit = DominatorSearchLimit; // Reset 1085 iterations_without_region_limit = DominatorSearchLimit; // Reset
1086
1087 // Try both paths for such Regions.
1088 // It is not accurate without regions dominating information.
1089 // With such information the other path should be checked for
1090 // the most dominating Region which was visited before.
1091 bool region_was_visited_before = false;
1079 uint i = 1; 1092 uint i = 1;
1080 uint size = nlist.size(); 1093 uint size = nlist.size();
1081 if (size == 0) { 1094 if (size == 0) {
1082 // No Region nodes (except Loops) were visited before. 1095 // No such Region nodes were visited before.
1083 // Take first valid path on the way up to 'this'. 1096 // Take first valid path on the way up to 'this'.
1084 } else if (nlist.at(size - 1) == sub) {
1085 // This Region node was just visited. Take other path.
1086 i = region_input + 1;
1087 nlist.pop();
1088 } else { 1097 } else {
1089 // Was this Region node visited before? 1098 // Was this Region node visited before?
1090 for (uint j = 0; j < size; j++) { 1099 intptr_t ni;
1091 if (nlist.at(j) == sub) { 1100 int j = size - 1;
1092 return false; // The Region node was visited before. Give up. 1101 for (; j >= 0; j--) {
1102 ni = (intptr_t)nlist.at(j);
1103 if ((Node*)(ni & ~1) == sub) {
1104 if ((ni & 1) != 0) {
1105 break; // Visited 2 paths. Give up.
1106 } else {
1107 // The Region node was visited before only once.
1108 nlist.remove(j);
1109 region_was_visited_before = true;
1110 for (; i < sub->req(); i++) {
1111 Node* in = sub->in(i);
1112 if (in != NULL && !in->is_top() && in != sub) {
1113 break;
1114 }
1115 }
1116 i++; // Take other path.
1117 break;
1118 }
1093 } 1119 }
1094 } 1120 }
1121 if (j >= 0 && (ni & 1) != 0) {
1122 result = false; // Visited 2 paths. Give up.
1123 break;
1124 }
1095 // The Region node was not visited before. 1125 // The Region node was not visited before.
1096 // Take first valid path on the way up to 'this'.
1097 } 1126 }
1098 for (; i < sub->req(); i++) { 1127 for (; i < sub->req(); i++) {
1099 Node* in = sub->in(i); 1128 Node* in = sub->in(i);
1100 if (in != NULL && !in->is_top() && in != sub) { 1129 if (in != NULL && !in->is_top() && in != sub) {
1101 break; 1130 break;
1102 } 1131 }
1103 } 1132 }
1104 if (i < sub->req()) { 1133 if (i < sub->req()) {
1105 nlist.push(sub);
1106 up = sub->in(i); 1134 up = sub->in(i);
1107 region_input = i; 1135 if (region_was_visited_before && sub != up) {
1136 // Set 0 bit to indicate that both paths were taken.
1137 nlist.push((Node*)((intptr_t)sub + 1));
1138 } else {
1139 nlist.push(sub);
1140 }
1108 } 1141 }
1109 } 1142 }
1110 if (sub == up) 1143 if (sub == up) {
1111 return false; // some kind of tight cycle 1144 result = false; // some kind of tight cycle
1112 1145 break;
1113 if (--iterations_without_region_limit < 0) 1146 }
1114 return false; // dead cycle 1147 if (--iterations_without_region_limit < 0) {
1115 1148 result = false; // dead cycle
1149 break;
1150 }
1116 sub = up; 1151 sub = up;
1117 } 1152 }
1118 return false; 1153 return result;
1119 } 1154 }
1120 1155
1121 //------------------------------remove_dead_region----------------------------- 1156 //------------------------------remove_dead_region-----------------------------
1122 // This control node is dead. Follow the subgraph below it making everything 1157 // This control node is dead. Follow the subgraph below it making everything
1123 // using it dead as well. This will happen normally via the usual IterGVN 1158 // using it dead as well. This will happen normally via the usual IterGVN