Fri, 18 Mar 2011 15:52:42 -0700
7028374: race in fix_oop_relocations for scavengeable nmethods
Reviewed-by: kvn
1 /*
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3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
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25 #ifndef SHARE_VM_CODE_CODECACHE_HPP
26 #define SHARE_VM_CODE_CODECACHE_HPP
28 #include "code/codeBlob.hpp"
29 #include "memory/allocation.hpp"
30 #include "memory/heap.hpp"
31 #include "oops/instanceKlass.hpp"
32 #include "oops/oopsHierarchy.hpp"
34 // The CodeCache implements the code cache for various pieces of generated
35 // code, e.g., compiled java methods, runtime stubs, transition frames, etc.
36 // The entries in the CodeCache are all CodeBlob's.
38 // Implementation:
39 // - Each CodeBlob occupies one chunk of memory.
40 // - Like the offset table in oldspace the zone has at table for
41 // locating a method given a addess of an instruction.
43 class OopClosure;
44 class DepChange;
46 class CodeCache : AllStatic {
47 friend class VMStructs;
48 private:
49 // CodeHeap is malloc()'ed at startup and never deleted during shutdown,
50 // so that the generated assembly code is always there when it's needed.
51 // This may cause memory leak, but is necessary, for now. See 4423824,
52 // 4422213 or 4436291 for details.
53 static CodeHeap * _heap;
54 static int _number_of_blobs;
55 static int _number_of_adapters;
56 static int _number_of_nmethods;
57 static int _number_of_nmethods_with_dependencies;
58 static bool _needs_cache_clean;
59 static nmethod* _scavenge_root_nmethods; // linked via nm->scavenge_root_link()
60 static nmethod* _saved_nmethods; // linked via nm->saved_nmethod_look()
62 static void verify_if_often() PRODUCT_RETURN;
64 static void mark_scavenge_root_nmethods() PRODUCT_RETURN;
65 static void verify_perm_nmethods(CodeBlobClosure* f_or_null) PRODUCT_RETURN;
67 public:
69 // Initialization
70 static void initialize();
72 // Allocation/administration
73 static CodeBlob* allocate(int size); // allocates a new CodeBlob
74 static void commit(CodeBlob* cb); // called when the allocated CodeBlob has been filled
75 static int alignment_unit(); // guaranteed alignment of all CodeBlobs
76 static int alignment_offset(); // guaranteed offset of first CodeBlob byte within alignment unit (i.e., allocation header)
77 static void free(CodeBlob* cb); // frees a CodeBlob
78 static void flush(); // flushes all CodeBlobs
79 static bool contains(void *p); // returns whether p is included
80 static void blobs_do(void f(CodeBlob* cb)); // iterates over all CodeBlobs
81 static void blobs_do(CodeBlobClosure* f); // iterates over all CodeBlobs
82 static void nmethods_do(void f(nmethod* nm)); // iterates over all nmethods
84 // Lookup
85 static CodeBlob* find_blob(void* start);
86 static nmethod* find_nmethod(void* start);
88 // Lookup that does not fail if you lookup a zombie method (if you call this, be sure to know
89 // what you are doing)
90 static CodeBlob* find_blob_unsafe(void* start) {
91 CodeBlob* result = (CodeBlob*)_heap->find_start(start);
92 // this assert is too strong because the heap code will return the
93 // heapblock containing start. That block can often be larger than
94 // the codeBlob itself. If you look up an address that is within
95 // the heapblock but not in the codeBlob you will assert.
96 //
97 // Most things will not lookup such bad addresses. However
98 // AsyncGetCallTrace can see intermediate frames and get that kind
99 // of invalid address and so can a developer using hsfind.
100 //
101 // The more correct answer is to return NULL if blob_contains() returns
102 // false.
103 // assert(result == NULL || result->blob_contains((address)start), "found wrong CodeBlob");
105 if (result != NULL && !result->blob_contains((address)start)) {
106 result = NULL;
107 }
108 return result;
109 }
111 // Iteration
112 static CodeBlob* first();
113 static CodeBlob* next (CodeBlob* cb);
114 static CodeBlob* alive(CodeBlob *cb);
115 static nmethod* alive_nmethod(CodeBlob *cb);
116 static nmethod* first_nmethod();
117 static nmethod* next_nmethod (CodeBlob* cb);
118 static int nof_blobs() { return _number_of_blobs; }
119 static int nof_adapters() { return _number_of_adapters; }
120 static int nof_nmethods() { return _number_of_nmethods; }
122 // GC support
123 static void gc_epilogue();
124 static void gc_prologue();
125 static void verify_oops();
126 // If "unloading_occurred" is true, then unloads (i.e., breaks root links
127 // to) any unmarked codeBlobs in the cache. Sets "marked_for_unloading"
128 // to "true" iff some code got unloaded.
129 static void do_unloading(BoolObjectClosure* is_alive,
130 OopClosure* keep_alive,
131 bool unloading_occurred);
132 static void oops_do(OopClosure* f) {
133 CodeBlobToOopClosure oopc(f, /*do_marking=*/ false);
134 blobs_do(&oopc);
135 }
136 static void asserted_non_scavengable_nmethods_do(CodeBlobClosure* f = NULL) PRODUCT_RETURN;
137 static void scavenge_root_nmethods_do(CodeBlobClosure* f);
139 static nmethod* scavenge_root_nmethods() { return _scavenge_root_nmethods; }
140 static void set_scavenge_root_nmethods(nmethod* nm) { _scavenge_root_nmethods = nm; }
141 static void add_scavenge_root_nmethod(nmethod* nm);
142 static void drop_scavenge_root_nmethod(nmethod* nm);
143 static void prune_scavenge_root_nmethods();
145 // Printing/debugging
146 static void print() PRODUCT_RETURN; // prints summary
147 static void print_internals();
148 static void verify(); // verifies the code cache
149 static void print_trace(const char* event, CodeBlob* cb, int size = 0) PRODUCT_RETURN;
150 static void print_bounds(outputStream* st); // Prints a summary of the bounds of the code cache
151 static void log_state(outputStream* st);
153 // The full limits of the codeCache
154 static address low_bound() { return (address) _heap->low_boundary(); }
155 static address high_bound() { return (address) _heap->high_boundary(); }
157 // Profiling
158 static address first_address(); // first address used for CodeBlobs
159 static address last_address(); // last address used for CodeBlobs
160 static size_t capacity() { return _heap->capacity(); }
161 static size_t max_capacity() { return _heap->max_capacity(); }
162 static size_t unallocated_capacity() { return _heap->unallocated_capacity(); }
163 static size_t largest_free_block() { return _heap->largest_free_block(); }
164 static bool needs_flushing() { return largest_free_block() < CodeCacheFlushingMinimumFreeSpace; }
166 static bool needs_cache_clean() { return _needs_cache_clean; }
167 static void set_needs_cache_clean(bool v) { _needs_cache_clean = v; }
168 static void clear_inline_caches(); // clear all inline caches
170 static nmethod* find_and_remove_saved_code(methodOop m);
171 static void remove_saved_code(nmethod* nm);
172 static void speculatively_disconnect(nmethod* nm);
174 // Deoptimization
175 static int mark_for_deoptimization(DepChange& changes);
176 #ifdef HOTSWAP
177 static int mark_for_evol_deoptimization(instanceKlassHandle dependee);
178 #endif // HOTSWAP
180 static void mark_all_nmethods_for_deoptimization();
181 static int mark_for_deoptimization(methodOop dependee);
182 static void make_marked_nmethods_zombies();
183 static void make_marked_nmethods_not_entrant();
185 // tells how many nmethods have dependencies
186 static int number_of_nmethods_with_dependencies();
187 };
189 #endif // SHARE_VM_CODE_CODECACHE_HPP