1 /* 2 * Copyright (c) 1997, 2018, Oracle and/or its affiliates. All rights reserved. 3 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. 4 * 5 * This code is free software; you can redistribute it and/or modify it 6 * under the terms of the GNU General Public License version 2 only, as 7 * published by the Free Software Foundation. 8 * 9 * This code is distributed in the hope that it will be useful, but WITHOUT 10 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or 11 * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License 12 * version 2 for more details (a copy is included in the LICENSE file that 13 * accompanied this code). 14 * 15 * You should have received a copy of the GNU General Public License version 16 * 2 along with this work; if not, write to the Free Software Foundation, 17 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. 18 * 19 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA 20 * or visit www.oracle.com if you need additional information or have any 21 * questions. 22 * 23 */ 24 25 #ifndef SHARE_VM_CODE_VTABLESTUBS_HPP 26 #define SHARE_VM_CODE_VTABLESTUBS_HPP 27 28 #include "code/vmreg.hpp" 29 #include "memory/allocation.hpp" 30 31 // A VtableStub holds an individual code stub for a pair (vtable index, #args) for either itables or vtables 32 // There's a one-to-one relationship between a VtableStub and such a pair. 33 34 class VtableStub { 35 private: 36 friend class VtableStubs; 37 38 static address _chunk; // For allocation 39 static address _chunk_end; // For allocation 40 static VMReg _receiver_location; // Where to find receiver 41 42 VtableStub* _next; // Pointer to next entry in hash table 43 const short _index; // vtable index 44 short _ame_offset; // Where an AbstractMethodError might occur 45 short _npe_offset; // Where a NullPointerException might occur 46 bool _is_vtable_stub; // True if vtable stub, false, is itable stub 47 /* code follows here */ // The vtableStub code 48 49 void* operator new(size_t size, int code_size) throw(); 50 51 VtableStub(bool is_vtable_stub, int index) 52 : _next(NULL), _is_vtable_stub(is_vtable_stub), 53 _index(index), _ame_offset(-1), _npe_offset(-1) {} 54 VtableStub* next() const { return _next; } 55 int index() const { return _index; } 56 static VMReg receiver_location() { return _receiver_location; } 57 void set_next(VtableStub* n) { _next = n; } 58 59 public: 60 address code_begin() const { return (address)(this + 1); } 61 address code_end() const { return code_begin() + pd_code_size_limit(_is_vtable_stub); } 62 address entry_point() const { return code_begin(); } 63 static int entry_offset() { return sizeof(class VtableStub); } 64 65 bool matches(bool is_vtable_stub, int index) const { 66 return _index == index && _is_vtable_stub == is_vtable_stub; 67 } 68 bool contains(address pc) const { return code_begin() <= pc && pc < code_end(); } 69 70 private: 71 void set_exception_points(address npe_addr, address ame_addr) { 72 _npe_offset = npe_addr - code_begin(); 73 _ame_offset = ame_addr - code_begin(); 74 assert(is_abstract_method_error(ame_addr), "offset must be correct"); 75 assert(is_null_pointer_exception(npe_addr), "offset must be correct"); 76 assert(!is_abstract_method_error(npe_addr), "offset must be correct"); 77 assert(!is_null_pointer_exception(ame_addr), "offset must be correct"); 78 } 79 80 // platform-dependent routines 81 static int pd_code_size_limit(bool is_vtable_stub); 82 static int pd_code_alignment(); 83 // CNC: Removed because vtable stubs are now made with an ideal graph 84 // static bool pd_disregard_arg_size(); 85 86 static void align_chunk() { 87 uintptr_t off = (uintptr_t)( _chunk + sizeof(VtableStub) ) % pd_code_alignment(); 88 if (off != 0) _chunk += pd_code_alignment() - off; 89 } 90 91 public: 92 // Query 93 bool is_itable_stub() { return !_is_vtable_stub; } 94 bool is_vtable_stub() { return _is_vtable_stub; } 95 bool is_abstract_method_error(address epc) { return epc == code_begin()+_ame_offset; } 96 bool is_null_pointer_exception(address epc) { return epc == code_begin()+_npe_offset; } 97 98 void print_on(outputStream* st) const; 99 void print() const { print_on(tty); } 100 101 }; 102 103 104 // VtableStubs creates the code stubs for compiled calls through vtables. 105 // There is one stub per (vtable index, args_size) pair, and the stubs are 106 // never deallocated. They don't need to be GCed because they contain no oops. 107 108 class VtableStubs : AllStatic { 109 public: // N must be public (some compilers need this for _table) 110 enum { 111 N = 256, // size of stub table; must be power of two 112 mask = N - 1 113 }; 114 115 private: 116 static VtableStub* _table[N]; // table of existing stubs 117 static int _number_of_vtable_stubs; // number of stubs created so far (for statistics) 118 119 static VtableStub* create_vtable_stub(int vtable_index); 120 static VtableStub* create_itable_stub(int vtable_index); 121 static VtableStub* lookup (bool is_vtable_stub, int vtable_index); 122 static void enter (bool is_vtable_stub, int vtable_index, VtableStub* s); 123 static inline uint hash (bool is_vtable_stub, int vtable_index); 124 static address find_stub (bool is_vtable_stub, int vtable_index); 125 126 public: 127 static address find_vtable_stub(int vtable_index) { return find_stub(true, vtable_index); } 128 static address find_itable_stub(int itable_index) { return find_stub(false, itable_index); } 129 static VtableStub* entry_point(address pc); // vtable stub entry point for a pc 130 static bool contains(address pc); // is pc within any stub? 131 static VtableStub* stub_containing(address pc); // stub containing pc or NULL 132 static int number_of_vtable_stubs() { return _number_of_vtable_stubs; } 133 static void initialize(); 134 static void vtable_stub_do(void f(VtableStub*)); // iterates over all vtable stubs 135 }; 136 137 #endif // SHARE_VM_CODE_VTABLESTUBS_HPP