1 /* 2 * Copyright (C) 2008, 2009 Apple Inc. All rights reserved. 3 * 4 * Redistribution and use in source and binary forms, with or without 5 * modification, are permitted provided that the following conditions 6 * are met: 7 * 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 3. Neither the name of Apple Computer, Inc. ("Apple") nor the names of 14 * its contributors may be used to endorse or promote products derived 15 * from this software without specific prior written permission. 16 * 17 * THIS SOFTWARE IS PROVIDED BY APPLE AND ITS CONTRIBUTORS "AS IS" AND ANY 18 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED 19 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE 20 * DISCLAIMED. IN NO EVENT SHALL APPLE OR ITS CONTRIBUTORS BE LIABLE FOR ANY 21 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES 22 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; 23 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND 24 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT 25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF 26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 27 */ 28 29 #ifndef RegisterFile_h 30 #define RegisterFile_h 31 32 #include "Collector.h" 33 #include "ExecutableAllocator.h" 34 #include "Register.h" 35 #include <stdio.h> 36 #include <wtf/Noncopyable.h> 37 #include <wtf/VMTags.h> 38 39 #if HAVE(MMAP) 40 #include <errno.h> 41 #include <sys/mman.h> 42 #endif 43 44 namespace JSC { 45 46 /* 47 A register file is a stack of register frames. We represent a register 48 frame by its offset from "base", the logical first entry in the register 49 file. The bottom-most register frame's offset from base is 0. 50 51 In a program where function "a" calls function "b" (global code -> a -> b), 52 the register file might look like this: 53 54 | global frame | call frame | call frame | spare capacity | 55 ----------------------------------------------------------------------------------------------------- 56 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | 12 | 13 | 14 | | | | | | <-- index in buffer 57 ----------------------------------------------------------------------------------------------------- 58 | -3 | -2 | -1 | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | 9 | 10 | 11 | | | | | | <-- index relative to base 59 ----------------------------------------------------------------------------------------------------- 60 | <-globals | temps-> | <-vars | temps-> | <-vars | 61 ^ ^ ^ ^ 62 | | | | 63 buffer base (frame 0) frame 1 frame 2 64 65 Since all variables, including globals, are accessed by negative offsets 66 from their register frame pointers, to keep old global offsets correct, new 67 globals must appear at the beginning of the register file, shifting base 68 to the right. 69 70 If we added one global variable to the register file depicted above, it 71 would look like this: 72 73 | global frame |< > 74 -------------------------------> < 75 | 0 | 1 | 2 | 3 | 4 | 5 |< >snip< > <-- index in buffer 76 -------------------------------> < 77 | -4 | -3 | -2 | -1 | 0 | 1 |< > <-- index relative to base 78 -------------------------------> < 79 | <-globals | temps-> | 80 ^ ^ 81 | | 82 buffer base (frame 0) 83 84 As you can see, global offsets relative to base have stayed constant, 85 but base itself has moved. To keep up with possible changes to base, 86 clients keep an indirect pointer, so their calculations update 87 automatically when base changes. 88 89 For client simplicity, the RegisterFile measures size and capacity from 90 "base", not "buffer". 91 */ 92 93 class JSGlobalObject; 94 95 class RegisterFile : public Noncopyable { 96 friend class JIT; 97 public: 98 enum CallFrameHeaderEntry { 99 CallFrameHeaderSize = 8, 100 101 CodeBlock = -8, 102 ScopeChain = -7, 103 CallerFrame = -6, 104 ReturnPC = -5, // This is either an Instruction* or a pointer into JIT generated code stored as an Instruction*. 105 ReturnValueRegister = -4, 106 ArgumentCount = -3, 107 Callee = -2, 108 OptionalCalleeArguments = -1, 109 }; 110 111 enum { ProgramCodeThisRegister = -CallFrameHeaderSize - 1 }; 112 enum { ArgumentsRegister = 0 }; 113 114 static const size_t defaultCapacity = 524288; 115 static const size_t defaultMaxGlobals = 8192; 116 static const size_t commitSize = 1 << 14; 117 // Allow 8k of excess registers before we start trying to reap the registerfile 118 static const ptrdiff_t maxExcessCapacity = 8 * 1024; 119 120 RegisterFile(size_t capacity = defaultCapacity, size_t maxGlobals = defaultMaxGlobals); 121 ~RegisterFile(); 122 123 Register* start() const { return m_start; } 124 Register* end() const { return m_end; } 125 size_t size() const { return m_end - m_start; } 126 127 void setGlobalObject(JSGlobalObject* globalObject) { m_globalObject = globalObject; } 128 JSGlobalObject* globalObject() { return m_globalObject; } 129 130 bool grow(Register* newEnd); 131 void shrink(Register* newEnd); 132 133 void setNumGlobals(size_t numGlobals) { m_numGlobals = numGlobals; } 134 int numGlobals() const { return m_numGlobals; } 135 size_t maxGlobals() const { return m_maxGlobals; } 136 137 Register* lastGlobal() const { return m_start - m_numGlobals; } 138 139 void markGlobals(MarkStack& markStack, Heap* heap) { heap->markConservatively(markStack, lastGlobal(), m_start); } 140 void markCallFrames(MarkStack& markStack, Heap* heap) { heap->markConservatively(markStack, m_start, m_end); } 141 142 private: 143 void releaseExcessCapacity(); 144 size_t m_numGlobals; 145 const size_t m_maxGlobals; 146 Register* m_start; 147 Register* m_end; 148 Register* m_max; 149 Register* m_buffer; 150 Register* m_maxUsed; 151 152 #if HAVE(VIRTUALALLOC) 153 Register* m_commitEnd; 154 #endif 155 156 JSGlobalObject* m_globalObject; // The global object whose vars are currently stored in the register file. 157 }; 158 159 // FIXME: Add a generic getpagesize() to WTF, then move this function to WTF as well. 160 inline bool isPageAligned(size_t size) { return size != 0 && size % (8 * 1024) == 0; } 161 162 inline RegisterFile::RegisterFile(size_t capacity, size_t maxGlobals) 163 : m_numGlobals(0) 164 , m_maxGlobals(maxGlobals) 165 , m_start(0) 166 , m_end(0) 167 , m_max(0) 168 , m_buffer(0) 169 , m_globalObject(0) 170 { 171 // Verify that our values will play nice with mmap and VirtualAlloc. 172 ASSERT(isPageAligned(maxGlobals)); 173 ASSERT(isPageAligned(capacity)); 174 175 size_t bufferLength = (capacity + maxGlobals) * sizeof(Register); 176 #if HAVE(MMAP) 177 m_buffer = static_cast<Register*>(mmap(0, bufferLength, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANON, VM_TAG_FOR_REGISTERFILE_MEMORY, 0)); 178 if (m_buffer == MAP_FAILED) { 179 #if OS(WINCE) 180 fprintf(stderr, "Could not allocate register file: %d\n", GetLastError()); 181 #else 182 fprintf(stderr, "Could not allocate register file: %d\n", errno); 183 #endif 184 CRASH(); 185 } 186 #elif HAVE(VIRTUALALLOC) 187 m_buffer = static_cast<Register*>(VirtualAlloc(0, roundUpAllocationSize(bufferLength, commitSize), MEM_RESERVE, PAGE_READWRITE)); 188 if (!m_buffer) { 189 #if OS(WINCE) 190 fprintf(stderr, "Could not allocate register file: %d\n", GetLastError()); 191 #else 192 fprintf(stderr, "Could not allocate register file: %d\n", errno); 193 #endif 194 CRASH(); 195 } 196 size_t committedSize = roundUpAllocationSize(maxGlobals * sizeof(Register), commitSize); 197 void* commitCheck = VirtualAlloc(m_buffer, committedSize, MEM_COMMIT, PAGE_READWRITE); 198 if (commitCheck != m_buffer) { 199 #if OS(WINCE) 200 fprintf(stderr, "Could not allocate register file: %d\n", GetLastError()); 201 #else 202 fprintf(stderr, "Could not allocate register file: %d\n", errno); 203 #endif 204 CRASH(); 205 } 206 m_commitEnd = reinterpret_cast<Register*>(reinterpret_cast<char*>(m_buffer) + committedSize); 207 #else 208 /* 209 * If neither MMAP nor VIRTUALALLOC are available - use fastMalloc instead. 210 * 211 * Please note that this is the fallback case, which is non-optimal. 212 * If any possible, the platform should provide for a better memory 213 * allocation mechanism that allows for "lazy commit" or dynamic 214 * pre-allocation, similar to mmap or VirtualAlloc, to avoid waste of memory. 215 */ 216 m_buffer = static_cast<Register*>(fastMalloc(bufferLength)); 217 #endif 218 m_start = m_buffer + maxGlobals; 219 m_end = m_start; 220 m_maxUsed = m_end; 221 m_max = m_start + capacity; 222 } 223 224 inline void RegisterFile::shrink(Register* newEnd) 225 { 226 if (newEnd >= m_end) 227 return; 228 m_end = newEnd; 229 if (m_end == m_start && (m_maxUsed - m_start) > maxExcessCapacity) 230 releaseExcessCapacity(); 231 } 232 233 inline bool RegisterFile::grow(Register* newEnd) 234 { 235 if (newEnd < m_end) 236 return true; 237 238 if (newEnd > m_max) 239 return false; 240 241 #if !HAVE(MMAP) && HAVE(VIRTUALALLOC) 242 if (newEnd > m_commitEnd) { 243 size_t size = roundUpAllocationSize(reinterpret_cast<char*>(newEnd) - reinterpret_cast<char*>(m_commitEnd), commitSize); 244 if (!VirtualAlloc(m_commitEnd, size, MEM_COMMIT, PAGE_READWRITE)) { 245 #if OS(WINCE) 246 fprintf(stderr, "Could not allocate register file: %d\n", GetLastError()); 247 #else 248 fprintf(stderr, "Could not allocate register file: %d\n", errno); 249 #endif 250 CRASH(); 251 } 252 m_commitEnd = reinterpret_cast<Register*>(reinterpret_cast<char*>(m_commitEnd) + size); 253 } 254 #endif 255 256 if (newEnd > m_maxUsed) 257 m_maxUsed = newEnd; 258 259 m_end = newEnd; 260 return true; 261 } 262 263 } // namespace JSC 264 265 #endif // RegisterFile_h 266
