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| 1 // Copyright 2010 the V8 project authors. All rights reserved. | |
| 2 // Redistribution and use in source and binary forms, with or without | |
| 3 // modification, are permitted provided that the following conditions are | |
| 4 // met: | |
| 5 // | |
| 6 // * Redistributions of source code must retain the above copyright | |
| 7 // notice, this list of conditions and the following disclaimer. | |
| 8 // * Redistributions in binary form must reproduce the above | |
| 9 // copyright notice, this list of conditions and the following | |
| 10 // disclaimer in the documentation and/or other materials provided | |
| 11 // with the distribution. | |
| 12 // * Neither the name of Google Inc. nor the names of its | |
| 13 // contributors may be used to endorse or promote products derived | |
| 14 // from this software without specific prior written permission. | |
| 15 // | |
| 16 // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS | |
| 17 // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT | |
| 18 // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR | |
| 19 // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT | |
| 20 // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
| 21 // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT | |
| 22 // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, | |
| 23 // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY | |
| 24 // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT | |
| 25 // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE | |
| 26 // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. | |
| 27 | |
| 28 #include "v8.h" | |
| 29 | |
| 30 #include "codegen-inl.h" | |
| 31 #include "register-allocator-inl.h" | |
| 32 #include "virtual-frame-inl.h" | |
| 33 | |
| 34 namespace v8 { | |
| 35 namespace internal { | |
| 36 | |
| 37 void VirtualFrame::SetElementAt(int index, Result* value) { | |
| 38 int frame_index = element_count() - index - 1; | |
| 39 ASSERT(frame_index >= 0); | |
| 40 ASSERT(frame_index < element_count()); | |
| 41 ASSERT(value->is_valid()); | |
| 42 FrameElement original = elements_[frame_index]; | |
| 43 | |
| 44 // Early exit if the element is the same as the one being set. | |
| 45 bool same_register = original.is_register() | |
| 46 && value->is_register() | |
| 47 && original.reg().is(value->reg()); | |
| 48 bool same_constant = original.is_constant() | |
| 49 && value->is_constant() | |
| 50 && original.handle().is_identical_to(value->handle()); | |
| 51 if (same_register || same_constant) { | |
| 52 value->Unuse(); | |
| 53 return; | |
| 54 } | |
| 55 | |
| 56 InvalidateFrameSlotAt(frame_index); | |
| 57 | |
| 58 if (value->is_register()) { | |
| 59 if (is_used(value->reg())) { | |
| 60 // The register already appears on the frame. Either the existing | |
| 61 // register element, or the new element at frame_index, must be made | |
| 62 // a copy. | |
| 63 int i = register_location(value->reg()); | |
| 64 | |
| 65 if (i < frame_index) { | |
| 66 // The register FrameElement is lower in the frame than the new copy. | |
| 67 elements_[frame_index] = CopyElementAt(i); | |
| 68 } else { | |
| 69 // There was an early bailout for the case of setting a | |
| 70 // register element to itself. | |
| 71 ASSERT(i != frame_index); | |
| 72 elements_[frame_index] = elements_[i]; | |
| 73 elements_[i] = CopyElementAt(frame_index); | |
| 74 if (elements_[frame_index].is_synced()) { | |
| 75 elements_[i].set_sync(); | |
| 76 } | |
| 77 elements_[frame_index].clear_sync(); | |
| 78 set_register_location(value->reg(), frame_index); | |
| 79 for (int j = i + 1; j < element_count(); j++) { | |
| 80 if (elements_[j].is_copy() && elements_[j].index() == i) { | |
| 81 elements_[j].set_index(frame_index); | |
| 82 } | |
| 83 } | |
| 84 } | |
| 85 } else { | |
| 86 // The register value->reg() was not already used on the frame. | |
| 87 Use(value->reg(), frame_index); | |
| 88 elements_[frame_index] = | |
| 89 FrameElement::RegisterElement(value->reg(), | |
| 90 FrameElement::NOT_SYNCED, | |
| 91 value->type_info()); | |
| 92 } | |
| 93 } else { | |
| 94 ASSERT(value->is_constant()); | |
| 95 elements_[frame_index] = | |
| 96 FrameElement::ConstantElement(value->handle(), | |
| 97 FrameElement::NOT_SYNCED); | |
| 98 } | |
| 99 value->Unuse(); | |
| 100 } | |
| 101 | |
| 102 | |
| 103 // Create a duplicate of an existing valid frame element. | |
| 104 // We can pass an optional number type information that will override the | |
| 105 // existing information about the backing element. The new information must | |
| 106 // not conflict with the existing type information and must be equally or | |
| 107 // more precise. The default parameter value kUninitialized means that there | |
| 108 // is no additional information. | |
| 109 FrameElement VirtualFrame::CopyElementAt(int index, TypeInfo info) { | |
| 110 ASSERT(index >= 0); | |
| 111 ASSERT(index < element_count()); | |
| 112 | |
| 113 FrameElement target = elements_[index]; | |
| 114 FrameElement result; | |
| 115 | |
| 116 switch (target.type()) { | |
| 117 case FrameElement::CONSTANT: | |
| 118 // We do not copy constants and instead return a fresh unsynced | |
| 119 // constant. | |
| 120 result = FrameElement::ConstantElement(target.handle(), | |
| 121 FrameElement::NOT_SYNCED); | |
| 122 break; | |
| 123 | |
| 124 case FrameElement::COPY: | |
| 125 // We do not allow copies of copies, so we follow one link to | |
| 126 // the actual backing store of a copy before making a copy. | |
| 127 index = target.index(); | |
| 128 ASSERT(elements_[index].is_memory() || elements_[index].is_register()); | |
| 129 // Fall through. | |
| 130 | |
| 131 case FrameElement::MEMORY: // Fall through. | |
| 132 case FrameElement::REGISTER: { | |
| 133 // All copies are backed by memory or register locations. | |
| 134 result.set_type(FrameElement::COPY); | |
| 135 result.clear_copied(); | |
| 136 result.clear_sync(); | |
| 137 result.set_index(index); | |
| 138 elements_[index].set_copied(); | |
| 139 // Update backing element's number information. | |
| 140 TypeInfo existing = elements_[index].type_info(); | |
| 141 ASSERT(!existing.IsUninitialized()); | |
| 142 // Assert that the new type information (a) does not conflict with the | |
| 143 // existing one and (b) is equally or more precise. | |
| 144 ASSERT((info.ToInt() & existing.ToInt()) == existing.ToInt()); | |
| 145 ASSERT((info.ToInt() | existing.ToInt()) == info.ToInt()); | |
| 146 | |
| 147 elements_[index].set_type_info(!info.IsUninitialized() | |
| 148 ? info | |
| 149 : existing); | |
| 150 break; | |
| 151 } | |
| 152 case FrameElement::INVALID: | |
| 153 // We should not try to copy invalid elements. | |
| 154 UNREACHABLE(); | |
| 155 break; | |
| 156 } | |
| 157 return result; | |
| 158 } | |
| 159 | |
| 160 | |
| 161 // Modify the state of the virtual frame to match the actual frame by adding | |
| 162 // extra in-memory elements to the top of the virtual frame. The extra | |
| 163 // elements will be externally materialized on the actual frame (eg, by | |
| 164 // pushing an exception handler). No code is emitted. | |
| 165 void VirtualFrame::Adjust(int count) { | |
| 166 ASSERT(count >= 0); | |
| 167 ASSERT(stack_pointer_ == element_count() - 1); | |
| 168 | |
| 169 for (int i = 0; i < count; i++) { | |
| 170 elements_.Add(FrameElement::MemoryElement(TypeInfo::Unknown())); | |
| 171 } | |
| 172 stack_pointer_ += count; | |
| 173 } | |
| 174 | |
| 175 | |
| 176 void VirtualFrame::ForgetElements(int count) { | |
| 177 ASSERT(count >= 0); | |
| 178 ASSERT(element_count() >= count); | |
| 179 | |
| 180 for (int i = 0; i < count; i++) { | |
| 181 FrameElement last = elements_.RemoveLast(); | |
| 182 if (last.is_register()) { | |
| 183 // A hack to properly count register references for the code | |
| 184 // generator's current frame and also for other frames. The | |
| 185 // same code appears in PrepareMergeTo. | |
| 186 if (cgen()->frame() == this) { | |
| 187 Unuse(last.reg()); | |
| 188 } else { | |
| 189 set_register_location(last.reg(), kIllegalIndex); | |
| 190 } | |
| 191 } | |
| 192 } | |
| 193 } | |
| 194 | |
| 195 | |
| 196 // Make the type of the element at a given index be MEMORY. | |
| 197 void VirtualFrame::SpillElementAt(int index) { | |
| 198 if (!elements_[index].is_valid()) return; | |
| 199 | |
| 200 SyncElementAt(index); | |
| 201 // Number type information is preserved. | |
| 202 // Copies get their number information from their backing element. | |
| 203 TypeInfo info; | |
| 204 if (!elements_[index].is_copy()) { | |
| 205 info = elements_[index].type_info(); | |
| 206 } else { | |
| 207 info = elements_[elements_[index].index()].type_info(); | |
| 208 } | |
| 209 // The element is now in memory. Its copied flag is preserved. | |
| 210 FrameElement new_element = FrameElement::MemoryElement(info); | |
| 211 if (elements_[index].is_copied()) { | |
| 212 new_element.set_copied(); | |
| 213 } | |
| 214 if (elements_[index].is_untagged_int32()) { | |
| 215 new_element.set_untagged_int32(true); | |
| 216 } | |
| 217 if (elements_[index].is_register()) { | |
| 218 Unuse(elements_[index].reg()); | |
| 219 } | |
| 220 elements_[index] = new_element; | |
| 221 } | |
| 222 | |
| 223 | |
| 224 // Clear the dirty bit for the element at a given index. | |
| 225 void VirtualFrame::SyncElementAt(int index) { | |
| 226 if (index <= stack_pointer_) { | |
| 227 if (!elements_[index].is_synced()) SyncElementBelowStackPointer(index); | |
| 228 } else if (index == stack_pointer_ + 1) { | |
| 229 SyncElementByPushing(index); | |
| 230 } else { | |
| 231 SyncRange(stack_pointer_ + 1, index); | |
| 232 } | |
| 233 } | |
| 234 | |
| 235 | |
| 236 void VirtualFrame::PrepareMergeTo(VirtualFrame* expected) { | |
| 237 // Perform state changes on this frame that will make merge to the | |
| 238 // expected frame simpler or else increase the likelihood that his | |
| 239 // frame will match another. | |
| 240 for (int i = 0; i < element_count(); i++) { | |
| 241 FrameElement source = elements_[i]; | |
| 242 FrameElement target = expected->elements_[i]; | |
| 243 | |
| 244 if (!target.is_valid() || | |
| 245 (target.is_memory() && !source.is_memory() && source.is_synced())) { | |
| 246 // No code needs to be generated to invalidate valid elements. | |
| 247 // No code needs to be generated to move values to memory if | |
| 248 // they are already synced. We perform those moves here, before | |
| 249 // merging. | |
| 250 if (source.is_register()) { | |
| 251 // If the frame is the code generator's current frame, we have | |
| 252 // to decrement both the frame-internal and global register | |
| 253 // counts. | |
| 254 if (cgen()->frame() == this) { | |
| 255 Unuse(source.reg()); | |
| 256 } else { | |
| 257 set_register_location(source.reg(), kIllegalIndex); | |
| 258 } | |
| 259 } | |
| 260 elements_[i] = target; | |
| 261 } else if (target.is_register() && !target.is_synced() && | |
| 262 !source.is_memory()) { | |
| 263 // If an element's target is a register that doesn't need to be | |
| 264 // synced, and the element is not in memory, then the sync state | |
| 265 // of the element is irrelevant. We clear the sync bit. | |
| 266 ASSERT(source.is_valid()); | |
| 267 elements_[i].clear_sync(); | |
| 268 } | |
| 269 } | |
| 270 } | |
| 271 | |
| 272 | |
| 273 void VirtualFrame::PrepareForCall(int spilled_args, int dropped_args) { | |
| 274 ASSERT(height() >= dropped_args); | |
| 275 ASSERT(height() >= spilled_args); | |
| 276 ASSERT(dropped_args <= spilled_args); | |
| 277 | |
| 278 SyncRange(0, element_count() - 1); | |
| 279 // Spill registers. | |
| 280 for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) { | |
| 281 if (is_used(i)) { | |
| 282 SpillElementAt(register_location(i)); | |
| 283 } | |
| 284 } | |
| 285 | |
| 286 // Spill the arguments. | |
| 287 for (int i = element_count() - spilled_args; i < element_count(); i++) { | |
| 288 if (!elements_[i].is_memory()) { | |
| 289 SpillElementAt(i); | |
| 290 } | |
| 291 } | |
| 292 | |
| 293 // Forget the frame elements that will be popped by the call. | |
| 294 Forget(dropped_args); | |
| 295 } | |
| 296 | |
| 297 | |
| 298 // If there are any registers referenced only by the frame, spill one. | |
| 299 Register VirtualFrame::SpillAnyRegister() { | |
| 300 // Find the leftmost (ordered by register number) register whose only | |
| 301 // reference is in the frame. | |
| 302 for (int i = 0; i < RegisterAllocator::kNumRegisters; i++) { | |
| 303 if (is_used(i) && cgen()->allocator()->count(i) == 1) { | |
| 304 SpillElementAt(register_location(i)); | |
| 305 ASSERT(!cgen()->allocator()->is_used(i)); | |
| 306 return RegisterAllocator::ToRegister(i); | |
| 307 } | |
| 308 } | |
| 309 return no_reg; | |
| 310 } | |
| 311 | |
| 312 } } // namespace v8::internal | |
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Chromium Code Reviews
Issue 6811012:
Remove some dead code. (Closed)
Base URL: https://v8.googlecode.com/svn/branches/bleeding_edge