LegalizeTypes.cpp revision 3866b1c7d4aee4a039018c21125059385152eee2
1//===-- LegalizeTypes.cpp - Common code for DAG type legalizer ------------===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This file implements the SelectionDAG::LegalizeTypes method. It transforms 11// an arbitrary well-formed SelectionDAG to only consist of legal types. This 12// is common code shared among the LegalizeTypes*.cpp files. 13// 14//===----------------------------------------------------------------------===// 15 16#include "LegalizeTypes.h" 17#include "llvm/CallingConv.h" 18#include "llvm/Constants.h" 19#include "llvm/DerivedTypes.h" 20#include "llvm/Support/CommandLine.h" 21#include "llvm/Support/MathExtras.h" 22using namespace llvm; 23 24#ifndef NDEBUG 25static cl::opt<bool> 26ViewLegalizeTypesDAGs("view-legalize-types-dags", cl::Hidden, 27 cl::desc("Pop up a window to show dags before legalize types")); 28#else 29static const bool ViewLegalizeTypesDAGs = 0; 30#endif 31 32 33 34/// run - This is the main entry point for the type legalizer. This does a 35/// top-down traversal of the dag, legalizing types as it goes. 36void DAGTypeLegalizer::run() { 37 // Create a dummy node (which is not added to allnodes), that adds a reference 38 // to the root node, preventing it from being deleted, and tracking any 39 // changes of the root. 40 HandleSDNode Dummy(DAG.getRoot()); 41 42 // The root of the dag may dangle to deleted nodes until the type legalizer is 43 // done. Set it to null to avoid confusion. 44 DAG.setRoot(SDOperand()); 45 46 // Walk all nodes in the graph, assigning them a NodeID of 'ReadyToProcess' 47 // (and remembering them) if they are leaves and assigning 'NewNode' if 48 // non-leaves. 49 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(), 50 E = DAG.allnodes_end(); I != E; ++I) { 51 if (I->getNumOperands() == 0) { 52 I->setNodeId(ReadyToProcess); 53 Worklist.push_back(I); 54 } else { 55 I->setNodeId(NewNode); 56 } 57 } 58 59 // Now that we have a set of nodes to process, handle them all. 60 while (!Worklist.empty()) { 61 SDNode *N = Worklist.back(); 62 Worklist.pop_back(); 63 assert(N->getNodeId() == ReadyToProcess && 64 "Node should be ready if on worklist!"); 65 66 // Scan the values produced by the node, checking to see if any result 67 // types are illegal. 68 unsigned i = 0; 69 unsigned NumResults = N->getNumValues(); 70 do { 71 MVT ResultVT = N->getValueType(i); 72 switch (getTypeAction(ResultVT)) { 73 default: 74 assert(false && "Unknown action!"); 75 case Legal: 76 break; 77 case Promote: 78 PromoteResult(N, i); 79 goto NodeDone; 80 case Expand: 81 ExpandResult(N, i); 82 goto NodeDone; 83 case FloatToInt: 84 FloatToIntResult(N, i); 85 goto NodeDone; 86 case Scalarize: 87 ScalarizeResult(N, i); 88 goto NodeDone; 89 case Split: 90 SplitResult(N, i); 91 goto NodeDone; 92 } 93 } while (++i < NumResults); 94 95 // Scan the operand list for the node, handling any nodes with operands that 96 // are illegal. 97 { 98 unsigned NumOperands = N->getNumOperands(); 99 bool NeedsRevisit = false; 100 for (i = 0; i != NumOperands; ++i) { 101 MVT OpVT = N->getOperand(i).getValueType(); 102 switch (getTypeAction(OpVT)) { 103 default: 104 assert(false && "Unknown action!"); 105 case Legal: 106 continue; 107 case Promote: 108 NeedsRevisit = PromoteOperand(N, i); 109 break; 110 case Expand: 111 NeedsRevisit = ExpandOperand(N, i); 112 break; 113 case FloatToInt: 114 NeedsRevisit = FloatToIntOperand(N, i); 115 break; 116 case Scalarize: 117 NeedsRevisit = ScalarizeOperand(N, i); 118 break; 119 case Split: 120 NeedsRevisit = SplitOperand(N, i); 121 break; 122 } 123 break; 124 } 125 126 // If the node needs revisiting, don't add all users to the worklist etc. 127 if (NeedsRevisit) 128 continue; 129 130 if (i == NumOperands) 131 DEBUG(cerr << "Legally typed node: "; N->dump(&DAG); cerr << "\n"); 132 } 133NodeDone: 134 135 // If we reach here, the node was processed, potentially creating new nodes. 136 // Mark it as processed and add its users to the worklist as appropriate. 137 N->setNodeId(Processed); 138 139 for (SDNode::use_iterator UI = N->use_begin(), E = N->use_end(); 140 UI != E; ++UI) { 141 SDNode *User = UI->getUser(); 142 int NodeID = User->getNodeId(); 143 assert(NodeID != ReadyToProcess && NodeID != Processed && 144 "Invalid node id for user of unprocessed node!"); 145 146 // This node has two options: it can either be a new node or its Node ID 147 // may be a count of the number of operands it has that are not ready. 148 if (NodeID > 0) { 149 User->setNodeId(NodeID-1); 150 151 // If this was the last use it was waiting on, add it to the ready list. 152 if (NodeID-1 == ReadyToProcess) 153 Worklist.push_back(User); 154 continue; 155 } 156 157 // Otherwise, this node is new: this is the first operand of it that 158 // became ready. Its new NodeID is the number of operands it has minus 1 159 // (as this node is now processed). 160 assert(NodeID == NewNode && "Unknown node ID!"); 161 User->setNodeId(User->getNumOperands()-1); 162 163 // If the node only has a single operand, it is now ready. 164 if (User->getNumOperands() == 1) 165 Worklist.push_back(User); 166 } 167 } 168 169 // If the root changed (e.g. it was a dead load, update the root). 170 DAG.setRoot(Dummy.getValue()); 171 172 //DAG.viewGraph(); 173 174 // Remove dead nodes. This is important to do for cleanliness but also before 175 // the checking loop below. Implicit folding by the DAG.getNode operators can 176 // cause unreachable nodes to be around with their flags set to new. 177 DAG.RemoveDeadNodes(); 178 179 // In a debug build, scan all the nodes to make sure we found them all. This 180 // ensures that there are no cycles and that everything got processed. 181#ifndef NDEBUG 182 for (SelectionDAG::allnodes_iterator I = DAG.allnodes_begin(), 183 E = DAG.allnodes_end(); I != E; ++I) { 184 bool Failed = false; 185 186 // Check that all result types are legal. 187 for (unsigned i = 0, NumVals = I->getNumValues(); i < NumVals; ++i) 188 if (!isTypeLegal(I->getValueType(i))) { 189 cerr << "Result type " << i << " illegal!\n"; 190 Failed = true; 191 } 192 193 // Check that all operand types are legal. 194 for (unsigned i = 0, NumOps = I->getNumOperands(); i < NumOps; ++i) 195 if (!isTypeLegal(I->getOperand(i).getValueType())) { 196 cerr << "Operand type " << i << " illegal!\n"; 197 Failed = true; 198 } 199 200 if (I->getNodeId() != Processed) { 201 if (I->getNodeId() == NewNode) 202 cerr << "New node not 'noticed'?\n"; 203 else if (I->getNodeId() > 0) 204 cerr << "Operand not processed?\n"; 205 else if (I->getNodeId() == ReadyToProcess) 206 cerr << "Not added to worklist?\n"; 207 Failed = true; 208 } 209 210 if (Failed) { 211 I->dump(&DAG); cerr << "\n"; 212 abort(); 213 } 214 } 215#endif 216} 217 218/// AnalyzeNewNode - The specified node is the root of a subtree of potentially 219/// new nodes. Correct any processed operands (this may change the node) and 220/// calculate the NodeId. 221void DAGTypeLegalizer::AnalyzeNewNode(SDNode *&N) { 222 // If this was an existing node that is already done, we're done. 223 if (N->getNodeId() != NewNode) 224 return; 225 226 // Okay, we know that this node is new. Recursively walk all of its operands 227 // to see if they are new also. The depth of this walk is bounded by the size 228 // of the new tree that was constructed (usually 2-3 nodes), so we don't worry 229 // about revisiting of nodes. 230 // 231 // As we walk the operands, keep track of the number of nodes that are 232 // processed. If non-zero, this will become the new nodeid of this node. 233 // Already processed operands may need to be remapped to the node that 234 // replaced them, which can result in our node changing. Since remapping 235 // is rare, the code tries to minimize overhead in the non-remapping case. 236 237 SmallVector<SDOperand, 8> NewOps; 238 unsigned NumProcessed = 0; 239 for (unsigned i = 0, e = N->getNumOperands(); i != e; ++i) { 240 SDOperand OrigOp = N->getOperand(i); 241 SDOperand Op = OrigOp; 242 243 if (Op.Val->getNodeId() == Processed) 244 RemapNode(Op); 245 246 if (Op.Val->getNodeId() == NewNode) 247 AnalyzeNewNode(Op.Val); 248 else if (Op.Val->getNodeId() == Processed) 249 ++NumProcessed; 250 251 if (!NewOps.empty()) { 252 // Some previous operand changed. Add this one to the list. 253 NewOps.push_back(Op); 254 } else if (Op != OrigOp) { 255 // This is the first operand to change - add all operands so far. 256 for (unsigned j = 0; j < i; ++j) 257 NewOps.push_back(N->getOperand(j)); 258 NewOps.push_back(Op); 259 } 260 } 261 262 // Some operands changed - update the node. 263 if (!NewOps.empty()) 264 N = DAG.UpdateNodeOperands(SDOperand(N, 0), &NewOps[0], NewOps.size()).Val; 265 266 N->setNodeId(N->getNumOperands()-NumProcessed); 267 if (N->getNodeId() == ReadyToProcess) 268 Worklist.push_back(N); 269} 270 271namespace { 272 /// NodeUpdateListener - This class is a DAGUpdateListener that listens for 273 /// updates to nodes and recomputes their ready state. 274 class VISIBILITY_HIDDEN NodeUpdateListener : 275 public SelectionDAG::DAGUpdateListener { 276 DAGTypeLegalizer &DTL; 277 public: 278 NodeUpdateListener(DAGTypeLegalizer &dtl) : DTL(dtl) {} 279 280 virtual void NodeDeleted(SDNode *N, SDNode *E) { 281 assert(N->getNodeId() != DAGTypeLegalizer::Processed && 282 N->getNodeId() != DAGTypeLegalizer::ReadyToProcess && 283 "RAUW deleted processed node!"); 284 // It is possible, though rare, for the deleted node N to occur as a 285 // target in a map, so note the replacement N -> E in ReplacedNodes. 286 assert(E && "Node not replaced?"); 287 for (unsigned i = 0, e = E->getNumValues(); i != e; ++i) 288 DTL.NoteReplacement(SDOperand(N, i), SDOperand(E, i)); 289 } 290 291 virtual void NodeUpdated(SDNode *N) { 292 // Node updates can mean pretty much anything. It is possible that an 293 // operand was set to something already processed (f.e.) in which case 294 // this node could become ready. Recompute its flags. 295 assert(N->getNodeId() != DAGTypeLegalizer::Processed && 296 N->getNodeId() != DAGTypeLegalizer::ReadyToProcess && 297 "RAUW updated processed node!"); 298 DTL.ReanalyzeNode(N); 299 } 300 }; 301} 302 303 304/// ReplaceValueWith - The specified value was legalized to the specified other 305/// value. If they are different, update the DAG and NodeIDs replacing any uses 306/// of From to use To instead. 307void DAGTypeLegalizer::ReplaceValueWith(SDOperand From, SDOperand To) { 308 if (From == To) return; 309 310 // If expansion produced new nodes, make sure they are properly marked. 311 AnalyzeNewNode(To.Val); 312 313 // Anything that used the old node should now use the new one. Note that this 314 // can potentially cause recursive merging. 315 NodeUpdateListener NUL(*this); 316 DAG.ReplaceAllUsesOfValueWith(From, To, &NUL); 317 318 // The old node may still be present in a map like ExpandedNodes or 319 // PromotedNodes. Inform maps about the replacement. 320 NoteReplacement(From, To); 321} 322 323/// ReplaceNodeWith - Replace uses of the 'from' node's results with the 'to' 324/// node's results. The from and to node must define identical result types. 325void DAGTypeLegalizer::ReplaceNodeWith(SDNode *From, SDNode *To) { 326 if (From == To) return; 327 328 // If expansion produced new nodes, make sure they are properly marked. 329 AnalyzeNewNode(To); 330 331 assert(From->getNumValues() == To->getNumValues() && 332 "Node results don't match"); 333 334 // Anything that used the old node should now use the new one. Note that this 335 // can potentially cause recursive merging. 336 NodeUpdateListener NUL(*this); 337 DAG.ReplaceAllUsesWith(From, To, &NUL); 338 339 // The old node may still be present in a map like ExpandedNodes or 340 // PromotedNodes. Inform maps about the replacement. 341 for (unsigned i = 0, e = From->getNumValues(); i != e; ++i) { 342 assert(From->getValueType(i) == To->getValueType(i) && 343 "Node results don't match"); 344 NoteReplacement(SDOperand(From, i), SDOperand(To, i)); 345 } 346} 347 348 349/// RemapNode - If the specified value was already legalized to another value, 350/// replace it by that value. 351void DAGTypeLegalizer::RemapNode(SDOperand &N) { 352 DenseMap<SDOperand, SDOperand>::iterator I = ReplacedNodes.find(N); 353 if (I != ReplacedNodes.end()) { 354 // Use path compression to speed up future lookups if values get multiply 355 // replaced with other values. 356 RemapNode(I->second); 357 N = I->second; 358 } 359} 360 361/// ExpungeNode - If this is a deleted value that was kept around to speed up 362/// remapping, remove it globally now. The only map that can have a deleted 363/// node as a source is ReplacedNodes. Other maps can have deleted nodes as 364/// targets, but since their looked-up values are always immediately remapped 365/// using RemapNode, resulting in a not-deleted node, this is harmless as long 366/// as ReplacedNodes/RemapNode always performs correct mappings. The mapping 367/// will always be correct as long as ExpungeNode is called on the source when 368/// adding a new node to ReplacedNodes, and called on the target when adding 369/// a new node to any map. 370void DAGTypeLegalizer::ExpungeNode(SDOperand N) { 371 SDOperand Replacement = N; 372 RemapNode(Replacement); 373 if (Replacement != N) { 374 // Remove N from all maps - this is expensive but extremely rare. 375 ReplacedNodes.erase(N); 376 377 for (DenseMap<SDOperand, SDOperand>::iterator I = ReplacedNodes.begin(), 378 E = ReplacedNodes.end(); I != E; ++I) { 379 if (I->second == N) 380 I->second = Replacement; 381 } 382 383 for (DenseMap<SDOperand, SDOperand>::iterator I = PromotedNodes.begin(), 384 E = PromotedNodes.end(); I != E; ++I) { 385 assert(I->first != N); 386 if (I->second == N) 387 I->second = Replacement; 388 } 389 390 for (DenseMap<SDOperand, SDOperand>::iterator I = FloatToIntedNodes.begin(), 391 E = FloatToIntedNodes.end(); I != E; ++I) { 392 assert(I->first != N); 393 if (I->second == N) 394 I->second = Replacement; 395 } 396 397 for (DenseMap<SDOperand, SDOperand>::iterator I = ScalarizedNodes.begin(), 398 E = ScalarizedNodes.end(); I != E; ++I) { 399 assert(I->first != N); 400 if (I->second == N) 401 I->second = Replacement; 402 } 403 404 for (DenseMap<SDOperand, std::pair<SDOperand, SDOperand> >::iterator 405 I = ExpandedNodes.begin(), E = ExpandedNodes.end(); I != E; ++I) { 406 assert(I->first != N); 407 if (I->second.first == N) 408 I->second.first = Replacement; 409 if (I->second.second == N) 410 I->second.second = Replacement; 411 } 412 413 for (DenseMap<SDOperand, std::pair<SDOperand, SDOperand> >::iterator 414 I = SplitNodes.begin(), E = SplitNodes.end(); I != E; ++I) { 415 assert(I->first != N); 416 if (I->second.first == N) 417 I->second.first = Replacement; 418 if (I->second.second == N) 419 I->second.second = Replacement; 420 } 421 } 422} 423 424 425void DAGTypeLegalizer::SetPromotedOp(SDOperand Op, SDOperand Result) { 426 ExpungeNode(Result); 427 AnalyzeNewNode(Result.Val); 428 429 SDOperand &OpEntry = PromotedNodes[Op]; 430 assert(OpEntry.Val == 0 && "Node is already promoted!"); 431 OpEntry = Result; 432} 433 434void DAGTypeLegalizer::SetIntegerOp(SDOperand Op, SDOperand Result) { 435 ExpungeNode(Result); 436 AnalyzeNewNode(Result.Val); 437 438 SDOperand &OpEntry = FloatToIntedNodes[Op]; 439 assert(OpEntry.Val == 0 && "Node is already converted to integer!"); 440 OpEntry = Result; 441} 442 443void DAGTypeLegalizer::SetScalarizedOp(SDOperand Op, SDOperand Result) { 444 ExpungeNode(Result); 445 AnalyzeNewNode(Result.Val); 446 447 SDOperand &OpEntry = ScalarizedNodes[Op]; 448 assert(OpEntry.Val == 0 && "Node is already scalarized!"); 449 OpEntry = Result; 450} 451 452void DAGTypeLegalizer::GetExpandedOp(SDOperand Op, SDOperand &Lo, 453 SDOperand &Hi) { 454 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op]; 455 RemapNode(Entry.first); 456 RemapNode(Entry.second); 457 assert(Entry.first.Val && "Operand isn't expanded"); 458 Lo = Entry.first; 459 Hi = Entry.second; 460} 461 462void DAGTypeLegalizer::SetExpandedOp(SDOperand Op, SDOperand Lo, SDOperand Hi) { 463 ExpungeNode(Lo); 464 ExpungeNode(Hi); 465 466 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant. 467 AnalyzeNewNode(Lo.Val); 468 AnalyzeNewNode(Hi.Val); 469 470 // Remember that this is the result of the node. 471 std::pair<SDOperand, SDOperand> &Entry = ExpandedNodes[Op]; 472 assert(Entry.first.Val == 0 && "Node already expanded"); 473 Entry.first = Lo; 474 Entry.second = Hi; 475} 476 477void DAGTypeLegalizer::GetSplitOp(SDOperand Op, SDOperand &Lo, SDOperand &Hi) { 478 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op]; 479 RemapNode(Entry.first); 480 RemapNode(Entry.second); 481 assert(Entry.first.Val && "Operand isn't split"); 482 Lo = Entry.first; 483 Hi = Entry.second; 484} 485 486void DAGTypeLegalizer::SetSplitOp(SDOperand Op, SDOperand Lo, SDOperand Hi) { 487 ExpungeNode(Lo); 488 ExpungeNode(Hi); 489 490 // Lo/Hi may have been newly allocated, if so, add nodeid's as relevant. 491 AnalyzeNewNode(Lo.Val); 492 AnalyzeNewNode(Hi.Val); 493 494 // Remember that this is the result of the node. 495 std::pair<SDOperand, SDOperand> &Entry = SplitNodes[Op]; 496 assert(Entry.first.Val == 0 && "Node already split"); 497 Entry.first = Lo; 498 Entry.second = Hi; 499} 500 501 502/// BitConvertToInteger - Convert to an integer of the same size. 503SDOperand DAGTypeLegalizer::BitConvertToInteger(SDOperand Op) { 504 unsigned BitWidth = Op.getValueType().getSizeInBits(); 505 return DAG.getNode(ISD::BIT_CONVERT, MVT::getIntegerVT(BitWidth), Op); 506} 507 508SDOperand DAGTypeLegalizer::CreateStackStoreLoad(SDOperand Op, 509 MVT DestVT) { 510 // Create the stack frame object. 511 SDOperand FIPtr = DAG.CreateStackTemporary(DestVT); 512 513 // Emit a store to the stack slot. 514 SDOperand Store = DAG.getStore(DAG.getEntryNode(), Op, FIPtr, NULL, 0); 515 // Result is a load from the stack slot. 516 return DAG.getLoad(DestVT, Store, FIPtr, NULL, 0); 517} 518 519/// JoinIntegers - Build an integer with low bits Lo and high bits Hi. 520SDOperand DAGTypeLegalizer::JoinIntegers(SDOperand Lo, SDOperand Hi) { 521 MVT LVT = Lo.getValueType(); 522 MVT HVT = Hi.getValueType(); 523 MVT NVT = MVT::getIntegerVT(LVT.getSizeInBits() + HVT.getSizeInBits()); 524 525 Lo = DAG.getNode(ISD::ZERO_EXTEND, NVT, Lo); 526 Hi = DAG.getNode(ISD::ANY_EXTEND, NVT, Hi); 527 Hi = DAG.getNode(ISD::SHL, NVT, Hi, DAG.getConstant(LVT.getSizeInBits(), 528 TLI.getShiftAmountTy())); 529 return DAG.getNode(ISD::OR, NVT, Lo, Hi); 530} 531 532/// SplitInteger - Return the lower LoVT bits of Op in Lo and the upper HiVT 533/// bits in Hi. 534void DAGTypeLegalizer::SplitInteger(SDOperand Op, 535 MVT LoVT, MVT HiVT, 536 SDOperand &Lo, SDOperand &Hi) { 537 assert(LoVT.getSizeInBits() + HiVT.getSizeInBits() == 538 Op.getValueType().getSizeInBits() && "Invalid integer splitting!"); 539 Lo = DAG.getNode(ISD::TRUNCATE, LoVT, Op); 540 Hi = DAG.getNode(ISD::SRL, Op.getValueType(), Op, 541 DAG.getConstant(LoVT.getSizeInBits(), 542 TLI.getShiftAmountTy())); 543 Hi = DAG.getNode(ISD::TRUNCATE, HiVT, Hi); 544} 545 546/// SplitInteger - Return the lower and upper halves of Op's bits in a value type 547/// half the size of Op's. 548void DAGTypeLegalizer::SplitInteger(SDOperand Op, 549 SDOperand &Lo, SDOperand &Hi) { 550 MVT HalfVT = MVT::getIntegerVT(Op.getValueType().getSizeInBits()/2); 551 SplitInteger(Op, HalfVT, HalfVT, Lo, Hi); 552} 553 554/// MakeLibCall - Generate a libcall taking the given operands as arguments and 555/// returning a result of type RetVT. 556SDOperand DAGTypeLegalizer::MakeLibCall(RTLIB::Libcall LC, MVT RetVT, 557 const SDOperand *Ops, unsigned NumOps, 558 bool isSigned) { 559 TargetLowering::ArgListTy Args; 560 Args.reserve(NumOps); 561 562 TargetLowering::ArgListEntry Entry; 563 for (unsigned i = 0; i != NumOps; ++i) { 564 Entry.Node = Ops[i]; 565 Entry.Ty = Entry.Node.getValueType().getTypeForMVT(); 566 Entry.isSExt = isSigned; 567 Entry.isZExt = !isSigned; 568 Args.push_back(Entry); 569 } 570 SDOperand Callee = DAG.getExternalSymbol(TLI.getLibcallName(LC), 571 TLI.getPointerTy()); 572 573 const Type *RetTy = RetVT.getTypeForMVT(); 574 std::pair<SDOperand,SDOperand> CallInfo = 575 TLI.LowerCallTo(DAG.getEntryNode(), RetTy, isSigned, !isSigned, false, 576 CallingConv::C, false, Callee, Args, DAG); 577 return CallInfo.first; 578} 579 580//===----------------------------------------------------------------------===// 581// Entry Point 582//===----------------------------------------------------------------------===// 583 584/// LegalizeTypes - This transforms the SelectionDAG into a SelectionDAG that 585/// only uses types natively supported by the target. 586/// 587/// Note that this is an involved process that may invalidate pointers into 588/// the graph. 589void SelectionDAG::LegalizeTypes() { 590 if (ViewLegalizeTypesDAGs) viewGraph(); 591 592 DAGTypeLegalizer(*this).run(); 593} 594