MachineBasicBlock.cpp revision b5257664795d49ada0d4669fe8ed1cd49c04fbf3
1//===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===// 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// Collect the sequence of machine instructions for a basic block. 11// 12//===----------------------------------------------------------------------===// 13 14#include "llvm/CodeGen/MachineBasicBlock.h" 15#include "llvm/BasicBlock.h" 16#include "llvm/CodeGen/MachineFunction.h" 17#include "llvm/Target/TargetRegisterInfo.h" 18#include "llvm/Target/TargetData.h" 19#include "llvm/Target/TargetInstrDesc.h" 20#include "llvm/Target/TargetMachine.h" 21#include "llvm/Support/LeakDetector.h" 22#include "llvm/Support/raw_ostream.h" 23#include <algorithm> 24using namespace llvm; 25 26MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb) 27 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false) { 28 Insts.Parent = this; 29} 30 31MachineBasicBlock::~MachineBasicBlock() { 32 LeakDetector::removeGarbageObject(this); 33} 34 35std::ostream& llvm::operator<<(std::ostream &OS, const MachineBasicBlock &MBB) { 36 MBB.print(OS); 37 return OS; 38} 39raw_ostream& llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) { 40 MBB.print(OS); 41 return OS; 42} 43 44/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the 45/// parent pointer of the MBB, the MBB numbering, and any instructions in the 46/// MBB to be on the right operand list for registers. 47/// 48/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it 49/// gets the next available unique MBB number. If it is removed from a 50/// MachineFunction, it goes back to being #-1. 51void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock* N) { 52 MachineFunction &MF = *N->getParent(); 53 N->Number = MF.addToMBBNumbering(N); 54 55 // Make sure the instructions have their operands in the reginfo lists. 56 MachineRegisterInfo &RegInfo = MF.getRegInfo(); 57 for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I) 58 I->AddRegOperandsToUseLists(RegInfo); 59 60 LeakDetector::removeGarbageObject(N); 61} 62 63void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock* N) { 64 N->getParent()->removeFromMBBNumbering(N->Number); 65 N->Number = -1; 66 LeakDetector::addGarbageObject(N); 67} 68 69 70/// addNodeToList (MI) - When we add an instruction to a basic block 71/// list, we update its parent pointer and add its operands from reg use/def 72/// lists if appropriate. 73void ilist_traits<MachineInstr>::addNodeToList(MachineInstr* N) { 74 assert(N->getParent() == 0 && "machine instruction already in a basic block"); 75 N->setParent(Parent); 76 77 // Add the instruction's register operands to their corresponding 78 // use/def lists. 79 MachineFunction *MF = Parent->getParent(); 80 N->AddRegOperandsToUseLists(MF->getRegInfo()); 81 82 LeakDetector::removeGarbageObject(N); 83} 84 85/// removeNodeFromList (MI) - When we remove an instruction from a basic block 86/// list, we update its parent pointer and remove its operands from reg use/def 87/// lists if appropriate. 88void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr* N) { 89 assert(N->getParent() != 0 && "machine instruction not in a basic block"); 90 91 // Remove from the use/def lists. 92 N->RemoveRegOperandsFromUseLists(); 93 94 N->setParent(0); 95 96 LeakDetector::addGarbageObject(N); 97} 98 99/// transferNodesFromList (MI) - When moving a range of instructions from one 100/// MBB list to another, we need to update the parent pointers and the use/def 101/// lists. 102void ilist_traits<MachineInstr>::transferNodesFromList( 103 ilist_traits<MachineInstr>& fromList, 104 MachineBasicBlock::iterator first, 105 MachineBasicBlock::iterator last) { 106 assert(Parent->getParent() == fromList.Parent->getParent() && 107 "MachineInstr parent mismatch!"); 108 109 // Splice within the same MBB -> no change. 110 if (Parent == fromList.Parent) return; 111 112 // If splicing between two blocks within the same function, just update the 113 // parent pointers. 114 for (; first != last; ++first) 115 first->setParent(Parent); 116} 117 118void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) { 119 assert(!MI->getParent() && "MI is still in a block!"); 120 Parent->getParent()->DeleteMachineInstr(MI); 121} 122 123MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() { 124 iterator I = end(); 125 while (I != begin() && (--I)->getDesc().isTerminator()) 126 ; /*noop */ 127 if (I != end() && !I->getDesc().isTerminator()) ++I; 128 return I; 129} 130 131bool 132MachineBasicBlock::isOnlyReachableByFallthrough() const { 133 return !isLandingPad() && 134 !pred_empty() && 135 next(pred_begin()) == pred_end() && 136 (*pred_begin())->isLayoutSuccessor(this) && 137 ((*pred_begin())->empty() || 138 !(*pred_begin())->back().getDesc().isBarrier()); 139} 140 141void MachineBasicBlock::dump() const { 142 print(*cerr.stream()); 143} 144 145static inline void OutputReg(raw_ostream &os, unsigned RegNo, 146 const TargetRegisterInfo *TRI = 0) { 147 if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) { 148 if (TRI) 149 os << " %" << TRI->get(RegNo).Name; 150 else 151 os << " %mreg(" << RegNo << ")"; 152 } else 153 os << " %reg" << RegNo; 154} 155 156void MachineBasicBlock::print(std::ostream &OS, 157 const PrefixPrinter &prefix) const { 158 raw_os_ostream RawOS(OS); 159 print(RawOS, prefix); 160} 161 162void MachineBasicBlock::print(raw_ostream &OS, 163 const PrefixPrinter &prefix) const { 164 const MachineFunction *MF = getParent(); 165 if(!MF) { 166 OS << "Can't print out MachineBasicBlock because parent MachineFunction" 167 << " is null\n"; 168 return; 169 } 170 171 const BasicBlock *LBB = getBasicBlock(); 172 OS << "\n"; 173 if (LBB) OS << LBB->getName() << ": "; 174 OS << (const void*)this 175 << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber(); 176 if (Alignment) OS << ", Alignment " << Alignment; 177 if (isLandingPad()) OS << ", EH LANDING PAD"; 178 OS << ":\n"; 179 180 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo(); 181 if (!livein_empty()) { 182 OS << "Live Ins:"; 183 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I) 184 OutputReg(OS, *I, TRI); 185 OS << "\n"; 186 } 187 // Print the preds of this block according to the CFG. 188 if (!pred_empty()) { 189 OS << " Predecessors according to CFG:"; 190 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI) 191 OS << " " << *PI << " (#" << (*PI)->getNumber() << ")"; 192 OS << "\n"; 193 } 194 195 for (const_iterator I = begin(); I != end(); ++I) { 196 prefix(OS, *I) << "\t"; 197 I->print(OS, &getParent()->getTarget()); 198 } 199 200 // Print the successors of this block according to the CFG. 201 if (!succ_empty()) { 202 OS << " Successors according to CFG:"; 203 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) 204 OS << " " << *SI << " (#" << (*SI)->getNumber() << ")"; 205 OS << "\n"; 206 } 207} 208 209void MachineBasicBlock::removeLiveIn(unsigned Reg) { 210 livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 211 assert(I != livein_end() && "Not a live in!"); 212 LiveIns.erase(I); 213} 214 215bool MachineBasicBlock::isLiveIn(unsigned Reg) const { 216 const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 217 return I != livein_end(); 218} 219 220void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) { 221 getParent()->splice(NewAfter, this); 222} 223 224void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) { 225 MachineFunction::iterator BBI = NewBefore; 226 getParent()->splice(++BBI, this); 227} 228 229 230void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) { 231 Successors.push_back(succ); 232 succ->addPredecessor(this); 233} 234 235void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) { 236 succ->removePredecessor(this); 237 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ); 238 assert(I != Successors.end() && "Not a current successor!"); 239 Successors.erase(I); 240} 241 242MachineBasicBlock::succ_iterator 243MachineBasicBlock::removeSuccessor(succ_iterator I) { 244 assert(I != Successors.end() && "Not a current successor!"); 245 (*I)->removePredecessor(this); 246 return Successors.erase(I); 247} 248 249void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) { 250 Predecessors.push_back(pred); 251} 252 253void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) { 254 std::vector<MachineBasicBlock *>::iterator I = 255 std::find(Predecessors.begin(), Predecessors.end(), pred); 256 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!"); 257 Predecessors.erase(I); 258} 259 260void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) 261{ 262 if (this == fromMBB) 263 return; 264 265 for(MachineBasicBlock::succ_iterator iter = fromMBB->succ_begin(), 266 end = fromMBB->succ_end(); iter != end; ++iter) { 267 addSuccessor(*iter); 268 } 269 while(!fromMBB->succ_empty()) 270 fromMBB->removeSuccessor(fromMBB->succ_begin()); 271} 272 273bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const { 274 std::vector<MachineBasicBlock *>::const_iterator I = 275 std::find(Successors.begin(), Successors.end(), MBB); 276 return I != Successors.end(); 277} 278 279bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const { 280 MachineFunction::const_iterator I(this); 281 return next(I) == MachineFunction::const_iterator(MBB); 282} 283 284/// removeFromParent - This method unlinks 'this' from the containing function, 285/// and returns it, but does not delete it. 286MachineBasicBlock *MachineBasicBlock::removeFromParent() { 287 assert(getParent() && "Not embedded in a function!"); 288 getParent()->remove(this); 289 return this; 290} 291 292 293/// eraseFromParent - This method unlinks 'this' from the containing function, 294/// and deletes it. 295void MachineBasicBlock::eraseFromParent() { 296 assert(getParent() && "Not embedded in a function!"); 297 getParent()->erase(this); 298} 299 300 301/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 302/// 'Old', change the code and CFG so that it branches to 'New' instead. 303void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old, 304 MachineBasicBlock *New) { 305 assert(Old != New && "Cannot replace self with self!"); 306 307 MachineBasicBlock::iterator I = end(); 308 while (I != begin()) { 309 --I; 310 if (!I->getDesc().isTerminator()) break; 311 312 // Scan the operands of this machine instruction, replacing any uses of Old 313 // with New. 314 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 315 if (I->getOperand(i).isMBB() && 316 I->getOperand(i).getMBB() == Old) 317 I->getOperand(i).setMBB(New); 318 } 319 320 // Update the successor information. 321 removeSuccessor(Old); 322 addSuccessor(New); 323} 324 325/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the 326/// CFG to be inserted. If we have proven that MBB can only branch to DestA and 327/// DestB, remove any other MBB successors from the CFG. DestA and DestB can 328/// be null. 329/// Besides DestA and DestB, retain other edges leading to LandingPads 330/// (currently there can be only one; we don't check or require that here). 331/// Note it is possible that DestA and/or DestB are LandingPads. 332bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA, 333 MachineBasicBlock *DestB, 334 bool isCond) { 335 bool MadeChange = false; 336 bool AddedFallThrough = false; 337 338 MachineFunction::iterator FallThru = next(MachineFunction::iterator(this)); 339 340 // If this block ends with a conditional branch that falls through to its 341 // successor, set DestB as the successor. 342 if (isCond) { 343 if (DestB == 0 && FallThru != getParent()->end()) { 344 DestB = FallThru; 345 AddedFallThrough = true; 346 } 347 } else { 348 // If this is an unconditional branch with no explicit dest, it must just be 349 // a fallthrough into DestB. 350 if (DestA == 0 && FallThru != getParent()->end()) { 351 DestA = FallThru; 352 AddedFallThrough = true; 353 } 354 } 355 356 MachineBasicBlock::succ_iterator SI = succ_begin(); 357 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB; 358 while (SI != succ_end()) { 359 if (*SI == DestA && DestA == DestB) { 360 DestA = DestB = 0; 361 ++SI; 362 } else if (*SI == DestA) { 363 DestA = 0; 364 ++SI; 365 } else if (*SI == DestB) { 366 DestB = 0; 367 ++SI; 368 } else if ((*SI)->isLandingPad() && 369 *SI!=OrigDestA && *SI!=OrigDestB) { 370 ++SI; 371 } else { 372 // Otherwise, this is a superfluous edge, remove it. 373 SI = removeSuccessor(SI); 374 MadeChange = true; 375 } 376 } 377 if (!AddedFallThrough) { 378 assert(DestA == 0 && DestB == 0 && 379 "MachineCFG is missing edges!"); 380 } else if (isCond) { 381 assert(DestA == 0 && "MachineCFG is missing edges!"); 382 } 383 return MadeChange; 384} 385