MachineBasicBlock.cpp revision 3f1d2c3a512eacb997c35e6f1277549b31c892cb
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 <algorithm> 23using namespace llvm; 24 25MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb) 26 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false) { 27 Insts.Parent = this; 28} 29 30MachineBasicBlock::~MachineBasicBlock() { 31 LeakDetector::removeGarbageObject(this); 32} 33 34std::ostream& llvm::operator<<(std::ostream &OS, const MachineBasicBlock &MBB) { 35 MBB.print(OS); 36 return OS; 37} 38 39/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the 40/// parent pointer of the MBB, the MBB numbering, and any instructions in the 41/// MBB to be on the right operand list for registers. 42/// 43/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it 44/// gets the next available unique MBB number. If it is removed from a 45/// MachineFunction, it goes back to being #-1. 46void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock* N) { 47 MachineFunction &MF = *N->getParent(); 48 N->Number = MF.addToMBBNumbering(N); 49 50 // Make sure the instructions have their operands in the reginfo lists. 51 MachineRegisterInfo &RegInfo = MF.getRegInfo(); 52 for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I) 53 I->AddRegOperandsToUseLists(RegInfo); 54 55 LeakDetector::removeGarbageObject(N); 56} 57 58void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock* N) { 59 N->getParent()->removeFromMBBNumbering(N->Number); 60 N->Number = -1; 61 LeakDetector::addGarbageObject(N); 62} 63 64 65/// addNodeToList (MI) - When we add an instruction to a basic block 66/// list, we update its parent pointer and add its operands from reg use/def 67/// lists if appropriate. 68void ilist_traits<MachineInstr>::addNodeToList(MachineInstr* N) { 69 assert(N->getParent() == 0 && "machine instruction already in a basic block"); 70 N->setParent(Parent); 71 72 // Add the instruction's register operands to their corresponding 73 // use/def lists. 74 MachineFunction *MF = Parent->getParent(); 75 N->AddRegOperandsToUseLists(MF->getRegInfo()); 76 77 LeakDetector::removeGarbageObject(N); 78} 79 80/// removeNodeFromList (MI) - When we remove an instruction from a basic block 81/// list, we update its parent pointer and remove its operands from reg use/def 82/// lists if appropriate. 83void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr* N) { 84 assert(N->getParent() != 0 && "machine instruction not in a basic block"); 85 86 // Remove from the use/def lists. 87 N->RemoveRegOperandsFromUseLists(); 88 89 N->setParent(0); 90 91 LeakDetector::addGarbageObject(N); 92} 93 94/// transferNodesFromList (MI) - When moving a range of instructions from one 95/// MBB list to another, we need to update the parent pointers and the use/def 96/// lists. 97void ilist_traits<MachineInstr>::transferNodesFromList( 98 ilist_traits<MachineInstr>& fromList, 99 MachineBasicBlock::iterator first, 100 MachineBasicBlock::iterator last) { 101 assert(Parent->getParent() == fromList.Parent->getParent() && 102 "MachineInstr parent mismatch!"); 103 104 // Splice within the same MBB -> no change. 105 if (Parent == fromList.Parent) return; 106 107 // If splicing between two blocks within the same function, just update the 108 // parent pointers. 109 for (; first != last; ++first) 110 first->setParent(Parent); 111} 112 113void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) { 114 assert(!MI->getParent() && "MI is still in a block!"); 115 Parent->getParent()->DeleteMachineInstr(MI); 116} 117 118MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() { 119 iterator I = end(); 120 while (I != begin() && (--I)->getDesc().isTerminator()) 121 ; /*noop */ 122 if (I != end() && !I->getDesc().isTerminator()) ++I; 123 return I; 124} 125 126bool 127MachineBasicBlock::isOnlyReachableByFallthrough() const { 128 return !isLandingPad() && 129 !pred_empty() && 130 next(pred_begin()) == pred_end() && 131 (*pred_begin())->isLayoutSuccessor(this) && 132 ((*pred_begin())->empty() || 133 !(*pred_begin())->back().getDesc().isBarrier()); 134} 135 136void MachineBasicBlock::dump() const { 137 print(*cerr.stream()); 138} 139 140static inline void OutputReg(std::ostream &os, unsigned RegNo, 141 const TargetRegisterInfo *TRI = 0) { 142 if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) { 143 if (TRI) 144 os << " %" << TRI->get(RegNo).Name; 145 else 146 os << " %mreg(" << RegNo << ")"; 147 } else 148 os << " %reg" << RegNo; 149} 150 151void MachineBasicBlock::print(std::ostream &OS) const { 152 const MachineFunction *MF = getParent(); 153 if(!MF) { 154 OS << "Can't print out MachineBasicBlock because parent MachineFunction" 155 << " is null\n"; 156 return; 157 } 158 159 const BasicBlock *LBB = getBasicBlock(); 160 OS << "\n"; 161 if (LBB) OS << LBB->getName() << ": "; 162 OS << (const void*)this 163 << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber(); 164 if (Alignment) OS << ", Alignment " << Alignment; 165 if (isLandingPad()) OS << ", EH LANDING PAD"; 166 OS << ":\n"; 167 168 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo(); 169 if (!livein_empty()) { 170 OS << "Live Ins:"; 171 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I) 172 OutputReg(OS, *I, TRI); 173 OS << "\n"; 174 } 175 // Print the preds of this block according to the CFG. 176 if (!pred_empty()) { 177 OS << " Predecessors according to CFG:"; 178 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI) 179 OS << " " << *PI << " (#" << (*PI)->getNumber() << ")"; 180 OS << "\n"; 181 } 182 183 for (const_iterator I = begin(); I != end(); ++I) { 184 OS << "\t"; 185 I->print(OS, &getParent()->getTarget()); 186 } 187 188 // Print the successors of this block according to the CFG. 189 if (!succ_empty()) { 190 OS << " Successors according to CFG:"; 191 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) 192 OS << " " << *SI << " (#" << (*SI)->getNumber() << ")"; 193 OS << "\n"; 194 } 195} 196 197void MachineBasicBlock::removeLiveIn(unsigned Reg) { 198 livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 199 assert(I != livein_end() && "Not a live in!"); 200 LiveIns.erase(I); 201} 202 203bool MachineBasicBlock::isLiveIn(unsigned Reg) const { 204 const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 205 return I != livein_end(); 206} 207 208void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) { 209 getParent()->splice(NewAfter, this); 210} 211 212void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) { 213 MachineFunction::iterator BBI = NewBefore; 214 getParent()->splice(++BBI, this); 215} 216 217 218void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) { 219 Successors.push_back(succ); 220 succ->addPredecessor(this); 221} 222 223void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) { 224 succ->removePredecessor(this); 225 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ); 226 assert(I != Successors.end() && "Not a current successor!"); 227 Successors.erase(I); 228} 229 230MachineBasicBlock::succ_iterator 231MachineBasicBlock::removeSuccessor(succ_iterator I) { 232 assert(I != Successors.end() && "Not a current successor!"); 233 (*I)->removePredecessor(this); 234 return Successors.erase(I); 235} 236 237void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) { 238 Predecessors.push_back(pred); 239} 240 241void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) { 242 std::vector<MachineBasicBlock *>::iterator I = 243 std::find(Predecessors.begin(), Predecessors.end(), pred); 244 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!"); 245 Predecessors.erase(I); 246} 247 248void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) 249{ 250 if (this == fromMBB) 251 return; 252 253 for(MachineBasicBlock::succ_iterator iter = fromMBB->succ_begin(), 254 end = fromMBB->succ_end(); iter != end; ++iter) { 255 addSuccessor(*iter); 256 } 257 while(!fromMBB->succ_empty()) 258 fromMBB->removeSuccessor(fromMBB->succ_begin()); 259} 260 261bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const { 262 std::vector<MachineBasicBlock *>::const_iterator I = 263 std::find(Successors.begin(), Successors.end(), MBB); 264 return I != Successors.end(); 265} 266 267bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const { 268 MachineFunction::const_iterator I(this); 269 return next(I) == MachineFunction::const_iterator(MBB); 270} 271 272/// removeFromParent - This method unlinks 'this' from the containing function, 273/// and returns it, but does not delete it. 274MachineBasicBlock *MachineBasicBlock::removeFromParent() { 275 assert(getParent() && "Not embedded in a function!"); 276 getParent()->remove(this); 277 return this; 278} 279 280 281/// eraseFromParent - This method unlinks 'this' from the containing function, 282/// and deletes it. 283void MachineBasicBlock::eraseFromParent() { 284 assert(getParent() && "Not embedded in a function!"); 285 getParent()->erase(this); 286} 287 288 289/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 290/// 'Old', change the code and CFG so that it branches to 'New' instead. 291void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old, 292 MachineBasicBlock *New) { 293 assert(Old != New && "Cannot replace self with self!"); 294 295 MachineBasicBlock::iterator I = end(); 296 while (I != begin()) { 297 --I; 298 if (!I->getDesc().isTerminator()) break; 299 300 // Scan the operands of this machine instruction, replacing any uses of Old 301 // with New. 302 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 303 if (I->getOperand(i).isMBB() && 304 I->getOperand(i).getMBB() == Old) 305 I->getOperand(i).setMBB(New); 306 } 307 308 // Update the successor information. 309 removeSuccessor(Old); 310 addSuccessor(New); 311} 312 313/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the 314/// CFG to be inserted. If we have proven that MBB can only branch to DestA and 315/// DestB, remove any other MBB successors from the CFG. DestA and DestB can 316/// be null. 317/// Besides DestA and DestB, retain other edges leading to LandingPads 318/// (currently there can be only one; we don't check or require that here). 319/// Note it is possible that DestA and/or DestB are LandingPads. 320bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA, 321 MachineBasicBlock *DestB, 322 bool isCond) { 323 bool MadeChange = false; 324 bool AddedFallThrough = false; 325 326 MachineFunction::iterator FallThru = next(MachineFunction::iterator(this)); 327 328 // If this block ends with a conditional branch that falls through to its 329 // successor, set DestB as the successor. 330 if (isCond) { 331 if (DestB == 0 && FallThru != getParent()->end()) { 332 DestB = FallThru; 333 AddedFallThrough = true; 334 } 335 } else { 336 // If this is an unconditional branch with no explicit dest, it must just be 337 // a fallthrough into DestB. 338 if (DestA == 0 && FallThru != getParent()->end()) { 339 DestA = FallThru; 340 AddedFallThrough = true; 341 } 342 } 343 344 MachineBasicBlock::succ_iterator SI = succ_begin(); 345 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB; 346 while (SI != succ_end()) { 347 if (*SI == DestA && DestA == DestB) { 348 DestA = DestB = 0; 349 ++SI; 350 } else if (*SI == DestA) { 351 DestA = 0; 352 ++SI; 353 } else if (*SI == DestB) { 354 DestB = 0; 355 ++SI; 356 } else if ((*SI)->isLandingPad() && 357 *SI!=OrigDestA && *SI!=OrigDestB) { 358 ++SI; 359 } else { 360 // Otherwise, this is a superfluous edge, remove it. 361 SI = removeSuccessor(SI); 362 MadeChange = true; 363 } 364 } 365 if (!AddedFallThrough) { 366 assert(DestA == 0 && DestB == 0 && 367 "MachineCFG is missing edges!"); 368 } else if (isCond) { 369 assert(DestA == 0 && "MachineCFG is missing edges!"); 370 } 371 return MadeChange; 372} 373