MachineBasicBlock.cpp revision 5d5ee80ea8bf300d1ee8ccbd7174466d98a1e99e
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 126void MachineBasicBlock::dump() const { 127 print(*cerr.stream()); 128} 129 130static inline void OutputReg(std::ostream &os, unsigned RegNo, 131 const TargetRegisterInfo *TRI = 0) { 132 if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) { 133 if (TRI) 134 os << " %" << TRI->get(RegNo).Name; 135 else 136 os << " %mreg(" << RegNo << ")"; 137 } else 138 os << " %reg" << RegNo; 139} 140 141void MachineBasicBlock::print(std::ostream &OS) const { 142 const MachineFunction *MF = getParent(); 143 if(!MF) { 144 OS << "Can't print out MachineBasicBlock because parent MachineFunction" 145 << " is null\n"; 146 return; 147 } 148 149 const BasicBlock *LBB = getBasicBlock(); 150 OS << "\n"; 151 if (LBB) OS << LBB->getName() << ": "; 152 OS << (const void*)this 153 << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber(); 154 if (Alignment) OS << ", Alignment " << Alignment; 155 if (isLandingPad()) OS << ", EH LANDING PAD"; 156 OS << ":\n"; 157 158 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo(); 159 if (!livein_empty()) { 160 OS << "Live Ins:"; 161 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I) 162 OutputReg(OS, *I, TRI); 163 OS << "\n"; 164 } 165 // Print the preds of this block according to the CFG. 166 if (!pred_empty()) { 167 OS << " Predecessors according to CFG:"; 168 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI) 169 OS << " " << *PI << " (#" << (*PI)->getNumber() << ")"; 170 OS << "\n"; 171 } 172 173 for (const_iterator I = begin(); I != end(); ++I) { 174 OS << "\t"; 175 I->print(OS, &getParent()->getTarget()); 176 } 177 178 // Print the successors of this block according to the CFG. 179 if (!succ_empty()) { 180 OS << " Successors according to CFG:"; 181 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI) 182 OS << " " << *SI << " (#" << (*SI)->getNumber() << ")"; 183 OS << "\n"; 184 } 185} 186 187void MachineBasicBlock::removeLiveIn(unsigned Reg) { 188 livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 189 assert(I != livein_end() && "Not a live in!"); 190 LiveIns.erase(I); 191} 192 193bool MachineBasicBlock::isLiveIn(unsigned Reg) const { 194 const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg); 195 return I != livein_end(); 196} 197 198void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) { 199 getParent()->splice(NewAfter, this); 200} 201 202void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) { 203 MachineFunction::iterator BBI = NewBefore; 204 getParent()->splice(++BBI, this); 205} 206 207 208void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) { 209 Successors.push_back(succ); 210 succ->addPredecessor(this); 211} 212 213void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) { 214 succ->removePredecessor(this); 215 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ); 216 assert(I != Successors.end() && "Not a current successor!"); 217 Successors.erase(I); 218} 219 220MachineBasicBlock::succ_iterator 221MachineBasicBlock::removeSuccessor(succ_iterator I) { 222 assert(I != Successors.end() && "Not a current successor!"); 223 (*I)->removePredecessor(this); 224 return Successors.erase(I); 225} 226 227void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) { 228 Predecessors.push_back(pred); 229} 230 231void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) { 232 std::vector<MachineBasicBlock *>::iterator I = 233 std::find(Predecessors.begin(), Predecessors.end(), pred); 234 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!"); 235 Predecessors.erase(I); 236} 237 238void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) 239{ 240 if (this == fromMBB) 241 return; 242 243 for(MachineBasicBlock::succ_iterator iter = fromMBB->succ_begin(), 244 end = fromMBB->succ_end(); iter != end; ++iter) { 245 addSuccessor(*iter); 246 } 247 while(!fromMBB->succ_empty()) 248 fromMBB->removeSuccessor(fromMBB->succ_begin()); 249} 250 251bool MachineBasicBlock::isSuccessor(MachineBasicBlock *MBB) const { 252 std::vector<MachineBasicBlock *>::const_iterator I = 253 std::find(Successors.begin(), Successors.end(), MBB); 254 return I != Successors.end(); 255} 256 257bool MachineBasicBlock::isLayoutSuccessor(MachineBasicBlock *MBB) const { 258 MachineFunction::const_iterator I(this); 259 return next(I) == MachineFunction::const_iterator(MBB); 260} 261 262/// removeFromParent - This method unlinks 'this' from the containing function, 263/// and returns it, but does not delete it. 264MachineBasicBlock *MachineBasicBlock::removeFromParent() { 265 assert(getParent() && "Not embedded in a function!"); 266 getParent()->remove(this); 267 return this; 268} 269 270 271/// eraseFromParent - This method unlinks 'this' from the containing function, 272/// and deletes it. 273void MachineBasicBlock::eraseFromParent() { 274 assert(getParent() && "Not embedded in a function!"); 275 getParent()->erase(this); 276} 277 278 279/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to 280/// 'Old', change the code and CFG so that it branches to 'New' instead. 281void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old, 282 MachineBasicBlock *New) { 283 assert(Old != New && "Cannot replace self with self!"); 284 285 MachineBasicBlock::iterator I = end(); 286 while (I != begin()) { 287 --I; 288 if (!I->getDesc().isTerminator()) break; 289 290 // Scan the operands of this machine instruction, replacing any uses of Old 291 // with New. 292 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i) 293 if (I->getOperand(i).isMBB() && 294 I->getOperand(i).getMBB() == Old) 295 I->getOperand(i).setMBB(New); 296 } 297 298 // Update the successor information. If New was already a successor, just 299 // remove the link to Old instead of creating another one. PR 1444. 300 removeSuccessor(Old); 301 if (!isSuccessor(New)) 302 addSuccessor(New); 303} 304 305/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the 306/// CFG to be inserted. If we have proven that MBB can only branch to DestA and 307/// DestB, remove any other MBB successors from the CFG. DestA and DestB can 308/// be null. 309/// Besides DestA and DestB, retain other edges leading to LandingPads 310/// (currently there can be only one; we don't check or require that here). 311/// Note it is possible that DestA and/or DestB are LandingPads. 312bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA, 313 MachineBasicBlock *DestB, 314 bool isCond) { 315 bool MadeChange = false; 316 bool AddedFallThrough = false; 317 318 MachineFunction::iterator FallThru = next(MachineFunction::iterator(this)); 319 320 // If this block ends with a conditional branch that falls through to its 321 // successor, set DestB as the successor. 322 if (isCond) { 323 if (DestB == 0 && FallThru != getParent()->end()) { 324 DestB = FallThru; 325 AddedFallThrough = true; 326 } 327 } else { 328 // If this is an unconditional branch with no explicit dest, it must just be 329 // a fallthrough into DestB. 330 if (DestA == 0 && FallThru != getParent()->end()) { 331 DestA = FallThru; 332 AddedFallThrough = true; 333 } 334 } 335 336 MachineBasicBlock::succ_iterator SI = succ_begin(); 337 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB; 338 while (SI != succ_end()) { 339 if (*SI == DestA && DestA == DestB) { 340 DestA = DestB = 0; 341 ++SI; 342 } else if (*SI == DestA) { 343 DestA = 0; 344 ++SI; 345 } else if (*SI == DestB) { 346 DestB = 0; 347 ++SI; 348 } else if ((*SI)->isLandingPad() && 349 *SI!=OrigDestA && *SI!=OrigDestB) { 350 ++SI; 351 } else { 352 // Otherwise, this is a superfluous edge, remove it. 353 SI = removeSuccessor(SI); 354 MadeChange = true; 355 } 356 } 357 if (!AddedFallThrough) { 358 assert(DestA == 0 && DestB == 0 && 359 "MachineCFG is missing edges!"); 360 } else if (isCond) { 361 assert(DestA == 0 && "MachineCFG is missing edges!"); 362 } 363 return MadeChange; 364} 365