1 //===-- llvm/CodeGen/MachineBasicBlock.cpp ----------------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // Collect the sequence of machine instructions for a basic block.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/CodeGen/MachineBasicBlock.h"
15 #include "llvm/BasicBlock.h"
16 #include "llvm/CodeGen/MachineFunction.h"
17 #include "llvm/CodeGen/MachineInstr.h"
18 #include "llvm/Target/MRegisterInfo.h"
19 #include "llvm/Target/TargetData.h"
20 #include "llvm/Target/TargetInstrInfo.h"
21 #include "llvm/Target/TargetMachine.h"
22 #include "llvm/Support/LeakDetector.h"
26 MachineBasicBlock::~MachineBasicBlock() {
27 LeakDetector::removeGarbageObject(this);
30 std::ostream& llvm::operator<<(std::ostream &OS, const MachineBasicBlock &MBB) {
35 // MBBs start out as #-1. When a MBB is added to a MachineFunction, it
36 // gets the next available unique MBB number. If it is removed from a
37 // MachineFunction, it goes back to being #-1.
38 void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock* N) {
39 assert(N->Parent == 0 && "machine instruction already in a basic block");
41 N->Number = Parent->addToMBBNumbering(N);
42 LeakDetector::removeGarbageObject(N);
45 void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock* N) {
46 assert(N->Parent != 0 && "machine instruction not in a basic block");
47 N->Parent->removeFromMBBNumbering(N->Number);
50 LeakDetector::addGarbageObject(N);
54 MachineInstr* ilist_traits<MachineInstr>::createSentinel() {
55 MachineInstr* dummy = new MachineInstr();
56 LeakDetector::removeGarbageObject(dummy);
60 void ilist_traits<MachineInstr>::addNodeToList(MachineInstr* N) {
61 assert(N->parent == 0 && "machine instruction already in a basic block");
63 LeakDetector::removeGarbageObject(N);
66 void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr* N) {
67 assert(N->parent != 0 && "machine instruction not in a basic block");
69 LeakDetector::addGarbageObject(N);
72 void ilist_traits<MachineInstr>::transferNodesFromList(
73 iplist<MachineInstr, ilist_traits<MachineInstr> >& fromList,
74 ilist_iterator<MachineInstr> first,
75 ilist_iterator<MachineInstr> last) {
76 if (parent != fromList.parent)
77 for (; first != last; ++first)
78 first->parent = parent;
81 MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
82 const TargetInstrInfo& TII = *getParent()->getTarget().getInstrInfo();
84 while (I != begin() && TII.isTerminatorInstr((--I)->getOpcode()));
85 if (I != end() && !TII.isTerminatorInstr(I->getOpcode())) ++I;
89 void MachineBasicBlock::dump() const {
90 print(*cerr.stream());
93 static inline void OutputReg(std::ostream &os, unsigned RegNo,
94 const MRegisterInfo *MRI = 0) {
95 if (!RegNo || MRegisterInfo::isPhysicalRegister(RegNo)) {
97 os << " %" << MRI->get(RegNo).Name;
99 os << " %mreg(" << RegNo << ")";
101 os << " %reg" << RegNo;
104 void MachineBasicBlock::print(std::ostream &OS) const {
105 const MachineFunction *MF = getParent();
107 OS << "Can't print out MachineBasicBlock because parent MachineFunction"
112 const BasicBlock *LBB = getBasicBlock();
114 if (LBB) OS << LBB->getName() << ": ";
115 OS << (const void*)this
116 << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber();
117 if (isLandingPad()) OS << ", EH LANDING PAD";
120 const MRegisterInfo *MRI = MF->getTarget().getRegisterInfo();
121 if (livein_begin() != livein_end()) {
123 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
124 OutputReg(OS, *I, MRI);
127 // Print the preds of this block according to the CFG.
129 OS << " Predecessors according to CFG:";
130 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
131 OS << " " << *PI << " (#" << (*PI)->getNumber() << ")";
135 for (const_iterator I = begin(); I != end(); ++I) {
137 I->print(OS, &getParent()->getTarget());
140 // Print the successors of this block according to the CFG.
142 OS << " Successors according to CFG:";
143 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
144 OS << " " << *SI << " (#" << (*SI)->getNumber() << ")";
149 void MachineBasicBlock::removeLiveIn(unsigned Reg) {
150 livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
151 assert(I != livein_end() && "Not a live in!");
155 void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
156 MachineFunction::BasicBlockListType &BBList =getParent()->getBasicBlockList();
157 getParent()->getBasicBlockList().splice(NewAfter, BBList, this);
160 void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
161 MachineFunction::BasicBlockListType &BBList =getParent()->getBasicBlockList();
162 MachineFunction::iterator BBI = NewBefore;
163 getParent()->getBasicBlockList().splice(++BBI, BBList, this);
167 void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
168 Successors.push_back(succ);
169 succ->addPredecessor(this);
172 void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
173 succ->removePredecessor(this);
174 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
175 assert(I != Successors.end() && "Not a current successor!");
179 MachineBasicBlock::succ_iterator MachineBasicBlock::removeSuccessor(succ_iterator I) {
180 assert(I != Successors.end() && "Not a current successor!");
181 (*I)->removePredecessor(this);
182 return(Successors.erase(I));
185 void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
186 Predecessors.push_back(pred);
189 void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
190 std::vector<MachineBasicBlock *>::iterator I =
191 std::find(Predecessors.begin(), Predecessors.end(), pred);
192 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
193 Predecessors.erase(I);
196 bool MachineBasicBlock::isSuccessor(MachineBasicBlock *MBB) const {
197 std::vector<MachineBasicBlock *>::const_iterator I =
198 std::find(Successors.begin(), Successors.end(), MBB);
199 return I != Successors.end();
202 /// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
203 /// 'Old', change the code and CFG so that it branches to 'New' instead.
204 void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
205 MachineBasicBlock *New) {
206 assert(Old != New && "Cannot replace self with self!");
208 MachineBasicBlock::iterator I = end();
209 while (I != begin()) {
211 if (!(I->getInstrDescriptor()->Flags & M_TERMINATOR_FLAG)) break;
213 // Scan the operands of this machine instruction, replacing any uses of Old
215 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
216 if (I->getOperand(i).isMachineBasicBlock() &&
217 I->getOperand(i).getMachineBasicBlock() == Old)
218 I->getOperand(i).setMachineBasicBlock(New);
221 // Update the successor information. If New was already a successor, just
222 // remove the link to Old instead of creating another one. PR 1444.
223 removeSuccessor(Old);
224 if (!isSuccessor(New))
228 /// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
229 /// CFG to be inserted. If we have proven that MBB can only branch to DestA and
230 /// DestB, remove any other MBB successors from the CFG. DestA and DestB can
232 /// Besides DestA and DestB, retain other edges leading to LandingPads (currently
233 /// there can be only one; we don't check or require that here).
234 /// Note it is possible that DestA and/or DestB are LandingPads.
235 bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
236 MachineBasicBlock *DestB,
238 bool MadeChange = false;
239 bool AddedFallThrough = false;
241 MachineBasicBlock *FallThru = getNext();
243 // If this block ends with a conditional branch that falls through to its
244 // successor, set DestB as the successor.
246 if (DestB == 0 && FallThru != getParent()->end()) {
248 AddedFallThrough = true;
251 // If this is an unconditional branch with no explicit dest, it must just be
252 // a fallthrough into DestB.
253 if (DestA == 0 && FallThru != getParent()->end()) {
255 AddedFallThrough = true;
259 MachineBasicBlock::succ_iterator SI = succ_begin();
260 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
261 while (SI != succ_end()) {
262 if (*SI == DestA && DestA == DestB) {
265 } else if (*SI == DestA) {
268 } else if (*SI == DestB) {
271 } else if ((*SI)->isLandingPad() &&
272 *SI!=OrigDestA && *SI!=OrigDestB) {
275 // Otherwise, this is a superfluous edge, remove it.
276 SI = removeSuccessor(SI);
280 if (!AddedFallThrough) {
281 assert(DestA == 0 && DestB == 0 &&
282 "MachineCFG is missing edges!");
284 assert(DestA == 0 && "MachineCFG is missing edges!");