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"
| 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 "llvm/Assembly/Writer.h"
|
23#include <algorithm>
24using namespace llvm;
25
26MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
| 24#include <algorithm>
25using namespace llvm;
26
27MachineBasicBlock::MachineBasicBlock(MachineFunction &mf, const BasicBlock *bb)
|
27 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false) {
| 28 : BB(bb), Number(-1), xParent(&mf), Alignment(0), IsLandingPad(false),
29 AddressTaken(false) {
|
28 Insts.Parent = this;
29}
30
31MachineBasicBlock::~MachineBasicBlock() {
32 LeakDetector::removeGarbageObject(this);
33}
34
35raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
36 MBB.print(OS);
37 return OS;
38}
39
40/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
41/// parent pointer of the MBB, the MBB numbering, and any instructions in the
42/// MBB to be on the right operand list for registers.
43///
44/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it
45/// gets the next available unique MBB number. If it is removed from a
46/// MachineFunction, it goes back to being #-1.
47void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) {
48 MachineFunction &MF = *N->getParent();
49 N->Number = MF.addToMBBNumbering(N);
50
51 // Make sure the instructions have their operands in the reginfo lists.
52 MachineRegisterInfo &RegInfo = MF.getRegInfo();
53 for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I)
54 I->AddRegOperandsToUseLists(RegInfo);
55
56 LeakDetector::removeGarbageObject(N);
57}
58
59void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) {
60 N->getParent()->removeFromMBBNumbering(N->Number);
61 N->Number = -1;
62 LeakDetector::addGarbageObject(N);
63}
64
65
66/// addNodeToList (MI) - When we add an instruction to a basic block
67/// list, we update its parent pointer and add its operands from reg use/def
68/// lists if appropriate.
69void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
70 assert(N->getParent() == 0 && "machine instruction already in a basic block");
71 N->setParent(Parent);
72
73 // Add the instruction's register operands to their corresponding
74 // use/def lists.
75 MachineFunction *MF = Parent->getParent();
76 N->AddRegOperandsToUseLists(MF->getRegInfo());
77
78 LeakDetector::removeGarbageObject(N);
79}
80
81/// removeNodeFromList (MI) - When we remove an instruction from a basic block
82/// list, we update its parent pointer and remove its operands from reg use/def
83/// lists if appropriate.
84void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
85 assert(N->getParent() != 0 && "machine instruction not in a basic block");
86
87 // Remove from the use/def lists.
88 N->RemoveRegOperandsFromUseLists();
89
90 N->setParent(0);
91
92 LeakDetector::addGarbageObject(N);
93}
94
95/// transferNodesFromList (MI) - When moving a range of instructions from one
96/// MBB list to another, we need to update the parent pointers and the use/def
97/// lists.
98void ilist_traits<MachineInstr>::
99transferNodesFromList(ilist_traits<MachineInstr> &fromList,
100 MachineBasicBlock::iterator first,
101 MachineBasicBlock::iterator last) {
102 assert(Parent->getParent() == fromList.Parent->getParent() &&
103 "MachineInstr parent mismatch!");
104
105 // Splice within the same MBB -> no change.
106 if (Parent == fromList.Parent) return;
107
108 // If splicing between two blocks within the same function, just update the
109 // parent pointers.
110 for (; first != last; ++first)
111 first->setParent(Parent);
112}
113
114void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
115 assert(!MI->getParent() && "MI is still in a block!");
116 Parent->getParent()->DeleteMachineInstr(MI);
117}
118
119MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
120 iterator I = end();
121 while (I != begin() && (--I)->getDesc().isTerminator())
122 ; /*noop */
123 if (I != end() && !I->getDesc().isTerminator()) ++I;
124 return I;
125}
126
127/// isOnlyReachableViaFallthough - Return true if this basic block has
128/// exactly one predecessor and the control transfer mechanism between
129/// the predecessor and this block is a fall-through.
130bool MachineBasicBlock::isOnlyReachableByFallthrough() const {
131 // If this is a landing pad, it isn't a fall through. If it has no preds,
132 // then nothing falls through to it.
133 if (isLandingPad() || pred_empty())
134 return false;
135
136 // If there isn't exactly one predecessor, it can't be a fall through.
137 const_pred_iterator PI = pred_begin(), PI2 = PI;
138 ++PI2;
139 if (PI2 != pred_end())
140 return false;
141
142 // The predecessor has to be immediately before this block.
143 const MachineBasicBlock *Pred = *PI;
144
145 if (!Pred->isLayoutSuccessor(this))
146 return false;
147
148 // If the block is completely empty, then it definitely does fall through.
149 if (Pred->empty())
150 return true;
151
152 // Otherwise, check the last instruction.
153 const MachineInstr &LastInst = Pred->back();
154 return !LastInst.getDesc().isBarrier();
155}
156
157void MachineBasicBlock::dump() const {
158 print(errs());
159}
160
161static inline void OutputReg(raw_ostream &os, unsigned RegNo,
162 const TargetRegisterInfo *TRI = 0) {
| 30 Insts.Parent = this;
31}
32
33MachineBasicBlock::~MachineBasicBlock() {
34 LeakDetector::removeGarbageObject(this);
35}
36
37raw_ostream &llvm::operator<<(raw_ostream &OS, const MachineBasicBlock &MBB) {
38 MBB.print(OS);
39 return OS;
40}
41
42/// addNodeToList (MBB) - When an MBB is added to an MF, we need to update the
43/// parent pointer of the MBB, the MBB numbering, and any instructions in the
44/// MBB to be on the right operand list for registers.
45///
46/// MBBs start out as #-1. When a MBB is added to a MachineFunction, it
47/// gets the next available unique MBB number. If it is removed from a
48/// MachineFunction, it goes back to being #-1.
49void ilist_traits<MachineBasicBlock>::addNodeToList(MachineBasicBlock *N) {
50 MachineFunction &MF = *N->getParent();
51 N->Number = MF.addToMBBNumbering(N);
52
53 // Make sure the instructions have their operands in the reginfo lists.
54 MachineRegisterInfo &RegInfo = MF.getRegInfo();
55 for (MachineBasicBlock::iterator I = N->begin(), E = N->end(); I != E; ++I)
56 I->AddRegOperandsToUseLists(RegInfo);
57
58 LeakDetector::removeGarbageObject(N);
59}
60
61void ilist_traits<MachineBasicBlock>::removeNodeFromList(MachineBasicBlock *N) {
62 N->getParent()->removeFromMBBNumbering(N->Number);
63 N->Number = -1;
64 LeakDetector::addGarbageObject(N);
65}
66
67
68/// addNodeToList (MI) - When we add an instruction to a basic block
69/// list, we update its parent pointer and add its operands from reg use/def
70/// lists if appropriate.
71void ilist_traits<MachineInstr>::addNodeToList(MachineInstr *N) {
72 assert(N->getParent() == 0 && "machine instruction already in a basic block");
73 N->setParent(Parent);
74
75 // Add the instruction's register operands to their corresponding
76 // use/def lists.
77 MachineFunction *MF = Parent->getParent();
78 N->AddRegOperandsToUseLists(MF->getRegInfo());
79
80 LeakDetector::removeGarbageObject(N);
81}
82
83/// removeNodeFromList (MI) - When we remove an instruction from a basic block
84/// list, we update its parent pointer and remove its operands from reg use/def
85/// lists if appropriate.
86void ilist_traits<MachineInstr>::removeNodeFromList(MachineInstr *N) {
87 assert(N->getParent() != 0 && "machine instruction not in a basic block");
88
89 // Remove from the use/def lists.
90 N->RemoveRegOperandsFromUseLists();
91
92 N->setParent(0);
93
94 LeakDetector::addGarbageObject(N);
95}
96
97/// transferNodesFromList (MI) - When moving a range of instructions from one
98/// MBB list to another, we need to update the parent pointers and the use/def
99/// lists.
100void ilist_traits<MachineInstr>::
101transferNodesFromList(ilist_traits<MachineInstr> &fromList,
102 MachineBasicBlock::iterator first,
103 MachineBasicBlock::iterator last) {
104 assert(Parent->getParent() == fromList.Parent->getParent() &&
105 "MachineInstr parent mismatch!");
106
107 // Splice within the same MBB -> no change.
108 if (Parent == fromList.Parent) return;
109
110 // If splicing between two blocks within the same function, just update the
111 // parent pointers.
112 for (; first != last; ++first)
113 first->setParent(Parent);
114}
115
116void ilist_traits<MachineInstr>::deleteNode(MachineInstr* MI) {
117 assert(!MI->getParent() && "MI is still in a block!");
118 Parent->getParent()->DeleteMachineInstr(MI);
119}
120
121MachineBasicBlock::iterator MachineBasicBlock::getFirstTerminator() {
122 iterator I = end();
123 while (I != begin() && (--I)->getDesc().isTerminator())
124 ; /*noop */
125 if (I != end() && !I->getDesc().isTerminator()) ++I;
126 return I;
127}
128
129/// isOnlyReachableViaFallthough - Return true if this basic block has
130/// exactly one predecessor and the control transfer mechanism between
131/// the predecessor and this block is a fall-through.
132bool MachineBasicBlock::isOnlyReachableByFallthrough() const {
133 // If this is a landing pad, it isn't a fall through. If it has no preds,
134 // then nothing falls through to it.
135 if (isLandingPad() || pred_empty())
136 return false;
137
138 // If there isn't exactly one predecessor, it can't be a fall through.
139 const_pred_iterator PI = pred_begin(), PI2 = PI;
140 ++PI2;
141 if (PI2 != pred_end())
142 return false;
143
144 // The predecessor has to be immediately before this block.
145 const MachineBasicBlock *Pred = *PI;
146
147 if (!Pred->isLayoutSuccessor(this))
148 return false;
149
150 // If the block is completely empty, then it definitely does fall through.
151 if (Pred->empty())
152 return true;
153
154 // Otherwise, check the last instruction.
155 const MachineInstr &LastInst = Pred->back();
156 return !LastInst.getDesc().isBarrier();
157}
158
159void MachineBasicBlock::dump() const {
160 print(errs());
161}
162
163static inline void OutputReg(raw_ostream &os, unsigned RegNo,
164 const TargetRegisterInfo *TRI = 0) {
|
163 if (!RegNo || TargetRegisterInfo::isPhysicalRegister(RegNo)) {
| 165 if (RegNo != 0 && TargetRegisterInfo::isPhysicalRegister(RegNo)) {
|
164 if (TRI)
165 os << " %" << TRI->get(RegNo).Name;
166 else
| 166 if (TRI)
167 os << " %" << TRI->get(RegNo).Name;
168 else
|
167 os << " %mreg(" << RegNo << ")";
| 169 os << " %physreg" << RegNo;
|
168 } else
169 os << " %reg" << RegNo;
170}
171
172void MachineBasicBlock::print(raw_ostream &OS) const {
173 const MachineFunction *MF = getParent();
174 if (!MF) {
175 OS << "Can't print out MachineBasicBlock because parent MachineFunction"
176 << " is null\n";
177 return;
178 }
179
| 170 } else
171 os << " %reg" << RegNo;
172}
173
174void MachineBasicBlock::print(raw_ostream &OS) const {
175 const MachineFunction *MF = getParent();
176 if (!MF) {
177 OS << "Can't print out MachineBasicBlock because parent MachineFunction"
178 << " is null\n";
179 return;
180 }
181
|
180 const BasicBlock *LBB = getBasicBlock();
| 182 if (Alignment) { OS << "Alignment " << Alignment << "\n"; }
183
184 OS << "BB#" << getNumber() << ": ";
185
186 const char *Comma = "";
187 if (const BasicBlock *LBB = getBasicBlock()) {
188 OS << Comma << "derived from LLVM BB ";
189 WriteAsOperand(OS, LBB, /*PrintType=*/false);
190 Comma = ", ";
191 }
192 if (isLandingPad()) { OS << Comma << "EH LANDING PAD"; Comma = ", "; }
193 if (hasAddressTaken()) { OS << Comma << "ADDRESS TAKEN"; Comma = ", "; }
|
181 OS << '\n';
| 194 OS << '\n';
|
182 if (LBB) OS << LBB->getName() << ": ";
183 OS << (const void*)this
184 << ", LLVM BB @" << (const void*) LBB << ", ID#" << getNumber();
185 if (Alignment) OS << ", Alignment " << Alignment;
186 if (isLandingPad()) OS << ", EH LANDING PAD";
187 OS << ":\n";
| |
188
189 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
190 if (!livein_empty()) {
| 195
196 const TargetRegisterInfo *TRI = MF->getTarget().getRegisterInfo();
197 if (!livein_empty()) {
|
191 OS << "Live Ins:";
| 198 OS << " Live Ins:";
|
192 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
193 OutputReg(OS, *I, TRI);
194 OS << '\n';
195 }
196 // Print the preds of this block according to the CFG.
197 if (!pred_empty()) {
198 OS << " Predecessors according to CFG:";
199 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
| 199 for (const_livein_iterator I = livein_begin(),E = livein_end(); I != E; ++I)
200 OutputReg(OS, *I, TRI);
201 OS << '\n';
202 }
203 // Print the preds of this block according to the CFG.
204 if (!pred_empty()) {
205 OS << " Predecessors according to CFG:";
206 for (const_pred_iterator PI = pred_begin(), E = pred_end(); PI != E; ++PI)
|
200 OS << ' ' << *PI << " (#" << (*PI)->getNumber() << ')';
| 207 OS << " BB#" << (*PI)->getNumber();
|
201 OS << '\n';
202 }
203
204 for (const_iterator I = begin(); I != end(); ++I) {
205 OS << '\t';
206 I->print(OS, &getParent()->getTarget());
207 }
208
209 // Print the successors of this block according to the CFG.
210 if (!succ_empty()) {
211 OS << " Successors according to CFG:";
212 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
| 208 OS << '\n';
209 }
210
211 for (const_iterator I = begin(); I != end(); ++I) {
212 OS << '\t';
213 I->print(OS, &getParent()->getTarget());
214 }
215
216 // Print the successors of this block according to the CFG.
217 if (!succ_empty()) {
218 OS << " Successors according to CFG:";
219 for (const_succ_iterator SI = succ_begin(), E = succ_end(); SI != E; ++SI)
|
213 OS << ' ' << *SI << " (#" << (*SI)->getNumber() << ')';
| 220 OS << " BB#" << (*SI)->getNumber();
|
214 OS << '\n';
215 }
216}
217
218void MachineBasicBlock::removeLiveIn(unsigned Reg) {
219 livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
220 assert(I != livein_end() && "Not a live in!");
221 LiveIns.erase(I);
222}
223
224bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
225 const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
226 return I != livein_end();
227}
228
229void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
230 getParent()->splice(NewAfter, this);
231}
232
233void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
234 MachineFunction::iterator BBI = NewBefore;
235 getParent()->splice(++BBI, this);
236}
237
238
239void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
240 Successors.push_back(succ);
241 succ->addPredecessor(this);
242}
243
244void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
245 succ->removePredecessor(this);
246 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
247 assert(I != Successors.end() && "Not a current successor!");
248 Successors.erase(I);
249}
250
251MachineBasicBlock::succ_iterator
252MachineBasicBlock::removeSuccessor(succ_iterator I) {
253 assert(I != Successors.end() && "Not a current successor!");
254 (*I)->removePredecessor(this);
255 return Successors.erase(I);
256}
257
258void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
259 Predecessors.push_back(pred);
260}
261
262void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
263 std::vector<MachineBasicBlock *>::iterator I =
264 std::find(Predecessors.begin(), Predecessors.end(), pred);
265 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
266 Predecessors.erase(I);
267}
268
269void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
270 if (this == fromMBB)
271 return;
272
273 for (MachineBasicBlock::succ_iterator I = fromMBB->succ_begin(),
274 E = fromMBB->succ_end(); I != E; ++I)
275 addSuccessor(*I);
276
277 while (!fromMBB->succ_empty())
278 fromMBB->removeSuccessor(fromMBB->succ_begin());
279}
280
281bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
282 std::vector<MachineBasicBlock *>::const_iterator I =
283 std::find(Successors.begin(), Successors.end(), MBB);
284 return I != Successors.end();
285}
286
287bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
288 MachineFunction::const_iterator I(this);
289 return next(I) == MachineFunction::const_iterator(MBB);
290}
291
292/// removeFromParent - This method unlinks 'this' from the containing function,
293/// and returns it, but does not delete it.
294MachineBasicBlock *MachineBasicBlock::removeFromParent() {
295 assert(getParent() && "Not embedded in a function!");
296 getParent()->remove(this);
297 return this;
298}
299
300
301/// eraseFromParent - This method unlinks 'this' from the containing function,
302/// and deletes it.
303void MachineBasicBlock::eraseFromParent() {
304 assert(getParent() && "Not embedded in a function!");
305 getParent()->erase(this);
306}
307
308
309/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
310/// 'Old', change the code and CFG so that it branches to 'New' instead.
311void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
312 MachineBasicBlock *New) {
313 assert(Old != New && "Cannot replace self with self!");
314
315 MachineBasicBlock::iterator I = end();
316 while (I != begin()) {
317 --I;
318 if (!I->getDesc().isTerminator()) break;
319
320 // Scan the operands of this machine instruction, replacing any uses of Old
321 // with New.
322 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
323 if (I->getOperand(i).isMBB() &&
324 I->getOperand(i).getMBB() == Old)
325 I->getOperand(i).setMBB(New);
326 }
327
328 // Update the successor information.
329 removeSuccessor(Old);
330 addSuccessor(New);
331}
332
333/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
334/// CFG to be inserted. If we have proven that MBB can only branch to DestA and
335/// DestB, remove any other MBB successors from the CFG. DestA and DestB can
336/// be null.
337/// Besides DestA and DestB, retain other edges leading to LandingPads
338/// (currently there can be only one; we don't check or require that here).
339/// Note it is possible that DestA and/or DestB are LandingPads.
340bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
341 MachineBasicBlock *DestB,
342 bool isCond) {
343 bool MadeChange = false;
344 bool AddedFallThrough = false;
345
346 MachineFunction::iterator FallThru = next(MachineFunction::iterator(this));
347
348 // If this block ends with a conditional branch that falls through to its
349 // successor, set DestB as the successor.
350 if (isCond) {
351 if (DestB == 0 && FallThru != getParent()->end()) {
352 DestB = FallThru;
353 AddedFallThrough = true;
354 }
355 } else {
356 // If this is an unconditional branch with no explicit dest, it must just be
357 // a fallthrough into DestB.
358 if (DestA == 0 && FallThru != getParent()->end()) {
359 DestA = FallThru;
360 AddedFallThrough = true;
361 }
362 }
363
364 MachineBasicBlock::succ_iterator SI = succ_begin();
365 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
366 while (SI != succ_end()) {
367 if (*SI == DestA && DestA == DestB) {
368 DestA = DestB = 0;
369 ++SI;
370 } else if (*SI == DestA) {
371 DestA = 0;
372 ++SI;
373 } else if (*SI == DestB) {
374 DestB = 0;
375 ++SI;
376 } else if ((*SI)->isLandingPad() &&
377 *SI!=OrigDestA && *SI!=OrigDestB) {
378 ++SI;
379 } else {
380 // Otherwise, this is a superfluous edge, remove it.
381 SI = removeSuccessor(SI);
382 MadeChange = true;
383 }
384 }
385 if (!AddedFallThrough) {
386 assert(DestA == 0 && DestB == 0 &&
387 "MachineCFG is missing edges!");
388 } else if (isCond) {
389 assert(DestA == 0 && "MachineCFG is missing edges!");
390 }
391 return MadeChange;
392}
| 221 OS << '\n';
222 }
223}
224
225void MachineBasicBlock::removeLiveIn(unsigned Reg) {
226 livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
227 assert(I != livein_end() && "Not a live in!");
228 LiveIns.erase(I);
229}
230
231bool MachineBasicBlock::isLiveIn(unsigned Reg) const {
232 const_livein_iterator I = std::find(livein_begin(), livein_end(), Reg);
233 return I != livein_end();
234}
235
236void MachineBasicBlock::moveBefore(MachineBasicBlock *NewAfter) {
237 getParent()->splice(NewAfter, this);
238}
239
240void MachineBasicBlock::moveAfter(MachineBasicBlock *NewBefore) {
241 MachineFunction::iterator BBI = NewBefore;
242 getParent()->splice(++BBI, this);
243}
244
245
246void MachineBasicBlock::addSuccessor(MachineBasicBlock *succ) {
247 Successors.push_back(succ);
248 succ->addPredecessor(this);
249}
250
251void MachineBasicBlock::removeSuccessor(MachineBasicBlock *succ) {
252 succ->removePredecessor(this);
253 succ_iterator I = std::find(Successors.begin(), Successors.end(), succ);
254 assert(I != Successors.end() && "Not a current successor!");
255 Successors.erase(I);
256}
257
258MachineBasicBlock::succ_iterator
259MachineBasicBlock::removeSuccessor(succ_iterator I) {
260 assert(I != Successors.end() && "Not a current successor!");
261 (*I)->removePredecessor(this);
262 return Successors.erase(I);
263}
264
265void MachineBasicBlock::addPredecessor(MachineBasicBlock *pred) {
266 Predecessors.push_back(pred);
267}
268
269void MachineBasicBlock::removePredecessor(MachineBasicBlock *pred) {
270 std::vector<MachineBasicBlock *>::iterator I =
271 std::find(Predecessors.begin(), Predecessors.end(), pred);
272 assert(I != Predecessors.end() && "Pred is not a predecessor of this block!");
273 Predecessors.erase(I);
274}
275
276void MachineBasicBlock::transferSuccessors(MachineBasicBlock *fromMBB) {
277 if (this == fromMBB)
278 return;
279
280 for (MachineBasicBlock::succ_iterator I = fromMBB->succ_begin(),
281 E = fromMBB->succ_end(); I != E; ++I)
282 addSuccessor(*I);
283
284 while (!fromMBB->succ_empty())
285 fromMBB->removeSuccessor(fromMBB->succ_begin());
286}
287
288bool MachineBasicBlock::isSuccessor(const MachineBasicBlock *MBB) const {
289 std::vector<MachineBasicBlock *>::const_iterator I =
290 std::find(Successors.begin(), Successors.end(), MBB);
291 return I != Successors.end();
292}
293
294bool MachineBasicBlock::isLayoutSuccessor(const MachineBasicBlock *MBB) const {
295 MachineFunction::const_iterator I(this);
296 return next(I) == MachineFunction::const_iterator(MBB);
297}
298
299/// removeFromParent - This method unlinks 'this' from the containing function,
300/// and returns it, but does not delete it.
301MachineBasicBlock *MachineBasicBlock::removeFromParent() {
302 assert(getParent() && "Not embedded in a function!");
303 getParent()->remove(this);
304 return this;
305}
306
307
308/// eraseFromParent - This method unlinks 'this' from the containing function,
309/// and deletes it.
310void MachineBasicBlock::eraseFromParent() {
311 assert(getParent() && "Not embedded in a function!");
312 getParent()->erase(this);
313}
314
315
316/// ReplaceUsesOfBlockWith - Given a machine basic block that branched to
317/// 'Old', change the code and CFG so that it branches to 'New' instead.
318void MachineBasicBlock::ReplaceUsesOfBlockWith(MachineBasicBlock *Old,
319 MachineBasicBlock *New) {
320 assert(Old != New && "Cannot replace self with self!");
321
322 MachineBasicBlock::iterator I = end();
323 while (I != begin()) {
324 --I;
325 if (!I->getDesc().isTerminator()) break;
326
327 // Scan the operands of this machine instruction, replacing any uses of Old
328 // with New.
329 for (unsigned i = 0, e = I->getNumOperands(); i != e; ++i)
330 if (I->getOperand(i).isMBB() &&
331 I->getOperand(i).getMBB() == Old)
332 I->getOperand(i).setMBB(New);
333 }
334
335 // Update the successor information.
336 removeSuccessor(Old);
337 addSuccessor(New);
338}
339
340/// CorrectExtraCFGEdges - Various pieces of code can cause excess edges in the
341/// CFG to be inserted. If we have proven that MBB can only branch to DestA and
342/// DestB, remove any other MBB successors from the CFG. DestA and DestB can
343/// be null.
344/// Besides DestA and DestB, retain other edges leading to LandingPads
345/// (currently there can be only one; we don't check or require that here).
346/// Note it is possible that DestA and/or DestB are LandingPads.
347bool MachineBasicBlock::CorrectExtraCFGEdges(MachineBasicBlock *DestA,
348 MachineBasicBlock *DestB,
349 bool isCond) {
350 bool MadeChange = false;
351 bool AddedFallThrough = false;
352
353 MachineFunction::iterator FallThru = next(MachineFunction::iterator(this));
354
355 // If this block ends with a conditional branch that falls through to its
356 // successor, set DestB as the successor.
357 if (isCond) {
358 if (DestB == 0 && FallThru != getParent()->end()) {
359 DestB = FallThru;
360 AddedFallThrough = true;
361 }
362 } else {
363 // If this is an unconditional branch with no explicit dest, it must just be
364 // a fallthrough into DestB.
365 if (DestA == 0 && FallThru != getParent()->end()) {
366 DestA = FallThru;
367 AddedFallThrough = true;
368 }
369 }
370
371 MachineBasicBlock::succ_iterator SI = succ_begin();
372 MachineBasicBlock *OrigDestA = DestA, *OrigDestB = DestB;
373 while (SI != succ_end()) {
374 if (*SI == DestA && DestA == DestB) {
375 DestA = DestB = 0;
376 ++SI;
377 } else if (*SI == DestA) {
378 DestA = 0;
379 ++SI;
380 } else if (*SI == DestB) {
381 DestB = 0;
382 ++SI;
383 } else if ((*SI)->isLandingPad() &&
384 *SI!=OrigDestA && *SI!=OrigDestB) {
385 ++SI;
386 } else {
387 // Otherwise, this is a superfluous edge, remove it.
388 SI = removeSuccessor(SI);
389 MadeChange = true;
390 }
391 }
392 if (!AddedFallThrough) {
393 assert(DestA == 0 && DestB == 0 &&
394 "MachineCFG is missing edges!");
395 } else if (isCond) {
396 assert(DestA == 0 && "MachineCFG is missing edges!");
397 }
398 return MadeChange;
399}
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