1 //===- GVNPRE.cpp - Eliminate redundant values and expressions ------------===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the Owen Anderson and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This pass performs a hybrid of global value numbering and partial redundancy
11 // elimination, known as GVN-PRE. It performs partial redundancy elimination on
12 // values, rather than lexical expressions, allowing a more comprehensive view
13 // the optimization. It replaces redundant values with uses of earlier
14 // occurences of the same value. While this is beneficial in that it eliminates
15 // unneeded computation, it also increases register pressure by creating large
16 // live ranges, and should be used with caution on platforms that are very
17 // sensitive to register pressure.
19 //===----------------------------------------------------------------------===//
21 #define DEBUG_TYPE "gvnpre"
22 #include "llvm/Value.h"
23 #include "llvm/Transforms/Scalar.h"
24 #include "llvm/Instructions.h"
25 #include "llvm/Function.h"
26 #include "llvm/DerivedTypes.h"
27 #include "llvm/Analysis/Dominators.h"
28 #include "llvm/ADT/BitVector.h"
29 #include "llvm/ADT/DenseMap.h"
30 #include "llvm/ADT/DepthFirstIterator.h"
31 #include "llvm/ADT/PostOrderIterator.h"
32 #include "llvm/ADT/SmallPtrSet.h"
33 #include "llvm/ADT/Statistic.h"
34 #include "llvm/Support/CFG.h"
35 #include "llvm/Support/Compiler.h"
36 #include "llvm/Support/Debug.h"
44 //===----------------------------------------------------------------------===//
46 //===----------------------------------------------------------------------===//
48 /// This class holds the mapping between values and value numbers. It is used
49 /// as an efficient mechanism to determine the expression-wise equivalence of
53 class VISIBILITY_HIDDEN ValueTable {
56 enum ExpressionOpcode { ADD, SUB, MUL, UDIV, SDIV, FDIV, UREM, SREM,
57 FREM, SHL, LSHR, ASHR, AND, OR, XOR, ICMPEQ,
58 ICMPNE, ICMPUGT, ICMPUGE, ICMPULT, ICMPULE,
59 ICMPSGT, ICMPSGE, ICMPSLT, ICMPSLE, FCMPOEQ,
60 FCMPOGT, FCMPOGE, FCMPOLT, FCMPOLE, FCMPONE,
61 FCMPORD, FCMPUNO, FCMPUEQ, FCMPUGT, FCMPUGE,
62 FCMPULT, FCMPULE, FCMPUNE, EXTRACT, INSERT,
63 SHUFFLE, SELECT, TRUNC, ZEXT, SEXT, FPTOUI,
64 FPTOSI, UITOFP, SITOFP, FPTRUNC, FPEXT,
65 PTRTOINT, INTTOPTR, BITCAST, GEP};
67 ExpressionOpcode opcode;
72 std::vector<uint32_t> varargs;
74 bool operator< (const Expression& other) const {
75 if (opcode < other.opcode)
77 else if (opcode > other.opcode)
79 else if (type < other.type)
81 else if (type > other.type)
83 else if (firstVN < other.firstVN)
85 else if (firstVN > other.firstVN)
87 else if (secondVN < other.secondVN)
89 else if (secondVN > other.secondVN)
91 else if (thirdVN < other.thirdVN)
93 else if (thirdVN > other.thirdVN)
96 if (varargs.size() < other.varargs.size())
98 else if (varargs.size() > other.varargs.size())
101 for (size_t i = 0; i < varargs.size(); ++i)
102 if (varargs[i] < other.varargs[i])
104 else if (varargs[i] > other.varargs[i])
113 DenseMap<Value*, uint32_t> valueNumbering;
114 std::map<Expression, uint32_t> expressionNumbering;
116 uint32_t nextValueNumber;
118 Expression::ExpressionOpcode getOpcode(BinaryOperator* BO);
119 Expression::ExpressionOpcode getOpcode(CmpInst* C);
120 Expression::ExpressionOpcode getOpcode(CastInst* C);
121 Expression create_expression(BinaryOperator* BO);
122 Expression create_expression(CmpInst* C);
123 Expression create_expression(ShuffleVectorInst* V);
124 Expression create_expression(ExtractElementInst* C);
125 Expression create_expression(InsertElementInst* V);
126 Expression create_expression(SelectInst* V);
127 Expression create_expression(CastInst* C);
128 Expression create_expression(GetElementPtrInst* G);
130 ValueTable() { nextValueNumber = 1; }
131 uint32_t lookup_or_add(Value* V);
132 uint32_t lookup(Value* V) const;
133 void add(Value* V, uint32_t num);
135 void erase(Value* v);
140 //===----------------------------------------------------------------------===//
141 // ValueTable Internal Functions
142 //===----------------------------------------------------------------------===//
143 ValueTable::Expression::ExpressionOpcode
144 ValueTable::getOpcode(BinaryOperator* BO) {
145 switch(BO->getOpcode()) {
146 case Instruction::Add:
147 return Expression::ADD;
148 case Instruction::Sub:
149 return Expression::SUB;
150 case Instruction::Mul:
151 return Expression::MUL;
152 case Instruction::UDiv:
153 return Expression::UDIV;
154 case Instruction::SDiv:
155 return Expression::SDIV;
156 case Instruction::FDiv:
157 return Expression::FDIV;
158 case Instruction::URem:
159 return Expression::UREM;
160 case Instruction::SRem:
161 return Expression::SREM;
162 case Instruction::FRem:
163 return Expression::FREM;
164 case Instruction::Shl:
165 return Expression::SHL;
166 case Instruction::LShr:
167 return Expression::LSHR;
168 case Instruction::AShr:
169 return Expression::ASHR;
170 case Instruction::And:
171 return Expression::AND;
172 case Instruction::Or:
173 return Expression::OR;
174 case Instruction::Xor:
175 return Expression::XOR;
177 // THIS SHOULD NEVER HAPPEN
179 assert(0 && "Binary operator with unknown opcode?");
180 return Expression::ADD;
184 ValueTable::Expression::ExpressionOpcode ValueTable::getOpcode(CmpInst* C) {
185 if (C->getOpcode() == Instruction::ICmp) {
186 switch (C->getPredicate()) {
187 case ICmpInst::ICMP_EQ:
188 return Expression::ICMPEQ;
189 case ICmpInst::ICMP_NE:
190 return Expression::ICMPNE;
191 case ICmpInst::ICMP_UGT:
192 return Expression::ICMPUGT;
193 case ICmpInst::ICMP_UGE:
194 return Expression::ICMPUGE;
195 case ICmpInst::ICMP_ULT:
196 return Expression::ICMPULT;
197 case ICmpInst::ICMP_ULE:
198 return Expression::ICMPULE;
199 case ICmpInst::ICMP_SGT:
200 return Expression::ICMPSGT;
201 case ICmpInst::ICMP_SGE:
202 return Expression::ICMPSGE;
203 case ICmpInst::ICMP_SLT:
204 return Expression::ICMPSLT;
205 case ICmpInst::ICMP_SLE:
206 return Expression::ICMPSLE;
208 // THIS SHOULD NEVER HAPPEN
210 assert(0 && "Comparison with unknown predicate?");
211 return Expression::ICMPEQ;
214 switch (C->getPredicate()) {
215 case FCmpInst::FCMP_OEQ:
216 return Expression::FCMPOEQ;
217 case FCmpInst::FCMP_OGT:
218 return Expression::FCMPOGT;
219 case FCmpInst::FCMP_OGE:
220 return Expression::FCMPOGE;
221 case FCmpInst::FCMP_OLT:
222 return Expression::FCMPOLT;
223 case FCmpInst::FCMP_OLE:
224 return Expression::FCMPOLE;
225 case FCmpInst::FCMP_ONE:
226 return Expression::FCMPONE;
227 case FCmpInst::FCMP_ORD:
228 return Expression::FCMPORD;
229 case FCmpInst::FCMP_UNO:
230 return Expression::FCMPUNO;
231 case FCmpInst::FCMP_UEQ:
232 return Expression::FCMPUEQ;
233 case FCmpInst::FCMP_UGT:
234 return Expression::FCMPUGT;
235 case FCmpInst::FCMP_UGE:
236 return Expression::FCMPUGE;
237 case FCmpInst::FCMP_ULT:
238 return Expression::FCMPULT;
239 case FCmpInst::FCMP_ULE:
240 return Expression::FCMPULE;
241 case FCmpInst::FCMP_UNE:
242 return Expression::FCMPUNE;
244 // THIS SHOULD NEVER HAPPEN
246 assert(0 && "Comparison with unknown predicate?");
247 return Expression::FCMPOEQ;
252 ValueTable::Expression::ExpressionOpcode
253 ValueTable::getOpcode(CastInst* C) {
254 switch(C->getOpcode()) {
255 case Instruction::Trunc:
256 return Expression::TRUNC;
257 case Instruction::ZExt:
258 return Expression::ZEXT;
259 case Instruction::SExt:
260 return Expression::SEXT;
261 case Instruction::FPToUI:
262 return Expression::FPTOUI;
263 case Instruction::FPToSI:
264 return Expression::FPTOSI;
265 case Instruction::UIToFP:
266 return Expression::UITOFP;
267 case Instruction::SIToFP:
268 return Expression::SITOFP;
269 case Instruction::FPTrunc:
270 return Expression::FPTRUNC;
271 case Instruction::FPExt:
272 return Expression::FPEXT;
273 case Instruction::PtrToInt:
274 return Expression::PTRTOINT;
275 case Instruction::IntToPtr:
276 return Expression::INTTOPTR;
277 case Instruction::BitCast:
278 return Expression::BITCAST;
280 // THIS SHOULD NEVER HAPPEN
282 assert(0 && "Cast operator with unknown opcode?");
283 return Expression::BITCAST;
287 ValueTable::Expression ValueTable::create_expression(BinaryOperator* BO) {
290 e.firstVN = lookup_or_add(BO->getOperand(0));
291 e.secondVN = lookup_or_add(BO->getOperand(1));
293 e.type = BO->getType();
294 e.opcode = getOpcode(BO);
299 ValueTable::Expression ValueTable::create_expression(CmpInst* C) {
302 e.firstVN = lookup_or_add(C->getOperand(0));
303 e.secondVN = lookup_or_add(C->getOperand(1));
305 e.type = C->getType();
306 e.opcode = getOpcode(C);
311 ValueTable::Expression ValueTable::create_expression(CastInst* C) {
314 e.firstVN = lookup_or_add(C->getOperand(0));
317 e.type = C->getType();
318 e.opcode = getOpcode(C);
323 ValueTable::Expression ValueTable::create_expression(ShuffleVectorInst* S) {
326 e.firstVN = lookup_or_add(S->getOperand(0));
327 e.secondVN = lookup_or_add(S->getOperand(1));
328 e.thirdVN = lookup_or_add(S->getOperand(2));
329 e.type = S->getType();
330 e.opcode = Expression::SHUFFLE;
335 ValueTable::Expression ValueTable::create_expression(ExtractElementInst* E) {
338 e.firstVN = lookup_or_add(E->getOperand(0));
339 e.secondVN = lookup_or_add(E->getOperand(1));
341 e.type = E->getType();
342 e.opcode = Expression::EXTRACT;
347 ValueTable::Expression ValueTable::create_expression(InsertElementInst* I) {
350 e.firstVN = lookup_or_add(I->getOperand(0));
351 e.secondVN = lookup_or_add(I->getOperand(1));
352 e.thirdVN = lookup_or_add(I->getOperand(2));
353 e.type = I->getType();
354 e.opcode = Expression::INSERT;
359 ValueTable::Expression ValueTable::create_expression(SelectInst* I) {
362 e.firstVN = lookup_or_add(I->getCondition());
363 e.secondVN = lookup_or_add(I->getTrueValue());
364 e.thirdVN = lookup_or_add(I->getFalseValue());
365 e.type = I->getType();
366 e.opcode = Expression::SELECT;
371 ValueTable::Expression ValueTable::create_expression(GetElementPtrInst* G) {
374 e.firstVN = lookup_or_add(G->getPointerOperand());
377 e.type = G->getType();
378 e.opcode = Expression::SELECT;
380 for (GetElementPtrInst::op_iterator I = G->idx_begin(), E = G->idx_end();
382 e.varargs.push_back(lookup_or_add(*I));
387 //===----------------------------------------------------------------------===//
388 // ValueTable External Functions
389 //===----------------------------------------------------------------------===//
391 /// lookup_or_add - Returns the value number for the specified value, assigning
392 /// it a new number if it did not have one before.
393 uint32_t ValueTable::lookup_or_add(Value* V) {
394 DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
395 if (VI != valueNumbering.end())
399 if (BinaryOperator* BO = dyn_cast<BinaryOperator>(V)) {
400 Expression e = create_expression(BO);
402 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
403 if (EI != expressionNumbering.end()) {
404 valueNumbering.insert(std::make_pair(V, EI->second));
407 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
408 valueNumbering.insert(std::make_pair(V, nextValueNumber));
410 return nextValueNumber++;
412 } else if (CmpInst* C = dyn_cast<CmpInst>(V)) {
413 Expression e = create_expression(C);
415 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
416 if (EI != expressionNumbering.end()) {
417 valueNumbering.insert(std::make_pair(V, EI->second));
420 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
421 valueNumbering.insert(std::make_pair(V, nextValueNumber));
423 return nextValueNumber++;
425 } else if (ShuffleVectorInst* U = dyn_cast<ShuffleVectorInst>(V)) {
426 Expression e = create_expression(U);
428 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
429 if (EI != expressionNumbering.end()) {
430 valueNumbering.insert(std::make_pair(V, EI->second));
433 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
434 valueNumbering.insert(std::make_pair(V, nextValueNumber));
436 return nextValueNumber++;
438 } else if (ExtractElementInst* U = dyn_cast<ExtractElementInst>(V)) {
439 Expression e = create_expression(U);
441 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
442 if (EI != expressionNumbering.end()) {
443 valueNumbering.insert(std::make_pair(V, EI->second));
446 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
447 valueNumbering.insert(std::make_pair(V, nextValueNumber));
449 return nextValueNumber++;
451 } else if (InsertElementInst* U = dyn_cast<InsertElementInst>(V)) {
452 Expression e = create_expression(U);
454 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
455 if (EI != expressionNumbering.end()) {
456 valueNumbering.insert(std::make_pair(V, EI->second));
459 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
460 valueNumbering.insert(std::make_pair(V, nextValueNumber));
462 return nextValueNumber++;
464 } else if (SelectInst* U = dyn_cast<SelectInst>(V)) {
465 Expression e = create_expression(U);
467 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
468 if (EI != expressionNumbering.end()) {
469 valueNumbering.insert(std::make_pair(V, EI->second));
472 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
473 valueNumbering.insert(std::make_pair(V, nextValueNumber));
475 return nextValueNumber++;
477 } else if (CastInst* U = dyn_cast<CastInst>(V)) {
478 Expression e = create_expression(U);
480 std::map<Expression, uint32_t>::iterator EI = expressionNumbering.find(e);
481 if (EI != expressionNumbering.end()) {
482 valueNumbering.insert(std::make_pair(V, EI->second));
485 expressionNumbering.insert(std::make_pair(e, nextValueNumber));
486 valueNumbering.insert(std::make_pair(V, nextValueNumber));
488 return nextValueNumber++;
491 valueNumbering.insert(std::make_pair(V, nextValueNumber));
492 return nextValueNumber++;
496 /// lookup - Returns the value number of the specified value. Fails if
497 /// the value has not yet been numbered.
498 uint32_t ValueTable::lookup(Value* V) const {
499 DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
500 if (VI != valueNumbering.end())
503 assert(0 && "Value not numbered?");
508 /// add - Add the specified value with the given value number, removing
509 /// its old number, if any
510 void ValueTable::add(Value* V, uint32_t num) {
511 DenseMap<Value*, uint32_t>::iterator VI = valueNumbering.find(V);
512 if (VI != valueNumbering.end())
513 valueNumbering.erase(VI);
514 valueNumbering.insert(std::make_pair(V, num));
517 /// clear - Remove all entries from the ValueTable
518 void ValueTable::clear() {
519 valueNumbering.clear();
520 expressionNumbering.clear();
524 /// erase - Remove a value from the value numbering
525 void ValueTable::erase(Value* V) {
526 valueNumbering.erase(V);
529 /// size - Return the number of assigned value numbers
530 unsigned ValueTable::size() {
531 // NOTE: zero is never assigned
532 return nextValueNumber;
535 //===----------------------------------------------------------------------===//
537 //===----------------------------------------------------------------------===//
541 class VISIBILITY_HIDDEN GVNPRE : public FunctionPass {
542 bool runOnFunction(Function &F);
544 static char ID; // Pass identification, replacement for typeid
545 GVNPRE() : FunctionPass((intptr_t)&ID) { }
549 std::vector<Instruction*> createdExpressions;
551 std::map<BasicBlock*, SmallPtrSet<Value*, 16> > availableOut;
552 std::map<BasicBlock*, SmallPtrSet<Value*, 16> > anticipatedIn;
554 // This transformation requires dominator postdominator info
555 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
556 AU.setPreservesCFG();
557 AU.addRequired<DominatorTree>();
561 // FIXME: eliminate or document these better
562 void dump(const SmallPtrSet<Value*, 16>& s) const;
563 void clean(SmallPtrSet<Value*, 16>& set, BitVector& presentInSet);
564 Value* find_leader(SmallPtrSet<Value*, 16>& vals,
566 Value* phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ);
567 void phi_translate_set(SmallPtrSet<Value*, 16>& anticIn, BasicBlock* pred,
568 BasicBlock* succ, SmallPtrSet<Value*, 16>& out);
570 void topo_sort(SmallPtrSet<Value*, 16>& set,
571 std::vector<Value*>& vec);
576 void val_insert(SmallPtrSet<Value*, 16>& s, Value* v);
577 void val_replace(SmallPtrSet<Value*, 16>& s, Value* v);
578 bool dependsOnInvoke(Value* V);
579 void buildsets_availout(BasicBlock::iterator I,
580 SmallPtrSet<Value*, 16>& currAvail,
581 SmallPtrSet<PHINode*, 16>& currPhis,
582 SmallPtrSet<Value*, 16>& currExps,
583 SmallPtrSet<Value*, 16>& currTemps,
584 BitVector& availNumbers,
585 BitVector& expNumbers);
586 bool buildsets_anticout(BasicBlock* BB,
587 SmallPtrSet<Value*, 16>& anticOut,
588 std::set<BasicBlock*>& visited);
589 unsigned buildsets_anticin(BasicBlock* BB,
590 SmallPtrSet<Value*, 16>& anticOut,
591 SmallPtrSet<Value*, 16>& currExps,
592 SmallPtrSet<Value*, 16>& currTemps,
593 std::set<BasicBlock*>& visited);
594 void buildsets(Function& F);
596 void insertion_pre(Value* e, BasicBlock* BB,
597 std::map<BasicBlock*, Value*>& avail,
598 SmallPtrSet<Value*, 16>& new_set);
599 unsigned insertion_mergepoint(std::vector<Value*>& workList,
600 df_iterator<DomTreeNode*>& D,
601 SmallPtrSet<Value*, 16>& new_set);
602 bool insertion(Function& F);
610 // createGVNPREPass - The public interface to this file...
611 FunctionPass *llvm::createGVNPREPass() { return new GVNPRE(); }
613 RegisterPass<GVNPRE> X("gvnpre",
614 "Global Value Numbering/Partial Redundancy Elimination");
617 STATISTIC(NumInsertedVals, "Number of values inserted");
618 STATISTIC(NumInsertedPhis, "Number of PHI nodes inserted");
619 STATISTIC(NumEliminated, "Number of redundant instructions eliminated");
621 /// find_leader - Given a set and a value number, return the first
622 /// element of the set with that value number, or 0 if no such element
624 Value* GVNPRE::find_leader(SmallPtrSet<Value*, 16>& vals, uint32_t v) {
625 for (SmallPtrSet<Value*, 16>::iterator I = vals.begin(), E = vals.end();
627 if (v == VN.lookup(*I))
633 /// val_insert - Insert a value into a set only if there is not a value
634 /// with the same value number already in the set
635 void GVNPRE::val_insert(SmallPtrSet<Value*, 16>& s, Value* v) {
636 uint32_t num = VN.lookup(v);
637 Value* leader = find_leader(s, num);
642 /// val_replace - Insert a value into a set, replacing any values already in
643 /// the set that have the same value number
644 void GVNPRE::val_replace(SmallPtrSet<Value*, 16>& s, Value* v) {
645 uint32_t num = VN.lookup(v);
646 Value* leader = find_leader(s, num);
647 while (leader != 0) {
649 leader = find_leader(s, num);
654 /// phi_translate - Given a value, its parent block, and a predecessor of its
655 /// parent, translate the value into legal for the predecessor block. This
656 /// means translating its operands (and recursively, their operands) through
657 /// any phi nodes in the parent into values available in the predecessor
658 Value* GVNPRE::phi_translate(Value* V, BasicBlock* pred, BasicBlock* succ) {
663 if (CastInst* U = dyn_cast<CastInst>(V)) {
665 if (isa<Instruction>(U->getOperand(0)))
666 newOp1 = phi_translate(U->getOperand(0), pred, succ);
668 newOp1 = U->getOperand(0);
673 if (newOp1 != U->getOperand(0)) {
674 Instruction* newVal = 0;
675 if (CastInst* C = dyn_cast<CastInst>(U))
676 newVal = CastInst::create(C->getOpcode(),
677 newOp1, C->getType(),
678 C->getName()+".expr");
680 uint32_t v = VN.lookup_or_add(newVal);
682 Value* leader = find_leader(availableOut[pred], v);
684 createdExpressions.push_back(newVal);
694 } if (isa<BinaryOperator>(V) || isa<CmpInst>(V) ||
695 isa<ExtractElementInst>(V)) {
696 User* U = cast<User>(V);
699 if (isa<Instruction>(U->getOperand(0)))
700 newOp1 = phi_translate(U->getOperand(0), pred, succ);
702 newOp1 = U->getOperand(0);
708 if (isa<Instruction>(U->getOperand(1)))
709 newOp2 = phi_translate(U->getOperand(1), pred, succ);
711 newOp2 = U->getOperand(1);
716 if (newOp1 != U->getOperand(0) || newOp2 != U->getOperand(1)) {
717 Instruction* newVal = 0;
718 if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
719 newVal = BinaryOperator::create(BO->getOpcode(),
721 BO->getName()+".expr");
722 else if (CmpInst* C = dyn_cast<CmpInst>(U))
723 newVal = CmpInst::create(C->getOpcode(),
726 C->getName()+".expr");
727 else if (ExtractElementInst* E = dyn_cast<ExtractElementInst>(U))
728 newVal = new ExtractElementInst(newOp1, newOp2, E->getName()+".expr");
730 uint32_t v = VN.lookup_or_add(newVal);
732 Value* leader = find_leader(availableOut[pred], v);
734 createdExpressions.push_back(newVal);
743 // Ternary Operations
744 } else if (isa<ShuffleVectorInst>(V) || isa<InsertElementInst>(V) ||
745 isa<SelectInst>(V)) {
746 User* U = cast<User>(V);
749 if (isa<Instruction>(U->getOperand(0)))
750 newOp1 = phi_translate(U->getOperand(0), pred, succ);
752 newOp1 = U->getOperand(0);
758 if (isa<Instruction>(U->getOperand(1)))
759 newOp2 = phi_translate(U->getOperand(1), pred, succ);
761 newOp2 = U->getOperand(1);
767 if (isa<Instruction>(U->getOperand(2)))
768 newOp3 = phi_translate(U->getOperand(2), pred, succ);
770 newOp3 = U->getOperand(2);
775 if (newOp1 != U->getOperand(0) ||
776 newOp2 != U->getOperand(1) ||
777 newOp3 != U->getOperand(2)) {
778 Instruction* newVal = 0;
779 if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
780 newVal = new ShuffleVectorInst(newOp1, newOp2, newOp3,
781 S->getName()+".expr");
782 else if (InsertElementInst* I = dyn_cast<InsertElementInst>(U))
783 newVal = new InsertElementInst(newOp1, newOp2, newOp3,
784 I->getName()+".expr");
785 else if (SelectInst* I = dyn_cast<SelectInst>(U))
786 newVal = new SelectInst(newOp1, newOp2, newOp3, I->getName()+".expr");
788 uint32_t v = VN.lookup_or_add(newVal);
790 Value* leader = find_leader(availableOut[pred], v);
792 createdExpressions.push_back(newVal);
802 } else if (PHINode* P = dyn_cast<PHINode>(V)) {
803 if (P->getParent() == succ)
804 return P->getIncomingValueForBlock(pred);
810 /// phi_translate_set - Perform phi translation on every element of a set
811 void GVNPRE::phi_translate_set(SmallPtrSet<Value*, 16>& anticIn,
812 BasicBlock* pred, BasicBlock* succ,
813 SmallPtrSet<Value*, 16>& out) {
814 for (SmallPtrSet<Value*, 16>::iterator I = anticIn.begin(),
815 E = anticIn.end(); I != E; ++I) {
816 Value* V = phi_translate(*I, pred, succ);
822 /// dependsOnInvoke - Test if a value has an phi node as an operand, any of
823 /// whose inputs is an invoke instruction. If this is true, we cannot safely
824 /// PRE the instruction or anything that depends on it.
825 bool GVNPRE::dependsOnInvoke(Value* V) {
826 if (PHINode* p = dyn_cast<PHINode>(V)) {
827 for (PHINode::op_iterator I = p->op_begin(), E = p->op_end(); I != E; ++I)
828 if (isa<InvokeInst>(*I))
836 /// clean - Remove all non-opaque values from the set whose operands are not
837 /// themselves in the set, as well as all values that depend on invokes (see
839 void GVNPRE::clean(SmallPtrSet<Value*, 16>& set, BitVector& presentInSet) {
840 std::vector<Value*> worklist;
841 worklist.reserve(set.size());
842 topo_sort(set, worklist);
844 for (unsigned i = 0; i < worklist.size(); ++i) {
845 Value* v = worklist[i];
848 if (CastInst* U = dyn_cast<CastInst>(v)) {
849 bool lhsValid = !isa<Instruction>(U->getOperand(0));
850 lhsValid |= presentInSet.test(VN.lookup(U->getOperand(0)));
852 lhsValid = !dependsOnInvoke(U->getOperand(0));
856 presentInSet.flip(VN.lookup(U));
860 } else if (isa<BinaryOperator>(v) || isa<CmpInst>(v) ||
861 isa<ExtractElementInst>(v)) {
862 User* U = cast<User>(v);
864 bool lhsValid = !isa<Instruction>(U->getOperand(0));
865 lhsValid |= presentInSet.test(VN.lookup(U->getOperand(0)));
867 lhsValid = !dependsOnInvoke(U->getOperand(0));
869 bool rhsValid = !isa<Instruction>(U->getOperand(1));
870 rhsValid |= presentInSet.test(VN.lookup(U->getOperand(1)));
872 rhsValid = !dependsOnInvoke(U->getOperand(1));
874 if (!lhsValid || !rhsValid) {
876 presentInSet.flip(VN.lookup(U));
879 // Handle ternary ops
880 } else if (isa<ShuffleVectorInst>(v) || isa<InsertElementInst>(v) ||
881 isa<SelectInst>(v)) {
882 User* U = cast<User>(v);
884 bool lhsValid = !isa<Instruction>(U->getOperand(0));
885 lhsValid |= presentInSet.test(VN.lookup(U->getOperand(0)));
887 lhsValid = !dependsOnInvoke(U->getOperand(0));
889 bool rhsValid = !isa<Instruction>(U->getOperand(1));
890 rhsValid |= presentInSet.test(VN.lookup(U->getOperand(1)));
892 rhsValid = !dependsOnInvoke(U->getOperand(1));
894 bool thirdValid = !isa<Instruction>(U->getOperand(2));
895 thirdValid |= presentInSet.test(VN.lookup(U->getOperand(2)));
897 thirdValid = !dependsOnInvoke(U->getOperand(2));
899 if (!lhsValid || !rhsValid || !thirdValid) {
901 presentInSet.flip(VN.lookup(U));
907 /// topo_sort - Given a set of values, sort them by topological
908 /// order into the provided vector.
909 void GVNPRE::topo_sort(SmallPtrSet<Value*, 16>& set, std::vector<Value*>& vec) {
910 SmallPtrSet<Value*, 16> visited;
911 std::vector<Value*> stack;
912 for (SmallPtrSet<Value*, 16>::iterator I = set.begin(), E = set.end();
914 if (visited.count(*I) == 0)
917 while (!stack.empty()) {
918 Value* e = stack.back();
921 if (CastInst* U = dyn_cast<CastInst>(e)) {
922 Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
924 if (l != 0 && isa<Instruction>(l) &&
925 visited.count(l) == 0)
934 } else if (isa<BinaryOperator>(e) || isa<CmpInst>(e) ||
935 isa<ExtractElementInst>(e)) {
936 User* U = cast<User>(e);
937 Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
938 Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
940 if (l != 0 && isa<Instruction>(l) &&
941 visited.count(l) == 0)
943 else if (r != 0 && isa<Instruction>(r) &&
944 visited.count(r) == 0)
952 // Handle ternary ops
953 } else if (isa<InsertElementInst>(e) || isa<ShuffleVectorInst>(e) ||
954 isa<SelectInst>(e)) {
955 User* U = cast<User>(e);
956 Value* l = find_leader(set, VN.lookup(U->getOperand(0)));
957 Value* r = find_leader(set, VN.lookup(U->getOperand(1)));
958 Value* m = find_leader(set, VN.lookup(U->getOperand(2)));
960 if (l != 0 && isa<Instruction>(l) &&
961 visited.count(l) == 0)
963 else if (r != 0 && isa<Instruction>(r) &&
964 visited.count(r) == 0)
966 else if (m != 0 && isa<Instruction>(m) &&
967 visited.count(m) == 0)
987 /// dump - Dump a set of values to standard error
988 void GVNPRE::dump(const SmallPtrSet<Value*, 16>& s) const {
990 for (SmallPtrSet<Value*, 16>::iterator I = s.begin(), E = s.end();
992 DOUT << "" << VN.lookup(*I) << ": ";
998 /// elimination - Phase 3 of the main algorithm. Perform full redundancy
999 /// elimination by walking the dominator tree and removing any instruction that
1000 /// is dominated by another instruction with the same value number.
1001 bool GVNPRE::elimination() {
1002 DOUT << "\n\nPhase 3: Elimination\n\n";
1004 bool changed_function = false;
1006 std::vector<std::pair<Instruction*, Value*> > replace;
1007 std::vector<Instruction*> erase;
1009 DominatorTree& DT = getAnalysis<DominatorTree>();
1011 for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
1012 E = df_end(DT.getRootNode()); DI != E; ++DI) {
1013 BasicBlock* BB = DI->getBlock();
1015 //DOUT << "Block: " << BB->getName() << "\n";
1016 //dump(availableOut[BB]);
1019 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
1022 if (isa<BinaryOperator>(BI) || isa<CmpInst>(BI) ||
1023 isa<ShuffleVectorInst>(BI) || isa<InsertElementInst>(BI) ||
1024 isa<ExtractElementInst>(BI) || isa<SelectInst>(BI) ||
1025 isa<CastInst>(BI)) {
1026 Value *leader = find_leader(availableOut[BB], VN.lookup(BI));
1029 if (Instruction* Instr = dyn_cast<Instruction>(leader))
1030 if (Instr->getParent() != 0 && Instr != BI) {
1031 replace.push_back(std::make_pair(BI, leader));
1032 erase.push_back(BI);
1039 while (!replace.empty()) {
1040 std::pair<Instruction*, Value*> rep = replace.back();
1042 rep.first->replaceAllUsesWith(rep.second);
1043 changed_function = true;
1046 for (std::vector<Instruction*>::iterator I = erase.begin(), E = erase.end();
1048 (*I)->eraseFromParent();
1050 return changed_function;
1053 /// cleanup - Delete any extraneous values that were created to represent
1054 /// expressions without leaders.
1055 void GVNPRE::cleanup() {
1056 while (!createdExpressions.empty()) {
1057 Instruction* I = createdExpressions.back();
1058 createdExpressions.pop_back();
1064 /// buildsets_availout - When calculating availability, handle an instruction
1065 /// by inserting it into the appropriate sets
1066 void GVNPRE::buildsets_availout(BasicBlock::iterator I,
1067 SmallPtrSet<Value*, 16>& currAvail,
1068 SmallPtrSet<PHINode*, 16>& currPhis,
1069 SmallPtrSet<Value*, 16>& currExps,
1070 SmallPtrSet<Value*, 16>& currTemps,
1071 BitVector& availNumbers,
1072 BitVector& expNumbers) {
1074 if (PHINode* p = dyn_cast<PHINode>(I)) {
1075 VN.lookup_or_add(p);
1076 expNumbers.resize(VN.size());
1077 availNumbers.resize(VN.size());
1082 } else if (CastInst* U = dyn_cast<CastInst>(I)) {
1083 Value* leftValue = U->getOperand(0);
1085 unsigned num = VN.lookup_or_add(U);
1086 expNumbers.resize(VN.size());
1087 availNumbers.resize(VN.size());
1089 if (isa<Instruction>(leftValue))
1090 if (!expNumbers.test(VN.lookup(leftValue))) {
1091 currExps.insert(leftValue);
1092 expNumbers.set(VN.lookup(leftValue));
1095 if (!expNumbers.test(VN.lookup(U))) {
1097 expNumbers.set(num);
1100 // Handle binary ops
1101 } else if (isa<BinaryOperator>(I) || isa<CmpInst>(I) ||
1102 isa<ExtractElementInst>(I)) {
1103 User* U = cast<User>(I);
1104 Value* leftValue = U->getOperand(0);
1105 Value* rightValue = U->getOperand(1);
1107 unsigned num = VN.lookup_or_add(U);
1108 expNumbers.resize(VN.size());
1109 availNumbers.resize(VN.size());
1111 if (isa<Instruction>(leftValue))
1112 if (!expNumbers.test(VN.lookup(leftValue))) {
1113 currExps.insert(leftValue);
1114 expNumbers.set(VN.lookup(leftValue));
1117 if (isa<Instruction>(rightValue))
1118 if (!expNumbers.test(VN.lookup(rightValue))) {
1119 currExps.insert(rightValue);
1120 expNumbers.set(VN.lookup(rightValue));
1123 if (!expNumbers.test(VN.lookup(U))) {
1125 expNumbers.set(num);
1128 // Handle ternary ops
1129 } else if (isa<InsertElementInst>(I) || isa<ShuffleVectorInst>(I) ||
1130 isa<SelectInst>(I)) {
1131 User* U = cast<User>(I);
1132 Value* leftValue = U->getOperand(0);
1133 Value* rightValue = U->getOperand(1);
1134 Value* thirdValue = U->getOperand(2);
1136 VN.lookup_or_add(U);
1138 unsigned num = VN.lookup_or_add(U);
1139 expNumbers.resize(VN.size());
1140 availNumbers.resize(VN.size());
1142 if (isa<Instruction>(leftValue))
1143 if (!expNumbers.test(VN.lookup(leftValue))) {
1144 currExps.insert(leftValue);
1145 expNumbers.set(VN.lookup(leftValue));
1147 if (isa<Instruction>(rightValue))
1148 if (!expNumbers.test(VN.lookup(rightValue))) {
1149 currExps.insert(rightValue);
1150 expNumbers.set(VN.lookup(rightValue));
1152 if (isa<Instruction>(thirdValue))
1153 if (!expNumbers.test(VN.lookup(thirdValue))) {
1154 currExps.insert(thirdValue);
1155 expNumbers.set(VN.lookup(thirdValue));
1158 if (!expNumbers.test(VN.lookup(U))) {
1160 expNumbers.set(num);
1163 // Handle opaque ops
1164 } else if (!I->isTerminator()){
1165 VN.lookup_or_add(I);
1166 expNumbers.resize(VN.size());
1167 availNumbers.resize(VN.size());
1169 currTemps.insert(I);
1172 if (!I->isTerminator())
1173 if (!availNumbers.test(VN.lookup(I))) {
1174 currAvail.insert(I);
1175 availNumbers.set(VN.lookup(I));
1179 /// buildsets_anticout - When walking the postdom tree, calculate the ANTIC_OUT
1180 /// set as a function of the ANTIC_IN set of the block's predecessors
1181 bool GVNPRE::buildsets_anticout(BasicBlock* BB,
1182 SmallPtrSet<Value*, 16>& anticOut,
1183 std::set<BasicBlock*>& visited) {
1184 if (BB->getTerminator()->getNumSuccessors() == 1) {
1185 if (BB->getTerminator()->getSuccessor(0) != BB &&
1186 visited.count(BB->getTerminator()->getSuccessor(0)) == 0) {
1187 DOUT << "DEFER: " << BB->getName() << "\n";
1191 phi_translate_set(anticipatedIn[BB->getTerminator()->getSuccessor(0)],
1192 BB, BB->getTerminator()->getSuccessor(0), anticOut);
1194 } else if (BB->getTerminator()->getNumSuccessors() > 1) {
1195 BasicBlock* first = BB->getTerminator()->getSuccessor(0);
1196 anticOut.insert(anticipatedIn[first].begin(), anticipatedIn[first].end());
1198 for (unsigned i = 1; i < BB->getTerminator()->getNumSuccessors(); ++i) {
1199 BasicBlock* currSucc = BB->getTerminator()->getSuccessor(i);
1200 SmallPtrSet<Value*, 16>& succAnticIn = anticipatedIn[currSucc];
1202 std::vector<Value*> temp;
1204 for (SmallPtrSet<Value*, 16>::iterator I = anticOut.begin(),
1205 E = anticOut.end(); I != E; ++I)
1206 if (succAnticIn.count(*I) == 0)
1209 for (std::vector<Value*>::iterator I = temp.begin(), E = temp.end();
1218 /// buildsets_anticin - Walk the postdom tree, calculating ANTIC_OUT for
1219 /// each block. ANTIC_IN is then a function of ANTIC_OUT and the GEN
1220 /// sets populated in buildsets_availout
1221 unsigned GVNPRE::buildsets_anticin(BasicBlock* BB,
1222 SmallPtrSet<Value*, 16>& anticOut,
1223 SmallPtrSet<Value*, 16>& currExps,
1224 SmallPtrSet<Value*, 16>& currTemps,
1225 std::set<BasicBlock*>& visited) {
1226 SmallPtrSet<Value*, 16>& anticIn = anticipatedIn[BB];
1227 unsigned old = anticIn.size();
1229 bool defer = buildsets_anticout(BB, anticOut, visited);
1235 BitVector numbers(VN.size());
1236 for (SmallPtrSet<Value*, 16>::iterator I = anticOut.begin(),
1237 E = anticOut.end(); I != E; ++I) {
1238 unsigned num = VN.lookup_or_add(*I);
1239 numbers.resize(VN.size());
1241 if (isa<Instruction>(*I)) {
1246 for (SmallPtrSet<Value*, 16>::iterator I = currExps.begin(),
1247 E = currExps.end(); I != E; ++I) {
1248 if (!numbers.test(VN.lookup_or_add(*I))) {
1250 numbers.set(VN.lookup(*I));
1254 for (SmallPtrSet<Value*, 16>::iterator I = currTemps.begin(),
1255 E = currTemps.end(); I != E; ++I) {
1257 numbers.flip(VN.lookup(*I));
1260 clean(anticIn, numbers);
1263 if (old != anticIn.size())
1269 /// buildsets - Phase 1 of the main algorithm. Construct the AVAIL_OUT
1270 /// and the ANTIC_IN sets.
1271 void GVNPRE::buildsets(Function& F) {
1272 std::map<BasicBlock*, SmallPtrSet<Value*, 16> > generatedExpressions;
1273 std::map<BasicBlock*, SmallPtrSet<PHINode*, 16> > generatedPhis;
1274 std::map<BasicBlock*, SmallPtrSet<Value*, 16> > generatedTemporaries;
1276 DominatorTree &DT = getAnalysis<DominatorTree>();
1278 // Phase 1, Part 1: calculate AVAIL_OUT
1280 // Top-down walk of the dominator tree
1281 for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
1282 E = df_end(DT.getRootNode()); DI != E; ++DI) {
1284 // Get the sets to update for this block
1285 SmallPtrSet<Value*, 16>& currExps = generatedExpressions[DI->getBlock()];
1286 SmallPtrSet<PHINode*, 16>& currPhis = generatedPhis[DI->getBlock()];
1287 SmallPtrSet<Value*, 16>& currTemps = generatedTemporaries[DI->getBlock()];
1288 SmallPtrSet<Value*, 16>& currAvail = availableOut[DI->getBlock()];
1290 BasicBlock* BB = DI->getBlock();
1292 // A block inherits AVAIL_OUT from its dominator
1293 if (DI->getIDom() != 0)
1294 currAvail.insert(availableOut[DI->getIDom()->getBlock()].begin(),
1295 availableOut[DI->getIDom()->getBlock()].end());
1297 BitVector availNumbers(VN.size());
1298 for (SmallPtrSet<Value*, 16>::iterator I = currAvail.begin(),
1299 E = currAvail.end(); I != E; ++I)
1300 availNumbers.set(VN.lookup(*I));
1302 BitVector expNumbers(VN.size());
1303 for (BasicBlock::iterator BI = BB->begin(), BE = BB->end();
1305 buildsets_availout(BI, currAvail, currPhis, currExps,
1306 currTemps, availNumbers, expNumbers);
1310 // Phase 1, Part 2: calculate ANTIC_IN
1312 std::set<BasicBlock*> visited;
1313 SmallPtrSet<BasicBlock*, 4> block_changed;
1314 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI)
1315 block_changed.insert(FI);
1317 bool changed = true;
1318 unsigned iterations = 0;
1322 SmallPtrSet<Value*, 16> anticOut;
1324 // Postorder walk of the CFG
1325 for (po_iterator<BasicBlock*> BBI = po_begin(&F.getEntryBlock()),
1326 BBE = po_end(&F.getEntryBlock()); BBI != BBE; ++BBI) {
1327 BasicBlock* BB = *BBI;
1329 if (block_changed.count(BB) != 0) {
1330 unsigned ret = buildsets_anticin(BB, anticOut,generatedExpressions[BB],
1331 generatedTemporaries[BB], visited);
1340 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB);
1342 block_changed.insert(*PI);
1345 block_changed.erase(BB);
1347 changed |= (ret == 2);
1355 DOUT << "ITERATIONS: " << iterations << "\n";
1358 /// insertion_pre - When a partial redundancy has been identified, eliminate it
1359 /// by inserting appropriate values into the predecessors and a phi node in
1361 void GVNPRE::insertion_pre(Value* e, BasicBlock* BB,
1362 std::map<BasicBlock*, Value*>& avail,
1363 SmallPtrSet<Value*, 16>& new_set) {
1364 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1365 Value* e2 = avail[*PI];
1366 if (!find_leader(availableOut[*PI], VN.lookup(e2))) {
1367 User* U = cast<User>(e2);
1370 if (isa<BinaryOperator>(U->getOperand(0)) ||
1371 isa<CmpInst>(U->getOperand(0)) ||
1372 isa<ShuffleVectorInst>(U->getOperand(0)) ||
1373 isa<ExtractElementInst>(U->getOperand(0)) ||
1374 isa<InsertElementInst>(U->getOperand(0)) ||
1375 isa<SelectInst>(U->getOperand(0)) ||
1376 isa<CastInst>(U->getOperand(0)))
1377 s1 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(0)));
1379 s1 = U->getOperand(0);
1383 if (isa<BinaryOperator>(U) ||
1385 isa<ShuffleVectorInst>(U) ||
1386 isa<ExtractElementInst>(U) ||
1387 isa<InsertElementInst>(U) ||
1389 if (isa<BinaryOperator>(U->getOperand(1)) ||
1390 isa<CmpInst>(U->getOperand(1)) ||
1391 isa<ShuffleVectorInst>(U->getOperand(1)) ||
1392 isa<ExtractElementInst>(U->getOperand(1)) ||
1393 isa<InsertElementInst>(U->getOperand(1)) ||
1394 isa<SelectInst>(U->getOperand(1)) ||
1395 isa<CastInst>(U->getOperand(1))) {
1396 s2 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(1)));
1398 s2 = U->getOperand(1);
1401 // Ternary Operators
1403 if (isa<ShuffleVectorInst>(U) ||
1404 isa<InsertElementInst>(U) ||
1406 if (isa<BinaryOperator>(U->getOperand(2)) ||
1407 isa<CmpInst>(U->getOperand(2)) ||
1408 isa<ShuffleVectorInst>(U->getOperand(2)) ||
1409 isa<ExtractElementInst>(U->getOperand(2)) ||
1410 isa<InsertElementInst>(U->getOperand(2)) ||
1411 isa<SelectInst>(U->getOperand(2)) ||
1412 isa<CastInst>(U->getOperand(2))) {
1413 s3 = find_leader(availableOut[*PI], VN.lookup(U->getOperand(2)));
1415 s3 = U->getOperand(2);
1419 if (BinaryOperator* BO = dyn_cast<BinaryOperator>(U))
1420 newVal = BinaryOperator::create(BO->getOpcode(), s1, s2,
1421 BO->getName()+".gvnpre",
1422 (*PI)->getTerminator());
1423 else if (CmpInst* C = dyn_cast<CmpInst>(U))
1424 newVal = CmpInst::create(C->getOpcode(), C->getPredicate(), s1, s2,
1425 C->getName()+".gvnpre",
1426 (*PI)->getTerminator());
1427 else if (ShuffleVectorInst* S = dyn_cast<ShuffleVectorInst>(U))
1428 newVal = new ShuffleVectorInst(s1, s2, s3, S->getName()+".gvnpre",
1429 (*PI)->getTerminator());
1430 else if (InsertElementInst* S = dyn_cast<InsertElementInst>(U))
1431 newVal = new InsertElementInst(s1, s2, s3, S->getName()+".gvnpre",
1432 (*PI)->getTerminator());
1433 else if (ExtractElementInst* S = dyn_cast<ExtractElementInst>(U))
1434 newVal = new ExtractElementInst(s1, s2, S->getName()+".gvnpre",
1435 (*PI)->getTerminator());
1436 else if (SelectInst* S = dyn_cast<SelectInst>(U))
1437 newVal = new SelectInst(S->getCondition(), S->getTrueValue(),
1438 S->getFalseValue(), S->getName()+".gvnpre",
1439 (*PI)->getTerminator());
1440 else if (CastInst* C = dyn_cast<CastInst>(U))
1441 newVal = CastInst::create(C->getOpcode(), s1, C->getType(),
1442 C->getName()+".gvnpre",
1443 (*PI)->getTerminator());
1446 VN.add(newVal, VN.lookup(U));
1448 SmallPtrSet<Value*, 16>& predAvail = availableOut[*PI];
1449 val_replace(predAvail, newVal);
1451 std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
1452 if (av != avail.end())
1454 avail.insert(std::make_pair(*PI, newVal));
1462 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE; ++PI) {
1464 p = new PHINode(avail[*PI]->getType(), "gvnpre-join", BB->begin());
1466 p->addIncoming(avail[*PI], *PI);
1469 VN.add(p, VN.lookup(e));
1470 val_replace(availableOut[BB], p);
1476 /// insertion_mergepoint - When walking the dom tree, check at each merge
1477 /// block for the possibility of a partial redundancy. If present, eliminate it
1478 unsigned GVNPRE::insertion_mergepoint(std::vector<Value*>& workList,
1479 df_iterator<DomTreeNode*>& D,
1480 SmallPtrSet<Value*, 16>& new_set) {
1481 bool changed_function = false;
1482 bool new_stuff = false;
1484 BasicBlock* BB = D->getBlock();
1485 for (unsigned i = 0; i < workList.size(); ++i) {
1486 Value* e = workList[i];
1488 if (isa<BinaryOperator>(e) || isa<CmpInst>(e) ||
1489 isa<ExtractElementInst>(e) || isa<InsertElementInst>(e) ||
1490 isa<ShuffleVectorInst>(e) || isa<SelectInst>(e) || isa<CastInst>(e)) {
1491 if (find_leader(availableOut[D->getIDom()->getBlock()],
1495 std::map<BasicBlock*, Value*> avail;
1496 bool by_some = false;
1499 for (pred_iterator PI = pred_begin(BB), PE = pred_end(BB); PI != PE;
1501 Value *e2 = phi_translate(e, *PI, BB);
1502 Value *e3 = find_leader(availableOut[*PI], VN.lookup(e2));
1505 std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
1506 if (av != avail.end())
1508 avail.insert(std::make_pair(*PI, e2));
1510 std::map<BasicBlock*, Value*>::iterator av = avail.find(*PI);
1511 if (av != avail.end())
1513 avail.insert(std::make_pair(*PI, e3));
1520 if (by_some && num_avail < std::distance(pred_begin(BB), pred_end(BB))) {
1521 insertion_pre(e, BB, avail, new_set);
1523 changed_function = true;
1529 unsigned retval = 0;
1530 if (changed_function)
1538 /// insert - Phase 2 of the main algorithm. Walk the dominator tree looking for
1539 /// merge points. When one is found, check for a partial redundancy. If one is
1540 /// present, eliminate it. Repeat this walk until no changes are made.
1541 bool GVNPRE::insertion(Function& F) {
1542 bool changed_function = false;
1544 DominatorTree &DT = getAnalysis<DominatorTree>();
1546 std::map<BasicBlock*, SmallPtrSet<Value*, 16> > new_sets;
1547 bool new_stuff = true;
1550 for (df_iterator<DomTreeNode*> DI = df_begin(DT.getRootNode()),
1551 E = df_end(DT.getRootNode()); DI != E; ++DI) {
1552 BasicBlock* BB = DI->getBlock();
1557 SmallPtrSet<Value*, 16>& new_set = new_sets[BB];
1558 SmallPtrSet<Value*, 16>& availOut = availableOut[BB];
1559 SmallPtrSet<Value*, 16>& anticIn = anticipatedIn[BB];
1563 // Replace leaders with leaders inherited from dominator
1564 if (DI->getIDom() != 0) {
1565 SmallPtrSet<Value*, 16>& dom_set = new_sets[DI->getIDom()->getBlock()];
1566 for (SmallPtrSet<Value*, 16>::iterator I = dom_set.begin(),
1567 E = dom_set.end(); I != E; ++I) {
1569 val_replace(availOut, *I);
1573 // If there is more than one predecessor...
1574 if (pred_begin(BB) != pred_end(BB) && ++pred_begin(BB) != pred_end(BB)) {
1575 std::vector<Value*> workList;
1576 workList.reserve(anticIn.size());
1577 topo_sort(anticIn, workList);
1579 unsigned result = insertion_mergepoint(workList, DI, new_set);
1581 changed_function = true;
1588 return changed_function;
1591 // GVNPRE::runOnFunction - This is the main transformation entry point for a
1594 bool GVNPRE::runOnFunction(Function &F) {
1595 // Clean out global sets from any previous functions
1597 createdExpressions.clear();
1598 availableOut.clear();
1599 anticipatedIn.clear();
1601 bool changed_function = false;
1603 // Phase 1: BuildSets
1604 // This phase calculates the AVAIL_OUT and ANTIC_IN sets
1607 for (Function::iterator FI = F.begin(), FE = F.end(); FI != FE; ++FI) {
1608 DOUT << "AVAIL_OUT: " << FI->getName() << "\n";
1609 dump(availableOut[FI]);
1611 DOUT << "ANTIC_IN: " << FI->getName() << "\n";
1612 dump(anticipatedIn[FI]);
1617 // This phase inserts values to make partially redundant values
1619 changed_function |= insertion(F);
1621 // Phase 3: Eliminate
1622 // This phase performs trivial full redundancy elimination
1623 changed_function |= elimination();
1626 // This phase cleans up values that were created solely
1627 // as leaders for expressions
1630 return changed_function;