LLVM  6.0.0svn
Reassociate.cpp
Go to the documentation of this file.
1 //===- Reassociate.cpp - Reassociate binary expressions -------------------===//
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 // This pass reassociates commutative expressions in an order that is designed
11 // to promote better constant propagation, GCSE, LICM, PRE, etc.
12 //
13 // For example: 4 + (x + 5) -> x + (4 + 5)
14 //
15 // In the implementation of this algorithm, constants are assigned rank = 0,
16 // function arguments are rank = 1, and other values are assigned ranks
17 // corresponding to the reverse post order traversal of current function
18 // (starting at 2), which effectively gives values in deep loops higher rank
19 // than values not in loops.
20 //
21 //===----------------------------------------------------------------------===//
22 
24 #include "llvm/ADT/DenseMap.h"
26 #include "llvm/ADT/STLExtras.h"
27 #include "llvm/ADT/SetVector.h"
28 #include "llvm/ADT/Statistic.h"
31 #include "llvm/IR/CFG.h"
32 #include "llvm/IR/Constants.h"
33 #include "llvm/IR/DerivedTypes.h"
34 #include "llvm/IR/Function.h"
35 #include "llvm/IR/IRBuilder.h"
36 #include "llvm/IR/Instructions.h"
37 #include "llvm/IR/IntrinsicInst.h"
38 #include "llvm/IR/PatternMatch.h"
39 #include "llvm/IR/ValueHandle.h"
40 #include "llvm/Pass.h"
41 #include "llvm/Support/Debug.h"
43 #include "llvm/Transforms/Scalar.h"
45 #include <algorithm>
46 using namespace llvm;
47 using namespace reassociate;
48 
49 #define DEBUG_TYPE "reassociate"
50 
51 STATISTIC(NumChanged, "Number of insts reassociated");
52 STATISTIC(NumAnnihil, "Number of expr tree annihilated");
53 STATISTIC(NumFactor , "Number of multiplies factored");
54 
55 #ifndef NDEBUG
56 /// Print out the expression identified in the Ops list.
57 ///
59  Module *M = I->getModule();
60  dbgs() << Instruction::getOpcodeName(I->getOpcode()) << " "
61  << *Ops[0].Op->getType() << '\t';
62  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
63  dbgs() << "[ ";
64  Ops[i].Op->printAsOperand(dbgs(), false, M);
65  dbgs() << ", #" << Ops[i].Rank << "] ";
66  }
67 }
68 #endif
69 
70 /// Utility class representing a non-constant Xor-operand. We classify
71 /// non-constant Xor-Operands into two categories:
72 /// C1) The operand is in the form "X & C", where C is a constant and C != ~0
73 /// C2)
74 /// C2.1) The operand is in the form of "X | C", where C is a non-zero
75 /// constant.
76 /// C2.2) Any operand E which doesn't fall into C1 and C2.1, we view this
77 /// operand as "E | 0"
79 public:
80  XorOpnd(Value *V);
81 
82  bool isInvalid() const { return SymbolicPart == nullptr; }
83  bool isOrExpr() const { return isOr; }
84  Value *getValue() const { return OrigVal; }
85  Value *getSymbolicPart() const { return SymbolicPart; }
86  unsigned getSymbolicRank() const { return SymbolicRank; }
87  const APInt &getConstPart() const { return ConstPart; }
88 
89  void Invalidate() { SymbolicPart = OrigVal = nullptr; }
90  void setSymbolicRank(unsigned R) { SymbolicRank = R; }
91 
92 private:
93  Value *OrigVal;
94  Value *SymbolicPart;
95  APInt ConstPart;
96  unsigned SymbolicRank;
97  bool isOr;
98 };
99 
101  assert(!isa<ConstantInt>(V) && "No ConstantInt");
102  OrigVal = V;
104  SymbolicRank = 0;
105 
106  if (I && (I->getOpcode() == Instruction::Or ||
107  I->getOpcode() == Instruction::And)) {
108  Value *V0 = I->getOperand(0);
109  Value *V1 = I->getOperand(1);
110  const APInt *C;
111  if (match(V0, PatternMatch::m_APInt(C)))
112  std::swap(V0, V1);
113 
114  if (match(V1, PatternMatch::m_APInt(C))) {
115  ConstPart = *C;
116  SymbolicPart = V0;
117  isOr = (I->getOpcode() == Instruction::Or);
118  return;
119  }
120  }
121 
122  // view the operand as "V | 0"
123  SymbolicPart = V;
124  ConstPart = APInt::getNullValue(V->getType()->getScalarSizeInBits());
125  isOr = true;
126 }
127 
128 /// Return true if V is an instruction of the specified opcode and if it
129 /// only has one use.
130 static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode) {
131  if (V->hasOneUse() && isa<Instruction>(V) &&
132  cast<Instruction>(V)->getOpcode() == Opcode &&
133  (!isa<FPMathOperator>(V) ||
134  cast<Instruction>(V)->hasUnsafeAlgebra()))
135  return cast<BinaryOperator>(V);
136  return nullptr;
137 }
138 
139 static BinaryOperator *isReassociableOp(Value *V, unsigned Opcode1,
140  unsigned Opcode2) {
141  if (V->hasOneUse() && isa<Instruction>(V) &&
142  (cast<Instruction>(V)->getOpcode() == Opcode1 ||
143  cast<Instruction>(V)->getOpcode() == Opcode2) &&
144  (!isa<FPMathOperator>(V) ||
145  cast<Instruction>(V)->hasUnsafeAlgebra()))
146  return cast<BinaryOperator>(V);
147  return nullptr;
148 }
149 
150 void ReassociatePass::BuildRankMap(Function &F,
152  unsigned i = 2;
153 
154  // Assign distinct ranks to function arguments.
155  for (Function::arg_iterator I = F.arg_begin(), E = F.arg_end(); I != E; ++I) {
156  ValueRankMap[&*I] = ++i;
157  DEBUG(dbgs() << "Calculated Rank[" << I->getName() << "] = " << i << "\n");
158  }
159 
160  // Traverse basic blocks in ReversePostOrder
161  for (BasicBlock *BB : RPOT) {
162  unsigned BBRank = RankMap[BB] = ++i << 16;
163 
164  // Walk the basic block, adding precomputed ranks for any instructions that
165  // we cannot move. This ensures that the ranks for these instructions are
166  // all different in the block.
167  for (Instruction &I : *BB)
168  if (mayBeMemoryDependent(I))
169  ValueRankMap[&I] = ++BBRank;
170  }
171 }
172 
173 unsigned ReassociatePass::getRank(Value *V) {
175  if (!I) {
176  if (isa<Argument>(V)) return ValueRankMap[V]; // Function argument.
177  return 0; // Otherwise it's a global or constant, rank 0.
178  }
179 
180  if (unsigned Rank = ValueRankMap[I])
181  return Rank; // Rank already known?
182 
183  // If this is an expression, return the 1+MAX(rank(LHS), rank(RHS)) so that
184  // we can reassociate expressions for code motion! Since we do not recurse
185  // for PHI nodes, we cannot have infinite recursion here, because there
186  // cannot be loops in the value graph that do not go through PHI nodes.
187  unsigned Rank = 0, MaxRank = RankMap[I->getParent()];
188  for (unsigned i = 0, e = I->getNumOperands();
189  i != e && Rank != MaxRank; ++i)
190  Rank = std::max(Rank, getRank(I->getOperand(i)));
191 
192  // If this is a not or neg instruction, do not count it for rank. This
193  // assures us that X and ~X will have the same rank.
196  ++Rank;
197 
198  DEBUG(dbgs() << "Calculated Rank[" << V->getName() << "] = " << Rank << "\n");
199 
200  return ValueRankMap[I] = Rank;
201 }
202 
203 // Canonicalize constants to RHS. Otherwise, sort the operands by rank.
204 void ReassociatePass::canonicalizeOperands(Instruction *I) {
205  assert(isa<BinaryOperator>(I) && "Expected binary operator.");
206  assert(I->isCommutative() && "Expected commutative operator.");
207 
208  Value *LHS = I->getOperand(0);
209  Value *RHS = I->getOperand(1);
210  unsigned LHSRank = getRank(LHS);
211  unsigned RHSRank = getRank(RHS);
212 
213  if (isa<Constant>(RHS))
214  return;
215 
216  if (isa<Constant>(LHS) || RHSRank < LHSRank)
217  cast<BinaryOperator>(I)->swapOperands();
218 }
219 
220 static BinaryOperator *CreateAdd(Value *S1, Value *S2, const Twine &Name,
221  Instruction *InsertBefore, Value *FlagsOp) {
222  if (S1->getType()->isIntOrIntVectorTy())
223  return BinaryOperator::CreateAdd(S1, S2, Name, InsertBefore);
224  else {
225  BinaryOperator *Res =
226  BinaryOperator::CreateFAdd(S1, S2, Name, InsertBefore);
227  Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
228  return Res;
229  }
230 }
231 
232 static BinaryOperator *CreateMul(Value *S1, Value *S2, const Twine &Name,
233  Instruction *InsertBefore, Value *FlagsOp) {
234  if (S1->getType()->isIntOrIntVectorTy())
235  return BinaryOperator::CreateMul(S1, S2, Name, InsertBefore);
236  else {
237  BinaryOperator *Res =
238  BinaryOperator::CreateFMul(S1, S2, Name, InsertBefore);
239  Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
240  return Res;
241  }
242 }
243 
245  Instruction *InsertBefore, Value *FlagsOp) {
246  if (S1->getType()->isIntOrIntVectorTy())
247  return BinaryOperator::CreateNeg(S1, Name, InsertBefore);
248  else {
249  BinaryOperator *Res = BinaryOperator::CreateFNeg(S1, Name, InsertBefore);
250  Res->setFastMathFlags(cast<FPMathOperator>(FlagsOp)->getFastMathFlags());
251  return Res;
252  }
253 }
254 
255 /// Replace 0-X with X*-1.
257  Type *Ty = Neg->getType();
258  Constant *NegOne = Ty->isIntOrIntVectorTy() ?
260 
261  BinaryOperator *Res = CreateMul(Neg->getOperand(1), NegOne, "", Neg, Neg);
262  Neg->setOperand(1, Constant::getNullValue(Ty)); // Drop use of op.
263  Res->takeName(Neg);
264  Neg->replaceAllUsesWith(Res);
265  Res->setDebugLoc(Neg->getDebugLoc());
266  return Res;
267 }
268 
269 /// Returns k such that lambda(2^Bitwidth) = 2^k, where lambda is the Carmichael
270 /// function. This means that x^(2^k) === 1 mod 2^Bitwidth for
271 /// every odd x, i.e. x^(2^k) = 1 for every odd x in Bitwidth-bit arithmetic.
272 /// Note that 0 <= k < Bitwidth, and if Bitwidth > 3 then x^(2^k) = 0 for every
273 /// even x in Bitwidth-bit arithmetic.
274 static unsigned CarmichaelShift(unsigned Bitwidth) {
275  if (Bitwidth < 3)
276  return Bitwidth - 1;
277  return Bitwidth - 2;
278 }
279 
280 /// Add the extra weight 'RHS' to the existing weight 'LHS',
281 /// reducing the combined weight using any special properties of the operation.
282 /// The existing weight LHS represents the computation X op X op ... op X where
283 /// X occurs LHS times. The combined weight represents X op X op ... op X with
284 /// X occurring LHS + RHS times. If op is "Xor" for example then the combined
285 /// operation is equivalent to X if LHS + RHS is odd, or 0 if LHS + RHS is even;
286 /// the routine returns 1 in LHS in the first case, and 0 in LHS in the second.
287 static void IncorporateWeight(APInt &LHS, const APInt &RHS, unsigned Opcode) {
288  // If we were working with infinite precision arithmetic then the combined
289  // weight would be LHS + RHS. But we are using finite precision arithmetic,
290  // and the APInt sum LHS + RHS may not be correct if it wraps (it is correct
291  // for nilpotent operations and addition, but not for idempotent operations
292  // and multiplication), so it is important to correctly reduce the combined
293  // weight back into range if wrapping would be wrong.
294 
295  // If RHS is zero then the weight didn't change.
296  if (RHS.isMinValue())
297  return;
298  // If LHS is zero then the combined weight is RHS.
299  if (LHS.isMinValue()) {
300  LHS = RHS;
301  return;
302  }
303  // From this point on we know that neither LHS nor RHS is zero.
304 
305  if (Instruction::isIdempotent(Opcode)) {
306  // Idempotent means X op X === X, so any non-zero weight is equivalent to a
307  // weight of 1. Keeping weights at zero or one also means that wrapping is
308  // not a problem.
309  assert(LHS == 1 && RHS == 1 && "Weights not reduced!");
310  return; // Return a weight of 1.
311  }
312  if (Instruction::isNilpotent(Opcode)) {
313  // Nilpotent means X op X === 0, so reduce weights modulo 2.
314  assert(LHS == 1 && RHS == 1 && "Weights not reduced!");
315  LHS = 0; // 1 + 1 === 0 modulo 2.
316  return;
317  }
318  if (Opcode == Instruction::Add || Opcode == Instruction::FAdd) {
319  // TODO: Reduce the weight by exploiting nsw/nuw?
320  LHS += RHS;
321  return;
322  }
323 
324  assert((Opcode == Instruction::Mul || Opcode == Instruction::FMul) &&
325  "Unknown associative operation!");
326  unsigned Bitwidth = LHS.getBitWidth();
327  // If CM is the Carmichael number then a weight W satisfying W >= CM+Bitwidth
328  // can be replaced with W-CM. That's because x^W=x^(W-CM) for every Bitwidth
329  // bit number x, since either x is odd in which case x^CM = 1, or x is even in
330  // which case both x^W and x^(W - CM) are zero. By subtracting off multiples
331  // of CM like this weights can always be reduced to the range [0, CM+Bitwidth)
332  // which by a happy accident means that they can always be represented using
333  // Bitwidth bits.
334  // TODO: Reduce the weight by exploiting nsw/nuw? (Could do much better than
335  // the Carmichael number).
336  if (Bitwidth > 3) {
337  /// CM - The value of Carmichael's lambda function.
338  APInt CM = APInt::getOneBitSet(Bitwidth, CarmichaelShift(Bitwidth));
339  // Any weight W >= Threshold can be replaced with W - CM.
340  APInt Threshold = CM + Bitwidth;
341  assert(LHS.ult(Threshold) && RHS.ult(Threshold) && "Weights not reduced!");
342  // For Bitwidth 4 or more the following sum does not overflow.
343  LHS += RHS;
344  while (LHS.uge(Threshold))
345  LHS -= CM;
346  } else {
347  // To avoid problems with overflow do everything the same as above but using
348  // a larger type.
349  unsigned CM = 1U << CarmichaelShift(Bitwidth);
350  unsigned Threshold = CM + Bitwidth;
351  assert(LHS.getZExtValue() < Threshold && RHS.getZExtValue() < Threshold &&
352  "Weights not reduced!");
353  unsigned Total = LHS.getZExtValue() + RHS.getZExtValue();
354  while (Total >= Threshold)
355  Total -= CM;
356  LHS = Total;
357  }
358 }
359 
360 typedef std::pair<Value*, APInt> RepeatedValue;
361 
362 /// Given an associative binary expression, return the leaf
363 /// nodes in Ops along with their weights (how many times the leaf occurs). The
364 /// original expression is the same as
365 /// (Ops[0].first op Ops[0].first op ... Ops[0].first) <- Ops[0].second times
366 /// op
367 /// (Ops[1].first op Ops[1].first op ... Ops[1].first) <- Ops[1].second times
368 /// op
369 /// ...
370 /// op
371 /// (Ops[N].first op Ops[N].first op ... Ops[N].first) <- Ops[N].second times
372 ///
373 /// Note that the values Ops[0].first, ..., Ops[N].first are all distinct.
374 ///
375 /// This routine may modify the function, in which case it returns 'true'. The
376 /// changes it makes may well be destructive, changing the value computed by 'I'
377 /// to something completely different. Thus if the routine returns 'true' then
378 /// you MUST either replace I with a new expression computed from the Ops array,
379 /// or use RewriteExprTree to put the values back in.
380 ///
381 /// A leaf node is either not a binary operation of the same kind as the root
382 /// node 'I' (i.e. is not a binary operator at all, or is, but with a different
383 /// opcode), or is the same kind of binary operator but has a use which either
384 /// does not belong to the expression, or does belong to the expression but is
385 /// a leaf node. Every leaf node has at least one use that is a non-leaf node
386 /// of the expression, while for non-leaf nodes (except for the root 'I') every
387 /// use is a non-leaf node of the expression.
388 ///
389 /// For example:
390 /// expression graph node names
391 ///
392 /// + | I
393 /// / \ |
394 /// + + | A, B
395 /// / \ / \ |
396 /// * + * | C, D, E
397 /// / \ / \ / \ |
398 /// + * | F, G
399 ///
400 /// The leaf nodes are C, E, F and G. The Ops array will contain (maybe not in
401 /// that order) (C, 1), (E, 1), (F, 2), (G, 2).
402 ///
403 /// The expression is maximal: if some instruction is a binary operator of the
404 /// same kind as 'I', and all of its uses are non-leaf nodes of the expression,
405 /// then the instruction also belongs to the expression, is not a leaf node of
406 /// it, and its operands also belong to the expression (but may be leaf nodes).
407 ///
408 /// NOTE: This routine will set operands of non-leaf non-root nodes to undef in
409 /// order to ensure that every non-root node in the expression has *exactly one*
410 /// use by a non-leaf node of the expression. This destruction means that the
411 /// caller MUST either replace 'I' with a new expression or use something like
412 /// RewriteExprTree to put the values back in if the routine indicates that it
413 /// made a change by returning 'true'.
414 ///
415 /// In the above example either the right operand of A or the left operand of B
416 /// will be replaced by undef. If it is B's operand then this gives:
417 ///
418 /// + | I
419 /// / \ |
420 /// + + | A, B - operand of B replaced with undef
421 /// / \ \ |
422 /// * + * | C, D, E
423 /// / \ / \ / \ |
424 /// + * | F, G
425 ///
426 /// Note that such undef operands can only be reached by passing through 'I'.
427 /// For example, if you visit operands recursively starting from a leaf node
428 /// then you will never see such an undef operand unless you get back to 'I',
429 /// which requires passing through a phi node.
430 ///
431 /// Note that this routine may also mutate binary operators of the wrong type
432 /// that have all uses inside the expression (i.e. only used by non-leaf nodes
433 /// of the expression) if it can turn them into binary operators of the right
434 /// type and thus make the expression bigger.
435 
438  DEBUG(dbgs() << "LINEARIZE: " << *I << '\n');
439  unsigned Bitwidth = I->getType()->getScalarType()->getPrimitiveSizeInBits();
440  unsigned Opcode = I->getOpcode();
441  assert(I->isAssociative() && I->isCommutative() &&
442  "Expected an associative and commutative operation!");
443 
444  // Visit all operands of the expression, keeping track of their weight (the
445  // number of paths from the expression root to the operand, or if you like
446  // the number of times that operand occurs in the linearized expression).
447  // For example, if I = X + A, where X = A + B, then I, X and B have weight 1
448  // while A has weight two.
449 
450  // Worklist of non-leaf nodes (their operands are in the expression too) along
451  // with their weights, representing a certain number of paths to the operator.
452  // If an operator occurs in the worklist multiple times then we found multiple
453  // ways to get to it.
454  SmallVector<std::pair<BinaryOperator*, APInt>, 8> Worklist; // (Op, Weight)
455  Worklist.push_back(std::make_pair(I, APInt(Bitwidth, 1)));
456  bool Changed = false;
457 
458  // Leaves of the expression are values that either aren't the right kind of
459  // operation (eg: a constant, or a multiply in an add tree), or are, but have
460  // some uses that are not inside the expression. For example, in I = X + X,
461  // X = A + B, the value X has two uses (by I) that are in the expression. If
462  // X has any other uses, for example in a return instruction, then we consider
463  // X to be a leaf, and won't analyze it further. When we first visit a value,
464  // if it has more than one use then at first we conservatively consider it to
465  // be a leaf. Later, as the expression is explored, we may discover some more
466  // uses of the value from inside the expression. If all uses turn out to be
467  // from within the expression (and the value is a binary operator of the right
468  // kind) then the value is no longer considered to be a leaf, and its operands
469  // are explored.
470 
471  // Leaves - Keeps track of the set of putative leaves as well as the number of
472  // paths to each leaf seen so far.
473  typedef DenseMap<Value*, APInt> LeafMap;
474  LeafMap Leaves; // Leaf -> Total weight so far.
475  SmallVector<Value*, 8> LeafOrder; // Ensure deterministic leaf output order.
476 
477 #ifndef NDEBUG
478  SmallPtrSet<Value*, 8> Visited; // For sanity checking the iteration scheme.
479 #endif
480  while (!Worklist.empty()) {
481  std::pair<BinaryOperator*, APInt> P = Worklist.pop_back_val();
482  I = P.first; // We examine the operands of this binary operator.
483 
484  for (unsigned OpIdx = 0; OpIdx < 2; ++OpIdx) { // Visit operands.
485  Value *Op = I->getOperand(OpIdx);
486  APInt Weight = P.second; // Number of paths to this operand.
487  DEBUG(dbgs() << "OPERAND: " << *Op << " (" << Weight << ")\n");
488  assert(!Op->use_empty() && "No uses, so how did we get to it?!");
489 
490  // If this is a binary operation of the right kind with only one use then
491  // add its operands to the expression.
492  if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
493  assert(Visited.insert(Op).second && "Not first visit!");
494  DEBUG(dbgs() << "DIRECT ADD: " << *Op << " (" << Weight << ")\n");
495  Worklist.push_back(std::make_pair(BO, Weight));
496  continue;
497  }
498 
499  // Appears to be a leaf. Is the operand already in the set of leaves?
500  LeafMap::iterator It = Leaves.find(Op);
501  if (It == Leaves.end()) {
502  // Not in the leaf map. Must be the first time we saw this operand.
503  assert(Visited.insert(Op).second && "Not first visit!");
504  if (!Op->hasOneUse()) {
505  // This value has uses not accounted for by the expression, so it is
506  // not safe to modify. Mark it as being a leaf.
507  DEBUG(dbgs() << "ADD USES LEAF: " << *Op << " (" << Weight << ")\n");
508  LeafOrder.push_back(Op);
509  Leaves[Op] = Weight;
510  continue;
511  }
512  // No uses outside the expression, try morphing it.
513  } else {
514  // Already in the leaf map.
515  assert(It != Leaves.end() && Visited.count(Op) &&
516  "In leaf map but not visited!");
517 
518  // Update the number of paths to the leaf.
519  IncorporateWeight(It->second, Weight, Opcode);
520 
521 #if 0 // TODO: Re-enable once PR13021 is fixed.
522  // The leaf already has one use from inside the expression. As we want
523  // exactly one such use, drop this new use of the leaf.
524  assert(!Op->hasOneUse() && "Only one use, but we got here twice!");
525  I->setOperand(OpIdx, UndefValue::get(I->getType()));
526  Changed = true;
527 
528  // If the leaf is a binary operation of the right kind and we now see
529  // that its multiple original uses were in fact all by nodes belonging
530  // to the expression, then no longer consider it to be a leaf and add
531  // its operands to the expression.
532  if (BinaryOperator *BO = isReassociableOp(Op, Opcode)) {
533  DEBUG(dbgs() << "UNLEAF: " << *Op << " (" << It->second << ")\n");
534  Worklist.push_back(std::make_pair(BO, It->second));
535  Leaves.erase(It);
536  continue;
537  }
538 #endif
539 
540  // If we still have uses that are not accounted for by the expression
541  // then it is not safe to modify the value.
542  if (!Op->hasOneUse())
543  continue;
544 
545  // No uses outside the expression, try morphing it.
546  Weight = It->second;
547  Leaves.erase(It); // Since the value may be morphed below.
548  }
549 
550  // At this point we have a value which, first of all, is not a binary
551  // expression of the right kind, and secondly, is only used inside the
552  // expression. This means that it can safely be modified. See if we
553  // can usefully morph it into an expression of the right kind.
554  assert((!isa<Instruction>(Op) ||
555  cast<Instruction>(Op)->getOpcode() != Opcode
556  || (isa<FPMathOperator>(Op) &&
557  !cast<Instruction>(Op)->hasUnsafeAlgebra())) &&
558  "Should have been handled above!");
559  assert(Op->hasOneUse() && "Has uses outside the expression tree!");
560 
561  // If this is a multiply expression, turn any internal negations into
562  // multiplies by -1 so they can be reassociated.
563  if (BinaryOperator *BO = dyn_cast<BinaryOperator>(Op))
564  if ((Opcode == Instruction::Mul && BinaryOperator::isNeg(BO)) ||
565  (Opcode == Instruction::FMul && BinaryOperator::isFNeg(BO))) {
566  DEBUG(dbgs() << "MORPH LEAF: " << *Op << " (" << Weight << ") TO ");
567  BO = LowerNegateToMultiply(BO);
568  DEBUG(dbgs() << *BO << '\n');
569  Worklist.push_back(std::make_pair(BO, Weight));
570  Changed = true;
571  continue;
572  }
573 
574  // Failed to morph into an expression of the right type. This really is
575  // a leaf.
576  DEBUG(dbgs() << "ADD LEAF: " << *Op << " (" << Weight << ")\n");
577  assert(!isReassociableOp(Op, Opcode) && "Value was morphed?");
578  LeafOrder.push_back(Op);
579  Leaves[Op] = Weight;
580  }
581  }
582 
583  // The leaves, repeated according to their weights, represent the linearized
584  // form of the expression.
585  for (unsigned i = 0, e = LeafOrder.size(); i != e; ++i) {
586  Value *V = LeafOrder[i];
587  LeafMap::iterator It = Leaves.find(V);
588  if (It == Leaves.end())
589  // Node initially thought to be a leaf wasn't.
590  continue;
591  assert(!isReassociableOp(V, Opcode) && "Shouldn't be a leaf!");
592  APInt Weight = It->second;
593  if (Weight.isMinValue())
594  // Leaf already output or weight reduction eliminated it.
595  continue;
596  // Ensure the leaf is only output once.
597  It->second = 0;
598  Ops.push_back(std::make_pair(V, Weight));
599  }
600 
601  // For nilpotent operations or addition there may be no operands, for example
602  // because the expression was "X xor X" or consisted of 2^Bitwidth additions:
603  // in both cases the weight reduces to 0 causing the value to be skipped.
604  if (Ops.empty()) {
605  Constant *Identity = ConstantExpr::getBinOpIdentity(Opcode, I->getType());
606  assert(Identity && "Associative operation without identity!");
607  Ops.emplace_back(Identity, APInt(Bitwidth, 1));
608  }
609 
610  return Changed;
611 }
612 
613 /// Now that the operands for this expression tree are
614 /// linearized and optimized, emit them in-order.
615 void ReassociatePass::RewriteExprTree(BinaryOperator *I,
617  assert(Ops.size() > 1 && "Single values should be used directly!");
618 
619  // Since our optimizations should never increase the number of operations, the
620  // new expression can usually be written reusing the existing binary operators
621  // from the original expression tree, without creating any new instructions,
622  // though the rewritten expression may have a completely different topology.
623  // We take care to not change anything if the new expression will be the same
624  // as the original. If more than trivial changes (like commuting operands)
625  // were made then we are obliged to clear out any optional subclass data like
626  // nsw flags.
627 
628  /// NodesToRewrite - Nodes from the original expression available for writing
629  /// the new expression into.
630  SmallVector<BinaryOperator*, 8> NodesToRewrite;
631  unsigned Opcode = I->getOpcode();
632  BinaryOperator *Op = I;
633 
634  /// NotRewritable - The operands being written will be the leaves of the new
635  /// expression and must not be used as inner nodes (via NodesToRewrite) by
636  /// mistake. Inner nodes are always reassociable, and usually leaves are not
637  /// (if they were they would have been incorporated into the expression and so
638  /// would not be leaves), so most of the time there is no danger of this. But
639  /// in rare cases a leaf may become reassociable if an optimization kills uses
640  /// of it, or it may momentarily become reassociable during rewriting (below)
641  /// due it being removed as an operand of one of its uses. Ensure that misuse
642  /// of leaf nodes as inner nodes cannot occur by remembering all of the future
643  /// leaves and refusing to reuse any of them as inner nodes.
644  SmallPtrSet<Value*, 8> NotRewritable;
645  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
646  NotRewritable.insert(Ops[i].Op);
647 
648  // ExpressionChanged - Non-null if the rewritten expression differs from the
649  // original in some non-trivial way, requiring the clearing of optional flags.
650  // Flags are cleared from the operator in ExpressionChanged up to I inclusive.
651  BinaryOperator *ExpressionChanged = nullptr;
652  for (unsigned i = 0; ; ++i) {
653  // The last operation (which comes earliest in the IR) is special as both
654  // operands will come from Ops, rather than just one with the other being
655  // a subexpression.
656  if (i+2 == Ops.size()) {
657  Value *NewLHS = Ops[i].Op;
658  Value *NewRHS = Ops[i+1].Op;
659  Value *OldLHS = Op->getOperand(0);
660  Value *OldRHS = Op->getOperand(1);
661 
662  if (NewLHS == OldLHS && NewRHS == OldRHS)
663  // Nothing changed, leave it alone.
664  break;
665 
666  if (NewLHS == OldRHS && NewRHS == OldLHS) {
667  // The order of the operands was reversed. Swap them.
668  DEBUG(dbgs() << "RA: " << *Op << '\n');
669  Op->swapOperands();
670  DEBUG(dbgs() << "TO: " << *Op << '\n');
671  MadeChange = true;
672  ++NumChanged;
673  break;
674  }
675 
676  // The new operation differs non-trivially from the original. Overwrite
677  // the old operands with the new ones.
678  DEBUG(dbgs() << "RA: " << *Op << '\n');
679  if (NewLHS != OldLHS) {
680  BinaryOperator *BO = isReassociableOp(OldLHS, Opcode);
681  if (BO && !NotRewritable.count(BO))
682  NodesToRewrite.push_back(BO);
683  Op->setOperand(0, NewLHS);
684  }
685  if (NewRHS != OldRHS) {
686  BinaryOperator *BO = isReassociableOp(OldRHS, Opcode);
687  if (BO && !NotRewritable.count(BO))
688  NodesToRewrite.push_back(BO);
689  Op->setOperand(1, NewRHS);
690  }
691  DEBUG(dbgs() << "TO: " << *Op << '\n');
692 
693  ExpressionChanged = Op;
694  MadeChange = true;
695  ++NumChanged;
696 
697  break;
698  }
699 
700  // Not the last operation. The left-hand side will be a sub-expression
701  // while the right-hand side will be the current element of Ops.
702  Value *NewRHS = Ops[i].Op;
703  if (NewRHS != Op->getOperand(1)) {
704  DEBUG(dbgs() << "RA: " << *Op << '\n');
705  if (NewRHS == Op->getOperand(0)) {
706  // The new right-hand side was already present as the left operand. If
707  // we are lucky then swapping the operands will sort out both of them.
708  Op->swapOperands();
709  } else {
710  // Overwrite with the new right-hand side.
711  BinaryOperator *BO = isReassociableOp(Op->getOperand(1), Opcode);
712  if (BO && !NotRewritable.count(BO))
713  NodesToRewrite.push_back(BO);
714  Op->setOperand(1, NewRHS);
715  ExpressionChanged = Op;
716  }
717  DEBUG(dbgs() << "TO: " << *Op << '\n');
718  MadeChange = true;
719  ++NumChanged;
720  }
721 
722  // Now deal with the left-hand side. If this is already an operation node
723  // from the original expression then just rewrite the rest of the expression
724  // into it.
725  BinaryOperator *BO = isReassociableOp(Op->getOperand(0), Opcode);
726  if (BO && !NotRewritable.count(BO)) {
727  Op = BO;
728  continue;
729  }
730 
731  // Otherwise, grab a spare node from the original expression and use that as
732  // the left-hand side. If there are no nodes left then the optimizers made
733  // an expression with more nodes than the original! This usually means that
734  // they did something stupid but it might mean that the problem was just too
735  // hard (finding the mimimal number of multiplications needed to realize a
736  // multiplication expression is NP-complete). Whatever the reason, smart or
737  // stupid, create a new node if there are none left.
738  BinaryOperator *NewOp;
739  if (NodesToRewrite.empty()) {
742  Undef, Undef, "", I);
743  if (NewOp->getType()->isFPOrFPVectorTy())
744  NewOp->setFastMathFlags(I->getFastMathFlags());
745  } else {
746  NewOp = NodesToRewrite.pop_back_val();
747  }
748 
749  DEBUG(dbgs() << "RA: " << *Op << '\n');
750  Op->setOperand(0, NewOp);
751  DEBUG(dbgs() << "TO: " << *Op << '\n');
752  ExpressionChanged = Op;
753  MadeChange = true;
754  ++NumChanged;
755  Op = NewOp;
756  }
757 
758  // If the expression changed non-trivially then clear out all subclass data
759  // starting from the operator specified in ExpressionChanged, and compactify
760  // the operators to just before the expression root to guarantee that the
761  // expression tree is dominated by all of Ops.
762  if (ExpressionChanged)
763  do {
764  // Preserve FastMathFlags.
765  if (isa<FPMathOperator>(I)) {
767  ExpressionChanged->clearSubclassOptionalData();
768  ExpressionChanged->setFastMathFlags(Flags);
769  } else
770  ExpressionChanged->clearSubclassOptionalData();
771 
772  if (ExpressionChanged == I)
773  break;
774  ExpressionChanged->moveBefore(I);
775  ExpressionChanged = cast<BinaryOperator>(*ExpressionChanged->user_begin());
776  } while (1);
777 
778  // Throw away any left over nodes from the original expression.
779  for (unsigned i = 0, e = NodesToRewrite.size(); i != e; ++i)
780  RedoInsts.insert(NodesToRewrite[i]);
781 }
782 
783 /// Insert instructions before the instruction pointed to by BI,
784 /// that computes the negative version of the value specified. The negative
785 /// version of the value is returned, and BI is left pointing at the instruction
786 /// that should be processed next by the reassociation pass.
787 /// Also add intermediate instructions to the redo list that are modified while
788 /// pushing the negates through adds. These will be revisited to see if
789 /// additional opportunities have been exposed.
792  if (Constant *C = dyn_cast<Constant>(V)) {
793  if (C->getType()->isFPOrFPVectorTy()) {
794  return ConstantExpr::getFNeg(C);
795  }
796  return ConstantExpr::getNeg(C);
797  }
798 
799 
800  // We are trying to expose opportunity for reassociation. One of the things
801  // that we want to do to achieve this is to push a negation as deep into an
802  // expression chain as possible, to expose the add instructions. In practice,
803  // this means that we turn this:
804  // X = -(A+12+C+D) into X = -A + -12 + -C + -D = -12 + -A + -C + -D
805  // so that later, a: Y = 12+X could get reassociated with the -12 to eliminate
806  // the constants. We assume that instcombine will clean up the mess later if
807  // we introduce tons of unnecessary negation instructions.
808  //
809  if (BinaryOperator *I =
810  isReassociableOp(V, Instruction::Add, Instruction::FAdd)) {
811  // Push the negates through the add.
812  I->setOperand(0, NegateValue(I->getOperand(0), BI, ToRedo));
813  I->setOperand(1, NegateValue(I->getOperand(1), BI, ToRedo));
814  if (I->getOpcode() == Instruction::Add) {
815  I->setHasNoUnsignedWrap(false);
816  I->setHasNoSignedWrap(false);
817  }
818 
819  // We must move the add instruction here, because the neg instructions do
820  // not dominate the old add instruction in general. By moving it, we are
821  // assured that the neg instructions we just inserted dominate the
822  // instruction we are about to insert after them.
823  //
824  I->moveBefore(BI);
825  I->setName(I->getName()+".neg");
826 
827  // Add the intermediate negates to the redo list as processing them later
828  // could expose more reassociating opportunities.
829  ToRedo.insert(I);
830  return I;
831  }
832 
833  // Okay, we need to materialize a negated version of V with an instruction.
834  // Scan the use lists of V to see if we have one already.
835  for (User *U : V->users()) {
837  continue;
838 
839  // We found one! Now we have to make sure that the definition dominates
840  // this use. We do this by moving it to the entry block (if it is a
841  // non-instruction value) or right after the definition. These negates will
842  // be zapped by reassociate later, so we don't need much finesse here.
843  BinaryOperator *TheNeg = cast<BinaryOperator>(U);
844 
845  // Verify that the negate is in this function, V might be a constant expr.
846  if (TheNeg->getParent()->getParent() != BI->getParent()->getParent())
847  continue;
848 
849  BasicBlock::iterator InsertPt;
850  if (Instruction *InstInput = dyn_cast<Instruction>(V)) {
851  if (InvokeInst *II = dyn_cast<InvokeInst>(InstInput)) {
852  InsertPt = II->getNormalDest()->begin();
853  } else {
854  InsertPt = ++InstInput->getIterator();
855  }
856  while (isa<PHINode>(InsertPt)) ++InsertPt;
857  } else {
858  InsertPt = TheNeg->getParent()->getParent()->getEntryBlock().begin();
859  }
860  TheNeg->moveBefore(&*InsertPt);
861  if (TheNeg->getOpcode() == Instruction::Sub) {
862  TheNeg->setHasNoUnsignedWrap(false);
863  TheNeg->setHasNoSignedWrap(false);
864  } else {
865  TheNeg->andIRFlags(BI);
866  }
867  ToRedo.insert(TheNeg);
868  return TheNeg;
869  }
870 
871  // Insert a 'neg' instruction that subtracts the value from zero to get the
872  // negation.
873  BinaryOperator *NewNeg = CreateNeg(V, V->getName() + ".neg", BI, BI);
874  ToRedo.insert(NewNeg);
875  return NewNeg;
876 }
877 
878 /// Return true if we should break up this subtract of X-Y into (X + -Y).
880  // If this is a negation, we can't split it up!
882  return false;
883 
884  // Don't breakup X - undef.
885  if (isa<UndefValue>(Sub->getOperand(1)))
886  return false;
887 
888  // Don't bother to break this up unless either the LHS is an associable add or
889  // subtract or if this is only used by one.
890  Value *V0 = Sub->getOperand(0);
891  if (isReassociableOp(V0, Instruction::Add, Instruction::FAdd) ||
892  isReassociableOp(V0, Instruction::Sub, Instruction::FSub))
893  return true;
894  Value *V1 = Sub->getOperand(1);
895  if (isReassociableOp(V1, Instruction::Add, Instruction::FAdd) ||
896  isReassociableOp(V1, Instruction::Sub, Instruction::FSub))
897  return true;
898  Value *VB = Sub->user_back();
899  if (Sub->hasOneUse() &&
900  (isReassociableOp(VB, Instruction::Add, Instruction::FAdd) ||
901  isReassociableOp(VB, Instruction::Sub, Instruction::FSub)))
902  return true;
903 
904  return false;
905 }
906 
907 /// If we have (X-Y), and if either X is an add, or if this is only used by an
908 /// add, transform this into (X+(0-Y)) to promote better reassociation.
909 static BinaryOperator *
911  // Convert a subtract into an add and a neg instruction. This allows sub
912  // instructions to be commuted with other add instructions.
913  //
914  // Calculate the negative value of Operand 1 of the sub instruction,
915  // and set it as the RHS of the add instruction we just made.
916  //
917  Value *NegVal = NegateValue(Sub->getOperand(1), Sub, ToRedo);
918  BinaryOperator *New = CreateAdd(Sub->getOperand(0), NegVal, "", Sub, Sub);
919  Sub->setOperand(0, Constant::getNullValue(Sub->getType())); // Drop use of op.
920  Sub->setOperand(1, Constant::getNullValue(Sub->getType())); // Drop use of op.
921  New->takeName(Sub);
922 
923  // Everyone now refers to the add instruction.
924  Sub->replaceAllUsesWith(New);
925  New->setDebugLoc(Sub->getDebugLoc());
926 
927  DEBUG(dbgs() << "Negated: " << *New << '\n');
928  return New;
929 }
930 
931 /// If this is a shift of a reassociable multiply or is used by one, change
932 /// this into a multiply by a constant to assist with further reassociation.
934  Constant *MulCst = ConstantInt::get(Shl->getType(), 1);
935  MulCst = ConstantExpr::getShl(MulCst, cast<Constant>(Shl->getOperand(1)));
936 
937  BinaryOperator *Mul =
938  BinaryOperator::CreateMul(Shl->getOperand(0), MulCst, "", Shl);
939  Shl->setOperand(0, UndefValue::get(Shl->getType())); // Drop use of op.
940  Mul->takeName(Shl);
941 
942  // Everyone now refers to the mul instruction.
943  Shl->replaceAllUsesWith(Mul);
944  Mul->setDebugLoc(Shl->getDebugLoc());
945 
946  // We can safely preserve the nuw flag in all cases. It's also safe to turn a
947  // nuw nsw shl into a nuw nsw mul. However, nsw in isolation requires special
948  // handling.
949  bool NSW = cast<BinaryOperator>(Shl)->hasNoSignedWrap();
950  bool NUW = cast<BinaryOperator>(Shl)->hasNoUnsignedWrap();
951  if (NSW && NUW)
952  Mul->setHasNoSignedWrap(true);
953  Mul->setHasNoUnsignedWrap(NUW);
954  return Mul;
955 }
956 
957 /// Scan backwards and forwards among values with the same rank as element i
958 /// to see if X exists. If X does not exist, return i. This is useful when
959 /// scanning for 'x' when we see '-x' because they both get the same rank.
961  unsigned i, Value *X) {
962  unsigned XRank = Ops[i].Rank;
963  unsigned e = Ops.size();
964  for (unsigned j = i+1; j != e && Ops[j].Rank == XRank; ++j) {
965  if (Ops[j].Op == X)
966  return j;
967  if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
968  if (Instruction *I2 = dyn_cast<Instruction>(X))
969  if (I1->isIdenticalTo(I2))
970  return j;
971  }
972  // Scan backwards.
973  for (unsigned j = i-1; j != ~0U && Ops[j].Rank == XRank; --j) {
974  if (Ops[j].Op == X)
975  return j;
976  if (Instruction *I1 = dyn_cast<Instruction>(Ops[j].Op))
977  if (Instruction *I2 = dyn_cast<Instruction>(X))
978  if (I1->isIdenticalTo(I2))
979  return j;
980  }
981  return i;
982 }
983 
984 /// Emit a tree of add instructions, summing Ops together
985 /// and returning the result. Insert the tree before I.
988  if (Ops.size() == 1) return Ops.back();
989 
990  Value *V1 = Ops.back();
991  Ops.pop_back();
992  Value *V2 = EmitAddTreeOfValues(I, Ops);
993  return CreateAdd(V2, V1, "tmp", I, I);
994 }
995 
996 /// If V is an expression tree that is a multiplication sequence,
997 /// and if this sequence contains a multiply by Factor,
998 /// remove Factor from the tree and return the new tree.
999 Value *ReassociatePass::RemoveFactorFromExpression(Value *V, Value *Factor) {
1000  BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
1001  if (!BO)
1002  return nullptr;
1003 
1005  MadeChange |= LinearizeExprTree(BO, Tree);
1007  Factors.reserve(Tree.size());
1008  for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
1009  RepeatedValue E = Tree[i];
1010  Factors.append(E.second.getZExtValue(),
1011  ValueEntry(getRank(E.first), E.first));
1012  }
1013 
1014  bool FoundFactor = false;
1015  bool NeedsNegate = false;
1016  for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
1017  if (Factors[i].Op == Factor) {
1018  FoundFactor = true;
1019  Factors.erase(Factors.begin()+i);
1020  break;
1021  }
1022 
1023  // If this is a negative version of this factor, remove it.
1024  if (ConstantInt *FC1 = dyn_cast<ConstantInt>(Factor)) {
1025  if (ConstantInt *FC2 = dyn_cast<ConstantInt>(Factors[i].Op))
1026  if (FC1->getValue() == -FC2->getValue()) {
1027  FoundFactor = NeedsNegate = true;
1028  Factors.erase(Factors.begin()+i);
1029  break;
1030  }
1031  } else if (ConstantFP *FC1 = dyn_cast<ConstantFP>(Factor)) {
1032  if (ConstantFP *FC2 = dyn_cast<ConstantFP>(Factors[i].Op)) {
1033  const APFloat &F1 = FC1->getValueAPF();
1034  APFloat F2(FC2->getValueAPF());
1035  F2.changeSign();
1036  if (F1.compare(F2) == APFloat::cmpEqual) {
1037  FoundFactor = NeedsNegate = true;
1038  Factors.erase(Factors.begin() + i);
1039  break;
1040  }
1041  }
1042  }
1043  }
1044 
1045  if (!FoundFactor) {
1046  // Make sure to restore the operands to the expression tree.
1047  RewriteExprTree(BO, Factors);
1048  return nullptr;
1049  }
1050 
1051  BasicBlock::iterator InsertPt = ++BO->getIterator();
1052 
1053  // If this was just a single multiply, remove the multiply and return the only
1054  // remaining operand.
1055  if (Factors.size() == 1) {
1056  RedoInsts.insert(BO);
1057  V = Factors[0].Op;
1058  } else {
1059  RewriteExprTree(BO, Factors);
1060  V = BO;
1061  }
1062 
1063  if (NeedsNegate)
1064  V = CreateNeg(V, "neg", &*InsertPt, BO);
1065 
1066  return V;
1067 }
1068 
1069 /// If V is a single-use multiply, recursively add its operands as factors,
1070 /// otherwise add V to the list of factors.
1071 ///
1072 /// Ops is the top-level list of add operands we're trying to factor.
1074  SmallVectorImpl<Value*> &Factors) {
1075  BinaryOperator *BO = isReassociableOp(V, Instruction::Mul, Instruction::FMul);
1076  if (!BO) {
1077  Factors.push_back(V);
1078  return;
1079  }
1080 
1081  // Otherwise, add the LHS and RHS to the list of factors.
1082  FindSingleUseMultiplyFactors(BO->getOperand(1), Factors);
1083  FindSingleUseMultiplyFactors(BO->getOperand(0), Factors);
1084 }
1085 
1086 /// Optimize a series of operands to an 'and', 'or', or 'xor' instruction.
1087 /// This optimizes based on identities. If it can be reduced to a single Value,
1088 /// it is returned, otherwise the Ops list is mutated as necessary.
1089 static Value *OptimizeAndOrXor(unsigned Opcode,
1091  // Scan the operand lists looking for X and ~X pairs, along with X,X pairs.
1092  // If we find any, we can simplify the expression. X&~X == 0, X|~X == -1.
1093  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1094  // First, check for X and ~X in the operand list.
1095  assert(i < Ops.size());
1096  if (BinaryOperator::isNot(Ops[i].Op)) { // Cannot occur for ^.
1097  Value *X = BinaryOperator::getNotArgument(Ops[i].Op);
1098  unsigned FoundX = FindInOperandList(Ops, i, X);
1099  if (FoundX != i) {
1100  if (Opcode == Instruction::And) // ...&X&~X = 0
1101  return Constant::getNullValue(X->getType());
1102 
1103  if (Opcode == Instruction::Or) // ...|X|~X = -1
1104  return Constant::getAllOnesValue(X->getType());
1105  }
1106  }
1107 
1108  // Next, check for duplicate pairs of values, which we assume are next to
1109  // each other, due to our sorting criteria.
1110  assert(i < Ops.size());
1111  if (i+1 != Ops.size() && Ops[i+1].Op == Ops[i].Op) {
1112  if (Opcode == Instruction::And || Opcode == Instruction::Or) {
1113  // Drop duplicate values for And and Or.
1114  Ops.erase(Ops.begin()+i);
1115  --i; --e;
1116  ++NumAnnihil;
1117  continue;
1118  }
1119 
1120  // Drop pairs of values for Xor.
1121  assert(Opcode == Instruction::Xor);
1122  if (e == 2)
1123  return Constant::getNullValue(Ops[0].Op->getType());
1124 
1125  // Y ^ X^X -> Y
1126  Ops.erase(Ops.begin()+i, Ops.begin()+i+2);
1127  i -= 1; e -= 2;
1128  ++NumAnnihil;
1129  }
1130  }
1131  return nullptr;
1132 }
1133 
1134 /// Helper function of CombineXorOpnd(). It creates a bitwise-and
1135 /// instruction with the given two operands, and return the resulting
1136 /// instruction. There are two special cases: 1) if the constant operand is 0,
1137 /// it will return NULL. 2) if the constant is ~0, the symbolic operand will
1138 /// be returned.
1139 static Value *createAndInstr(Instruction *InsertBefore, Value *Opnd,
1140  const APInt &ConstOpnd) {
1141  if (ConstOpnd.isNullValue())
1142  return nullptr;
1143 
1144  if (ConstOpnd.isAllOnesValue())
1145  return Opnd;
1146 
1147  Instruction *I = BinaryOperator::CreateAnd(
1148  Opnd, ConstantInt::get(Opnd->getType(), ConstOpnd), "and.ra",
1149  InsertBefore);
1150  I->setDebugLoc(InsertBefore->getDebugLoc());
1151  return I;
1152 }
1153 
1154 // Helper function of OptimizeXor(). It tries to simplify "Opnd1 ^ ConstOpnd"
1155 // into "R ^ C", where C would be 0, and R is a symbolic value.
1156 //
1157 // If it was successful, true is returned, and the "R" and "C" is returned
1158 // via "Res" and "ConstOpnd", respectively; otherwise, false is returned,
1159 // and both "Res" and "ConstOpnd" remain unchanged.
1160 //
1161 bool ReassociatePass::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1,
1162  APInt &ConstOpnd, Value *&Res) {
1163  // Xor-Rule 1: (x | c1) ^ c2 = (x | c1) ^ (c1 ^ c1) ^ c2
1164  // = ((x | c1) ^ c1) ^ (c1 ^ c2)
1165  // = (x & ~c1) ^ (c1 ^ c2)
1166  // It is useful only when c1 == c2.
1167  if (!Opnd1->isOrExpr() || Opnd1->getConstPart().isNullValue())
1168  return false;
1169 
1170  if (!Opnd1->getValue()->hasOneUse())
1171  return false;
1172 
1173  const APInt &C1 = Opnd1->getConstPart();
1174  if (C1 != ConstOpnd)
1175  return false;
1176 
1177  Value *X = Opnd1->getSymbolicPart();
1178  Res = createAndInstr(I, X, ~C1);
1179  // ConstOpnd was C2, now C1 ^ C2.
1180  ConstOpnd ^= C1;
1181 
1182  if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
1183  RedoInsts.insert(T);
1184  return true;
1185 }
1186 
1187 
1188 // Helper function of OptimizeXor(). It tries to simplify
1189 // "Opnd1 ^ Opnd2 ^ ConstOpnd" into "R ^ C", where C would be 0, and R is a
1190 // symbolic value.
1191 //
1192 // If it was successful, true is returned, and the "R" and "C" is returned
1193 // via "Res" and "ConstOpnd", respectively (If the entire expression is
1194 // evaluated to a constant, the Res is set to NULL); otherwise, false is
1195 // returned, and both "Res" and "ConstOpnd" remain unchanged.
1196 bool ReassociatePass::CombineXorOpnd(Instruction *I, XorOpnd *Opnd1,
1197  XorOpnd *Opnd2, APInt &ConstOpnd,
1198  Value *&Res) {
1199  Value *X = Opnd1->getSymbolicPart();
1200  if (X != Opnd2->getSymbolicPart())
1201  return false;
1202 
1203  // This many instruction become dead.(At least "Opnd1 ^ Opnd2" will die.)
1204  int DeadInstNum = 1;
1205  if (Opnd1->getValue()->hasOneUse())
1206  DeadInstNum++;
1207  if (Opnd2->getValue()->hasOneUse())
1208  DeadInstNum++;
1209 
1210  // Xor-Rule 2:
1211  // (x | c1) ^ (x & c2)
1212  // = (x|c1) ^ (x&c2) ^ (c1 ^ c1) = ((x|c1) ^ c1) ^ (x & c2) ^ c1
1213  // = (x & ~c1) ^ (x & c2) ^ c1 // Xor-Rule 1
1214  // = (x & c3) ^ c1, where c3 = ~c1 ^ c2 // Xor-rule 3
1215  //
1216  if (Opnd1->isOrExpr() != Opnd2->isOrExpr()) {
1217  if (Opnd2->isOrExpr())
1218  std::swap(Opnd1, Opnd2);
1219 
1220  const APInt &C1 = Opnd1->getConstPart();
1221  const APInt &C2 = Opnd2->getConstPart();
1222  APInt C3((~C1) ^ C2);
1223 
1224  // Do not increase code size!
1225  if (!C3.isNullValue() && !C3.isAllOnesValue()) {
1226  int NewInstNum = ConstOpnd.getBoolValue() ? 1 : 2;
1227  if (NewInstNum > DeadInstNum)
1228  return false;
1229  }
1230 
1231  Res = createAndInstr(I, X, C3);
1232  ConstOpnd ^= C1;
1233 
1234  } else if (Opnd1->isOrExpr()) {
1235  // Xor-Rule 3: (x | c1) ^ (x | c2) = (x & c3) ^ c3 where c3 = c1 ^ c2
1236  //
1237  const APInt &C1 = Opnd1->getConstPart();
1238  const APInt &C2 = Opnd2->getConstPart();
1239  APInt C3 = C1 ^ C2;
1240 
1241  // Do not increase code size
1242  if (!C3.isNullValue() && !C3.isAllOnesValue()) {
1243  int NewInstNum = ConstOpnd.getBoolValue() ? 1 : 2;
1244  if (NewInstNum > DeadInstNum)
1245  return false;
1246  }
1247 
1248  Res = createAndInstr(I, X, C3);
1249  ConstOpnd ^= C3;
1250  } else {
1251  // Xor-Rule 4: (x & c1) ^ (x & c2) = (x & (c1^c2))
1252  //
1253  const APInt &C1 = Opnd1->getConstPart();
1254  const APInt &C2 = Opnd2->getConstPart();
1255  APInt C3 = C1 ^ C2;
1256  Res = createAndInstr(I, X, C3);
1257  }
1258 
1259  // Put the original operands in the Redo list; hope they will be deleted
1260  // as dead code.
1261  if (Instruction *T = dyn_cast<Instruction>(Opnd1->getValue()))
1262  RedoInsts.insert(T);
1263  if (Instruction *T = dyn_cast<Instruction>(Opnd2->getValue()))
1264  RedoInsts.insert(T);
1265 
1266  return true;
1267 }
1268 
1269 /// Optimize a series of operands to an 'xor' instruction. If it can be reduced
1270 /// to a single Value, it is returned, otherwise the Ops list is mutated as
1271 /// necessary.
1272 Value *ReassociatePass::OptimizeXor(Instruction *I,
1274  if (Value *V = OptimizeAndOrXor(Instruction::Xor, Ops))
1275  return V;
1276 
1277  if (Ops.size() == 1)
1278  return nullptr;
1279 
1281  SmallVector<XorOpnd*, 8> OpndPtrs;
1282  Type *Ty = Ops[0].Op->getType();
1283  APInt ConstOpnd(Ty->getScalarSizeInBits(), 0);
1284 
1285  // Step 1: Convert ValueEntry to XorOpnd
1286  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1287  Value *V = Ops[i].Op;
1288  const APInt *C;
1289  // TODO: Support non-splat vectors.
1290  if (match(V, PatternMatch::m_APInt(C))) {
1291  ConstOpnd ^= *C;
1292  } else {
1293  XorOpnd O(V);
1294  O.setSymbolicRank(getRank(O.getSymbolicPart()));
1295  Opnds.push_back(O);
1296  }
1297  }
1298 
1299  // NOTE: From this point on, do *NOT* add/delete element to/from "Opnds".
1300  // It would otherwise invalidate the "Opnds"'s iterator, and hence invalidate
1301  // the "OpndPtrs" as well. For the similar reason, do not fuse this loop
1302  // with the previous loop --- the iterator of the "Opnds" may be invalidated
1303  // when new elements are added to the vector.
1304  for (unsigned i = 0, e = Opnds.size(); i != e; ++i)
1305  OpndPtrs.push_back(&Opnds[i]);
1306 
1307  // Step 2: Sort the Xor-Operands in a way such that the operands containing
1308  // the same symbolic value cluster together. For instance, the input operand
1309  // sequence ("x | 123", "y & 456", "x & 789") will be sorted into:
1310  // ("x | 123", "x & 789", "y & 456").
1311  //
1312  // The purpose is twofold:
1313  // 1) Cluster together the operands sharing the same symbolic-value.
1314  // 2) Operand having smaller symbolic-value-rank is permuted earlier, which
1315  // could potentially shorten crital path, and expose more loop-invariants.
1316  // Note that values' rank are basically defined in RPO order (FIXME).
1317  // So, if Rank(X) < Rank(Y) < Rank(Z), it means X is defined earlier
1318  // than Y which is defined earlier than Z. Permute "x | 1", "Y & 2",
1319  // "z" in the order of X-Y-Z is better than any other orders.
1320  std::stable_sort(OpndPtrs.begin(), OpndPtrs.end(),
1321  [](XorOpnd *LHS, XorOpnd *RHS) {
1322  return LHS->getSymbolicRank() < RHS->getSymbolicRank();
1323  });
1324 
1325  // Step 3: Combine adjacent operands
1326  XorOpnd *PrevOpnd = nullptr;
1327  bool Changed = false;
1328  for (unsigned i = 0, e = Opnds.size(); i < e; i++) {
1329  XorOpnd *CurrOpnd = OpndPtrs[i];
1330  // The combined value
1331  Value *CV;
1332 
1333  // Step 3.1: Try simplifying "CurrOpnd ^ ConstOpnd"
1334  if (!ConstOpnd.isNullValue() &&
1335  CombineXorOpnd(I, CurrOpnd, ConstOpnd, CV)) {
1336  Changed = true;
1337  if (CV)
1338  *CurrOpnd = XorOpnd(CV);
1339  else {
1340  CurrOpnd->Invalidate();
1341  continue;
1342  }
1343  }
1344 
1345  if (!PrevOpnd || CurrOpnd->getSymbolicPart() != PrevOpnd->getSymbolicPart()) {
1346  PrevOpnd = CurrOpnd;
1347  continue;
1348  }
1349 
1350  // step 3.2: When previous and current operands share the same symbolic
1351  // value, try to simplify "PrevOpnd ^ CurrOpnd ^ ConstOpnd"
1352  //
1353  if (CombineXorOpnd(I, CurrOpnd, PrevOpnd, ConstOpnd, CV)) {
1354  // Remove previous operand
1355  PrevOpnd->Invalidate();
1356  if (CV) {
1357  *CurrOpnd = XorOpnd(CV);
1358  PrevOpnd = CurrOpnd;
1359  } else {
1360  CurrOpnd->Invalidate();
1361  PrevOpnd = nullptr;
1362  }
1363  Changed = true;
1364  }
1365  }
1366 
1367  // Step 4: Reassemble the Ops
1368  if (Changed) {
1369  Ops.clear();
1370  for (unsigned int i = 0, e = Opnds.size(); i < e; i++) {
1371  XorOpnd &O = Opnds[i];
1372  if (O.isInvalid())
1373  continue;
1374  ValueEntry VE(getRank(O.getValue()), O.getValue());
1375  Ops.push_back(VE);
1376  }
1377  if (!ConstOpnd.isNullValue()) {
1378  Value *C = ConstantInt::get(Ty, ConstOpnd);
1379  ValueEntry VE(getRank(C), C);
1380  Ops.push_back(VE);
1381  }
1382  unsigned Sz = Ops.size();
1383  if (Sz == 1)
1384  return Ops.back().Op;
1385  if (Sz == 0) {
1386  assert(ConstOpnd.isNullValue());
1387  return ConstantInt::get(Ty, ConstOpnd);
1388  }
1389  }
1390 
1391  return nullptr;
1392 }
1393 
1394 /// Optimize a series of operands to an 'add' instruction. This
1395 /// optimizes based on identities. If it can be reduced to a single Value, it
1396 /// is returned, otherwise the Ops list is mutated as necessary.
1397 Value *ReassociatePass::OptimizeAdd(Instruction *I,
1399  // Scan the operand lists looking for X and -X pairs. If we find any, we
1400  // can simplify expressions like X+-X == 0 and X+~X ==-1. While we're at it,
1401  // scan for any
1402  // duplicates. We want to canonicalize Y+Y+Y+Z -> 3*Y+Z.
1403 
1404  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1405  Value *TheOp = Ops[i].Op;
1406  // Check to see if we've seen this operand before. If so, we factor all
1407  // instances of the operand together. Due to our sorting criteria, we know
1408  // that these need to be next to each other in the vector.
1409  if (i+1 != Ops.size() && Ops[i+1].Op == TheOp) {
1410  // Rescan the list, remove all instances of this operand from the expr.
1411  unsigned NumFound = 0;
1412  do {
1413  Ops.erase(Ops.begin()+i);
1414  ++NumFound;
1415  } while (i != Ops.size() && Ops[i].Op == TheOp);
1416 
1417  DEBUG(dbgs() << "\nFACTORING [" << NumFound << "]: " << *TheOp << '\n');
1418  ++NumFactor;
1419 
1420  // Insert a new multiply.
1421  Type *Ty = TheOp->getType();
1422  Constant *C = Ty->isIntOrIntVectorTy() ?
1423  ConstantInt::get(Ty, NumFound) : ConstantFP::get(Ty, NumFound);
1424  Instruction *Mul = CreateMul(TheOp, C, "factor", I, I);
1425 
1426  // Now that we have inserted a multiply, optimize it. This allows us to
1427  // handle cases that require multiple factoring steps, such as this:
1428  // (X*2) + (X*2) + (X*2) -> (X*2)*3 -> X*6
1429  RedoInsts.insert(Mul);
1430 
1431  // If every add operand was a duplicate, return the multiply.
1432  if (Ops.empty())
1433  return Mul;
1434 
1435  // Otherwise, we had some input that didn't have the dupe, such as
1436  // "A + A + B" -> "A*2 + B". Add the new multiply to the list of
1437  // things being added by this operation.
1438  Ops.insert(Ops.begin(), ValueEntry(getRank(Mul), Mul));
1439 
1440  --i;
1441  e = Ops.size();
1442  continue;
1443  }
1444 
1445  // Check for X and -X or X and ~X in the operand list.
1446  if (!BinaryOperator::isNeg(TheOp) && !BinaryOperator::isFNeg(TheOp) &&
1447  !BinaryOperator::isNot(TheOp))
1448  continue;
1449 
1450  Value *X = nullptr;
1451  if (BinaryOperator::isNeg(TheOp) || BinaryOperator::isFNeg(TheOp))
1452  X = BinaryOperator::getNegArgument(TheOp);
1453  else if (BinaryOperator::isNot(TheOp))
1454  X = BinaryOperator::getNotArgument(TheOp);
1455 
1456  unsigned FoundX = FindInOperandList(Ops, i, X);
1457  if (FoundX == i)
1458  continue;
1459 
1460  // Remove X and -X from the operand list.
1461  if (Ops.size() == 2 &&
1462  (BinaryOperator::isNeg(TheOp) || BinaryOperator::isFNeg(TheOp)))
1463  return Constant::getNullValue(X->getType());
1464 
1465  // Remove X and ~X from the operand list.
1466  if (Ops.size() == 2 && BinaryOperator::isNot(TheOp))
1467  return Constant::getAllOnesValue(X->getType());
1468 
1469  Ops.erase(Ops.begin()+i);
1470  if (i < FoundX)
1471  --FoundX;
1472  else
1473  --i; // Need to back up an extra one.
1474  Ops.erase(Ops.begin()+FoundX);
1475  ++NumAnnihil;
1476  --i; // Revisit element.
1477  e -= 2; // Removed two elements.
1478 
1479  // if X and ~X we append -1 to the operand list.
1480  if (BinaryOperator::isNot(TheOp)) {
1482  Ops.insert(Ops.end(), ValueEntry(getRank(V), V));
1483  e += 1;
1484  }
1485  }
1486 
1487  // Scan the operand list, checking to see if there are any common factors
1488  // between operands. Consider something like A*A+A*B*C+D. We would like to
1489  // reassociate this to A*(A+B*C)+D, which reduces the number of multiplies.
1490  // To efficiently find this, we count the number of times a factor occurs
1491  // for any ADD operands that are MULs.
1492  DenseMap<Value*, unsigned> FactorOccurrences;
1493 
1494  // Keep track of each multiply we see, to avoid triggering on (X*4)+(X*4)
1495  // where they are actually the same multiply.
1496  unsigned MaxOcc = 0;
1497  Value *MaxOccVal = nullptr;
1498  for (unsigned i = 0, e = Ops.size(); i != e; ++i) {
1499  BinaryOperator *BOp =
1500  isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
1501  if (!BOp)
1502  continue;
1503 
1504  // Compute all of the factors of this added value.
1505  SmallVector<Value*, 8> Factors;
1506  FindSingleUseMultiplyFactors(BOp, Factors);
1507  assert(Factors.size() > 1 && "Bad linearize!");
1508 
1509  // Add one to FactorOccurrences for each unique factor in this op.
1510  SmallPtrSet<Value*, 8> Duplicates;
1511  for (unsigned i = 0, e = Factors.size(); i != e; ++i) {
1512  Value *Factor = Factors[i];
1513  if (!Duplicates.insert(Factor).second)
1514  continue;
1515 
1516  unsigned Occ = ++FactorOccurrences[Factor];
1517  if (Occ > MaxOcc) {
1518  MaxOcc = Occ;
1519  MaxOccVal = Factor;
1520  }
1521 
1522  // If Factor is a negative constant, add the negated value as a factor
1523  // because we can percolate the negate out. Watch for minint, which
1524  // cannot be positivified.
1525  if (ConstantInt *CI = dyn_cast<ConstantInt>(Factor)) {
1526  if (CI->isNegative() && !CI->isMinValue(true)) {
1527  Factor = ConstantInt::get(CI->getContext(), -CI->getValue());
1528  if (!Duplicates.insert(Factor).second)
1529  continue;
1530  unsigned Occ = ++FactorOccurrences[Factor];
1531  if (Occ > MaxOcc) {
1532  MaxOcc = Occ;
1533  MaxOccVal = Factor;
1534  }
1535  }
1536  } else if (ConstantFP *CF = dyn_cast<ConstantFP>(Factor)) {
1537  if (CF->isNegative()) {
1538  APFloat F(CF->getValueAPF());
1539  F.changeSign();
1540  Factor = ConstantFP::get(CF->getContext(), F);
1541  if (!Duplicates.insert(Factor).second)
1542  continue;
1543  unsigned Occ = ++FactorOccurrences[Factor];
1544  if (Occ > MaxOcc) {
1545  MaxOcc = Occ;
1546  MaxOccVal = Factor;
1547  }
1548  }
1549  }
1550  }
1551  }
1552 
1553  // If any factor occurred more than one time, we can pull it out.
1554  if (MaxOcc > 1) {
1555  DEBUG(dbgs() << "\nFACTORING [" << MaxOcc << "]: " << *MaxOccVal << '\n');
1556  ++NumFactor;
1557 
1558  // Create a new instruction that uses the MaxOccVal twice. If we don't do
1559  // this, we could otherwise run into situations where removing a factor
1560  // from an expression will drop a use of maxocc, and this can cause
1561  // RemoveFactorFromExpression on successive values to behave differently.
1562  Instruction *DummyInst =
1563  I->getType()->isIntOrIntVectorTy()
1564  ? BinaryOperator::CreateAdd(MaxOccVal, MaxOccVal)
1565  : BinaryOperator::CreateFAdd(MaxOccVal, MaxOccVal);
1566 
1568  for (unsigned i = 0; i != Ops.size(); ++i) {
1569  // Only try to remove factors from expressions we're allowed to.
1570  BinaryOperator *BOp =
1571  isReassociableOp(Ops[i].Op, Instruction::Mul, Instruction::FMul);
1572  if (!BOp)
1573  continue;
1574 
1575  if (Value *V = RemoveFactorFromExpression(Ops[i].Op, MaxOccVal)) {
1576  // The factorized operand may occur several times. Convert them all in
1577  // one fell swoop.
1578  for (unsigned j = Ops.size(); j != i;) {
1579  --j;
1580  if (Ops[j].Op == Ops[i].Op) {
1581  NewMulOps.push_back(V);
1582  Ops.erase(Ops.begin()+j);
1583  }
1584  }
1585  --i;
1586  }
1587  }
1588 
1589  // No need for extra uses anymore.
1590  DummyInst->deleteValue();
1591 
1592  unsigned NumAddedValues = NewMulOps.size();
1593  Value *V = EmitAddTreeOfValues(I, NewMulOps);
1594 
1595  // Now that we have inserted the add tree, optimize it. This allows us to
1596  // handle cases that require multiple factoring steps, such as this:
1597  // A*A*B + A*A*C --> A*(A*B+A*C) --> A*(A*(B+C))
1598  assert(NumAddedValues > 1 && "Each occurrence should contribute a value");
1599  (void)NumAddedValues;
1600  if (Instruction *VI = dyn_cast<Instruction>(V))
1601  RedoInsts.insert(VI);
1602 
1603  // Create the multiply.
1604  Instruction *V2 = CreateMul(V, MaxOccVal, "tmp", I, I);
1605 
1606  // Rerun associate on the multiply in case the inner expression turned into
1607  // a multiply. We want to make sure that we keep things in canonical form.
1608  RedoInsts.insert(V2);
1609 
1610  // If every add operand included the factor (e.g. "A*B + A*C"), then the
1611  // entire result expression is just the multiply "A*(B+C)".
1612  if (Ops.empty())
1613  return V2;
1614 
1615  // Otherwise, we had some input that didn't have the factor, such as
1616  // "A*B + A*C + D" -> "A*(B+C) + D". Add the new multiply to the list of
1617  // things being added by this operation.
1618  Ops.insert(Ops.begin(), ValueEntry(getRank(V2), V2));
1619  }
1620 
1621  return nullptr;
1622 }
1623 
1624 /// \brief Build up a vector of value/power pairs factoring a product.
1625 ///
1626 /// Given a series of multiplication operands, build a vector of factors and
1627 /// the powers each is raised to when forming the final product. Sort them in
1628 /// the order of descending power.
1629 ///
1630 /// (x*x) -> [(x, 2)]
1631 /// ((x*x)*x) -> [(x, 3)]
1632 /// ((((x*y)*x)*y)*x) -> [(x, 3), (y, 2)]
1633 ///
1634 /// \returns Whether any factors have a power greater than one.
1636  SmallVectorImpl<Factor> &Factors) {
1637  // FIXME: Have Ops be (ValueEntry, Multiplicity) pairs, simplifying this.
1638  // Compute the sum of powers of simplifiable factors.
1639  unsigned FactorPowerSum = 0;
1640  for (unsigned Idx = 1, Size = Ops.size(); Idx < Size; ++Idx) {
1641  Value *Op = Ops[Idx-1].Op;
1642 
1643  // Count the number of occurrences of this value.
1644  unsigned Count = 1;
1645  for (; Idx < Size && Ops[Idx].Op == Op; ++Idx)
1646  ++Count;
1647  // Track for simplification all factors which occur 2 or more times.
1648  if (Count > 1)
1649  FactorPowerSum += Count;
1650  }
1651 
1652  // We can only simplify factors if the sum of the powers of our simplifiable
1653  // factors is 4 or higher. When that is the case, we will *always* have
1654  // a simplification. This is an important invariant to prevent cyclicly
1655  // trying to simplify already minimal formations.
1656  if (FactorPowerSum < 4)
1657  return false;
1658 
1659  // Now gather the simplifiable factors, removing them from Ops.
1660  FactorPowerSum = 0;
1661  for (unsigned Idx = 1; Idx < Ops.size(); ++Idx) {
1662  Value *Op = Ops[Idx-1].Op;
1663 
1664  // Count the number of occurrences of this value.
1665  unsigned Count = 1;
1666  for (; Idx < Ops.size() && Ops[Idx].Op == Op; ++Idx)
1667  ++Count;
1668  if (Count == 1)
1669  continue;
1670  // Move an even number of occurrences to Factors.
1671  Count &= ~1U;
1672  Idx -= Count;
1673  FactorPowerSum += Count;
1674  Factors.push_back(Factor(Op, Count));
1675  Ops.erase(Ops.begin()+Idx, Ops.begin()+Idx+Count);
1676  }
1677 
1678  // None of the adjustments above should have reduced the sum of factor powers
1679  // below our mininum of '4'.
1680  assert(FactorPowerSum >= 4);
1681 
1682  std::stable_sort(Factors.begin(), Factors.end(),
1683  [](const Factor &LHS, const Factor &RHS) {
1684  return LHS.Power > RHS.Power;
1685  });
1686  return true;
1687 }
1688 
1689 /// \brief Build a tree of multiplies, computing the product of Ops.
1691  SmallVectorImpl<Value*> &Ops) {
1692  if (Ops.size() == 1)
1693  return Ops.back();
1694 
1695  Value *LHS = Ops.pop_back_val();
1696  do {
1697  if (LHS->getType()->isIntOrIntVectorTy())
1698  LHS = Builder.CreateMul(LHS, Ops.pop_back_val());
1699  else
1700  LHS = Builder.CreateFMul(LHS, Ops.pop_back_val());
1701  } while (!Ops.empty());
1702 
1703  return LHS;
1704 }
1705 
1706 /// \brief Build a minimal multiplication DAG for (a^x)*(b^y)*(c^z)*...
1707 ///
1708 /// Given a vector of values raised to various powers, where no two values are
1709 /// equal and the powers are sorted in decreasing order, compute the minimal
1710 /// DAG of multiplies to compute the final product, and return that product
1711 /// value.
1712 Value *
1713 ReassociatePass::buildMinimalMultiplyDAG(IRBuilder<> &Builder,
1714  SmallVectorImpl<Factor> &Factors) {
1715  assert(Factors[0].Power);
1716  SmallVector<Value *, 4> OuterProduct;
1717  for (unsigned LastIdx = 0, Idx = 1, Size = Factors.size();
1718  Idx < Size && Factors[Idx].Power > 0; ++Idx) {
1719  if (Factors[Idx].Power != Factors[LastIdx].Power) {
1720  LastIdx = Idx;
1721  continue;
1722  }
1723 
1724  // We want to multiply across all the factors with the same power so that
1725  // we can raise them to that power as a single entity. Build a mini tree
1726  // for that.
1727  SmallVector<Value *, 4> InnerProduct;
1728  InnerProduct.push_back(Factors[LastIdx].Base);
1729  do {
1730  InnerProduct.push_back(Factors[Idx].Base);
1731  ++Idx;
1732  } while (Idx < Size && Factors[Idx].Power == Factors[LastIdx].Power);
1733 
1734  // Reset the base value of the first factor to the new expression tree.
1735  // We'll remove all the factors with the same power in a second pass.
1736  Value *M = Factors[LastIdx].Base = buildMultiplyTree(Builder, InnerProduct);
1737  if (Instruction *MI = dyn_cast<Instruction>(M))
1738  RedoInsts.insert(MI);
1739 
1740  LastIdx = Idx;
1741  }
1742  // Unique factors with equal powers -- we've folded them into the first one's
1743  // base.
1744  Factors.erase(std::unique(Factors.begin(), Factors.end(),
1745  [](const Factor &LHS, const Factor &RHS) {
1746  return LHS.Power == RHS.Power;
1747  }),
1748  Factors.end());
1749 
1750  // Iteratively collect the base of each factor with an add power into the
1751  // outer product, and halve each power in preparation for squaring the
1752  // expression.
1753  for (unsigned Idx = 0, Size = Factors.size(); Idx != Size; ++Idx) {
1754  if (Factors[Idx].Power & 1)
1755  OuterProduct.push_back(Factors[Idx].Base);
1756  Factors[Idx].Power >>= 1;
1757  }
1758  if (Factors[0].Power) {
1759  Value *SquareRoot = buildMinimalMultiplyDAG(Builder, Factors);
1760  OuterProduct.push_back(SquareRoot);
1761  OuterProduct.push_back(SquareRoot);
1762  }
1763  if (OuterProduct.size() == 1)
1764  return OuterProduct.front();
1765 
1766  Value *V = buildMultiplyTree(Builder, OuterProduct);
1767  return V;
1768 }
1769 
1770 Value *ReassociatePass::OptimizeMul(BinaryOperator *I,
1772  // We can only optimize the multiplies when there is a chain of more than
1773  // three, such that a balanced tree might require fewer total multiplies.
1774  if (Ops.size() < 4)
1775  return nullptr;
1776 
1777  // Try to turn linear trees of multiplies without other uses of the
1778  // intermediate stages into minimal multiply DAGs with perfect sub-expression
1779  // re-use.
1780  SmallVector<Factor, 4> Factors;
1781  if (!collectMultiplyFactors(Ops, Factors))
1782  return nullptr; // All distinct factors, so nothing left for us to do.
1783 
1784  IRBuilder<> Builder(I);
1785  // The reassociate transformation for FP operations is performed only
1786  // if unsafe algebra is permitted by FastMathFlags. Propagate those flags
1787  // to the newly generated operations.
1788  if (auto FPI = dyn_cast<FPMathOperator>(I))
1789  Builder.setFastMathFlags(FPI->getFastMathFlags());
1790 
1791  Value *V = buildMinimalMultiplyDAG(Builder, Factors);
1792  if (Ops.empty())
1793  return V;
1794 
1795  ValueEntry NewEntry = ValueEntry(getRank(V), V);
1796  Ops.insert(std::lower_bound(Ops.begin(), Ops.end(), NewEntry), NewEntry);
1797  return nullptr;
1798 }
1799 
1800 Value *ReassociatePass::OptimizeExpression(BinaryOperator *I,
1802  // Now that we have the linearized expression tree, try to optimize it.
1803  // Start by folding any constants that we found.
1804  Constant *Cst = nullptr;
1805  unsigned Opcode = I->getOpcode();
1806  while (!Ops.empty() && isa<Constant>(Ops.back().Op)) {
1807  Constant *C = cast<Constant>(Ops.pop_back_val().Op);
1808  Cst = Cst ? ConstantExpr::get(Opcode, C, Cst) : C;
1809  }
1810  // If there was nothing but constants then we are done.
1811  if (Ops.empty())
1812  return Cst;
1813 
1814  // Put the combined constant back at the end of the operand list, except if
1815  // there is no point. For example, an add of 0 gets dropped here, while a
1816  // multiplication by zero turns the whole expression into zero.
1817  if (Cst && Cst != ConstantExpr::getBinOpIdentity(Opcode, I->getType())) {
1818  if (Cst == ConstantExpr::getBinOpAbsorber(Opcode, I->getType()))
1819  return Cst;
1820  Ops.push_back(ValueEntry(0, Cst));
1821  }
1822 
1823  if (Ops.size() == 1) return Ops[0].Op;
1824 
1825  // Handle destructive annihilation due to identities between elements in the
1826  // argument list here.
1827  unsigned NumOps = Ops.size();
1828  switch (Opcode) {
1829  default: break;
1830  case Instruction::And:
1831  case Instruction::Or:
1832  if (Value *Result = OptimizeAndOrXor(Opcode, Ops))
1833  return Result;
1834  break;
1835 
1836  case Instruction::Xor:
1837  if (Value *Result = OptimizeXor(I, Ops))
1838  return Result;
1839  break;
1840 
1841  case Instruction::Add:
1842  case Instruction::FAdd:
1843  if (Value *Result = OptimizeAdd(I, Ops))
1844  return Result;
1845  break;
1846 
1847  case Instruction::Mul:
1848  case Instruction::FMul:
1849  if (Value *Result = OptimizeMul(I, Ops))
1850  return Result;
1851  break;
1852  }
1853 
1854  if (Ops.size() != NumOps)
1855  return OptimizeExpression(I, Ops);
1856  return nullptr;
1857 }
1858 
1859 // Remove dead instructions and if any operands are trivially dead add them to
1860 // Insts so they will be removed as well.
1861 void ReassociatePass::RecursivelyEraseDeadInsts(
1863  assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!");
1864  SmallVector<Value *, 4> Ops(I->op_begin(), I->op_end());
1865  ValueRankMap.erase(I);
1866  Insts.remove(I);
1867  RedoInsts.remove(I);
1868  I->eraseFromParent();
1869  for (auto Op : Ops)
1870  if (Instruction *OpInst = dyn_cast<Instruction>(Op))
1871  if (OpInst->use_empty())
1872  Insts.insert(OpInst);
1873 }
1874 
1875 /// Zap the given instruction, adding interesting operands to the work list.
1876 void ReassociatePass::EraseInst(Instruction *I) {
1877  assert(isInstructionTriviallyDead(I) && "Trivially dead instructions only!");
1878  DEBUG(dbgs() << "Erasing dead inst: "; I->dump());
1879 
1880  SmallVector<Value*, 8> Ops(I->op_begin(), I->op_end());
1881  // Erase the dead instruction.
1882  ValueRankMap.erase(I);
1883  RedoInsts.remove(I);
1884  I->eraseFromParent();
1885  // Optimize its operands.
1886  SmallPtrSet<Instruction *, 8> Visited; // Detect self-referential nodes.
1887  for (unsigned i = 0, e = Ops.size(); i != e; ++i)
1888  if (Instruction *Op = dyn_cast<Instruction>(Ops[i])) {
1889  // If this is a node in an expression tree, climb to the expression root
1890  // and add that since that's where optimization actually happens.
1891  unsigned Opcode = Op->getOpcode();
1892  while (Op->hasOneUse() && Op->user_back()->getOpcode() == Opcode &&
1893  Visited.insert(Op).second)
1894  Op = Op->user_back();
1895  RedoInsts.insert(Op);
1896  }
1897 
1898  MadeChange = true;
1899 }
1900 
1901 // Canonicalize expressions of the following form:
1902 // x + (-Constant * y) -> x - (Constant * y)
1903 // x - (-Constant * y) -> x + (Constant * y)
1904 Instruction *ReassociatePass::canonicalizeNegConstExpr(Instruction *I) {
1905  if (!I->hasOneUse() || I->getType()->isVectorTy())
1906  return nullptr;
1907 
1908  // Must be a fmul or fdiv instruction.
1909  unsigned Opcode = I->getOpcode();
1910  if (Opcode != Instruction::FMul && Opcode != Instruction::FDiv)
1911  return nullptr;
1912 
1913  auto *C0 = dyn_cast<ConstantFP>(I->getOperand(0));
1914  auto *C1 = dyn_cast<ConstantFP>(I->getOperand(1));
1915 
1916  // Both operands are constant, let it get constant folded away.
1917  if (C0 && C1)
1918  return nullptr;
1919 
1920  ConstantFP *CF = C0 ? C0 : C1;
1921 
1922  // Must have one constant operand.
1923  if (!CF)
1924  return nullptr;
1925 
1926  // Must be a negative ConstantFP.
1927  if (!CF->isNegative())
1928  return nullptr;
1929 
1930  // User must be a binary operator with one or more uses.
1931  Instruction *User = I->user_back();
1932  if (!isa<BinaryOperator>(User) || User->use_empty())
1933  return nullptr;
1934 
1935  unsigned UserOpcode = User->getOpcode();
1936  if (UserOpcode != Instruction::FAdd && UserOpcode != Instruction::FSub)
1937  return nullptr;
1938 
1939  // Subtraction is not commutative. Explicitly, the following transform is
1940  // not valid: (-Constant * y) - x -> x + (Constant * y)
1941  if (!User->isCommutative() && User->getOperand(1) != I)
1942  return nullptr;
1943 
1944  // Change the sign of the constant.
1945  APFloat Val = CF->getValueAPF();
1946  Val.changeSign();
1947  I->setOperand(C0 ? 0 : 1, ConstantFP::get(CF->getContext(), Val));
1948 
1949  // Canonicalize I to RHS to simplify the next bit of logic. E.g.,
1950  // ((-Const*y) + x) -> (x + (-Const*y)).
1951  if (User->getOperand(0) == I && User->isCommutative())
1952  cast<BinaryOperator>(User)->swapOperands();
1953 
1954  Value *Op0 = User->getOperand(0);
1955  Value *Op1 = User->getOperand(1);
1956  BinaryOperator *NI;
1957  switch (UserOpcode) {
1958  default:
1959  llvm_unreachable("Unexpected Opcode!");
1960  case Instruction::FAdd:
1961  NI = BinaryOperator::CreateFSub(Op0, Op1);
1962  NI->setFastMathFlags(cast<FPMathOperator>(User)->getFastMathFlags());
1963  break;
1964  case Instruction::FSub:
1965  NI = BinaryOperator::CreateFAdd(Op0, Op1);
1966  NI->setFastMathFlags(cast<FPMathOperator>(User)->getFastMathFlags());
1967  break;
1968  }
1969 
1970  NI->insertBefore(User);
1971  NI->setName(User->getName());
1972  User->replaceAllUsesWith(NI);
1973  NI->setDebugLoc(I->getDebugLoc());
1974  RedoInsts.insert(I);
1975  MadeChange = true;
1976  return NI;
1977 }
1978 
1979 /// Inspect and optimize the given instruction. Note that erasing
1980 /// instructions is not allowed.
1981 void ReassociatePass::OptimizeInst(Instruction *I) {
1982  // Only consider operations that we understand.
1983  if (!isa<BinaryOperator>(I))
1984  return;
1985 
1986  if (I->getOpcode() == Instruction::Shl && isa<ConstantInt>(I->getOperand(1)))
1987  // If an operand of this shift is a reassociable multiply, or if the shift
1988  // is used by a reassociable multiply or add, turn into a multiply.
1989  if (isReassociableOp(I->getOperand(0), Instruction::Mul) ||
1990  (I->hasOneUse() &&
1991  (isReassociableOp(I->user_back(), Instruction::Mul) ||
1993  Instruction *NI = ConvertShiftToMul(I);
1994  RedoInsts.insert(I);
1995  MadeChange = true;
1996  I = NI;
1997  }
1998 
1999  // Canonicalize negative constants out of expressions.
2000  if (Instruction *Res = canonicalizeNegConstExpr(I))
2001  I = Res;
2002 
2003  // Commute binary operators, to canonicalize the order of their operands.
2004  // This can potentially expose more CSE opportunities, and makes writing other
2005  // transformations simpler.
2006  if (I->isCommutative())
2007  canonicalizeOperands(I);
2008 
2009  // Don't optimize floating point instructions that don't have unsafe algebra.
2010  if (I->getType()->isFPOrFPVectorTy() && !I->hasUnsafeAlgebra())
2011  return;
2012 
2013  // Do not reassociate boolean (i1) expressions. We want to preserve the
2014  // original order of evaluation for short-circuited comparisons that
2015  // SimplifyCFG has folded to AND/OR expressions. If the expression
2016  // is not further optimized, it is likely to be transformed back to a
2017  // short-circuited form for code gen, and the source order may have been
2018  // optimized for the most likely conditions.
2019  if (I->getType()->isIntegerTy(1))
2020  return;
2021 
2022  // If this is a subtract instruction which is not already in negate form,
2023  // see if we can convert it to X+-Y.
2024  if (I->getOpcode() == Instruction::Sub) {
2025  if (ShouldBreakUpSubtract(I)) {
2026  Instruction *NI = BreakUpSubtract(I, RedoInsts);
2027  RedoInsts.insert(I);
2028  MadeChange = true;
2029  I = NI;
2030  } else if (BinaryOperator::isNeg(I)) {
2031  // Otherwise, this is a negation. See if the operand is a multiply tree
2032  // and if this is not an inner node of a multiply tree.
2033  if (isReassociableOp(I->getOperand(1), Instruction::Mul) &&
2034  (!I->hasOneUse() ||
2035  !isReassociableOp(I->user_back(), Instruction::Mul))) {
2037  // If the negate was simplified, revisit the users to see if we can
2038  // reassociate further.
2039  for (User *U : NI->users()) {
2040  if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
2041  RedoInsts.insert(Tmp);
2042  }
2043  RedoInsts.insert(I);
2044  MadeChange = true;
2045  I = NI;
2046  }
2047  }
2048  } else if (I->getOpcode() == Instruction::FSub) {
2049  if (ShouldBreakUpSubtract(I)) {
2050  Instruction *NI = BreakUpSubtract(I, RedoInsts);
2051  RedoInsts.insert(I);
2052  MadeChange = true;
2053  I = NI;
2054  } else if (BinaryOperator::isFNeg(I)) {
2055  // Otherwise, this is a negation. See if the operand is a multiply tree
2056  // and if this is not an inner node of a multiply tree.
2057  if (isReassociableOp(I->getOperand(1), Instruction::FMul) &&
2058  (!I->hasOneUse() ||
2059  !isReassociableOp(I->user_back(), Instruction::FMul))) {
2060  // If the negate was simplified, revisit the users to see if we can
2061  // reassociate further.
2063  for (User *U : NI->users()) {
2064  if (BinaryOperator *Tmp = dyn_cast<BinaryOperator>(U))
2065  RedoInsts.insert(Tmp);
2066  }
2067  RedoInsts.insert(I);
2068  MadeChange = true;
2069  I = NI;
2070  }
2071  }
2072  }
2073 
2074  // If this instruction is an associative binary operator, process it.
2075  if (!I->isAssociative()) return;
2076  BinaryOperator *BO = cast<BinaryOperator>(I);
2077 
2078  // If this is an interior node of a reassociable tree, ignore it until we
2079  // get to the root of the tree, to avoid N^2 analysis.
2080  unsigned Opcode = BO->getOpcode();
2081  if (BO->hasOneUse() && BO->user_back()->getOpcode() == Opcode) {
2082  // During the initial run we will get to the root of the tree.
2083  // But if we get here while we are redoing instructions, there is no
2084  // guarantee that the root will be visited. So Redo later
2085  if (BO->user_back() != BO &&
2086  BO->getParent() == BO->user_back()->getParent())
2087  RedoInsts.insert(BO->user_back());
2088  return;
2089  }
2090 
2091  // If this is an add tree that is used by a sub instruction, ignore it
2092  // until we process the subtract.
2093  if (BO->hasOneUse() && BO->getOpcode() == Instruction::Add &&
2094  cast<Instruction>(BO->user_back())->getOpcode() == Instruction::Sub)
2095  return;
2096  if (BO->hasOneUse() && BO->getOpcode() == Instruction::FAdd &&
2097  cast<Instruction>(BO->user_back())->getOpcode() == Instruction::FSub)
2098  return;
2099 
2100  ReassociateExpression(BO);
2101 }
2102 
2103 void ReassociatePass::ReassociateExpression(BinaryOperator *I) {
2104  // First, walk the expression tree, linearizing the tree, collecting the
2105  // operand information.
2107  MadeChange |= LinearizeExprTree(I, Tree);
2109  Ops.reserve(Tree.size());
2110  for (unsigned i = 0, e = Tree.size(); i != e; ++i) {
2111  RepeatedValue E = Tree[i];
2112  Ops.append(E.second.getZExtValue(),
2113  ValueEntry(getRank(E.first), E.first));
2114  }
2115 
2116  DEBUG(dbgs() << "RAIn:\t"; PrintOps(I, Ops); dbgs() << '\n');
2117 
2118  // Now that we have linearized the tree to a list and have gathered all of
2119  // the operands and their ranks, sort the operands by their rank. Use a
2120  // stable_sort so that values with equal ranks will have their relative
2121  // positions maintained (and so the compiler is deterministic). Note that
2122  // this sorts so that the highest ranking values end up at the beginning of
2123  // the vector.
2124  std::stable_sort(Ops.begin(), Ops.end());
2125 
2126  // Now that we have the expression tree in a convenient
2127  // sorted form, optimize it globally if possible.
2128  if (Value *V = OptimizeExpression(I, Ops)) {
2129  if (V == I)
2130  // Self-referential expression in unreachable code.
2131  return;
2132  // This expression tree simplified to something that isn't a tree,
2133  // eliminate it.
2134  DEBUG(dbgs() << "Reassoc to scalar: " << *V << '\n');
2135  I->replaceAllUsesWith(V);
2136  if (Instruction *VI = dyn_cast<Instruction>(V))
2137  VI->setDebugLoc(I->getDebugLoc());
2138  RedoInsts.insert(I);
2139  ++NumAnnihil;
2140  return;
2141  }
2142 
2143  // We want to sink immediates as deeply as possible except in the case where
2144  // this is a multiply tree used only by an add, and the immediate is a -1.
2145  // In this case we reassociate to put the negation on the outside so that we
2146  // can fold the negation into the add: (-X)*Y + Z -> Z-X*Y
2147  if (I->hasOneUse()) {
2148  if (I->getOpcode() == Instruction::Mul &&
2149  cast<Instruction>(I->user_back())->getOpcode() == Instruction::Add &&
2150  isa<ConstantInt>(Ops.back().Op) &&
2151  cast<ConstantInt>(Ops.back().Op)->isMinusOne()) {
2152  ValueEntry Tmp = Ops.pop_back_val();
2153  Ops.insert(Ops.begin(), Tmp);
2154  } else if (I->getOpcode() == Instruction::FMul &&
2155  cast<Instruction>(I->user_back())->getOpcode() ==
2156  Instruction::FAdd &&
2157  isa<ConstantFP>(Ops.back().Op) &&
2158  cast<ConstantFP>(Ops.back().Op)->isExactlyValue(-1.0)) {
2159  ValueEntry Tmp = Ops.pop_back_val();
2160  Ops.insert(Ops.begin(), Tmp);
2161  }
2162  }
2163 
2164  DEBUG(dbgs() << "RAOut:\t"; PrintOps(I, Ops); dbgs() << '\n');
2165 
2166  if (Ops.size() == 1) {
2167  if (Ops[0].Op == I)
2168  // Self-referential expression in unreachable code.
2169  return;
2170 
2171  // This expression tree simplified to something that isn't a tree,
2172  // eliminate it.
2173  I->replaceAllUsesWith(Ops[0].Op);
2174  if (Instruction *OI = dyn_cast<Instruction>(Ops[0].Op))
2175  OI->setDebugLoc(I->getDebugLoc());
2176  RedoInsts.insert(I);
2177  return;
2178  }
2179 
2180  // Now that we ordered and optimized the expressions, splat them back into
2181  // the expression tree, removing any unneeded nodes.
2182  RewriteExprTree(I, Ops);
2183 }
2184 
2186  // Get the functions basic blocks in Reverse Post Order. This order is used by
2187  // BuildRankMap to pre calculate ranks correctly. It also excludes dead basic
2188  // blocks (it has been seen that the analysis in this pass could hang when
2189  // analysing dead basic blocks).
2191 
2192  // Calculate the rank map for F.
2193  BuildRankMap(F, RPOT);
2194 
2195  MadeChange = false;
2196  // Traverse the same blocks that was analysed by BuildRankMap.
2197  for (BasicBlock *BI : RPOT) {
2198  assert(RankMap.count(&*BI) && "BB should be ranked.");
2199  // Optimize every instruction in the basic block.
2200  for (BasicBlock::iterator II = BI->begin(), IE = BI->end(); II != IE;)
2201  if (isInstructionTriviallyDead(&*II)) {
2202  EraseInst(&*II++);
2203  } else {
2204  OptimizeInst(&*II);
2205  assert(II->getParent() == &*BI && "Moved to a different block!");
2206  ++II;
2207  }
2208 
2209  // Make a copy of all the instructions to be redone so we can remove dead
2210  // instructions.
2211  SetVector<AssertingVH<Instruction>> ToRedo(RedoInsts);
2212  // Iterate over all instructions to be reevaluated and remove trivially dead
2213  // instructions. If any operand of the trivially dead instruction becomes
2214  // dead mark it for deletion as well. Continue this process until all
2215  // trivially dead instructions have been removed.
2216  while (!ToRedo.empty()) {
2217  Instruction *I = ToRedo.pop_back_val();
2218  if (isInstructionTriviallyDead(I)) {
2219  RecursivelyEraseDeadInsts(I, ToRedo);
2220  MadeChange = true;
2221  }
2222  }
2223 
2224  // Now that we have removed dead instructions, we can reoptimize the
2225  // remaining instructions.
2226  while (!RedoInsts.empty()) {
2227  Instruction *I = RedoInsts.pop_back_val();
2229  EraseInst(I);
2230  else
2231  OptimizeInst(I);
2232  }
2233  }
2234 
2235  // We are done with the rank map.
2236  RankMap.clear();
2237  ValueRankMap.clear();
2238 
2239  if (MadeChange) {
2240  PreservedAnalyses PA;
2241  PA.preserveSet<CFGAnalyses>();
2242  PA.preserve<GlobalsAA>();
2243  return PA;
2244  }
2245 
2246  return PreservedAnalyses::all();
2247 }
2248 
2249 namespace {
2250  class ReassociateLegacyPass : public FunctionPass {
2251  ReassociatePass Impl;
2252  public:
2253  static char ID; // Pass identification, replacement for typeid
2254  ReassociateLegacyPass() : FunctionPass(ID) {
2256  }
2257 
2258  bool runOnFunction(Function &F) override {
2259  if (skipFunction(F))
2260  return false;
2261 
2262  FunctionAnalysisManager DummyFAM;
2263  auto PA = Impl.run(F, DummyFAM);
2264  return !PA.areAllPreserved();
2265  }
2266 
2267  void getAnalysisUsage(AnalysisUsage &AU) const override {
2268  AU.setPreservesCFG();
2270  }
2271  };
2272 }
2273 
2274 char ReassociateLegacyPass::ID = 0;
2275 INITIALIZE_PASS(ReassociateLegacyPass, "reassociate",
2276  "Reassociate expressions", false, false)
2277 
2278 // Public interface to the Reassociate pass
2280  return new ReassociateLegacyPass();
2281 }
Legacy wrapper pass to provide the GlobalsAAResult object.
uint64_t CallInst * C
SymbolTableList< Instruction >::iterator eraseFromParent()
This method unlinks &#39;this&#39; from the containing basic block and deletes it.
Definition: Instruction.cpp:69
void push_back(const T &Elt)
Definition: SmallVector.h:212
static GCMetadataPrinterRegistry::Add< ErlangGCPrinter > X("erlang", "erlang-compatible garbage collector")
void setFastMathFlags(FastMathFlags FMF)
Convenience function for setting multiple fast-math flags on this instruction, which must be an opera...
AnalysisUsage & addPreserved()
Add the specified Pass class to the set of analyses preserved by this pass.
static PassRegistry * getPassRegistry()
getPassRegistry - Access the global registry object, which is automatically initialized at applicatio...
uint64_t getZExtValue() const
Get zero extended value.
Definition: APInt.h:1542
GCNRegPressure max(const GCNRegPressure &P1, const GCNRegPressure &P2)
This class represents an incoming formal argument to a Function.
Definition: Argument.h:30
LLVM_NODISCARD T pop_back_val()
Definition: SetVector.h:228
static BinaryOperator * LowerNegateToMultiply(Instruction *Neg)
Replace 0-X with X*-1.
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
BinaryOps getOpcode() const
Definition: InstrTypes.h:523
INITIALIZE_PASS(ReassociateLegacyPass, "reassociate", "Reassociate expressions", false, false) FunctionPass *llvm
This is the interface for a simple mod/ref and alias analysis over globals.
A Module instance is used to store all the information related to an LLVM module. ...
Definition: Module.h:63
LLVM_ATTRIBUTE_ALWAYS_INLINE size_type size() const
Definition: SmallVector.h:136
bool isIdempotent() const
Return true if the instruction is idempotent:
Definition: Instruction.h:434
Utility class representing a non-constant Xor-operand.
Definition: Reassociate.cpp:78
static Constant * getBinOpIdentity(unsigned Opcode, Type *Ty)
Return the identity for the given binary operation, i.e.
Definition: Constants.cpp:2203
nary reassociate
Utility class representing a base and exponent pair which form one factor of some product...
Definition: Reassociate.h:48
LLVMContext & getContext() const
All values hold a context through their type.
Definition: Value.cpp:697
void deleteValue()
Delete a pointer to a generic Value.
Definition: Value.cpp:93
arg_iterator arg_end()
Definition: Function.h:604
STATISTIC(NumFunctions, "Total number of functions")
static unsigned FindInOperandList(const SmallVectorImpl< ValueEntry > &Ops, unsigned i, Value *X)
Scan backwards and forwards among values with the same rank as element i to see if X exists...
bool isVectorTy() const
True if this is an instance of VectorType.
Definition: Type.h:227
void changeSign()
Definition: APFloat.h:1050
void reserve(size_type N)
Definition: SmallVector.h:380
Reassociate commutative expressions.
Definition: Reassociate.h:58
op_iterator op_begin()
Definition: User.h:214
unsigned getBitWidth() const
Return the number of bits in the APInt.
Definition: APInt.h:1488
static Constant * getNullValue(Type *Ty)
Constructor to create a &#39;0&#39; constant of arbitrary type.
Definition: Constants.cpp:207
iterator begin()
Instruction iterator methods.
Definition: BasicBlock.h:252
bool swapOperands()
Exchange the two operands to this instruction.
void dump() const
Support for debugging, callable in GDB: V->dump()
Definition: AsmWriter.cpp:3606
bool match(Val *V, const Pattern &P)
Definition: PatternMatch.h:49
static const Value * getNegArgument(const Value *BinOp)
Helper functions to extract the unary argument of a NEG, FNEG or NOT operation implemented via Sub...
Twine - A lightweight data structure for efficiently representing the concatenation of temporary valu...
Definition: Twine.h:81
bool isNilpotent() const
Return true if the instruction is nilpotent:
Definition: Instruction.h:448
This class consists of common code factored out of the SmallVector class to reduce code duplication b...
Definition: APFloat.h:42
static bool collectMultiplyFactors(SmallVectorImpl< ValueEntry > &Ops, SmallVectorImpl< Factor > &Factors)
Build up a vector of value/power pairs factoring a product.
bool isIntegerTy() const
True if this is an instance of IntegerType.
Definition: Type.h:197
This provides a uniform API for creating instructions and inserting them into a basic block: either a...
Definition: IRBuilder.h:664
FunctionPass * createReassociatePass()
bool hasUnsafeAlgebra() const
Determine whether the unsafe-algebra flag is set.
static BinaryOperator * BreakUpSubtract(Instruction *Sub, SetVector< AssertingVH< Instruction >> &ToRedo)
If we have (X-Y), and if either X is an add, or if this is only used by an add, transform this into (...
void setName(const Twine &Name)
Change the name of the value.
Definition: Value.cpp:284
static Constant * get(unsigned Opcode, Constant *C1, Constant *C2, unsigned Flags=0, Type *OnlyIfReducedTy=nullptr)
get - Return a binary or shift operator constant expression, folding if possible. ...
Definition: Constants.cpp:1711
static Value * OptimizeAndOrXor(unsigned Opcode, SmallVectorImpl< ValueEntry > &Ops)
Optimize a series of operands to an &#39;and&#39;, &#39;or&#39;, or &#39;xor&#39; instruction.
FastMathFlags getFastMathFlags() const
Convenience function for getting all the fast-math flags, which must be an operator which supports th...
#define F(x, y, z)
Definition: MD5.cpp:55
Type * getType() const
All values are typed, get the type of this value.
Definition: Value.h:245
bool getBoolValue() const
Convert APInt to a boolean value.
Definition: APInt.h:471
std::pair< Value *, APInt > RepeatedValue
bool isNegative() const
Return true if the sign bit is set.
Definition: Constants.h:300
void andIRFlags(const Value *V)
Logical &#39;and&#39; of any supported wrapping, exact, and fast-math flags of V and this instruction...
static Value * createAndInstr(Instruction *InsertBefore, Value *Opnd, const APInt &ConstOpnd)
Helper function of CombineXorOpnd().
unsigned getOpcode() const
Returns a member of one of the enums like Instruction::Add.
Definition: Instruction.h:121
bool isIntOrIntVectorTy() const
Return true if this is an integer type or a vector of integer types.
Definition: Type.h:203
void replaceAllUsesWith(Value *V)
Change all uses of this to point to a new Value.
Definition: Value.cpp:428
void takeName(Value *V)
Transfer the name from V to this value.
Definition: Value.cpp:290
static BinaryOperator * CreateAdd(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
static const Value * getNotArgument(const Value *BinOp)
const char * Name
Value * getOperand(unsigned i) const
Definition: User.h:154
Type * getScalarType() const
If this is a vector type, return the element type, otherwise return &#39;this&#39;.
Definition: Type.h:301
const BasicBlock & getEntryBlock() const
Definition: Function.h:564
#define P(N)
static Constant * getFNeg(Constant *C)
Definition: Constants.cpp:2103
bool isAllOnesValue() const
Determine if all bits are set.
Definition: APInt.h:389
A set of analyses that are preserved following a run of a transformation pass.
Definition: PassManager.h:153
apint_match m_APInt(const APInt *&Res)
Match a ConstantInt or splatted ConstantVector, binding the specified pointer to the contained APInt...
Definition: PatternMatch.h:240
void setDebugLoc(DebugLoc Loc)
Set the debug location information for this instruction.
Definition: Instruction.h:277
bool areAllPreserved() const
Test whether all analyses are preserved (and none are abandoned).
Definition: PassManager.h:321
void insertBefore(Instruction *InsertPos)
Insert an unlinked instruction into a basic block immediately before the specified instruction...
Definition: Instruction.cpp:75
LLVM Basic Block Representation.
Definition: BasicBlock.h:59
The instances of the Type class are immutable: once they are created, they are never changed...
Definition: Type.h:46
bool ult(const APInt &RHS) const
Unsigned less than comparison.
Definition: APInt.h:1164
const char * getOpcodeName() const
Definition: Instruction.h:123
static Value * EmitAddTreeOfValues(Instruction *I, SmallVectorImpl< WeakTrackingVH > &Ops)
Emit a tree of add instructions, summing Ops together and returning the result.
This is an important base class in LLVM.
Definition: Constant.h:42
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator begin()
Definition: SmallVector.h:116
This file contains the declarations for the subclasses of Constant, which represent the different fla...
ConstantFP - Floating Point Values [float, double].
Definition: Constants.h:264
std::pair< iterator, bool > insert(PtrType Ptr)
Inserts Ptr if and only if there is no element in the container equal to Ptr.
Definition: SmallPtrSet.h:372
static APInt getOneBitSet(unsigned numBits, unsigned BitNo)
Return an APInt with exactly one bit set in the result.
Definition: APInt.h:581
bool isAssociative() const LLVM_READONLY
Return true if the instruction is associative:
Represent the analysis usage information of a pass.
op_iterator op_end()
Definition: User.h:216
Analysis pass providing a never-invalidated alias analysis result.
Value * getSymbolicPart() const
Definition: Reassociate.cpp:85
FunctionPass class - This class is used to implement most global optimizations.
Definition: Pass.h:298
arg_iterator arg_begin()
Definition: Function.h:595
static bool isNot(const Value *V)
size_type count(ConstPtrType Ptr) const
count - Return 1 if the specified pointer is in the set, 0 otherwise.
Definition: SmallPtrSet.h:383
self_iterator getIterator()
Definition: ilist_node.h:82
static Constant * getAllOnesValue(Type *Ty)
Get the all ones value.
Definition: Constants.cpp:261
NUW NUW NUW NUW Exact static Exact BinaryOperator * CreateNeg(Value *Op, const Twine &Name="", Instruction *InsertBefore=nullptr)
Helper functions to construct and inspect unary operations (NEG and NOT) via binary operators SUB and...
static UndefValue * get(Type *T)
Static factory methods - Return an &#39;undef&#39; object of the specified type.
Definition: Constants.cpp:1320
iterator erase(const_iterator CI)
Definition: SmallVector.h:449
static PreservedAnalyses all()
Construct a special preserved set that preserves all passes.
Definition: PassManager.h:159
static unsigned CarmichaelShift(unsigned Bitwidth)
Returns k such that lambda(2^Bitwidth) = 2^k, where lambda is the Carmichael function.
#define llvm_unreachable(msg)
Marks that the current location is not supposed to be reachable.
Value * CreateMul(Value *LHS, Value *RHS, const Twine &Name="", bool HasNUW=false, bool HasNSW=false)
Definition: IRBuilder.h:933
const APInt & getConstPart() const
Definition: Reassociate.cpp:87
const APFloat & getValueAPF() const
Definition: Constants.h:294
static BinaryOperator * CreateFNeg(Value *Op, const Twine &Name="", Instruction *InsertBefore=nullptr)
void setHasNoSignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
Value * getValue() const
Definition: Reassociate.cpp:84
Iterator for intrusive lists based on ilist_node.
SmallPtrSet - This class implements a set which is optimized for holding SmallSize or less elements...
Definition: SmallPtrSet.h:423
#define E
Definition: LargeTest.cpp:27
This is the shared class of boolean and integer constants.
Definition: Constants.h:84
unsigned getScalarSizeInBits() const LLVM_READONLY
If this is a vector type, return the getPrimitiveSizeInBits value for the element type...
Definition: Type.cpp:130
static Value * NegateValue(Value *V, Instruction *BI, SetVector< AssertingVH< Instruction >> &ToRedo)
Insert instructions before the instruction pointed to by BI, that computes the negative version of th...
This is a &#39;vector&#39; (really, a variable-sized array), optimized for the case when the array is small...
Definition: SmallVector.h:864
unsigned getSymbolicRank() const
Definition: Reassociate.cpp:86
Instruction * user_back()
Specialize the methods defined in Value, as we know that an instruction can only be used by other ins...
Definition: Instruction.h:63
LLVM_NODISCARD T pop_back_val()
Definition: SmallVector.h:385
static Constant * get(Type *Ty, uint64_t V, bool isSigned=false)
If Ty is a vector type, return a Constant with a splat of the given value.
Definition: Constants.cpp:560
void setSymbolicRank(unsigned R)
Definition: Reassociate.cpp:90
void setPreservesCFG()
This function should be called by the pass, iff they do not:
Definition: Pass.cpp:278
static Constant * get(Type *Ty, double V)
This returns a ConstantFP, or a vector containing a splat of a ConstantFP, for the specified value in...
Definition: Constants.cpp:623
Value handle that asserts if the Value is deleted.
Definition: ValueHandle.h:238
bool isCommutative() const
Return true if the instruction is commutative:
Definition: Instruction.h:416
void setOperand(unsigned i, Value *Val)
Definition: User.h:159
raw_ostream & dbgs()
dbgs() - This returns a reference to a raw_ostream for debugging messages.
Definition: Debug.cpp:132
void swap(llvm::BitVector &LHS, llvm::BitVector &RHS)
Implement std::swap in terms of BitVector swap.
Definition: BitVector.h:923
const Module * getModule() const
Return the module owning the function this instruction belongs to or nullptr it the function does not...
Definition: Instruction.cpp:57
static bool isNeg(const Value *V)
Check if the given Value is a NEG, FNeg, or NOT instruction.
Class for arbitrary precision integers.
Definition: APInt.h:69
static Value * buildMultiplyTree(IRBuilder<> &Builder, SmallVectorImpl< Value *> &Ops)
Build a tree of multiplies, computing the product of Ops.
static BinaryOperator * Create(BinaryOps Op, Value *S1, Value *S2, const Twine &Name=Twine(), Instruction *InsertBefore=nullptr)
Construct a binary instruction, given the opcode and the two operands.
iterator_range< user_iterator > users()
Definition: Value.h:395
Represents analyses that only rely on functions&#39; control flow.
Definition: PassManager.h:114
iterator insert(iterator I, T &&Elt)
Definition: SmallVector.h:482
void append(in_iter in_start, in_iter in_end)
Add the specified range to the end of the SmallVector.
Definition: SmallVector.h:398
constexpr char Size[]
Key for Kernel::Arg::Metadata::mSize.
static void FindSingleUseMultiplyFactors(Value *V, SmallVectorImpl< Value *> &Factors)
If V is a single-use multiply, recursively add its operands as factors, otherwise add V to the list o...
static Constant * getNeg(Constant *C, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2096
static std::vector< std::string > Flags
Definition: FlagsTest.cpp:8
LLVM_ATTRIBUTE_ALWAYS_INLINE iterator end()
Definition: SmallVector.h:120
iterator insert(iterator where, pointer New)
Definition: ilist.h:241
const DebugLoc & getDebugLoc() const
Return the debug location for this node as a DebugLoc.
Definition: Instruction.h:280
bool mayBeMemoryDependent(const Instruction &I)
Returns true if the result or effects of the given instructions I depend on or influence global memor...
void emplace_back(ArgTypes &&... Args)
Definition: SmallVector.h:656
LLVM_NODISCARD bool empty() const
Definition: SmallVector.h:61
static bool isFNeg(const Value *V, bool IgnoreZeroSign=false)
void preserveSet()
Mark an analysis set as preserved.
Definition: PassManager.h:189
StringRef getName() const
Return a constant reference to the value&#39;s name.
Definition: Value.cpp:218
const Function * getParent() const
Return the enclosing method, or null if none.
Definition: BasicBlock.h:108
static void PrintOps(Instruction *I, const SmallVectorImpl< ValueEntry > &Ops)
Print out the expression identified in the Ops list.
Definition: Reassociate.cpp:58
static void IncorporateWeight(APInt &LHS, const APInt &RHS, unsigned Opcode)
Add the extra weight &#39;RHS&#39; to the existing weight &#39;LHS&#39;, reducing the combined weight using any speci...
#define I(x, y, z)
Definition: MD5.cpp:58
bool empty() const
Determine if the SetVector is empty or not.
Definition: SetVector.h:73
LLVM_NODISCARD std::enable_if<!is_simple_type< Y >::value, typename cast_retty< X, const Y >::ret_type >::type dyn_cast(const Y &Val)
Definition: Casting.h:323
static Constant * getShl(Constant *C1, Constant *C2, bool HasNUW=false, bool HasNSW=false)
Definition: Constants.cpp:2186
void preserve()
Mark an analysis as preserved.
Definition: PassManager.h:174
static BinaryOperator * CreateNeg(Value *S1, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
bool isMinValue() const
Determine if this is the smallest unsigned value.
Definition: APInt.h:430
bool isFPOrFPVectorTy() const
Return true if this is a FP type or a vector of FP.
Definition: Type.h:185
static int const Threshold
TODO: Write a new FunctionPass AliasAnalysis so that it can keep a cache.
void setHasNoUnsignedWrap(bool b=true)
Set or clear the nsw flag on this instruction, which must be an operator which supports this flag...
Definition: Instruction.cpp:98
static BinaryOperator * ConvertShiftToMul(Instruction *Shl)
If this is a shift of a reassociable multiply or is used by one, change this into a multiply by a con...
assert(ImpDefSCC.getReg()==AMDGPU::SCC &&ImpDefSCC.isDef())
user_iterator user_begin()
Definition: Value.h:371
void initializeReassociateLegacyPassPass(PassRegistry &)
unsigned getPrimitiveSizeInBits() const LLVM_READONLY
Return the basic size of this type if it is a primitive type.
Definition: Type.cpp:115
bool isInstructionTriviallyDead(Instruction *I, const TargetLibraryInfo *TLI=nullptr)
Return true if the result produced by the instruction is not used, and the instruction has no side ef...
Definition: Local.cpp:293
LLVM Value Representation.
Definition: Value.h:73
A vector that has set insertion semantics.
Definition: SetVector.h:41
void clearSubclassOptionalData()
Clear the optional flags contained in this value.
Definition: Value.h:471
void setFastMathFlags(FastMathFlags NewFMF)
Set the fast-math flags to be used with generated fp-math operators.
Definition: IRBuilder.h:221
void moveBefore(Instruction *MovePos)
Unlink this instruction from its current basic block and insert it into the basic block that MovePos ...
Definition: Instruction.cpp:88
static BinaryOperator * isReassociableOp(Value *V, unsigned Opcode)
Return true if V is an instruction of the specified opcode and if it only has one use...
Invoke instruction.
#define DEBUG(X)
Definition: Debug.h:118
IRTranslator LLVM IR MI
bool hasOneUse() const
Return true if there is exactly one user of this value.
Definition: Value.h:408
Convenience struct for specifying and reasoning about fast-math flags.
Definition: Operator.h:160
A container for analyses that lazily runs them and caches their results.
static bool ShouldBreakUpSubtract(Instruction *Sub)
Return true if we should break up this subtract of X-Y into (X + -Y).
static APInt getNullValue(unsigned numBits)
Get the &#39;0&#39; value.
Definition: APInt.h:562
static BinaryOperator * CreateMul(Value *S1, Value *S2, const Twine &Name, Instruction *InsertBefore, Value *FlagsOp)
Value * CreateFMul(Value *LHS, Value *RHS, const Twine &Name="", MDNode *FPMathTag=nullptr)
Definition: IRBuilder.h:947
static Constant * getBinOpAbsorber(unsigned Opcode, Type *Ty)
Return the absorbing element for the given binary operation, i.e.
Definition: Constants.cpp:2222
static bool LinearizeExprTree(BinaryOperator *I, SmallVectorImpl< RepeatedValue > &Ops)
Given an associative binary expression, return the leaf nodes in Ops along with their weights (how ma...
bool use_empty() const
Definition: Value.h:322
bool isNullValue() const
Determine if all bits are clear.
Definition: APInt.h:399
cmpResult compare(const APFloat &RHS) const
Definition: APFloat.h:1102
const BasicBlock * getParent() const
Definition: Instruction.h:66
PreservedAnalyses run(Function &F, FunctionAnalysisManager &)