1 //===- InstCombineMulDivRem.cpp -------------------------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This file implements the visit functions for mul, fmul, sdiv, udiv, fdiv,
13 //===----------------------------------------------------------------------===//
15 #include "InstCombine.h"
16 #include "llvm/IntrinsicInst.h"
17 #include "llvm/Analysis/InstructionSimplify.h"
18 #include "llvm/Support/PatternMatch.h"
20 using namespace PatternMatch;
23 /// simplifyValueKnownNonZero - The specific integer value is used in a context
24 /// where it is known to be non-zero. If this allows us to simplify the
25 /// computation, do so and return the new operand, otherwise return null.
26 static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
27 // If V has multiple uses, then we would have to do more analysis to determine
28 // if this is safe. For example, the use could be in dynamically unreached
30 if (!V->hasOneUse()) return 0;
32 bool MadeChange = false;
34 // ((1 << A) >>u B) --> (1 << (A-B))
35 // Because V cannot be zero, we know that B is less than A.
36 Value *A = 0, *B = 0, *PowerOf2 = 0;
37 if (match(V, m_LShr(m_OneUse(m_Shl(m_Value(PowerOf2), m_Value(A))),
39 // The "1" can be any value known to be a power of 2.
40 isPowerOfTwo(PowerOf2, IC.getTargetData())) {
41 A = IC.Builder->CreateSub(A, B, "tmp");
42 return IC.Builder->CreateShl(PowerOf2, A);
45 // (PowerOfTwo >>u B) --> isExact since shifting out the result would make it
46 // inexact. Similarly for <<.
47 if (BinaryOperator *I = dyn_cast<BinaryOperator>(V))
48 if (I->isLogicalShift() &&
49 isPowerOfTwo(I->getOperand(0), IC.getTargetData())) {
50 // We know that this is an exact/nuw shift and that the input is a
51 // non-zero context as well.
52 if (Value *V2 = simplifyValueKnownNonZero(I->getOperand(0), IC)) {
57 if (I->getOpcode() == Instruction::LShr && !I->isExact()) {
62 if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) {
63 I->setHasNoUnsignedWrap();
68 // TODO: Lots more we could do here:
69 // If V is a phi node, we can call this on each of its operands.
70 // "select cond, X, 0" can simplify to "X".
72 return MadeChange ? V : 0;
76 /// MultiplyOverflows - True if the multiply can not be expressed in an int
78 static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
79 uint32_t W = C1->getBitWidth();
80 APInt LHSExt = C1->getValue(), RHSExt = C2->getValue();
82 LHSExt = LHSExt.sext(W * 2);
83 RHSExt = RHSExt.sext(W * 2);
85 LHSExt = LHSExt.zext(W * 2);
86 RHSExt = RHSExt.zext(W * 2);
89 APInt MulExt = LHSExt * RHSExt;
92 return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
94 APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
95 APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
96 return MulExt.slt(Min) || MulExt.sgt(Max);
99 Instruction *InstCombiner::visitMul(BinaryOperator &I) {
100 bool Changed = SimplifyAssociativeOrCommutative(I);
101 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
103 if (Value *V = SimplifyMulInst(Op0, Op1, TD))
104 return ReplaceInstUsesWith(I, V);
106 if (Value *V = SimplifyUsingDistributiveLaws(I))
107 return ReplaceInstUsesWith(I, V);
109 if (match(Op1, m_AllOnes())) // X * -1 == 0 - X
110 return BinaryOperator::CreateNeg(Op0, I.getName());
112 if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
114 // ((X << C1)*C2) == (X * (C2 << C1))
115 if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
116 if (SI->getOpcode() == Instruction::Shl)
117 if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
118 return BinaryOperator::CreateMul(SI->getOperand(0),
119 ConstantExpr::getShl(CI, ShOp));
121 const APInt &Val = CI->getValue();
122 if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
123 Constant *NewCst = ConstantInt::get(Op0->getType(), Val.logBase2());
124 BinaryOperator *Shl = BinaryOperator::CreateShl(Op0, NewCst);
125 if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap();
126 if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap();
130 // Canonicalize (X+C1)*CI -> X*CI+C1*CI.
131 { Value *X; ConstantInt *C1;
132 if (Op0->hasOneUse() &&
133 match(Op0, m_Add(m_Value(X), m_ConstantInt(C1)))) {
134 Value *Add = Builder->CreateMul(X, CI, "tmp");
135 return BinaryOperator::CreateAdd(Add, Builder->CreateMul(C1, CI));
139 // (1 - X) * (-2) -> (x - 1) * 2, for all positive nonzero powers of 2
140 // The "* 2" thus becomes a potential shifting opportunity.
142 const APInt & Val = CI->getValue();
143 const APInt &PosVal = Val.abs();
144 if (Val.isNegative() && PosVal.isPowerOf2()) {
146 if (match(Op0, m_Sub(m_One(), m_Value(X)))) {
147 // ConstantInt::get(Op0->getType(), 2);
148 Value *Sub = Builder->CreateSub(X, ConstantInt::get(X->getType(), 1),
150 return BinaryOperator::CreateMul(Sub, ConstantInt::get(X->getType(),
157 // Simplify mul instructions with a constant RHS.
158 if (isa<Constant>(Op1)) {
159 // Try to fold constant mul into select arguments.
160 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
161 if (Instruction *R = FoldOpIntoSelect(I, SI))
164 if (isa<PHINode>(Op0))
165 if (Instruction *NV = FoldOpIntoPhi(I))
169 if (Value *Op0v = dyn_castNegVal(Op0)) // -X * -Y = X*Y
170 if (Value *Op1v = dyn_castNegVal(Op1))
171 return BinaryOperator::CreateMul(Op0v, Op1v);
173 // (X / Y) * Y = X - (X % Y)
174 // (X / Y) * -Y = (X % Y) - X
177 BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
179 (BO->getOpcode() != Instruction::UDiv &&
180 BO->getOpcode() != Instruction::SDiv)) {
182 BO = dyn_cast<BinaryOperator>(Op1);
184 Value *Neg = dyn_castNegVal(Op1C);
185 if (BO && BO->hasOneUse() &&
186 (BO->getOperand(1) == Op1C || BO->getOperand(1) == Neg) &&
187 (BO->getOpcode() == Instruction::UDiv ||
188 BO->getOpcode() == Instruction::SDiv)) {
189 Value *Op0BO = BO->getOperand(0), *Op1BO = BO->getOperand(1);
191 // If the division is exact, X % Y is zero, so we end up with X or -X.
192 if (PossiblyExactOperator *SDiv = dyn_cast<PossiblyExactOperator>(BO))
193 if (SDiv->isExact()) {
195 return ReplaceInstUsesWith(I, Op0BO);
196 return BinaryOperator::CreateNeg(Op0BO);
200 if (BO->getOpcode() == Instruction::UDiv)
201 Rem = Builder->CreateURem(Op0BO, Op1BO);
203 Rem = Builder->CreateSRem(Op0BO, Op1BO);
207 return BinaryOperator::CreateSub(Op0BO, Rem);
208 return BinaryOperator::CreateSub(Rem, Op0BO);
212 /// i1 mul -> i1 and.
213 if (I.getType()->isIntegerTy(1))
214 return BinaryOperator::CreateAnd(Op0, Op1);
216 // X*(1 << Y) --> X << Y
217 // (1 << Y)*X --> X << Y
220 if (match(Op0, m_Shl(m_One(), m_Value(Y))))
221 return BinaryOperator::CreateShl(Op1, Y);
222 if (match(Op1, m_Shl(m_One(), m_Value(Y))))
223 return BinaryOperator::CreateShl(Op0, Y);
226 // If one of the operands of the multiply is a cast from a boolean value, then
227 // we know the bool is either zero or one, so this is a 'masking' multiply.
228 // X * Y (where Y is 0 or 1) -> X & (0-Y)
229 if (!I.getType()->isVectorTy()) {
230 // -2 is "-1 << 1" so it is all bits set except the low one.
231 APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
233 Value *BoolCast = 0, *OtherOp = 0;
234 if (MaskedValueIsZero(Op0, Negative2))
235 BoolCast = Op0, OtherOp = Op1;
236 else if (MaskedValueIsZero(Op1, Negative2))
237 BoolCast = Op1, OtherOp = Op0;
240 Value *V = Builder->CreateSub(Constant::getNullValue(I.getType()),
242 return BinaryOperator::CreateAnd(V, OtherOp);
246 return Changed ? &I : 0;
249 Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
250 bool Changed = SimplifyAssociativeOrCommutative(I);
251 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
253 // Simplify mul instructions with a constant RHS...
254 if (Constant *Op1C = dyn_cast<Constant>(Op1)) {
255 if (ConstantFP *Op1F = dyn_cast<ConstantFP>(Op1C)) {
256 // "In IEEE floating point, x*1 is not equivalent to x for nans. However,
257 // ANSI says we can drop signals, so we can do this anyway." (from GCC)
258 if (Op1F->isExactlyValue(1.0))
259 return ReplaceInstUsesWith(I, Op0); // Eliminate 'fmul double %X, 1.0'
260 } else if (Op1C->getType()->isVectorTy()) {
261 if (ConstantVector *Op1V = dyn_cast<ConstantVector>(Op1C)) {
262 // As above, vector X*splat(1.0) -> X in all defined cases.
263 if (Constant *Splat = Op1V->getSplatValue()) {
264 if (ConstantFP *F = dyn_cast<ConstantFP>(Splat))
265 if (F->isExactlyValue(1.0))
266 return ReplaceInstUsesWith(I, Op0);
271 // Try to fold constant mul into select arguments.
272 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
273 if (Instruction *R = FoldOpIntoSelect(I, SI))
276 if (isa<PHINode>(Op0))
277 if (Instruction *NV = FoldOpIntoPhi(I))
281 if (Value *Op0v = dyn_castFNegVal(Op0)) // -X * -Y = X*Y
282 if (Value *Op1v = dyn_castFNegVal(Op1))
283 return BinaryOperator::CreateFMul(Op0v, Op1v);
285 return Changed ? &I : 0;
288 /// SimplifyDivRemOfSelect - Try to fold a divide or remainder of a select
290 bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
291 SelectInst *SI = cast<SelectInst>(I.getOperand(1));
293 // div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
294 int NonNullOperand = -1;
295 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
296 if (ST->isNullValue())
298 // div/rem X, (Cond ? Y : 0) -> div/rem X, Y
299 if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
300 if (ST->isNullValue())
303 if (NonNullOperand == -1)
306 Value *SelectCond = SI->getOperand(0);
308 // Change the div/rem to use 'Y' instead of the select.
309 I.setOperand(1, SI->getOperand(NonNullOperand));
311 // Okay, we know we replace the operand of the div/rem with 'Y' with no
312 // problem. However, the select, or the condition of the select may have
313 // multiple uses. Based on our knowledge that the operand must be non-zero,
314 // propagate the known value for the select into other uses of it, and
315 // propagate a known value of the condition into its other users.
317 // If the select and condition only have a single use, don't bother with this,
319 if (SI->use_empty() && SelectCond->hasOneUse())
322 // Scan the current block backward, looking for other uses of SI.
323 BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
325 while (BBI != BBFront) {
327 // If we found a call to a function, we can't assume it will return, so
328 // information from below it cannot be propagated above it.
329 if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
332 // Replace uses of the select or its condition with the known values.
333 for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
336 *I = SI->getOperand(NonNullOperand);
338 } else if (*I == SelectCond) {
339 *I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) :
340 ConstantInt::getFalse(BBI->getContext());
345 // If we past the instruction, quit looking for it.
348 if (&*BBI == SelectCond)
351 // If we ran out of things to eliminate, break out of the loop.
352 if (SelectCond == 0 && SI == 0)
360 /// This function implements the transforms common to both integer division
361 /// instructions (udiv and sdiv). It is called by the visitors to those integer
362 /// division instructions.
363 /// @brief Common integer divide transforms
364 Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
365 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
367 // The RHS is known non-zero.
368 if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this)) {
373 // Handle cases involving: [su]div X, (select Cond, Y, Z)
374 // This does not apply for fdiv.
375 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
378 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
379 // (X / C1) / C2 -> X / (C1*C2)
380 if (Instruction *LHS = dyn_cast<Instruction>(Op0))
381 if (Instruction::BinaryOps(LHS->getOpcode()) == I.getOpcode())
382 if (ConstantInt *LHSRHS = dyn_cast<ConstantInt>(LHS->getOperand(1))) {
383 if (MultiplyOverflows(RHS, LHSRHS,
384 I.getOpcode()==Instruction::SDiv))
385 return ReplaceInstUsesWith(I, Constant::getNullValue(I.getType()));
386 return BinaryOperator::Create(I.getOpcode(), LHS->getOperand(0),
387 ConstantExpr::getMul(RHS, LHSRHS));
390 if (!RHS->isZero()) { // avoid X udiv 0
391 if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
392 if (Instruction *R = FoldOpIntoSelect(I, SI))
394 if (isa<PHINode>(Op0))
395 if (Instruction *NV = FoldOpIntoPhi(I))
400 // See if we can fold away this div instruction.
401 if (SimplifyDemandedInstructionBits(I))
404 // (X - (X rem Y)) / Y -> X / Y; usually originates as ((X / Y) * Y) / Y
405 Value *X = 0, *Z = 0;
406 if (match(Op0, m_Sub(m_Value(X), m_Value(Z)))) { // (X - Z) / Y; Y = Op1
407 bool isSigned = I.getOpcode() == Instruction::SDiv;
408 if ((isSigned && match(Z, m_SRem(m_Specific(X), m_Specific(Op1)))) ||
409 (!isSigned && match(Z, m_URem(m_Specific(X), m_Specific(Op1)))))
410 return BinaryOperator::Create(I.getOpcode(), X, Op1);
416 /// dyn_castZExtVal - Checks if V is a zext or constant that can
417 /// be truncated to Ty without losing bits.
418 static Value *dyn_castZExtVal(Value *V, const Type *Ty) {
419 if (ZExtInst *Z = dyn_cast<ZExtInst>(V)) {
420 if (Z->getSrcTy() == Ty)
421 return Z->getOperand(0);
422 } else if (ConstantInt *C = dyn_cast<ConstantInt>(V)) {
423 if (C->getValue().getActiveBits() <= cast<IntegerType>(Ty)->getBitWidth())
424 return ConstantExpr::getTrunc(C, Ty);
429 Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
430 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
432 if (Value *V = SimplifyUDivInst(Op0, Op1, TD))
433 return ReplaceInstUsesWith(I, V);
435 // Handle the integer div common cases
436 if (Instruction *Common = commonIDivTransforms(I))
439 if (ConstantInt *C = dyn_cast<ConstantInt>(Op1)) {
440 // X udiv 2^C -> X >> C
441 // Check to see if this is an unsigned division with an exact power of 2,
442 // if so, convert to a right shift.
443 if (C->getValue().isPowerOf2()) { // 0 not included in isPowerOf2
444 BinaryOperator *LShr =
445 BinaryOperator::CreateLShr(Op0,
446 ConstantInt::get(Op0->getType(), C->getValue().logBase2()));
447 if (I.isExact()) LShr->setIsExact();
451 // X udiv C, where C >= signbit
452 if (C->getValue().isNegative()) {
453 Value *IC = Builder->CreateICmpULT(Op0, C);
454 return SelectInst::Create(IC, Constant::getNullValue(I.getType()),
455 ConstantInt::get(I.getType(), 1));
459 // X udiv (C1 << N), where C1 is "1<<C2" --> X >> (N+C2)
460 { const APInt *CI; Value *N;
461 if (match(Op1, m_Shl(m_Power2(CI), m_Value(N)))) {
463 N = Builder->CreateAdd(N, ConstantInt::get(I.getType(), CI->logBase2()),
466 return BinaryOperator::CreateExactLShr(Op0, N);
467 return BinaryOperator::CreateLShr(Op0, N);
471 // udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
472 // where C1&C2 are powers of two.
473 { Value *Cond; const APInt *C1, *C2;
474 if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
475 // Construct the "on true" case of the select
476 Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t",
479 // Construct the "on false" case of the select
480 Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f",
483 // construct the select instruction and return it.
484 return SelectInst::Create(Cond, TSI, FSI);
488 // (zext A) udiv (zext B) --> zext (A udiv B)
489 if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
490 if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
491 return new ZExtInst(Builder->CreateUDiv(ZOp0->getOperand(0), ZOp1, "div",
498 Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
499 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
501 if (Value *V = SimplifySDivInst(Op0, Op1, TD))
502 return ReplaceInstUsesWith(I, V);
504 // Handle the integer div common cases
505 if (Instruction *Common = commonIDivTransforms(I))
508 if (ConstantInt *RHS = dyn_cast<ConstantInt>(Op1)) {
510 if (RHS->isAllOnesValue())
511 return BinaryOperator::CreateNeg(Op0);
513 // sdiv X, C --> ashr exact X, log2(C)
514 if (I.isExact() && RHS->getValue().isNonNegative() &&
515 RHS->getValue().isPowerOf2()) {
516 Value *ShAmt = llvm::ConstantInt::get(RHS->getType(),
517 RHS->getValue().exactLogBase2());
518 return BinaryOperator::CreateExactAShr(Op0, ShAmt, I.getName());
521 // -X/C --> X/-C provided the negation doesn't overflow.
522 if (SubOperator *Sub = dyn_cast<SubOperator>(Op0))
523 if (match(Sub->getOperand(0), m_Zero()) && Sub->hasNoSignedWrap())
524 return BinaryOperator::CreateSDiv(Sub->getOperand(1),
525 ConstantExpr::getNeg(RHS));
528 // If the sign bits of both operands are zero (i.e. we can prove they are
529 // unsigned inputs), turn this into a udiv.
530 if (I.getType()->isIntegerTy()) {
531 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
532 if (MaskedValueIsZero(Op0, Mask)) {
533 if (MaskedValueIsZero(Op1, Mask)) {
534 // X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
535 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
538 if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
539 // X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
540 // Safe because the only negative value (1 << Y) can take on is
541 // INT_MIN, and X sdiv INT_MIN == X udiv INT_MIN == 0 if X doesn't have
543 return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
551 Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
552 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
554 if (Value *V = SimplifyFDivInst(Op0, Op1, TD))
555 return ReplaceInstUsesWith(I, V);
557 if (ConstantFP *Op1C = dyn_cast<ConstantFP>(Op1)) {
558 const APFloat &Op1F = Op1C->getValueAPF();
560 // If the divisor has an exact multiplicative inverse we can turn the fdiv
561 // into a cheaper fmul.
562 APFloat Reciprocal(Op1F.getSemantics());
563 if (Op1F.getExactInverse(&Reciprocal)) {
564 ConstantFP *RFP = ConstantFP::get(Builder->getContext(), Reciprocal);
565 return BinaryOperator::CreateFMul(Op0, RFP);
572 /// This function implements the transforms common to both integer remainder
573 /// instructions (urem and srem). It is called by the visitors to those integer
574 /// remainder instructions.
575 /// @brief Common integer remainder transforms
576 Instruction *InstCombiner::commonIRemTransforms(BinaryOperator &I) {
577 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
579 // The RHS is known non-zero.
580 if (Value *V = simplifyValueKnownNonZero(I.getOperand(1), *this)) {
585 // Handle cases involving: rem X, (select Cond, Y, Z)
586 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
589 if (isa<ConstantInt>(Op1)) {
590 if (Instruction *Op0I = dyn_cast<Instruction>(Op0)) {
591 if (SelectInst *SI = dyn_cast<SelectInst>(Op0I)) {
592 if (Instruction *R = FoldOpIntoSelect(I, SI))
594 } else if (isa<PHINode>(Op0I)) {
595 if (Instruction *NV = FoldOpIntoPhi(I))
599 // See if we can fold away this rem instruction.
600 if (SimplifyDemandedInstructionBits(I))
608 Instruction *InstCombiner::visitURem(BinaryOperator &I) {
609 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
611 if (Value *V = SimplifyURemInst(Op0, Op1, TD))
612 return ReplaceInstUsesWith(I, V);
614 if (Instruction *common = commonIRemTransforms(I))
617 // X urem C^2 -> X and C-1
619 if (match(Op1, m_Power2(C)))
620 return BinaryOperator::CreateAnd(Op0,
621 ConstantInt::get(I.getType(), *C-1));
624 // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
625 if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
626 Constant *N1 = Constant::getAllOnesValue(I.getType());
627 Value *Add = Builder->CreateAdd(Op1, N1, "tmp");
628 return BinaryOperator::CreateAnd(Op0, Add);
631 // urem X, (select Cond, 2^C1, 2^C2) -->
632 // select Cond, (and X, C1-1), (and X, C2-1)
633 // when C1&C2 are powers of two.
634 { Value *Cond; const APInt *C1, *C2;
635 if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
636 Value *TrueAnd = Builder->CreateAnd(Op0, *C1-1, Op1->getName()+".t");
637 Value *FalseAnd = Builder->CreateAnd(Op0, *C2-1, Op1->getName()+".f");
638 return SelectInst::Create(Cond, TrueAnd, FalseAnd);
642 // (zext A) urem (zext B) --> zext (A urem B)
643 if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
644 if (Value *ZOp1 = dyn_castZExtVal(Op1, ZOp0->getSrcTy()))
645 return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1),
651 Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
652 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
654 if (Value *V = SimplifySRemInst(Op0, Op1, TD))
655 return ReplaceInstUsesWith(I, V);
657 // Handle the integer rem common cases
658 if (Instruction *Common = commonIRemTransforms(I))
661 if (Value *RHSNeg = dyn_castNegVal(Op1))
662 if (!isa<Constant>(RHSNeg) ||
663 (isa<ConstantInt>(RHSNeg) &&
664 cast<ConstantInt>(RHSNeg)->getValue().isStrictlyPositive())) {
666 Worklist.AddValue(I.getOperand(1));
667 I.setOperand(1, RHSNeg);
671 // If the sign bits of both operands are zero (i.e. we can prove they are
672 // unsigned inputs), turn this into a urem.
673 if (I.getType()->isIntegerTy()) {
674 APInt Mask(APInt::getSignBit(I.getType()->getPrimitiveSizeInBits()));
675 if (MaskedValueIsZero(Op1, Mask) && MaskedValueIsZero(Op0, Mask)) {
676 // X srem Y -> X urem Y, iff X and Y don't have sign bit set
677 return BinaryOperator::CreateURem(Op0, Op1, I.getName());
681 // If it's a constant vector, flip any negative values positive.
682 if (ConstantVector *RHSV = dyn_cast<ConstantVector>(Op1)) {
683 unsigned VWidth = RHSV->getNumOperands();
685 bool hasNegative = false;
686 for (unsigned i = 0; !hasNegative && i != VWidth; ++i)
687 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i)))
688 if (RHS->getValue().isNegative())
692 std::vector<Constant *> Elts(VWidth);
693 for (unsigned i = 0; i != VWidth; ++i) {
694 if (ConstantInt *RHS = dyn_cast<ConstantInt>(RHSV->getOperand(i))) {
695 if (RHS->getValue().isNegative())
696 Elts[i] = cast<ConstantInt>(ConstantExpr::getNeg(RHS));
702 Constant *NewRHSV = ConstantVector::get(Elts);
703 if (NewRHSV != RHSV) {
704 Worklist.AddValue(I.getOperand(1));
705 I.setOperand(1, NewRHSV);
714 Instruction *InstCombiner::visitFRem(BinaryOperator &I) {
715 Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
717 if (Value *V = SimplifyFRemInst(Op0, Op1, TD))
718 return ReplaceInstUsesWith(I, V);
720 // Handle cases involving: rem X, (select Cond, Y, Z)
721 if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))