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-rw-r--r--lib/Transforms/InstCombine/InstCombineMulDivRem.cpp205
1 files changed, 109 insertions, 96 deletions
diff --git a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
index 173f2bf..e36b762 100644
--- a/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
+++ b/lib/Transforms/InstCombine/InstCombineMulDivRem.cpp
@@ -28,7 +28,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
// if this is safe. For example, the use could be in dynamically unreached
// code.
if (!V->hasOneUse()) return 0;
-
+
bool MadeChange = false;
// ((1 << A) >>u B) --> (1 << (A-B))
@@ -41,7 +41,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
A = IC.Builder->CreateSub(A, B);
return IC.Builder->CreateShl(PowerOf2, A);
}
-
+
// (PowerOfTwo >>u B) --> isExact since shifting out the result would make it
// inexact. Similarly for <<.
if (BinaryOperator *I = dyn_cast<BinaryOperator>(V))
@@ -52,12 +52,12 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
I->setOperand(0, V2);
MadeChange = true;
}
-
+
if (I->getOpcode() == Instruction::LShr && !I->isExact()) {
I->setIsExact();
MadeChange = true;
}
-
+
if (I->getOpcode() == Instruction::Shl && !I->hasNoUnsignedWrap()) {
I->setHasNoUnsignedWrap();
MadeChange = true;
@@ -67,7 +67,7 @@ static Value *simplifyValueKnownNonZero(Value *V, InstCombiner &IC) {
// TODO: Lots more we could do here:
// If V is a phi node, we can call this on each of its operands.
// "select cond, X, 0" can simplify to "X".
-
+
return MadeChange ? V : 0;
}
@@ -84,17 +84,36 @@ static bool MultiplyOverflows(ConstantInt *C1, ConstantInt *C2, bool sign) {
LHSExt = LHSExt.zext(W * 2);
RHSExt = RHSExt.zext(W * 2);
}
-
+
APInt MulExt = LHSExt * RHSExt;
-
+
if (!sign)
return MulExt.ugt(APInt::getLowBitsSet(W * 2, W));
-
+
APInt Min = APInt::getSignedMinValue(W).sext(W * 2);
APInt Max = APInt::getSignedMaxValue(W).sext(W * 2);
return MulExt.slt(Min) || MulExt.sgt(Max);
}
+/// \brief A helper routine of InstCombiner::visitMul().
+///
+/// If C is a vector of known powers of 2, then this function returns
+/// a new vector obtained from C replacing each element with its logBase2.
+/// Return a null pointer otherwise.
+static Constant *getLogBase2Vector(ConstantDataVector *CV) {
+ const APInt *IVal;
+ SmallVector<Constant *, 4> Elts;
+
+ for (unsigned I = 0, E = CV->getNumElements(); I != E; ++I) {
+ Constant *Elt = CV->getElementAsConstant(I);
+ if (!match(Elt, m_APInt(IVal)) || !IVal->isPowerOf2())
+ return 0;
+ Elts.push_back(ConstantInt::get(Elt->getType(), IVal->logBase2()));
+ }
+
+ return ConstantVector::get(Elts);
+}
+
Instruction *InstCombiner::visitMul(BinaryOperator &I) {
bool Changed = SimplifyAssociativeOrCommutative(I);
Value *Op0 = I.getOperand(0), *Op1 = I.getOperand(1);
@@ -107,25 +126,38 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
if (match(Op1, m_AllOnes())) // X * -1 == 0 - X
return BinaryOperator::CreateNeg(Op0, I.getName());
-
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
-
- // ((X << C1)*C2) == (X * (C2 << C1))
- if (BinaryOperator *SI = dyn_cast<BinaryOperator>(Op0))
- if (SI->getOpcode() == Instruction::Shl)
- if (Constant *ShOp = dyn_cast<Constant>(SI->getOperand(1)))
- return BinaryOperator::CreateMul(SI->getOperand(0),
- ConstantExpr::getShl(CI, ShOp));
-
- const APInt &Val = CI->getValue();
- if (Val.isPowerOf2()) { // Replace X*(2^C) with X << C
- Constant *NewCst = ConstantInt::get(Op0->getType(), Val.logBase2());
- BinaryOperator *Shl = BinaryOperator::CreateShl(Op0, NewCst);
- if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap();
- if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap();
- return Shl;
+
+ // Also allow combining multiply instructions on vectors.
+ {
+ Value *NewOp;
+ Constant *C1, *C2;
+ const APInt *IVal;
+ if (match(&I, m_Mul(m_Shl(m_Value(NewOp), m_Constant(C2)),
+ m_Constant(C1))) &&
+ match(C1, m_APInt(IVal)))
+ // ((X << C1)*C2) == (X * (C2 << C1))
+ return BinaryOperator::CreateMul(NewOp, ConstantExpr::getShl(C1, C2));
+
+ if (match(&I, m_Mul(m_Value(NewOp), m_Constant(C1)))) {
+ Constant *NewCst = 0;
+ if (match(C1, m_APInt(IVal)) && IVal->isPowerOf2())
+ // Replace X*(2^C) with X << C, where C is either a scalar or a splat.
+ NewCst = ConstantInt::get(NewOp->getType(), IVal->logBase2());
+ else if (ConstantDataVector *CV = dyn_cast<ConstantDataVector>(C1))
+ // Replace X*(2^C) with X << C, where C is a vector of known
+ // constant powers of 2.
+ NewCst = getLogBase2Vector(CV);
+
+ if (NewCst) {
+ BinaryOperator *Shl = BinaryOperator::CreateShl(NewOp, NewCst);
+ if (I.hasNoSignedWrap()) Shl->setHasNoSignedWrap();
+ if (I.hasNoUnsignedWrap()) Shl->setHasNoUnsignedWrap();
+ return Shl;
+ }
}
-
+ }
+
+ if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1)) {
// Canonicalize (X+C1)*CI -> X*CI+C1*CI.
{ Value *X; ConstantInt *C1;
if (Op0->hasOneUse() &&
@@ -158,9 +190,9 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
}
}
}
-
+
// Simplify mul instructions with a constant RHS.
- if (isa<Constant>(Op1)) {
+ if (isa<Constant>(Op1)) {
// Try to fold constant mul into select arguments.
if (SelectInst *SI = dyn_cast<SelectInst>(Op0))
if (Instruction *R = FoldOpIntoSelect(I, SI))
@@ -181,7 +213,7 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
Value *Op1C = Op1;
BinaryOperator *BO = dyn_cast<BinaryOperator>(Op0);
if (!BO ||
- (BO->getOpcode() != Instruction::UDiv &&
+ (BO->getOpcode() != Instruction::UDiv &&
BO->getOpcode() != Instruction::SDiv)) {
Op1C = Op0;
BO = dyn_cast<BinaryOperator>(Op1);
@@ -227,14 +259,14 @@ Instruction *InstCombiner::visitMul(BinaryOperator &I) {
if (match(Op1, m_Shl(m_One(), m_Value(Y))))
return BinaryOperator::CreateShl(Op0, Y);
}
-
+
// If one of the operands of the multiply is a cast from a boolean value, then
// we know the bool is either zero or one, so this is a 'masking' multiply.
// X * Y (where Y is 0 or 1) -> X & (0-Y)
if (!I.getType()->isVectorTy()) {
// -2 is "-1 << 1" so it is all bits set except the low one.
APInt Negative2(I.getType()->getPrimitiveSizeInBits(), (uint64_t)-2, true);
-
+
Value *BoolCast = 0, *OtherOp = 0;
if (MaskedValueIsZero(Op0, Negative2))
BoolCast = Op0, OtherOp = Op1;
@@ -280,7 +312,7 @@ static void detectLog2OfHalf(Value *&Op, Value *&Y, IntrinsicInst *&Log2) {
return;
if (I->getOpcode() != Instruction::FMul || !I->hasUnsafeAlgebra())
return;
-
+
ConstantFP *CFP = dyn_cast<ConstantFP>(I->getOperand(0));
if (CFP && CFP->isExactlyValue(0.5)) {
Y = I->getOperand(1);
@@ -289,14 +321,14 @@ static void detectLog2OfHalf(Value *&Op, Value *&Y, IntrinsicInst *&Log2) {
CFP = dyn_cast<ConstantFP>(I->getOperand(1));
if (CFP && CFP->isExactlyValue(0.5))
Y = I->getOperand(0);
-}
+}
/// Helper function of InstCombiner::visitFMul(BinaryOperator(). It returns
/// true iff the given value is FMul or FDiv with one and only one operand
/// being a normal constant (i.e. not Zero/NaN/Infinity).
static bool isFMulOrFDivWithConstant(Value *V) {
Instruction *I = dyn_cast<Instruction>(V);
- if (!I || (I->getOpcode() != Instruction::FMul &&
+ if (!I || (I->getOpcode() != Instruction::FMul &&
I->getOpcode() != Instruction::FDiv))
return false;
@@ -318,10 +350,10 @@ static bool isNormalFp(const ConstantFP *C) {
/// foldFMulConst() is a helper routine of InstCombiner::visitFMul().
/// The input \p FMulOrDiv is a FMul/FDiv with one and only one operand
/// being a constant (i.e. isFMulOrFDivWithConstant(FMulOrDiv) == true).
-/// This function is to simplify "FMulOrDiv * C" and returns the
+/// This function is to simplify "FMulOrDiv * C" and returns the
/// resulting expression. Note that this function could return NULL in
/// case the constants cannot be folded into a normal floating-point.
-///
+///
Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, ConstantFP *C,
Instruction *InsertBefore) {
assert(isFMulOrFDivWithConstant(FMulOrDiv) && "V is invalid");
@@ -351,7 +383,7 @@ Value *InstCombiner::foldFMulConst(Instruction *FMulOrDiv, ConstantFP *C,
if (isNormalFp(F)) {
R = BinaryOperator::CreateFMul(Opnd0, F);
} else {
- // (X / C1) * C => X / (C1/C)
+ // (X / C1) * C => X / (C1/C)
Constant *F = ConstantExpr::getFDiv(C1, C);
if (isNormalFp(cast<ConstantFP>(F)))
R = BinaryOperator::CreateFDiv(Opnd0, F);
@@ -415,13 +447,13 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
if (C0) {
std::swap(C0, C1);
std::swap(Opnd0, Opnd1);
- Swap = true;
+ Swap = true;
}
if (C1 && C1->getValueAPF().isNormal() &&
isFMulOrFDivWithConstant(Opnd0)) {
Value *M1 = ConstantExpr::getFMul(C1, C);
- Value *M0 = isNormalFp(cast<ConstantFP>(M1)) ?
+ Value *M0 = isNormalFp(cast<ConstantFP>(M1)) ?
foldFMulConst(cast<Instruction>(Opnd0), C, &I) :
0;
if (M0 && M1) {
@@ -495,7 +527,7 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
}
// (X*Y) * X => (X*X) * Y where Y != X
- // The purpose is two-fold:
+ // The purpose is two-fold:
// 1) to form a power expression (of X).
// 2) potentially shorten the critical path: After transformation, the
// latency of the instruction Y is amortized by the expression of X*X,
@@ -537,7 +569,7 @@ Instruction *InstCombiner::visitFMul(BinaryOperator &I) {
/// instruction.
bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
SelectInst *SI = cast<SelectInst>(I.getOperand(1));
-
+
// div/rem X, (Cond ? 0 : Y) -> div/rem X, Y
int NonNullOperand = -1;
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(1)))
@@ -547,36 +579,36 @@ bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
if (Constant *ST = dyn_cast<Constant>(SI->getOperand(2)))
if (ST->isNullValue())
NonNullOperand = 1;
-
+
if (NonNullOperand == -1)
return false;
-
+
Value *SelectCond = SI->getOperand(0);
-
+
// Change the div/rem to use 'Y' instead of the select.
I.setOperand(1, SI->getOperand(NonNullOperand));
-
+
// Okay, we know we replace the operand of the div/rem with 'Y' with no
// problem. However, the select, or the condition of the select may have
// multiple uses. Based on our knowledge that the operand must be non-zero,
// propagate the known value for the select into other uses of it, and
// propagate a known value of the condition into its other users.
-
+
// If the select and condition only have a single use, don't bother with this,
// early exit.
if (SI->use_empty() && SelectCond->hasOneUse())
return true;
-
+
// Scan the current block backward, looking for other uses of SI.
BasicBlock::iterator BBI = &I, BBFront = I.getParent()->begin();
-
+
while (BBI != BBFront) {
--BBI;
// If we found a call to a function, we can't assume it will return, so
// information from below it cannot be propagated above it.
if (isa<CallInst>(BBI) && !isa<IntrinsicInst>(BBI))
break;
-
+
// Replace uses of the select or its condition with the known values.
for (Instruction::op_iterator I = BBI->op_begin(), E = BBI->op_end();
I != E; ++I) {
@@ -584,22 +616,21 @@ bool InstCombiner::SimplifyDivRemOfSelect(BinaryOperator &I) {
*I = SI->getOperand(NonNullOperand);
Worklist.Add(BBI);
} else if (*I == SelectCond) {
- *I = NonNullOperand == 1 ? ConstantInt::getTrue(BBI->getContext()) :
- ConstantInt::getFalse(BBI->getContext());
+ *I = Builder->getInt1(NonNullOperand == 1);
Worklist.Add(BBI);
}
}
-
+
// If we past the instruction, quit looking for it.
if (&*BBI == SI)
SI = 0;
if (&*BBI == SelectCond)
SelectCond = 0;
-
+
// If we ran out of things to eliminate, break out of the loop.
if (SelectCond == 0 && SI == 0)
break;
-
+
}
return true;
}
@@ -617,7 +648,7 @@ Instruction *InstCombiner::commonIDivTransforms(BinaryOperator &I) {
I.setOperand(1, V);
return &I;
}
-
+
// Handle cases involving: [su]div X, (select Cond, Y, Z)
// This does not apply for fdiv.
if (isa<SelectInst>(Op1) && SimplifyDivRemOfSelect(I))
@@ -683,16 +714,16 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
// Handle the integer div common cases
if (Instruction *Common = commonIDivTransforms(I))
return Common;
-
- {
+
+ {
// X udiv 2^C -> X >> C
// Check to see if this is an unsigned division with an exact power of 2,
// if so, convert to a right shift.
const APInt *C;
if (match(Op1, m_Power2(C))) {
BinaryOperator *LShr =
- BinaryOperator::CreateLShr(Op0,
- ConstantInt::get(Op0->getType(),
+ BinaryOperator::CreateLShr(Op0,
+ ConstantInt::get(Op0->getType(),
C->logBase2()));
if (I.isExact()) LShr->setIsExact();
return LShr;
@@ -732,7 +763,7 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
return BinaryOperator::CreateLShr(Op0, N);
}
}
-
+
// udiv X, (Select Cond, C1, C2) --> Select Cond, (shr X, C1), (shr X, C2)
// where C1&C2 are powers of two.
{ Value *Cond; const APInt *C1, *C2;
@@ -740,11 +771,11 @@ Instruction *InstCombiner::visitUDiv(BinaryOperator &I) {
// Construct the "on true" case of the select
Value *TSI = Builder->CreateLShr(Op0, C1->logBase2(), Op1->getName()+".t",
I.isExact());
-
+
// Construct the "on false" case of the select
Value *FSI = Builder->CreateLShr(Op0, C2->logBase2(), Op1->getName()+".f",
I.isExact());
-
+
// construct the select instruction and return it.
return SelectInst::Create(Cond, TSI, FSI);
}
@@ -799,7 +830,7 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
// X sdiv Y -> X udiv Y, iff X and Y don't have sign bit set
return BinaryOperator::CreateUDiv(Op0, Op1, I.getName());
}
-
+
if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
// X sdiv (1 << Y) -> X udiv (1 << Y) ( -> X u>> Y)
// Safe because the only negative value (1 << Y) can take on is
@@ -809,15 +840,15 @@ Instruction *InstCombiner::visitSDiv(BinaryOperator &I) {
}
}
}
-
+
return 0;
}
/// CvtFDivConstToReciprocal tries to convert X/C into X*1/C if C not a special
/// FP value and:
-/// 1) 1/C is exact, or
+/// 1) 1/C is exact, or
/// 2) reciprocal is allowed.
-/// If the convertion was successful, the simplified expression "X * 1/C" is
+/// If the conversion was successful, the simplified expression "X * 1/C" is
/// returned; otherwise, NULL is returned.
///
static Instruction *CvtFDivConstToReciprocal(Value *Dividend,
@@ -826,7 +857,7 @@ static Instruction *CvtFDivConstToReciprocal(Value *Dividend,
const APFloat &FpVal = Divisor->getValueAPF();
APFloat Reciprocal(FpVal.getSemantics());
bool Cvt = FpVal.getExactInverse(&Reciprocal);
-
+
if (!Cvt && AllowReciprocal && FpVal.isNormal()) {
Reciprocal = APFloat(FpVal.getSemantics(), 1.0f);
(void)Reciprocal.divide(FpVal, APFloat::rmNearestTiesToEven);
@@ -870,10 +901,10 @@ Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
Constant *C = ConstantExpr::getFMul(C1, C2);
const APFloat &F = cast<ConstantFP>(C)->getValueAPF();
if (F.isNormal() && !F.isDenormal()) {
- Res = CvtFDivConstToReciprocal(X, cast<ConstantFP>(C),
+ Res = CvtFDivConstToReciprocal(X, cast<ConstantFP>(C),
AllowReciprocal);
if (!Res)
- Res = BinaryOperator::CreateFDiv(X, C);
+ Res = BinaryOperator::CreateFDiv(X, C);
}
}
@@ -911,7 +942,7 @@ Instruction *InstCombiner::visitFDiv(BinaryOperator &I) {
if (Fold) {
const APFloat &FoldC = cast<ConstantFP>(Fold)->getValueAPF();
if (FoldC.isNormal() && !FoldC.isDenormal()) {
- Instruction *R = CreateDiv ?
+ Instruction *R = CreateDiv ?
BinaryOperator::CreateFDiv(Fold, X) :
BinaryOperator::CreateFMul(X, Fold);
R->setFastMathFlags(I.getFastMathFlags());
@@ -997,31 +1028,6 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
if (Instruction *common = commonIRemTransforms(I))
return common;
-
- // X urem C^2 -> X and C-1
- { const APInt *C;
- if (match(Op1, m_Power2(C)))
- return BinaryOperator::CreateAnd(Op0,
- ConstantInt::get(I.getType(), *C-1));
- }
-
- // Turn A % (C << N), where C is 2^k, into A & ((C << N)-1)
- if (match(Op1, m_Shl(m_Power2(), m_Value()))) {
- Constant *N1 = Constant::getAllOnesValue(I.getType());
- Value *Add = Builder->CreateAdd(Op1, N1);
- return BinaryOperator::CreateAnd(Op0, Add);
- }
-
- // urem X, (select Cond, 2^C1, 2^C2) -->
- // select Cond, (and X, C1-1), (and X, C2-1)
- // when C1&C2 are powers of two.
- { Value *Cond; const APInt *C1, *C2;
- if (match(Op1, m_Select(m_Value(Cond), m_Power2(C1), m_Power2(C2)))) {
- Value *TrueAnd = Builder->CreateAnd(Op0, *C1-1, Op1->getName()+".t");
- Value *FalseAnd = Builder->CreateAnd(Op0, *C2-1, Op1->getName()+".f");
- return SelectInst::Create(Cond, TrueAnd, FalseAnd);
- }
- }
// (zext A) urem (zext B) --> zext (A urem B)
if (ZExtInst *ZOp0 = dyn_cast<ZExtInst>(Op0))
@@ -1029,6 +1035,13 @@ Instruction *InstCombiner::visitURem(BinaryOperator &I) {
return new ZExtInst(Builder->CreateURem(ZOp0->getOperand(0), ZOp1),
I.getType());
+ // X urem Y -> X and Y-1, where Y is a power of 2,
+ if (isKnownToBeAPowerOfTwo(Op1, /*OrZero*/true)) {
+ Constant *N1 = Constant::getAllOnesValue(I.getType());
+ Value *Add = Builder->CreateAdd(Op1, N1);
+ return BinaryOperator::CreateAnd(Op0, Add);
+ }
+
return 0;
}
@@ -1041,7 +1054,7 @@ Instruction *InstCombiner::visitSRem(BinaryOperator &I) {
// Handle the integer rem common cases
if (Instruction *Common = commonIRemTransforms(I))
return Common;
-
+
if (Value *RHSNeg = dyn_castNegVal(Op1))
if (!isa<Constant>(RHSNeg) ||
(isa<ConstantInt>(RHSNeg) &&
generated by cgit v1.1 at 2025-07-04 06:20:32 +0000