if (Op0 == Op1)
return Constant::getNullValue(Op0->getType());
- // (X + Y) - Y -> X
- // (Y + X) - Y -> X
+ // (X*2) - X -> X
+ // (X<<1) - X -> X
Value *X = 0;
- if (match(Op0, m_Add(m_Value(X), m_Specific(Op1))) ||
- match(Op0, m_Add(m_Specific(Op1), m_Value(X))))
- return X;
+ if (match(Op0, m_Mul(m_Specific(Op1), m_ConstantInt<2>())) ||
+ match(Op0, m_Shl(m_Specific(Op1), m_One())))
+ return Op1;
- /// i1 sub -> xor.
- if (MaxRecurse && Op0->getType()->isIntegerTy(1))
- if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
- return V;
+ // (X + Y) - Z -> X + (Y - Z) or Y + (X - Z) if everything simplifies.
+ // For example, (X + Y) - Y -> X; (Y + X) - Y -> X
+ Value *Y = 0, *Z = Op1;
+ if (MaxRecurse && match(Op0, m_Add(m_Value(X), m_Value(Y)))) { // (X + Y) - Z
+ // See if "V === Y - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, Y, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "X + V" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, X, V, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ // See if "V === X - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "Y + V" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, Y, V, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ }
+
+ // X - (Y + Z) -> (X - Y) - Z or (X - Z) - Y if everything simplifies.
+ // For example, X - (X + 1) -> -1
+ X = Op0;
+ if (MaxRecurse && match(Op1, m_Add(m_Value(Y), m_Value(Z)))) { // X - (Y + Z)
+ // See if "V === X - Y" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Y, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V - Z" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Sub, V, Z, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ // See if "V === X - Z" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, X, Z, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V - Y" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Sub, V, Y, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
+ }
+
+ // Z - (X - Y) -> (Z - X) + Y if everything simplifies.
+ // For example, X - (X - Y) -> Y.
+ Z = Op0;
+ if (MaxRecurse && match(Op1, m_Sub(m_Value(X), m_Value(Y)))) // Z - (X - Y)
+ // See if "V === Z - X" simplifies.
+ if (Value *V = SimplifyBinOp(Instruction::Sub, Z, X, TD, DT, MaxRecurse-1))
+ // It does! Now see if "V + Y" simplifies.
+ if (Value *W = SimplifyBinOp(Instruction::Add, V, Y, TD, DT,
+ MaxRecurse-1)) {
+ // It does, we successfully reassociated!
+ ++NumReassoc;
+ return W;
+ }
// Mul distributes over Sub. Try some generic simplifications based on this.
if (Value *V = FactorizeBinOp(Instruction::Sub, Op0, Op1, Instruction::Mul,
TD, DT, MaxRecurse))
return V;
+ // i1 sub -> xor.
+ if (MaxRecurse && Op0->getType()->isIntegerTy(1))
+ if (Value *V = SimplifyXorInst(Op0, Op1, TD, DT, MaxRecurse-1))
+ return V;
+
// Threading Sub over selects and phi nodes is pointless, so don't bother.
// Threading over the select in "A - select(cond, B, C)" means evaluating
// "A-B" and "A-C" and seeing if they are equal; but they are equal if and
return ::SimplifyMulInst(Op0, Op1, TD, DT, RecursionLimit);
}
-/// SimplifyShlInst - Given operands for an Shl, see if we can
+/// SimplifyShift - Given operands for an Shl, LShr or AShr, see if we can
/// fold the result. If not, this returns null.
-static Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
- const DominatorTree *DT, unsigned MaxRecurse) {
+static Value *SimplifyShift(unsigned Opcode, Value *Op0, Value *Op1,
+ const TargetData *TD, const DominatorTree *DT,
+ unsigned MaxRecurse) {
if (Constant *C0 = dyn_cast<Constant>(Op0)) {
if (Constant *C1 = dyn_cast<Constant>(Op1)) {
Constant *Ops[] = { C0, C1 };
- return ConstantFoldInstOperands(Instruction::Shl, C0->getType(), Ops, 2,
- TD);
+ return ConstantFoldInstOperands(Opcode, C0->getType(), Ops, 2, TD);
}
}
- // 0 << X -> 0
+ // 0 shift by X -> 0
if (match(Op0, m_Zero()))
return Op0;
- // X << 0 -> X
+ // X shift by 0 -> X
if (match(Op1, m_Zero()))
return Op0;
- // undef << X -> 0
- if (isa<UndefValue>(Op0))
- return Constant::getNullValue(Op0->getType());
-
- // X << undef -> undef because it may shift by the bitwidth.
+ // X shift by undef -> undef because it may shift by the bitwidth.
if (isa<UndefValue>(Op1))
return Op1;
Op0->getType()->getScalarSizeInBits())
return UndefValue::get(Op0->getType());
+ // If the operation is with the result of a select instruction, check whether
+ // operating on either branch of the select always yields the same value.
+ if (isa<SelectInst>(Op0) || isa<SelectInst>(Op1))
+ if (Value *V = ThreadBinOpOverSelect(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // If the operation is with the result of a phi instruction, check whether
+ // operating on all incoming values of the phi always yields the same value.
+ if (isa<PHINode>(Op0) || isa<PHINode>(Op1))
+ if (Value *V = ThreadBinOpOverPHI(Opcode, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ return 0;
+}
+
+/// SimplifyShlInst - Given operands for an Shl, see if we can
+/// fold the result. If not, this returns null.
+static Value *SimplifyShlInst(Value *Op0, Value *Op1, const TargetData *TD,
+ const DominatorTree *DT, unsigned MaxRecurse) {
+ if (Value *V = SimplifyShift(Instruction::Shl, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
+
+ // undef << X -> 0
+ if (isa<UndefValue>(Op0))
+ return Constant::getNullValue(Op0->getType());
+
return 0;
}
/// fold the result. If not, this returns null.
static Value *SimplifyLShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
- if (Constant *C0 = dyn_cast<Constant>(Op0)) {
- if (Constant *C1 = dyn_cast<Constant>(Op1)) {
- Constant *Ops[] = { C0, C1 };
- return ConstantFoldInstOperands(Instruction::LShr, C0->getType(), Ops, 2,
- TD);
- }
- }
-
- // 0 >> X -> 0
- if (match(Op0, m_Zero()))
- return Op0;
+ if (Value *V = SimplifyShift(Instruction::LShr, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
// undef >>l X -> 0
if (isa<UndefValue>(Op0))
return Constant::getNullValue(Op0->getType());
- // X >> 0 -> X
- if (match(Op1, m_Zero()))
- return Op0;
-
- // X >> undef -> undef because it may shift by the bitwidth.
- if (isa<UndefValue>(Op1))
- return Op1;
-
- // Shifting by the bitwidth or more is undefined.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
- if (CI->getValue().getLimitedValue() >=
- Op0->getType()->getScalarSizeInBits())
- return UndefValue::get(Op0->getType());
-
return 0;
}
/// fold the result. If not, this returns null.
static Value *SimplifyAShrInst(Value *Op0, Value *Op1, const TargetData *TD,
const DominatorTree *DT, unsigned MaxRecurse) {
- if (Constant *C0 = dyn_cast<Constant>(Op0)) {
- if (Constant *C1 = dyn_cast<Constant>(Op1)) {
- Constant *Ops[] = { C0, C1 };
- return ConstantFoldInstOperands(Instruction::AShr, C0->getType(), Ops, 2,
- TD);
- }
- }
-
- // 0 >> X -> 0
- if (match(Op0, m_Zero()))
- return Op0;
+ if (Value *V = SimplifyShift(Instruction::AShr, Op0, Op1, TD, DT, MaxRecurse))
+ return V;
// all ones >>a X -> all ones
if (match(Op0, m_AllOnes()))
if (isa<UndefValue>(Op0))
return Constant::getAllOnesValue(Op0->getType());
- // X >> 0 -> X
- if (match(Op1, m_Zero()))
- return Op0;
-
- // X >> undef -> undef because it may shift by the bitwidth.
- if (isa<UndefValue>(Op1))
- return Op1;
-
- // Shifting by the bitwidth or more is undefined.
- if (ConstantInt *CI = dyn_cast<ConstantInt>(Op1))
- if (CI->getValue().getLimitedValue() >=
- Op0->getType()->getScalarSizeInBits())
- return UndefValue::get(Op0->getType());
-
return 0;
}
// We already know that LHS != LHS.
return ConstantInt::get(ITy, CmpInst::isFalseWhenEqual(Pred));
+ // Compare of cast, for example (zext X) != 0 -> X != 0
+ if (isa<CastInst>(LHS) && (isa<Constant>(RHS) || isa<CastInst>(RHS))) {
+ Instruction *LI = cast<CastInst>(LHS);
+ Value *SrcOp = LI->getOperand(0);
+ const Type *SrcTy = SrcOp->getType();
+ const Type *DstTy = LI->getType();
+
+ // Turn icmp (ptrtoint x), (ptrtoint/constant) into a compare of the input
+ // if the integer type is the same size as the pointer type.
+ if (MaxRecurse && TD && isa<PtrToIntInst>(LI) &&
+ TD->getPointerSizeInBits() == DstTy->getPrimitiveSizeInBits()) {
+ if (Constant *RHSC = dyn_cast<Constant>(RHS)) {
+ // Transfer the cast to the constant.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp,
+ ConstantExpr::getIntToPtr(RHSC, SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ } else if (PtrToIntInst *RI = dyn_cast<PtrToIntInst>(RHS)) {
+ if (RI->getOperand(0)->getType() == SrcTy)
+ // Compare without the cast.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
+ TD, DT, MaxRecurse-1))
+ return V;
+ }
+ }
+
+ if (isa<ZExtInst>(LHS)) {
+ // Turn icmp (zext X), (zext Y) into a compare of X and Y if they have the
+ // same type.
+ if (ZExtInst *RI = dyn_cast<ZExtInst>(RHS)) {
+ if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
+ // Compare X and Y. Note that signed predicates become unsigned.
+ if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
+ SrcOp, RI->getOperand(0), TD, DT,
+ MaxRecurse-1))
+ return V;
+ }
+ // Turn icmp (zext X), Cst into a compare of X and Cst if Cst is extended
+ // too. If not, then try to deduce the result of the comparison.
+ else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DstTy.
+ Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *RExt = ConstantExpr::getCast(CastInst::ZExt, Trunc, DstTy);
+
+ // If the re-extended constant didn't change then this is effectively
+ // also a case of comparing two zero-extended values.
+ if (RExt == CI && MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::getUnsignedPredicate(Pred),
+ SrcOp, Trunc, TD, DT, MaxRecurse-1))
+ return V;
+
+ // Otherwise the upper bits of LHS are zero while RHS has a non-zero bit
+ // there. Use this to work out the result of the comparison.
+ if (RExt != CI) {
+ switch (Pred) {
+ default:
+ assert(false && "Unknown ICmp predicate!");
+ // LHS <u RHS.
+ case ICmpInst::ICMP_EQ:
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE:
+ return ConstantInt::getFalse(CI->getContext());
+
+ case ICmpInst::ICMP_NE:
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ return ConstantInt::getTrue(CI->getContext());
+
+ // LHS is non-negative. If RHS is negative then LHS >s LHS. If RHS
+ // is non-negative then LHS <s RHS.
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getTrue(CI->getContext()) :
+ ConstantInt::getFalse(CI->getContext());
+
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getFalse(CI->getContext()) :
+ ConstantInt::getTrue(CI->getContext());
+ }
+ }
+ }
+ }
+
+ if (isa<SExtInst>(LHS)) {
+ // Turn icmp (sext X), (sext Y) into a compare of X and Y if they have the
+ // same type.
+ if (SExtInst *RI = dyn_cast<SExtInst>(RHS)) {
+ if (MaxRecurse && SrcTy == RI->getOperand(0)->getType())
+ // Compare X and Y. Note that the predicate does not change.
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, RI->getOperand(0),
+ TD, DT, MaxRecurse-1))
+ return V;
+ }
+ // Turn icmp (sext X), Cst into a compare of X and Cst if Cst is extended
+ // too. If not, then try to deduce the result of the comparison.
+ else if (ConstantInt *CI = dyn_cast<ConstantInt>(RHS)) {
+ // Compute the constant that would happen if we truncated to SrcTy then
+ // reextended to DstTy.
+ Constant *Trunc = ConstantExpr::getTrunc(CI, SrcTy);
+ Constant *RExt = ConstantExpr::getCast(CastInst::SExt, Trunc, DstTy);
+
+ // If the re-extended constant didn't change then this is effectively
+ // also a case of comparing two sign-extended values.
+ if (RExt == CI && MaxRecurse)
+ if (Value *V = SimplifyICmpInst(Pred, SrcOp, Trunc, TD, DT,
+ MaxRecurse-1))
+ return V;
+
+ // Otherwise the upper bits of LHS are all equal, while RHS has varying
+ // bits there. Use this to work out the result of the comparison.
+ if (RExt != CI) {
+ switch (Pred) {
+ default:
+ assert(false && "Unknown ICmp predicate!");
+ case ICmpInst::ICMP_EQ:
+ return ConstantInt::getFalse(CI->getContext());
+ case ICmpInst::ICMP_NE:
+ return ConstantInt::getTrue(CI->getContext());
+
+ // If RHS is non-negative then LHS <s RHS. If RHS is negative then
+ // LHS >s RHS.
+ case ICmpInst::ICMP_SGT:
+ case ICmpInst::ICMP_SGE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getTrue(CI->getContext()) :
+ ConstantInt::getFalse(CI->getContext());
+ case ICmpInst::ICMP_SLT:
+ case ICmpInst::ICMP_SLE:
+ return CI->getValue().isNegative() ?
+ ConstantInt::getFalse(CI->getContext()) :
+ ConstantInt::getTrue(CI->getContext());
+
+ // If LHS is non-negative then LHS <u RHS. If LHS is negative then
+ // LHS >u RHS.
+ case ICmpInst::ICMP_UGT:
+ case ICmpInst::ICMP_UGE:
+ // Comparison is true iff the LHS <s 0.
+ if (MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SLT, SrcOp,
+ Constant::getNullValue(SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ break;
+ case ICmpInst::ICMP_ULT:
+ case ICmpInst::ICMP_ULE:
+ // Comparison is true iff the LHS >=s 0.
+ if (MaxRecurse)
+ if (Value *V = SimplifyICmpInst(ICmpInst::ICMP_SGE, SrcOp,
+ Constant::getNullValue(SrcTy),
+ TD, DT, MaxRecurse-1))
+ return V;
+ break;
+ }
+ }
+ }
+ }
+ }
+
// If the comparison is with the result of a select instruction, check whether
// comparing with either branch of the select always yields the same value.
if (isa<SelectInst>(LHS) || isa<SelectInst>(RHS))
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