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Refactored and updated SimplifyUsingDistributiveLaws() to

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* Find factorization opportunities using identity values.
 * Find factorization opportunities by treating shl(X, C) as mul (X, shl(C))
 * Keep NSW flag while simplifying instruction using factorization.

This fixes PR19263.

Differential Revision: http://reviews.llvm.org/D3799



git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@211261 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Dinesh Dwivedi
2014-06-19 08:29:18 +00:00
parent c28beb254d
commit 8317509052
3 changed files with 210 additions and 105 deletions
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52
lib/Transforms/InstCombine/InstCombineAddSub.cpp
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@ -865,30 +865,6 @@ Value *FAddCombine::createAddendVal
return createFMul(OpndVal, Coeff.getValue(Instr->getType()));
}
// dyn_castFoldableMul - If this value is a multiply that can be folded into
// other computations (because it has a constant operand), return the
// non-constant operand of the multiply, and set CST to point to the multiplier.
// Otherwise, return null.
//
static inline Value *dyn_castFoldableMul(Value *V, Constant *&CST) {
if (!V->hasOneUse() || !V->getType()->isIntOrIntVectorTy())
return nullptr;
Instruction *I = dyn_cast<Instruction>(V);
if (!I) return nullptr;
if (I->getOpcode() == Instruction::Mul)
if ((CST = dyn_cast<Constant>(I->getOperand(1))))
return I->getOperand(0);
if (I->getOpcode() == Instruction::Shl)
if ((CST = dyn_cast<Constant>(I->getOperand(1)))) {
// The multiplier is really 1 << CST.
CST = ConstantExpr::getShl(ConstantInt::get(V->getType(), 1), CST);
return I->getOperand(0);
}
return nullptr;
}
// If one of the operands only has one non-zero bit, and if the other
// operand has a known-zero bit in a more significant place than it (not
// including the sign bit) the ripple may go up to and fill the zero, but
@ -1089,24 +1065,6 @@ Instruction *InstCombiner::visitAdd(BinaryOperator &I) {
if (Value *V = dyn_castNegVal(RHS))
return BinaryOperator::CreateSub(LHS, V);
{
Constant *C2;
if (Value *X = dyn_castFoldableMul(LHS, C2)) {
if (X == RHS) // X*C + X --> X * (C+1)
return BinaryOperator::CreateMul(RHS, AddOne(C2));
// X*C1 + X*C2 --> X * (C1+C2)
Constant *C1;
if (X == dyn_castFoldableMul(RHS, C1))
return BinaryOperator::CreateMul(X, ConstantExpr::getAdd(C1, C2));
}
// X + X*C --> X * (C+1)
if (dyn_castFoldableMul(RHS, C2) == LHS)
return BinaryOperator::CreateMul(LHS, AddOne(C2));
}
// A+B --> A|B iff A and B have no bits set in common.
if (IntegerType *IT = dyn_cast<IntegerType>(I.getType())) {
APInt LHSKnownOne(IT->getBitWidth(), 0);
@ -1593,16 +1551,6 @@ Instruction *InstCombiner::visitSub(BinaryOperator &I) {
}
}
Constant *C1;
if (Value *X = dyn_castFoldableMul(Op0, C1)) {
if (X == Op1) // X*C - X --> X * (C-1)
return BinaryOperator::CreateMul(Op1, SubOne(C1));
Constant *C2; // X*C1 - X*C2 -> X * (C1-C2)
if (X == dyn_castFoldableMul(Op1, C2))
return BinaryOperator::CreateMul(X, ConstantExpr::getSub(C1, C2));
}
// Optimize pointer differences into the same array into a size. Consider:
// &A[10] - &A[0]: we should compile this to "10".
if (DL) {