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Thread divisions over selects and phis. This doesn't fire much and has basically

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zero effect on the testsuite (it improves two Ada testcases).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@124496 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands 2011-01-28 18:50:50 +00:00
parent d11c57a937
commit a3e292c7e8
1 changed files with 19 additions and 9 deletions
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28
lib/Analysis/InstructionSimplify.cpp
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@ -759,6 +759,8 @@ static Value *SimplifyDiv(unsigned Opcode, Value *Op0, Value *Op1,
} }
} }
bool isSigned = Opcode == Instruction::SDiv;
// X / undef -> undef // X / undef -> undef
if (isa<UndefValue>(Op1)) if (isa<UndefValue>(Op1))
return Op1; return Op1;
@ -795,7 +797,6 @@ static Value *SimplifyDiv(unsigned Opcode, Value *Op0, Value *Op1,
if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1 if (Y != Op1) std::swap(X, Y); // Ensure expression is (X * Y) / Y, Y = Op1
BinaryOperator *Mul = dyn_cast<BinaryOperator>(Op0); BinaryOperator *Mul = dyn_cast<BinaryOperator>(Op0);
// If the Mul knows it does not overflow, then we are good to go. // If the Mul knows it does not overflow, then we are good to go.
bool isSigned = Opcode == Instruction::SDiv;
if ((isSigned && Mul->hasNoSignedWrap()) || if ((isSigned && Mul->hasNoSignedWrap()) ||
(!isSigned && Mul->hasNoUnsignedWrap())) (!isSigned && Mul->hasNoUnsignedWrap()))
return X; return X;
@ -805,6 +806,23 @@ static Value *SimplifyDiv(unsigned Opcode, Value *Op0, Value *Op1,
return X; return X;
} }
// (X rem Y) / Y -> 0
if ((isSigned && match(Op0, m_SRem(m_Value(), m_Specific(Op1)))) ||
(!isSigned && match(Op0, m_URem(m_Value(), m_Specific(Op1)))))
return Constant::getNullValue(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; return 0;
} }
@ -815,10 +833,6 @@ static Value *SimplifySDivInst(Value *Op0, Value *Op1, const TargetData *TD,
if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse)) if (Value *V = SimplifyDiv(Instruction::SDiv, Op0, Op1, TD, DT, MaxRecurse))
return V; return V;
// (X rem Y) / Y -> 0
if (match(Op0, m_SRem(m_Value(), m_Specific(Op1))))
return Constant::getNullValue(Op0->getType());
return 0; return 0;
} }
@ -834,10 +848,6 @@ static Value *SimplifyUDivInst(Value *Op0, Value *Op1, const TargetData *TD,
if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse)) if (Value *V = SimplifyDiv(Instruction::UDiv, Op0, Op1, TD, DT, MaxRecurse))
return V; return V;
// (X rem Y) / Y -> 0
if (match(Op0, m_URem(m_Value(), m_Specific(Op1))))
return Constant::getNullValue(Op0->getType());
return 0; return 0;
} }