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Fix constant fold of div by zero and rem by zero to match IEEE 754

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requirements. We must return NaN in some cases and correctly signed
infinity in other cases. Passes CFP2006 (not that that says much).


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@35277 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Reid Spencer 2007-03-23 05:33:23 +00:00
parent f62cc9f9e5
commit b8f1c1657f
1 changed files with 18 additions and 8 deletions
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26
lib/VMCore/ConstantFold.cpp
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@ -651,17 +651,27 @@ Constant *llvm::ConstantFoldBinaryInstruction(unsigned Opcode,
case Instruction::Mul:
return ConstantFP::get(CFP1->getType(), C1Val * C2Val);
case Instruction::FDiv:
if (CFP2->isExactlyValue(0.0))
return ConstantFP::get(CFP1->getType(),
std::numeric_limits<double>::infinity());
if (CFP2->isExactlyValue(-0.0))
return ConstantFP::get(CFP1->getType(),
-std::numeric_limits<double>::infinity());
if (CFP2->isExactlyValue(0.0) || CFP2->isExactlyValue(-0.0))
if (CFP1->isExactlyValue(0.0) || CFP1->isExactlyValue(-0.0))
// IEEE 754, Section 7.1, #4
return ConstantFP::get(CFP1->getType(),
std::numeric_limits<double>::quiet_NaN());
else if (CFP2->isExactlyValue(-0.0) || C1Val < 0.0)
// IEEE 754, Section 7.2, negative infinity case
return ConstantFP::get(CFP1->getType(),
-std::numeric_limits<double>::infinity());
else
// IEEE 754, Section 7.2, positive infinity case
return ConstantFP::get(CFP1->getType(),
std::numeric_limits<double>::infinity());
return ConstantFP::get(CFP1->getType(), C1Val / C2Val);
case Instruction::FRem:
if (CFP2->isNullValue())
return 0;
if (CFP2->isExactlyValue(0.0) || CFP2->isExactlyValue(-0.0))
// IEEE 754, Section 7.1, #5
return ConstantFP::get(CFP1->getType(),
std::numeric_limits<double>::quiet_NaN());
return ConstantFP::get(CFP1->getType(), std::fmod(C1Val, C2Val));
}
}
} else if (const ConstantVector *CP1 = dyn_cast<ConstantVector>(C1)) {