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Fold icmp ugt (udiv X, Y), X to false. Spotted by my super-optimizer

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in 186.crafty.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@143209 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Duncan Sands
2011-10-28 18:17:44 +00:00
parent cb9fed6655
commit c65c747bc4
2 changed files with 36 additions and 0 deletions
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12
lib/Analysis/InstructionSimplify.cpp
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@@ -1574,6 +1574,9 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
// 'srem x, CI2' produces (-|CI2|, |CI2|).
Upper = CI2->getValue().abs();
Lower = (-Upper) + 1;
} else if (match(LHS, m_UDiv(m_ConstantInt(CI2), m_Value()))) {
// 'udiv CI2, x' produces [0, CI2].
Upper = CI2->getValue();
} else if (match(LHS, m_UDiv(m_Value(), m_ConstantInt(CI2)))) {
// 'udiv x, CI2' produces [0, UINT_MAX / CI2].
APInt NegOne = APInt::getAllOnesValue(Width);
@@ -1880,6 +1883,15 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
}
}
// x udiv y <=u x.
if (LBO && match(LBO, m_UDiv(m_Specific(RHS), m_Value()))) {
// icmp pred (X /u Y), X
if (Pred == ICmpInst::ICMP_UGT)
return getFalse(ITy);
if (Pred == ICmpInst::ICMP_ULE)
return getTrue(ITy);
}
if (MaxRecurse && LBO && RBO && LBO->getOpcode() == RBO->getOpcode() &&
LBO->getOperand(1) == RBO->getOperand(1)) {
switch (LBO->getOpcode()) {