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[InstSimplify] add helper functions for SimplifyICmpInst; NFCI

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git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@288588 91177308-0d34-0410-b5e6-96231b3b80d8
This commit is contained in:
Sanjay Patel 2016-12-03 17:30:22 +00:00
parent ae10a1c682
commit b7a44fa355
1 changed files with 129 additions and 112 deletions
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241
lib/Analysis/InstructionSimplify.cpp
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@ -2167,6 +2167,131 @@ computePointerICmp(const DataLayout &DL, const TargetLibraryInfo *TLI,
return nullptr;
}
/// Fold an icmp when its operands have i1 scalar type.
static Value *simplifyICmpOfBools(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const Query &Q) {
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
if (!OpTy->getScalarType()->isIntegerTy(1))
return nullptr;
switch (Pred) {
default:
break;
case ICmpInst::ICMP_EQ:
// X == 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_NE:
// X != 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGT:
// X >u 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGE:
// X >=u 1 -> X
if (match(RHS, m_One()))
return LHS;
if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SGE:
/// For signed comparison, the values for an i1 are 0 and -1
/// respectively. This maps into a truth table of:
/// LHS | RHS | LHS >=s RHS | LHS implies RHS
/// 0 | 0 | 1 (0 >= 0) | 1
/// 0 | 1 | 1 (0 >= -1) | 1
/// 1 | 0 | 0 (-1 >= 0) | 0
/// 1 | 1 | 1 (-1 >= -1) | 1
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT:
// X <s 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_SLE:
// X <=s -1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_ULE:
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
return nullptr;
}
/// Try hard to fold icmp with zero RHS because this is a common case.
static Value *simplifyICmpWithZero(CmpInst::Predicate Pred, Value *LHS,
Value *RHS, const Query &Q) {
if (!match(RHS, m_Zero()))
return nullptr;
Type *ITy = GetCompareTy(LHS); // The return type.
bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
default:
llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_ULT:
return getFalse(ITy);
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative)
return getFalse(ITy);
break;
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative)
return getTrue(ITy);
break;
case ICmpInst::ICMP_SGT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative && isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
}
return nullptr;
}
static Value *simplifyICmpWithConstant(CmpInst::Predicate Pred, Value *LHS,
Value *RHS) {
const APInt *C;
@ -2323,7 +2448,6 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
}
Type *ITy = GetCompareTy(LHS); // The return type.
Type *OpTy = LHS->getType(); // The operand type.
// icmp X, X -> true/false
// X icmp undef -> true/false. For example, icmp ugt %X, undef -> false
@ -2331,118 +2455,11 @@ static Value *SimplifyICmpInst(unsigned Predicate, Value *LHS, Value *RHS,
if (LHS == RHS || isa<UndefValue>(RHS))
return ConstantInt::get(ITy, CmpInst::isTrueWhenEqual(Pred));
// Special case logic when the operands have i1 type.
if (OpTy->getScalarType()->isIntegerTy(1)) {
switch (Pred) {
default: break;
case ICmpInst::ICMP_EQ:
// X == 1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_NE:
// X != 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGT:
// X >u 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_UGE: {
// X >=u 1 -> X
if (match(RHS, m_One()))
return LHS;
if (isImpliedCondition(RHS, LHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
case ICmpInst::ICMP_SGE: {
/// For signed comparison, the values for an i1 are 0 and -1
/// respectively. This maps into a truth table of:
/// LHS | RHS | LHS >=s RHS | LHS implies RHS
/// 0 | 0 | 1 (0 >= 0) | 1
/// 0 | 1 | 1 (0 >= -1) | 1
/// 1 | 0 | 0 (-1 >= 0) | 0
/// 1 | 1 | 1 (-1 >= -1) | 1
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
case ICmpInst::ICMP_SLT:
// X <s 0 -> X
if (match(RHS, m_Zero()))
return LHS;
break;
case ICmpInst::ICMP_SLE:
// X <=s -1 -> X
if (match(RHS, m_One()))
return LHS;
break;
case ICmpInst::ICMP_ULE: {
if (isImpliedCondition(LHS, RHS, Q.DL).getValueOr(false))
return getTrue(ITy);
break;
}
}
}
if (Value *V = simplifyICmpOfBools(Pred, LHS, RHS, Q))
return V;
// If we are comparing with zero then try hard since this is a common case.
if (match(RHS, m_Zero())) {
bool LHSKnownNonNegative, LHSKnownNegative;
switch (Pred) {
default: llvm_unreachable("Unknown ICmp predicate!");
case ICmpInst::ICMP_ULT:
return getFalse(ITy);
case ICmpInst::ICMP_UGE:
return getTrue(ITy);
case ICmpInst::ICMP_EQ:
case ICmpInst::ICMP_ULE:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_NE:
case ICmpInst::ICMP_UGT:
if (isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
case ICmpInst::ICMP_SLT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative)
return getFalse(ITy);
break;
case ICmpInst::ICMP_SLE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getTrue(ITy);
if (LHSKnownNonNegative &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getFalse(ITy);
break;
case ICmpInst::ICMP_SGE:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative)
return getTrue(ITy);
break;
case ICmpInst::ICMP_SGT:
ComputeSignBit(LHS, LHSKnownNonNegative, LHSKnownNegative, Q.DL, 0, Q.AC,
Q.CxtI, Q.DT);
if (LHSKnownNegative)
return getFalse(ITy);
if (LHSKnownNonNegative &&
isKnownNonZero(LHS, Q.DL, 0, Q.AC, Q.CxtI, Q.DT))
return getTrue(ITy);
break;
}
}
if (Value *V = simplifyICmpWithZero(Pred, LHS, RHS, Q))
return V;
if (Value *V = simplifyICmpWithConstant(Pred, LHS, RHS))
return V;