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PatternMatch: Introduce a matcher for instructions with the "exact" bit. Use it to simplify a few matchers. 

llvm-svn: 147403
This commit is contained in:
Benjamin Kramer 2012-01-01 17:55:30 +00:00
parent c5bc4cccd5
commit 9442cd01f6
3 changed files with 30 additions and 19 deletions
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20
llvm/include/llvm/Support/PatternMatch.h
View File

@ -441,6 +441,26 @@ m_IDiv(const LHS &L, const RHS &R) {
return BinOp2_match<LHS, RHS, Instruction::SDiv, Instruction::UDiv>(L, R);
}
//===----------------------------------------------------------------------===//
// Class that matches exact binary ops.
//
template<typename SubPattern_t>
struct Exact_match {
SubPattern_t SubPattern;
Exact_match(const SubPattern_t &SP) : SubPattern(SP) {}
template<typename OpTy>
bool match(OpTy *V) {
if (PossiblyExactOperator *PEO = dyn_cast<PossiblyExactOperator>(V))
return PEO->isExact() && SubPattern.match(V);
return false;
}
};
template<typename T>
inline Exact_match<T> m_Exact(const T &SubPattern) { return SubPattern; }
//===----------------------------------------------------------------------===//
// Matchers for CmpInst classes
//

15
llvm/lib/Analysis/InstructionSimplify.cpp
View File

@ -812,14 +812,10 @@ static Value *SimplifyMulInst(Value *Op0, Value *Op1, const TargetData *TD,
return Op0;
// (X / Y) * Y -> X if the division is exact.
Value *X = 0, *Y = 0;
if ((match(Op0, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op1) || // (X / Y) * Y
(match(Op1, m_IDiv(m_Value(X), m_Value(Y))) && Y == Op0)) { // Y * (X / Y)
PossiblyExactOperator *Div =
cast<PossiblyExactOperator>(Y == Op1 ? Op0 : Op1);
if (Div->isExact())
return X;
}
Value *X = 0;
if (match(Op0, m_Exact(m_IDiv(m_Value(X), m_Specific(Op1)))) || // (X / Y) * Y
match(Op1, m_Exact(m_IDiv(m_Value(X), m_Specific(Op0))))) // Y * (X / Y)
return X;
// i1 mul -> and.
if (MaxRecurse && Op0->getType()->isIntegerTy(1))
@ -1162,8 +1158,7 @@ static Value *SimplifyShlInst(Value *Op0, Value *Op1, bool isNSW, bool isNUW,
// (X >> A) << A -> X
Value *X;
if (match(Op0, m_Shr(m_Value(X), m_Specific(Op1))) &&
cast<PossiblyExactOperator>(Op0)->isExact())
if (match(Op0, m_Exact(m_Shr(m_Value(X), m_Specific(Op1)))))
return X;
return 0;
}

14
llvm/lib/Analysis/ValueTracking.cpp
View File

@ -811,11 +811,9 @@ bool llvm::isPowerOfTwo(Value *V, const TargetData *TD, bool OrZero,
// An exact divide or right shift can only shift off zero bits, so the result
// is a power of two only if the first operand is a power of two and not
// copying a sign bit (sdiv int_min, 2).
if (match(V, m_LShr(m_Value(), m_Value())) ||
match(V, m_UDiv(m_Value(), m_Value()))) {
PossiblyExactOperator *PEO = cast<PossiblyExactOperator>(V);
if (PEO->isExact())
return isPowerOfTwo(PEO->getOperand(0), TD, OrZero, Depth);
if (match(V, m_Exact(m_LShr(m_Value(), m_Value()))) ||
match(V, m_Exact(m_UDiv(m_Value(), m_Value())))) {
return isPowerOfTwo(cast<Operator>(V)->getOperand(0), TD, OrZero, Depth);
}
return false;
@ -879,10 +877,8 @@ bool llvm::isKnownNonZero(Value *V, const TargetData *TD, unsigned Depth) {
return true;
}
// div exact can only produce a zero if the dividend is zero.
else if (match(V, m_IDiv(m_Value(X), m_Value()))) {
PossiblyExactOperator *BO = cast<PossiblyExactOperator>(V);
if (BO->isExact())
return isKnownNonZero(X, TD, Depth);
else if (match(V, m_Exact(m_IDiv(m_Value(X), m_Value())))) {
return isKnownNonZero(X, TD, Depth);
}
// X + Y.
else if (match(V, m_Add(m_Value(X), m_Value(Y)))) {