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Generalize the FoldOrWithConstant method to fold for any two constants which

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don't have overlapping bits.

llvm-svn: 60344
This commit is contained in:
Bill Wendling 2008-12-01 08:32:40 +00:00
parent 2a182b838d
commit 48b7cbbc01
1 changed files with 22 additions and 23 deletions
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45
lib/Transforms/Scalar/InstructionCombining.cpp
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@ -183,7 +183,7 @@ namespace {
Instruction *FoldAndOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
Instruction *visitAnd(BinaryOperator &I);
Instruction *FoldOrOfICmps(Instruction &I, ICmpInst *LHS, ICmpInst *RHS);
Instruction *FoldOrWithConstants(BinaryOperator &I,
Instruction *FoldOrWithConstants(BinaryOperator &I, Value *Op,
Value *A, Value *B, Value *C);
Instruction *visitOr (BinaryOperator &I);
Instruction *visitXor(BinaryOperator &I);
@ -4449,40 +4449,39 @@ Instruction *InstCombiner::FoldOrOfICmps(Instruction &I,
/// FoldOrWithConstants - This helper function folds:
///
/// ((A|B)&1)|(B&-2)
/// ((A | B) & 1) | (B & -2)
///
/// into:
///
/// (A&1) | B
Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I,
/// (A & 1) | B
///
/// The constants aren't important. Only that they don't overlap. (I.e., the XOR
/// of the two constants is "all ones".)
Instruction *InstCombiner::FoldOrWithConstants(BinaryOperator &I, Value *Op,
Value *A, Value *B, Value *C) {
Value *Op1 = I.getOperand(1);
if (ConstantInt *CI1 = dyn_cast<ConstantInt>(C)) {
Value *V1 = 0, *C2 = 0;
if (match(Op, m_And(m_Value(V1), m_Value(C2)))) {
ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
if (ConstantInt *CI = dyn_cast<ConstantInt>(C)) {
if (CI->getValue() == 1) {
Value *V1 = 0, *C2 = 0;
if (match(Op1, m_And(m_Value(V1), m_Value(C2)))) {
ConstantInt *CI2 = dyn_cast<ConstantInt>(C2);
if (!CI2) {
std::swap(V1, C2);
CI2 = dyn_cast<ConstantInt>(C2);
}
if (!CI2) {
std::swap(V1, C2);
CI2 = dyn_cast<ConstantInt>(C2);
}
if (CI2) {
APInt NegTwo = -APInt(CI2->getValue().getBitWidth(), 2, true);
if (CI2->getValue().eq(NegTwo)) {
if (CI2) {
APInt Xor = CI1->getValue() ^ CI2->getValue();
if (Xor.isAllOnesValue()) {
if (V1 == B) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI), I);
InsertNewInstBefore(BinaryOperator::CreateAnd(A, CI1), I);
return BinaryOperator::CreateOr(NewOp, B);
}
if (V1 == A) {
Instruction *NewOp =
InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI), I);
InsertNewInstBefore(BinaryOperator::CreateAnd(B, CI1), I);
return BinaryOperator::CreateOr(NewOp, A);
}
}
}
}
}
@ -4685,13 +4684,13 @@ Instruction *InstCombiner::visitOr(BinaryOperator &I) {
// ((A|B)&1)|(B&-2) -> (A&1) | B
if (match(Op0, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
match(Op0, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
Instruction *Ret = FoldOrWithConstants(I, A, B, C);
Instruction *Ret = FoldOrWithConstants(I, Op1, A, B, C);
if (Ret) return Ret;
}
// (B&-2)|((A|B)&1) -> (A&1) | B
if (match(Op1, m_And(m_Or(m_Value(A), m_Value(B)), m_Value(C))) ||
match(Op1, m_And(m_Value(C), m_Or(m_Value(A), m_Value(B))))) {
Instruction *Ret = FoldOrWithConstants(I, A, B, C);
Instruction *Ret = FoldOrWithConstants(I, Op0, A, B, C);
if (Ret) return Ret;
}