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[InstCombine] Remove redundant fptrunc of select fold (NFCI) #117182

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[InstCombine] Remove redundant fptrunc of select fold (NFCI) #117182

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18 changes: 0 additions & 18 deletions llvm/lib/Transforms/InstCombine/InstCombineCasts.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -1866,24 +1866,6 @@ Instruction *InstCombinerImpl::visitFPTrunc(FPTruncInst &FPT) {

return UnaryOperator::CreateFNegFMF(InnerTrunc, Op);
}

// If we are truncating a select that has an extended operand, we can
// narrow the other operand and do the select as a narrow op.
Value *Cond, *X, *Y;
if (match(Op, m_Select(m_Value(Cond), m_FPExt(m_Value(X)), m_Value(Y))) &&
X->getType() == Ty) {
// fptrunc (select Cond, (fpext X), Y --> select Cond, X, (fptrunc Y)
Value *NarrowY = Builder.CreateFPTrunc(Y, Ty);
Value *Sel = Builder.CreateSelect(Cond, X, NarrowY, "narrow.sel", Op);
return replaceInstUsesWith(FPT, Sel);
}
if (match(Op, m_Select(m_Value(Cond), m_Value(Y), m_FPExt(m_Value(X)))) &&
X->getType() == Ty) {
// fptrunc (select Cond, Y, (fpext X) --> select Cond, (fptrunc Y), X
Value *NarrowY = Builder.CreateFPTrunc(Y, Ty);
Value *Sel = Builder.CreateSelect(Cond, NarrowY, X, "narrow.sel", Op);
return replaceInstUsesWith(FPT, Sel);
}
}

if (auto *II = dyn_cast<IntrinsicInst>(FPT.getOperand(0))) {
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