72 строки
2.8 KiB
C++
72 строки
2.8 KiB
C++
//===----------- VectorUtils2.cpp - findScalarElement function -----------===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This file defines vectorizer utility function findScalarElement.
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// Splitting this function from VectorUtils.cpp into a separate file
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// makes dxilconv.dll 121kB smaller (x86 release, compiler optimization for size).
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//
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//===----------------------------------------------------------------------===//
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#include "llvm/Analysis/VectorUtils.h"
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#include "llvm/IR/PatternMatch.h"
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#include "llvm/IR/Value.h"
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/// \brief Given a vector and an element number, see if the scalar value is
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/// already around as a register, for example if it were inserted then extracted
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/// from the vector.
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llvm::Value *llvm::findScalarElement(llvm::Value *V, unsigned EltNo) {
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assert(V->getType()->isVectorTy() && "Not looking at a vector?");
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VectorType *VTy = cast<VectorType>(V->getType());
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unsigned Width = VTy->getNumElements();
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if (EltNo >= Width) // Out of range access.
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return UndefValue::get(VTy->getElementType());
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if (Constant *C = dyn_cast<Constant>(V))
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return C->getAggregateElement(EltNo);
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if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
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// If this is an insert to a variable element, we don't know what it is.
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if (!isa<ConstantInt>(III->getOperand(2)))
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return nullptr;
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unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
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// If this is an insert to the element we are looking for, return the
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// inserted value.
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if (EltNo == IIElt)
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return III->getOperand(1);
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// Otherwise, the insertelement doesn't modify the value, recurse on its
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// vector input.
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return findScalarElement(III->getOperand(0), EltNo);
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}
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if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
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unsigned LHSWidth = SVI->getOperand(0)->getType()->getVectorNumElements();
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int InEl = SVI->getMaskValue(EltNo);
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if (InEl < 0)
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return UndefValue::get(VTy->getElementType());
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if (InEl < (int)LHSWidth)
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return findScalarElement(SVI->getOperand(0), InEl);
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return findScalarElement(SVI->getOperand(1), InEl - LHSWidth);
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}
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// Extract a value from a vector add operation with a constant zero.
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Value *Val = nullptr; Constant *Con = nullptr;
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if (match(V,
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llvm::PatternMatch::m_Add(llvm::PatternMatch::m_Value(Val),
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llvm::PatternMatch::m_Constant(Con)))) {
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if (Constant *Elt = Con->getAggregateElement(EltNo))
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if (Elt->isNullValue())
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return findScalarElement(Val, EltNo);
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}
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// Otherwise, we don't know.
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return nullptr;
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}
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