DirectXShaderCompiler/lib/Analysis/VectorUtils.cpp

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//===----------- VectorUtils.cpp - Vectorizer utility functions -----------===//
//
// The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file defines vectorizer utilities.
//
//===----------------------------------------------------------------------===//
#include "llvm/Analysis/LoopInfo.h"
#include "llvm/Analysis/ScalarEvolutionExpressions.h"
#include "llvm/Analysis/ScalarEvolution.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/GetElementPtrTypeIterator.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/IR/Value.h"
/// \brief Identify if the intrinsic is trivially vectorizable.
/// This method returns true if the intrinsic's argument types are all
/// scalars for the scalar form of the intrinsic and all vectors for
/// the vector form of the intrinsic.
bool llvm::isTriviallyVectorizable(Intrinsic::ID ID) {
switch (ID) {
case Intrinsic::sqrt:
case Intrinsic::sin:
case Intrinsic::cos:
case Intrinsic::exp:
case Intrinsic::exp2:
case Intrinsic::log:
case Intrinsic::log10:
case Intrinsic::log2:
case Intrinsic::fabs:
case Intrinsic::minnum:
case Intrinsic::maxnum:
case Intrinsic::copysign:
case Intrinsic::floor:
case Intrinsic::ceil:
case Intrinsic::trunc:
case Intrinsic::rint:
case Intrinsic::nearbyint:
case Intrinsic::round:
case Intrinsic::bswap:
case Intrinsic::ctpop:
case Intrinsic::pow:
case Intrinsic::fma:
case Intrinsic::fmuladd:
case Intrinsic::ctlz:
case Intrinsic::cttz:
case Intrinsic::powi:
return true;
default:
return false;
}
}
/// \brief Identifies if the intrinsic has a scalar operand. It check for
/// ctlz,cttz and powi special intrinsics whose argument is scalar.
bool llvm::hasVectorInstrinsicScalarOpd(Intrinsic::ID ID,
unsigned ScalarOpdIdx) {
switch (ID) {
case Intrinsic::ctlz:
case Intrinsic::cttz:
case Intrinsic::powi:
return (ScalarOpdIdx == 1);
default:
return false;
}
}
/// \brief Check call has a unary float signature
/// It checks following:
/// a) call should have a single argument
/// b) argument type should be floating point type
/// c) call instruction type and argument type should be same
/// d) call should only reads memory.
/// If all these condition is met then return ValidIntrinsicID
/// else return not_intrinsic.
llvm::Intrinsic::ID
llvm::checkUnaryFloatSignature(const CallInst &I,
Intrinsic::ID ValidIntrinsicID) {
if (I.getNumArgOperands() != 1 ||
!I.getArgOperand(0)->getType()->isFloatingPointTy() ||
I.getType() != I.getArgOperand(0)->getType() || !I.onlyReadsMemory())
return Intrinsic::not_intrinsic;
return ValidIntrinsicID;
}
/// \brief Check call has a binary float signature
/// It checks following:
/// a) call should have 2 arguments.
/// b) arguments type should be floating point type
/// c) call instruction type and arguments type should be same
/// d) call should only reads memory.
/// If all these condition is met then return ValidIntrinsicID
/// else return not_intrinsic.
llvm::Intrinsic::ID
llvm::checkBinaryFloatSignature(const CallInst &I,
Intrinsic::ID ValidIntrinsicID) {
if (I.getNumArgOperands() != 2 ||
!I.getArgOperand(0)->getType()->isFloatingPointTy() ||
!I.getArgOperand(1)->getType()->isFloatingPointTy() ||
I.getType() != I.getArgOperand(0)->getType() ||
I.getType() != I.getArgOperand(1)->getType() || !I.onlyReadsMemory())
return Intrinsic::not_intrinsic;
return ValidIntrinsicID;
}
/// \brief Returns intrinsic ID for call.
/// For the input call instruction it finds mapping intrinsic and returns
/// its ID, in case it does not found it return not_intrinsic.
llvm::Intrinsic::ID llvm::getIntrinsicIDForCall(CallInst *CI,
const TargetLibraryInfo *TLI) {
// If we have an intrinsic call, check if it is trivially vectorizable.
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
Intrinsic::ID ID = II->getIntrinsicID();
if (isTriviallyVectorizable(ID) || ID == Intrinsic::lifetime_start ||
ID == Intrinsic::lifetime_end || ID == Intrinsic::assume)
return ID;
return Intrinsic::not_intrinsic;
}
if (!TLI)
return Intrinsic::not_intrinsic;
LibFunc::Func Func;
Function *F = CI->getCalledFunction();
// We're going to make assumptions on the semantics of the functions, check
// that the target knows that it's available in this environment and it does
// not have local linkage.
if (!F || F->hasLocalLinkage() || !TLI->getLibFunc(F->getName(), Func))
return Intrinsic::not_intrinsic;
// Otherwise check if we have a call to a function that can be turned into a
// vector intrinsic.
switch (Func) {
default:
break;
case LibFunc::sin:
case LibFunc::sinf:
case LibFunc::sinl:
return checkUnaryFloatSignature(*CI, Intrinsic::sin);
case LibFunc::cos:
case LibFunc::cosf:
case LibFunc::cosl:
return checkUnaryFloatSignature(*CI, Intrinsic::cos);
case LibFunc::exp:
case LibFunc::expf:
case LibFunc::expl:
return checkUnaryFloatSignature(*CI, Intrinsic::exp);
case LibFunc::exp2:
case LibFunc::exp2f:
case LibFunc::exp2l:
return checkUnaryFloatSignature(*CI, Intrinsic::exp2);
case LibFunc::log:
case LibFunc::logf:
case LibFunc::logl:
return checkUnaryFloatSignature(*CI, Intrinsic::log);
case LibFunc::log10:
case LibFunc::log10f:
case LibFunc::log10l:
return checkUnaryFloatSignature(*CI, Intrinsic::log10);
case LibFunc::log2:
case LibFunc::log2f:
case LibFunc::log2l:
return checkUnaryFloatSignature(*CI, Intrinsic::log2);
case LibFunc::fabs:
case LibFunc::fabsf:
case LibFunc::fabsl:
return checkUnaryFloatSignature(*CI, Intrinsic::fabs);
case LibFunc::fmin:
case LibFunc::fminf:
case LibFunc::fminl:
return checkBinaryFloatSignature(*CI, Intrinsic::minnum);
case LibFunc::fmax:
case LibFunc::fmaxf:
case LibFunc::fmaxl:
return checkBinaryFloatSignature(*CI, Intrinsic::maxnum);
case LibFunc::copysign:
case LibFunc::copysignf:
case LibFunc::copysignl:
return checkBinaryFloatSignature(*CI, Intrinsic::copysign);
case LibFunc::floor:
case LibFunc::floorf:
case LibFunc::floorl:
return checkUnaryFloatSignature(*CI, Intrinsic::floor);
case LibFunc::ceil:
case LibFunc::ceilf:
case LibFunc::ceill:
return checkUnaryFloatSignature(*CI, Intrinsic::ceil);
case LibFunc::trunc:
case LibFunc::truncf:
case LibFunc::truncl:
return checkUnaryFloatSignature(*CI, Intrinsic::trunc);
case LibFunc::rint:
case LibFunc::rintf:
case LibFunc::rintl:
return checkUnaryFloatSignature(*CI, Intrinsic::rint);
case LibFunc::nearbyint:
case LibFunc::nearbyintf:
case LibFunc::nearbyintl:
return checkUnaryFloatSignature(*CI, Intrinsic::nearbyint);
case LibFunc::round:
case LibFunc::roundf:
case LibFunc::roundl:
return checkUnaryFloatSignature(*CI, Intrinsic::round);
case LibFunc::pow:
case LibFunc::powf:
case LibFunc::powl:
return checkBinaryFloatSignature(*CI, Intrinsic::pow);
}
return Intrinsic::not_intrinsic;
}
/// \brief Find the operand of the GEP that should be checked for consecutive
/// stores. This ignores trailing indices that have no effect on the final
/// pointer.
unsigned llvm::getGEPInductionOperand(const GetElementPtrInst *Gep) {
const DataLayout &DL = Gep->getModule()->getDataLayout();
unsigned LastOperand = Gep->getNumOperands() - 1;
unsigned GEPAllocSize = DL.getTypeAllocSize(
cast<PointerType>(Gep->getType()->getScalarType())->getElementType());
// Walk backwards and try to peel off zeros.
while (LastOperand > 1 &&
match(Gep->getOperand(LastOperand), llvm::PatternMatch::m_Zero())) {
// Find the type we're currently indexing into.
gep_type_iterator GEPTI = gep_type_begin(Gep);
std::advance(GEPTI, LastOperand - 1);
// If it's a type with the same allocation size as the result of the GEP we
// can peel off the zero index.
if (DL.getTypeAllocSize(*GEPTI) != GEPAllocSize)
break;
--LastOperand;
}
return LastOperand;
}
/// \brief If the argument is a GEP, then returns the operand identified by
/// getGEPInductionOperand. However, if there is some other non-loop-invariant
/// operand, it returns that instead.
llvm::Value *llvm::stripGetElementPtr(llvm::Value *Ptr, ScalarEvolution *SE,
Loop *Lp) {
GetElementPtrInst *GEP = dyn_cast<GetElementPtrInst>(Ptr);
if (!GEP)
return Ptr;
unsigned InductionOperand = getGEPInductionOperand(GEP);
// Check that all of the gep indices are uniform except for our induction
// operand.
for (unsigned i = 0, e = GEP->getNumOperands(); i != e; ++i)
if (i != InductionOperand &&
!SE->isLoopInvariant(SE->getSCEV(GEP->getOperand(i)), Lp))
return Ptr;
return GEP->getOperand(InductionOperand);
}
/// \brief If a value has only one user that is a CastInst, return it.
llvm::Value *llvm::getUniqueCastUse(llvm::Value *Ptr, Loop *Lp, Type *Ty) {
llvm::Value *UniqueCast = nullptr;
for (User *U : Ptr->users()) {
CastInst *CI = dyn_cast<CastInst>(U);
if (CI && CI->getType() == Ty) {
if (!UniqueCast)
UniqueCast = CI;
else
return nullptr;
}
}
return UniqueCast;
}
/// \brief Get the stride of a pointer access in a loop. Looks for symbolic
/// strides "a[i*stride]". Returns the symbolic stride, or null otherwise.
llvm::Value *llvm::getStrideFromPointer(llvm::Value *Ptr, ScalarEvolution *SE,
Loop *Lp) {
const PointerType *PtrTy = dyn_cast<PointerType>(Ptr->getType());
if (!PtrTy || PtrTy->isAggregateType())
return nullptr;
// Try to remove a gep instruction to make the pointer (actually index at this
// point) easier analyzable. If OrigPtr is equal to Ptr we are analzying the
// pointer, otherwise, we are analyzing the index.
llvm::Value *OrigPtr = Ptr;
// The size of the pointer access.
int64_t PtrAccessSize = 1;
Ptr = stripGetElementPtr(Ptr, SE, Lp);
const SCEV *V = SE->getSCEV(Ptr);
if (Ptr != OrigPtr)
// Strip off casts.
while (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V))
V = C->getOperand();
const SCEVAddRecExpr *S = dyn_cast<SCEVAddRecExpr>(V);
if (!S)
return nullptr;
V = S->getStepRecurrence(*SE);
if (!V)
return nullptr;
// Strip off the size of access multiplication if we are still analyzing the
// pointer.
if (OrigPtr == Ptr) {
const DataLayout &DL = Lp->getHeader()->getModule()->getDataLayout();
DL.getTypeAllocSize(PtrTy->getElementType());
if (const SCEVMulExpr *M = dyn_cast<SCEVMulExpr>(V)) {
if (M->getOperand(0)->getSCEVType() != scConstant)
return nullptr;
const APInt &APStepVal =
cast<SCEVConstant>(M->getOperand(0))->getValue()->getValue();
// Huge step value - give up.
if (APStepVal.getBitWidth() > 64)
return nullptr;
int64_t StepVal = APStepVal.getSExtValue();
if (PtrAccessSize != StepVal)
return nullptr;
V = M->getOperand(1);
}
}
// Strip off casts.
Type *StripedOffRecurrenceCast = nullptr;
if (const SCEVCastExpr *C = dyn_cast<SCEVCastExpr>(V)) {
StripedOffRecurrenceCast = C->getType();
V = C->getOperand();
}
// Look for the loop invariant symbolic value.
const SCEVUnknown *U = dyn_cast<SCEVUnknown>(V);
if (!U)
return nullptr;
llvm::Value *Stride = U->getValue();
if (!Lp->isLoopInvariant(Stride))
return nullptr;
// If we have stripped off the recurrence cast we have to make sure that we
// return the value that is used in this loop so that we can replace it later.
if (StripedOffRecurrenceCast)
Stride = getUniqueCastUse(Stride, Lp, StripedOffRecurrenceCast);
return Stride;
}
/// \brief Given a vector and an element number, see if the scalar value is
/// already around as a register, for example if it were inserted then extracted
/// from the vector.
llvm::Value *llvm::findScalarElement(llvm::Value *V, unsigned EltNo) {
assert(V->getType()->isVectorTy() && "Not looking at a vector?");
VectorType *VTy = cast<VectorType>(V->getType());
unsigned Width = VTy->getNumElements();
if (EltNo >= Width) // Out of range access.
return UndefValue::get(VTy->getElementType());
if (Constant *C = dyn_cast<Constant>(V))
return C->getAggregateElement(EltNo);
if (InsertElementInst *III = dyn_cast<InsertElementInst>(V)) {
// If this is an insert to a variable element, we don't know what it is.
if (!isa<ConstantInt>(III->getOperand(2)))
return nullptr;
unsigned IIElt = cast<ConstantInt>(III->getOperand(2))->getZExtValue();
// If this is an insert to the element we are looking for, return the
// inserted value.
if (EltNo == IIElt)
return III->getOperand(1);
// Otherwise, the insertelement doesn't modify the value, recurse on its
// vector input.
return findScalarElement(III->getOperand(0), EltNo);
}
if (ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(V)) {
unsigned LHSWidth = SVI->getOperand(0)->getType()->getVectorNumElements();
int InEl = SVI->getMaskValue(EltNo);
if (InEl < 0)
return UndefValue::get(VTy->getElementType());
if (InEl < (int)LHSWidth)
return findScalarElement(SVI->getOperand(0), InEl);
return findScalarElement(SVI->getOperand(1), InEl - LHSWidth);
}
// Extract a value from a vector add operation with a constant zero.
Value *Val = nullptr; Constant *Con = nullptr;
if (match(V,
llvm::PatternMatch::m_Add(llvm::PatternMatch::m_Value(Val),
llvm::PatternMatch::m_Constant(Con)))) {
if (Constant *Elt = Con->getAggregateElement(EltNo))
if (Elt->isNullValue())
return findScalarElement(Val, EltNo);
}
// Otherwise, we don't know.
return nullptr;
}