287 lines
8.9 KiB
C++
287 lines
8.9 KiB
C++
//=----------------------- InterleavedAccessPass.cpp -----------------------==//
|
|
//
|
|
// The LLVM Compiler Infrastructure
|
|
//
|
|
// This file is distributed under the University of Illinois Open Source
|
|
// License. See LICENSE.TXT for details.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
//
|
|
// This file implements the Interleaved Access pass, which identifies
|
|
// interleaved memory accesses and transforms into target specific intrinsics.
|
|
//
|
|
// An interleaved load reads data from memory into several vectors, with
|
|
// DE-interleaving the data on a factor. An interleaved store writes several
|
|
// vectors to memory with RE-interleaving the data on a factor.
|
|
//
|
|
// As interleaved accesses are hard to be identified in CodeGen (mainly because
|
|
// the VECTOR_SHUFFLE DAG node is quite different from the shufflevector IR),
|
|
// we identify and transform them to intrinsics in this pass. So the intrinsics
|
|
// can be easily matched into target specific instructions later in CodeGen.
|
|
//
|
|
// E.g. An interleaved load (Factor = 2):
|
|
// %wide.vec = load <8 x i32>, <8 x i32>* %ptr
|
|
// %v0 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <0, 2, 4, 6>
|
|
// %v1 = shuffle <8 x i32> %wide.vec, <8 x i32> undef, <1, 3, 5, 7>
|
|
//
|
|
// It could be transformed into a ld2 intrinsic in AArch64 backend or a vld2
|
|
// intrinsic in ARM backend.
|
|
//
|
|
// E.g. An interleaved store (Factor = 3):
|
|
// %i.vec = shuffle <8 x i32> %v0, <8 x i32> %v1,
|
|
// <0, 4, 8, 1, 5, 9, 2, 6, 10, 3, 7, 11>
|
|
// store <12 x i32> %i.vec, <12 x i32>* %ptr
|
|
//
|
|
// It could be transformed into a st3 intrinsic in AArch64 backend or a vst3
|
|
// intrinsic in ARM backend.
|
|
//
|
|
//===----------------------------------------------------------------------===//
|
|
|
|
#include "llvm/CodeGen/Passes.h"
|
|
#include "llvm/IR/InstIterator.h"
|
|
#include "llvm/Support/Debug.h"
|
|
#include "llvm/Support/MathExtras.h"
|
|
#include "llvm/Support/raw_ostream.h"
|
|
#include "llvm/Target/TargetLowering.h"
|
|
#include "llvm/Target/TargetSubtargetInfo.h"
|
|
|
|
using namespace llvm;
|
|
|
|
#define DEBUG_TYPE "interleaved-access"
|
|
|
|
static cl::opt<bool> LowerInterleavedAccesses(
|
|
"lower-interleaved-accesses",
|
|
cl::desc("Enable lowering interleaved accesses to intrinsics"),
|
|
cl::init(true), cl::Hidden);
|
|
|
|
static unsigned MaxFactor; // The maximum supported interleave factor.
|
|
|
|
namespace llvm {
|
|
static void initializeInterleavedAccessPass(PassRegistry &);
|
|
}
|
|
|
|
namespace {
|
|
|
|
class InterleavedAccess : public FunctionPass {
|
|
|
|
public:
|
|
static char ID;
|
|
InterleavedAccess(const TargetMachine *TM = nullptr)
|
|
: FunctionPass(ID), TM(TM), TLI(nullptr) {
|
|
initializeInterleavedAccessPass(*PassRegistry::getPassRegistry());
|
|
}
|
|
|
|
const char *getPassName() const override { return "Interleaved Access Pass"; }
|
|
|
|
bool runOnFunction(Function &F) override;
|
|
|
|
private:
|
|
const TargetMachine *TM;
|
|
const TargetLowering *TLI;
|
|
|
|
/// \brief Transform an interleaved load into target specific intrinsics.
|
|
bool lowerInterleavedLoad(LoadInst *LI,
|
|
SmallVector<Instruction *, 32> &DeadInsts);
|
|
|
|
/// \brief Transform an interleaved store into target specific intrinsics.
|
|
bool lowerInterleavedStore(StoreInst *SI,
|
|
SmallVector<Instruction *, 32> &DeadInsts);
|
|
};
|
|
} // end anonymous namespace.
|
|
|
|
char InterleavedAccess::ID = 0;
|
|
INITIALIZE_TM_PASS(InterleavedAccess, "interleaved-access",
|
|
"Lower interleaved memory accesses to target specific intrinsics",
|
|
false, false)
|
|
|
|
FunctionPass *llvm::createInterleavedAccessPass(const TargetMachine *TM) {
|
|
return new InterleavedAccess(TM);
|
|
}
|
|
|
|
/// \brief Check if the mask is a DE-interleave mask of the given factor
|
|
/// \p Factor like:
|
|
/// <Index, Index+Factor, ..., Index+(NumElts-1)*Factor>
|
|
static bool isDeInterleaveMaskOfFactor(ArrayRef<int> Mask, unsigned Factor,
|
|
unsigned &Index) {
|
|
// Check all potential start indices from 0 to (Factor - 1).
|
|
for (Index = 0; Index < Factor; Index++) {
|
|
unsigned i = 0;
|
|
|
|
// Check that elements are in ascending order by Factor. Ignore undef
|
|
// elements.
|
|
for (; i < Mask.size(); i++)
|
|
if (Mask[i] >= 0 && static_cast<unsigned>(Mask[i]) != Index + i * Factor)
|
|
break;
|
|
|
|
if (i == Mask.size())
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/// \brief Check if the mask is a DE-interleave mask for an interleaved load.
|
|
///
|
|
/// E.g. DE-interleave masks (Factor = 2) could be:
|
|
/// <0, 2, 4, 6> (mask of index 0 to extract even elements)
|
|
/// <1, 3, 5, 7> (mask of index 1 to extract odd elements)
|
|
static bool isDeInterleaveMask(ArrayRef<int> Mask, unsigned &Factor,
|
|
unsigned &Index) {
|
|
if (Mask.size() < 2)
|
|
return false;
|
|
|
|
// Check potential Factors.
|
|
for (Factor = 2; Factor <= MaxFactor; Factor++)
|
|
if (isDeInterleaveMaskOfFactor(Mask, Factor, Index))
|
|
return true;
|
|
|
|
return false;
|
|
}
|
|
|
|
/// \brief Check if the mask is RE-interleave mask for an interleaved store.
|
|
///
|
|
/// I.e. <0, NumSubElts, ... , NumSubElts*(Factor - 1), 1, NumSubElts + 1, ...>
|
|
///
|
|
/// E.g. The RE-interleave mask (Factor = 2) could be:
|
|
/// <0, 4, 1, 5, 2, 6, 3, 7>
|
|
static bool isReInterleaveMask(ArrayRef<int> Mask, unsigned &Factor) {
|
|
unsigned NumElts = Mask.size();
|
|
if (NumElts < 4)
|
|
return false;
|
|
|
|
// Check potential Factors.
|
|
for (Factor = 2; Factor <= MaxFactor; Factor++) {
|
|
if (NumElts % Factor)
|
|
continue;
|
|
|
|
unsigned NumSubElts = NumElts / Factor;
|
|
if (!isPowerOf2_32(NumSubElts))
|
|
continue;
|
|
|
|
// Check whether each element matchs the RE-interleaved rule. Ignore undef
|
|
// elements.
|
|
unsigned i = 0;
|
|
for (; i < NumElts; i++)
|
|
if (Mask[i] >= 0 &&
|
|
static_cast<unsigned>(Mask[i]) !=
|
|
(i % Factor) * NumSubElts + i / Factor)
|
|
break;
|
|
|
|
// Find a RE-interleaved mask of current factor.
|
|
if (i == NumElts)
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
bool InterleavedAccess::lowerInterleavedLoad(
|
|
LoadInst *LI, SmallVector<Instruction *, 32> &DeadInsts) {
|
|
if (!LI->isSimple())
|
|
return false;
|
|
|
|
SmallVector<ShuffleVectorInst *, 4> Shuffles;
|
|
|
|
// Check if all users of this load are shufflevectors.
|
|
for (auto UI = LI->user_begin(), E = LI->user_end(); UI != E; UI++) {
|
|
ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(*UI);
|
|
if (!SVI || !isa<UndefValue>(SVI->getOperand(1)))
|
|
return false;
|
|
|
|
Shuffles.push_back(SVI);
|
|
}
|
|
|
|
if (Shuffles.empty())
|
|
return false;
|
|
|
|
unsigned Factor, Index;
|
|
|
|
// Check if the first shufflevector is DE-interleave shuffle.
|
|
if (!isDeInterleaveMask(Shuffles[0]->getShuffleMask(), Factor, Index))
|
|
return false;
|
|
|
|
// Holds the corresponding index for each DE-interleave shuffle.
|
|
SmallVector<unsigned, 4> Indices;
|
|
Indices.push_back(Index);
|
|
|
|
Type *VecTy = Shuffles[0]->getType();
|
|
|
|
// Check if other shufflevectors are also DE-interleaved of the same type
|
|
// and factor as the first shufflevector.
|
|
for (unsigned i = 1; i < Shuffles.size(); i++) {
|
|
if (Shuffles[i]->getType() != VecTy)
|
|
return false;
|
|
|
|
if (!isDeInterleaveMaskOfFactor(Shuffles[i]->getShuffleMask(), Factor,
|
|
Index))
|
|
return false;
|
|
|
|
Indices.push_back(Index);
|
|
}
|
|
|
|
DEBUG(dbgs() << "IA: Found an interleaved load: " << *LI << "\n");
|
|
|
|
// Try to create target specific intrinsics to replace the load and shuffles.
|
|
if (!TLI->lowerInterleavedLoad(LI, Shuffles, Indices, Factor))
|
|
return false;
|
|
|
|
for (auto SVI : Shuffles)
|
|
DeadInsts.push_back(SVI);
|
|
|
|
DeadInsts.push_back(LI);
|
|
return true;
|
|
}
|
|
|
|
bool InterleavedAccess::lowerInterleavedStore(
|
|
StoreInst *SI, SmallVector<Instruction *, 32> &DeadInsts) {
|
|
if (!SI->isSimple())
|
|
return false;
|
|
|
|
ShuffleVectorInst *SVI = dyn_cast<ShuffleVectorInst>(SI->getValueOperand());
|
|
if (!SVI || !SVI->hasOneUse())
|
|
return false;
|
|
|
|
// Check if the shufflevector is RE-interleave shuffle.
|
|
unsigned Factor;
|
|
if (!isReInterleaveMask(SVI->getShuffleMask(), Factor))
|
|
return false;
|
|
|
|
DEBUG(dbgs() << "IA: Found an interleaved store: " << *SI << "\n");
|
|
|
|
// Try to create target specific intrinsics to replace the store and shuffle.
|
|
if (!TLI->lowerInterleavedStore(SI, SVI, Factor))
|
|
return false;
|
|
|
|
// Already have a new target specific interleaved store. Erase the old store.
|
|
DeadInsts.push_back(SI);
|
|
DeadInsts.push_back(SVI);
|
|
return true;
|
|
}
|
|
|
|
bool InterleavedAccess::runOnFunction(Function &F) {
|
|
if (!TM || !LowerInterleavedAccesses)
|
|
return false;
|
|
|
|
DEBUG(dbgs() << "*** " << getPassName() << ": " << F.getName() << "\n");
|
|
|
|
TLI = TM->getSubtargetImpl(F)->getTargetLowering();
|
|
MaxFactor = TLI->getMaxSupportedInterleaveFactor();
|
|
|
|
// Holds dead instructions that will be erased later.
|
|
SmallVector<Instruction *, 32> DeadInsts;
|
|
bool Changed = false;
|
|
|
|
for (auto &I : instructions(F)) {
|
|
if (LoadInst *LI = dyn_cast<LoadInst>(&I))
|
|
Changed |= lowerInterleavedLoad(LI, DeadInsts);
|
|
|
|
if (StoreInst *SI = dyn_cast<StoreInst>(&I))
|
|
Changed |= lowerInterleavedStore(SI, DeadInsts);
|
|
}
|
|
|
|
for (auto I : DeadInsts)
|
|
I->eraseFromParent();
|
|
|
|
return Changed;
|
|
}
|