InterleavedAccessPass.cpp [plain text]
#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;
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;
bool lowerInterleavedLoad(LoadInst *LI,
SmallVector<Instruction *, 32> &DeadInsts);
bool lowerInterleavedStore(StoreInst *SI,
SmallVector<Instruction *, 32> &DeadInsts);
};
}
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);
}
static bool isDeInterleaveMaskOfFactor(ArrayRef<int> Mask, unsigned Factor,
unsigned &Index) {
for (Index = 0; Index < Factor; Index++) {
unsigned i = 0;
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;
}
static bool isDeInterleaveMask(ArrayRef<int> Mask, unsigned &Factor,
unsigned &Index) {
if (Mask.size() < 2)
return false;
for (Factor = 2; Factor <= MaxFactor; Factor++)
if (isDeInterleaveMaskOfFactor(Mask, Factor, Index))
return true;
return false;
}
static bool isReInterleaveMask(ArrayRef<int> Mask, unsigned &Factor) {
unsigned NumElts = Mask.size();
if (NumElts < 4)
return false;
for (Factor = 2; Factor <= MaxFactor; Factor++) {
if (NumElts % Factor)
continue;
unsigned NumSubElts = NumElts / Factor;
if (!isPowerOf2_32(NumSubElts))
continue;
unsigned i = 0;
for (; i < NumElts; i++)
if (Mask[i] >= 0 &&
static_cast<unsigned>(Mask[i]) !=
(i % Factor) * NumSubElts + i / Factor)
break;
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;
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;
if (!isDeInterleaveMask(Shuffles[0]->getShuffleMask(), Factor, Index))
return false;
SmallVector<unsigned, 4> Indices;
Indices.push_back(Index);
Type *VecTy = Shuffles[0]->getType();
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");
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;
unsigned Factor;
if (!isReInterleaveMask(SVI->getShuffleMask(), Factor))
return false;
DEBUG(dbgs() << "IA: Found an interleaved store: " << *SI << "\n");
if (!TLI->lowerInterleavedStore(SI, SVI, Factor))
return false;
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();
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;
}