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llvm-project/llvm/lib/Transforms/Scalar/LowerMatrixIntrinsics.cpp

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//===- LowerMatrixIntrinsics.cpp - Lower matrix intrinsics -----*- C++ -*-===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Lower matrix intrinsics to vector operations.
//
// TODO:
// * Improve fusion:
// * Support more cases, e.g. multiply-add, multiply-sub, operands/results
// transposed.
// * Improve cost-modeling, e.g. choose different number of rows/columns
// columns for tiles, consider cost of copies on alias.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/LowerMatrixIntrinsics.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/AliasAnalysis.h"
#include "llvm/Analysis/DomTreeUpdater.h"
#include "llvm/Analysis/OptimizationRemarkEmitter.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/ValueTracking.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/IR/DebugInfoMetadata.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/InitializePasses.h"
#include "llvm/Pass.h"
#include "llvm/Support/Debug.h"
#include "llvm/Transforms/Scalar.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
using namespace llvm;
using namespace PatternMatch;
#define DEBUG_TYPE "lower-matrix-intrinsics"
static cl::opt<bool> EnableShapePropagation(
"matrix-propagate-shape", cl::init(true), cl::Hidden,
cl::desc("Enable/disable shape propagation from matrix intrinsics to other "
"instructions."));
static cl::opt<bool>
FuseMatrix("fuse-matrix", cl::init(true), cl::Hidden,
cl::desc("Enable/disable fusing matrix instructions."));
// TODO: Allow and use non-square tiles.
static cl::opt<unsigned> TileSize(
"fuse-matrix-tile-size", cl::init(4), cl::Hidden,
cl::desc(
"Tile size for matrix instruction fusion using square-shaped tiles."));
static cl::opt<bool> ForceFusion(
"force-fuse-matrix", cl::init(false), cl::Hidden,
cl::desc("Force matrix instruction fusion even if not profitable."));
static cl::opt<bool> AllowContractEnabled(
"matrix-allow-contract", cl::init(false), cl::Hidden,
cl::desc("Allow the use of FMAs if available and profitable. This may "
"result in different results, due to less rounding error."));
enum class MatrixLayoutTy { ColumnMajor, RowMajor };
static cl::opt<MatrixLayoutTy> MatrixLayout(
"matrix-default-layout", cl::init(MatrixLayoutTy::ColumnMajor),
cl::desc("Sets the default matrix layout"),
cl::values(clEnumValN(MatrixLayoutTy::ColumnMajor, "column-major",
"Use column-major layout"),
clEnumValN(MatrixLayoutTy::RowMajor, "row-major",
"Use row-major layout")));
/// Helper function to either return Scope, if it is a subprogram or the
/// attached subprogram for a local scope.
static DISubprogram *getSubprogram(DIScope *Scope) {
if (auto *Subprogram = dyn_cast<DISubprogram>(Scope))
return Subprogram;
return cast<DILocalScope>(Scope)->getSubprogram();
}
namespace {
// Given an element pointer \p BasePtr to the start of a (sub) matrix, compute
// the start address of vector \p VecIdx with type (\p EltType x \p NumElements)
// assuming \p Stride elements between start two consecutive vectors.
// \p Stride must be >= \p NumElements.
// For column-major matrixes, the function computes the address of a column
// vectors and \p NumElements must be set to the number of elements in a column
// (= number of rows of the matrix). For row-major matrixes, the function
// computes the address of a row vector and \p NumElements must be set to the
// number of elements in a column (= number of columns of the matrix).
//
// Consider a 4x4 matrix in column-mjaor layout like below
//
// 0 1 2 3
// 0 v_0_0 v_0_1 v_0_2 v_0_3
// 1 v_1_0 v_1_1 v_1_2 v_1_3
// 2 v_2_0 v_2_1 v_2_2 v_2_3
// 3 v_3_0 v_3_1 v_3_2 v_3_3
// To compute the column addresses for a 2x3 sub-matrix at row 1 and column 1,
// we need a pointer to the first element of the submatrix as base pointer.
// Then we can use computeVectorAddr to compute the addresses for the columns
// of the sub-matrix.
//
// Column 0: computeVectorAddr(Base, 0 (column), 4 (stride), 2 (num rows), ..)
// -> just returns Base
// Column 1: computeVectorAddr(Base, 1 (column), 4 (stride), 2 (num rows), ..)
// -> returns Base + (1 * 4)
// Column 2: computeVectorAddr(Base, 2 (column), 4 (stride), 2 (num rows), ..)
// -> returns Base + (2 * 4)
//
// The graphic below illustrates the number of elements in a column (marked
// with |) and the number of skipped elements (marked with }).
//
// v_0_0 v_0_1 {v_0_2 {v_0_3
// Base Col 1 Col 2
// | | |
// v_1_0 |v_1_1 |v_1_2 |v_1_3
// v_2_0 |v_2_1 |v_2_2 |v_2_3
// v_3_0 {v_3_1 {v_3_2 v_3_3
//
Value *computeVectorAddr(Value *BasePtr, Value *VecIdx, Value *Stride,
unsigned NumElements, Type *EltType,
IRBuilder<> &Builder) {
assert((!isa<ConstantInt>(Stride) ||
cast<ConstantInt>(Stride)->getZExtValue() >= NumElements) &&
"Stride must be >= the number of elements in the result vector.");
unsigned AS = cast<PointerType>(BasePtr->getType())->getAddressSpace();
// Compute the start of the vector with index VecIdx as VecIdx * Stride.
Value *VecStart = Builder.CreateMul(VecIdx, Stride, "vec.start");
// Get pointer to the start of the selected vector. Skip GEP creation,
// if we select vector 0.
if (isa<ConstantInt>(VecStart) && cast<ConstantInt>(VecStart)->isZero())
VecStart = BasePtr;
else
VecStart = Builder.CreateGEP(EltType, BasePtr, VecStart, "vec.gep");
// Cast elementwise vector start pointer to a pointer to a vector
// (EltType x NumElements)*.
Type *VecType = VectorType::get(EltType, NumElements);
Type *VecPtrType = PointerType::get(VecType, AS);
return Builder.CreatePointerCast(VecStart, VecPtrType, "vec.cast");
}
/// LowerMatrixIntrinsics contains the methods used to lower matrix intrinsics.
///
/// Currently, the lowering for each matrix intrinsic is done as follows:
/// 1. Propagate the shape information from intrinsics to connected
/// instructions.
/// 2. Lower instructions with shape information (assuming column-major layout).
/// The lowering works similarly using row-major layout.
/// 2.1. Get column vectors for each argument. If we already lowered the
/// definition of an argument, use the produced column vectors directly.
/// If not, split the operand vector containing an embedded matrix into
/// a set of column vectors,
/// 2.2. Lower the instruction in terms of columnwise operations, which yields
/// a set of column vectors containing result matrix. Note that we lower
/// all instructions that have shape information. Besides the intrinsics,
/// this includes stores for example.
/// 2.3. Update uses of the lowered instruction. If we have shape information
/// for a user, there is nothing to do, as we will look up the result
/// column matrix when lowering the user. For other uses, we embed the
/// result matrix in a flat vector and update the use.
/// 2.4. Cache the result column matrix for the instruction we lowered
/// 3. After we lowered all instructions in a function, remove the now
/// obsolete instructions.
///
class LowerMatrixIntrinsics {
Function &Func;
const DataLayout &DL;
const TargetTransformInfo &TTI;
AliasAnalysis &AA;
DominatorTree &DT;
LoopInfo &LI;
OptimizationRemarkEmitter &ORE;
/// Contains estimates of the number of operations (loads, stores, compute) required to lower a matrix operation.
struct OpInfoTy {
/// Number of stores emitted to generate this matrix.
unsigned NumStores = 0;
/// Number of loads emitted to generate this matrix.
unsigned NumLoads = 0;
/// Number of compute operations emitted to generate this matrix.
unsigned NumComputeOps = 0;
OpInfoTy &operator+=(const OpInfoTy &RHS) {
NumStores += RHS.NumStores;
NumLoads += RHS.NumLoads;
NumComputeOps += RHS.NumComputeOps;
return *this;
}
};
/// Wrapper class representing a matrix as a set of vectors, either in row or
/// column major layout. All vectors must have the same vector type.
class MatrixTy {
SmallVector<Value *, 16> Vectors;
OpInfoTy OpInfo;
bool IsColumnMajor = true;
public:
MatrixTy()
: Vectors(),
IsColumnMajor(MatrixLayout == MatrixLayoutTy::ColumnMajor) {}
MatrixTy(ArrayRef<Value *> Vectors)
: Vectors(Vectors.begin(), Vectors.end()),
IsColumnMajor(MatrixLayout == MatrixLayoutTy::ColumnMajor) {}
MatrixTy(unsigned NumRows, unsigned NumColumns, Type *EltTy)
: IsColumnMajor(MatrixLayout == MatrixLayoutTy::ColumnMajor) {
unsigned D = isColumnMajor() ? NumColumns : NumRows;
for (unsigned J = 0; J < D; ++J)
addVector(UndefValue::get(
VectorType::get(EltTy, isColumnMajor() ? NumRows : NumColumns)));
}
Value *getVector(unsigned i) const { return Vectors[i]; }
Value *getColumn(unsigned i) const {
assert(isColumnMajor() && "only supported for column-major matrixes");
return Vectors[i];
}
Value *getRow(unsigned i) const {
assert(!isColumnMajor() && "only supported for row-major matrixes");
return Vectors[i];
}
void setVector(unsigned i, Value *V) { Vectors[i] = V; }
Type *getElementType() { return getVectorTy()->getElementType(); }
unsigned getNumVectors() const {
if (isColumnMajor())
return getNumColumns();
return getNumRows();
}
unsigned getNumColumns() const {
if (isColumnMajor())
return Vectors.size();
else {
assert(Vectors.size() > 0 && "Cannot call getNumRows without columns");
return cast<VectorType>(Vectors[0]->getType())->getNumElements();
}
}
unsigned getNumRows() const {
if (isColumnMajor()) {
assert(Vectors.size() > 0 && "Cannot call getNumRows without columns");
return cast<VectorType>(Vectors[0]->getType())->getNumElements();
} else
return Vectors.size();
}
void addVector(Value *V) { Vectors.push_back(V); }
VectorType *getColumnTy() {
assert(isColumnMajor() && "only supported for column-major matrixes");
return getVectorTy();
}
VectorType *getVectorTy() {
return cast<VectorType>(Vectors[0]->getType());
}
iterator_range<SmallVector<Value *, 8>::iterator> columns() {
assert(isColumnMajor() &&
"columns() only supported for column-major matrixes");
return make_range(Vectors.begin(), Vectors.end());
}
iterator_range<SmallVector<Value *, 8>::iterator> vectors() {
return make_range(Vectors.begin(), Vectors.end());
}
/// Embed the vectors of the matrix into a flat vector by concatenating
/// them.
Value *embedInVector(IRBuilder<> &Builder) const {
return Vectors.size() == 1 ? Vectors[0]
: concatenateVectors(Builder, Vectors);
}
MatrixTy &addNumLoads(unsigned N) {
OpInfo.NumLoads += N;
return *this;
}
void setNumLoads(unsigned N) { OpInfo.NumLoads = N; }
MatrixTy &addNumStores(unsigned N) {
OpInfo.NumStores += N;
return *this;
}
MatrixTy &addNumComputeOps(unsigned N) {
OpInfo.NumComputeOps += N;
return *this;
}
unsigned getNumStores() const { return OpInfo.NumStores; }
unsigned getNumLoads() const { return OpInfo.NumLoads; }
unsigned getNumComputeOps() const { return OpInfo.NumComputeOps; }
const OpInfoTy &getOpInfo() const { return OpInfo; }
bool isColumnMajor() const { return IsColumnMajor; }
unsigned getStride() const {
if (isColumnMajor())
return getNumRows();
return getNumColumns();
}
/// Extract a vector of \p NumElts starting at index (\p I, \p J). If the
/// matrix is column-major, the result vector is extracted from a column
/// vector, otherwise from a row vector.
Value *extractVector(unsigned I, unsigned J, unsigned NumElts,
IRBuilder<> &Builder) const {
Value *Vec = isColumnMajor() ? getColumn(J) : getRow(I);
Value *Undef = UndefValue::get(Vec->getType());
Constant *Mask =
createSequentialMask(Builder, isColumnMajor() ? I : J, NumElts, 0);
return Builder.CreateShuffleVector(Vec, Undef, Mask, "block");
}
};
struct ShapeInfo {
unsigned NumRows;
unsigned NumColumns;
bool IsColumnMajor;
ShapeInfo(unsigned NumRows = 0, unsigned NumColumns = 0)
: NumRows(NumRows), NumColumns(NumColumns),
IsColumnMajor(MatrixLayout == MatrixLayoutTy::ColumnMajor) {}
ShapeInfo(Value *NumRows, Value *NumColumns)
: ShapeInfo(cast<ConstantInt>(NumRows)->getZExtValue(),
cast<ConstantInt>(NumColumns)->getZExtValue()) {}
bool operator==(const ShapeInfo &other) {
return NumRows == other.NumRows && NumColumns == other.NumColumns;
}
bool operator!=(const ShapeInfo &other) { return !(*this == other); }
/// Returns true if shape-information is defined, meaning both dimensions
/// are != 0.
operator bool() const {
assert(NumRows == 0 || NumColumns != 0);
return NumRows != 0;
}
unsigned getStride() const {
if (IsColumnMajor)
return NumRows;
return NumColumns;
}
unsigned getNumVectors() const {
if (IsColumnMajor)
return NumColumns;
return NumRows;
}
};
/// Maps instructions to their shape information. The shape information
/// describes the shape to be used while lowering. This matches the shape of
/// the result value of the instruction, with the only exceptions being store
/// instructions and the matrix_columnwise_store intrinsics. For those, the
/// shape information indicates that those instructions should be lowered
/// using shape information as well.
DenseMap<Value *, ShapeInfo> ShapeMap;
/// List of instructions to remove. While lowering, we are not replacing all
/// users of a lowered instruction, if shape information is available and
/// those need to be removed after we finished lowering.
SmallVector<Instruction *, 16> ToRemove;
/// Map from instructions to their produced column matrix.
MapVector<Value *, MatrixTy> Inst2ColumnMatrix;
public:
LowerMatrixIntrinsics(Function &F, TargetTransformInfo &TTI,
AliasAnalysis &AA, DominatorTree &DT, LoopInfo &LI,
OptimizationRemarkEmitter &ORE)
: Func(F), DL(F.getParent()->getDataLayout()), TTI(TTI), AA(AA), DT(DT),
LI(LI), ORE(ORE) {}
unsigned getNumOps(Type *VT) {
assert(isa<VectorType>(VT) && "Expected vector type");
return getNumOps(VT->getScalarType(),
cast<VectorType>(VT)->getNumElements());
}
//
/// Return the estimated number of vector ops required for an operation on
/// \p VT * N.
unsigned getNumOps(Type *ST, unsigned N) {
return std::ceil((ST->getPrimitiveSizeInBits() * N).getFixedSize() /
double(TTI.getRegisterBitWidth(true)));
}
/// Return the set of vectors that a matrix value is lowered to.
///
/// If we lowered \p MatrixVal, just return the cache result matrix. Otherwise
/// split the flat vector \p MatrixVal containing a matrix with shape \p SI
/// into vectors.
MatrixTy getMatrix(Value *MatrixVal, const ShapeInfo &SI,
IRBuilder<> &Builder) {
VectorType *VType = dyn_cast<VectorType>(MatrixVal->getType());
assert(VType && "MatrixVal must be a vector type");
assert(VType->getNumElements() == SI.NumRows * SI.NumColumns &&
"The vector size must match the number of matrix elements");
// Check if we lowered MatrixVal using shape information. In that case,
// return the existing matrix, if it matches the requested shape
// information. If there is a mis-match, embed the result in a flat
// vector and split it later.
auto Found = Inst2ColumnMatrix.find(MatrixVal);
if (Found != Inst2ColumnMatrix.end()) {
MatrixTy &M = Found->second;
// Return the found matrix, if its shape matches the requested shape
// information
if (SI.NumRows == M.getNumRows() && SI.NumColumns == M.getNumColumns())
return M;
MatrixVal = M.embedInVector(Builder);
}
// Otherwise split MatrixVal.
SmallVector<Value *, 16> SplitVecs;
Value *Undef = UndefValue::get(VType);
for (unsigned MaskStart = 0; MaskStart < VType->getNumElements();
MaskStart += SI.getStride()) {
Constant *Mask =
createSequentialMask(Builder, MaskStart, SI.getStride(), 0);
Value *V = Builder.CreateShuffleVector(MatrixVal, Undef, Mask, "split");
SplitVecs.push_back(V);
}
return {SplitVecs};
}
/// If \p V already has a known shape return false. Otherwise set the shape
/// for instructions that support it.
bool setShapeInfo(Value *V, ShapeInfo Shape) {
assert(Shape && "Shape not set");
if (isa<UndefValue>(V) || !supportsShapeInfo(V))
return false;
auto SIter = ShapeMap.find(V);
if (SIter != ShapeMap.end()) {
LLVM_DEBUG(dbgs() << " not overriding existing shape: "
<< SIter->second.NumRows << " "
<< SIter->second.NumColumns << " for " << *V << "\n");
return false;
}
ShapeMap.insert({V, Shape});
LLVM_DEBUG(dbgs() << " " << Shape.NumRows << " x " << Shape.NumColumns
<< " for " << *V << "\n");
return true;
}
bool isUniformShape(Value *V) {
Instruction *I = dyn_cast<Instruction>(V);
if (!I)
return true;
switch (I->getOpcode()) {
case Instruction::FAdd:
case Instruction::FSub:
case Instruction::FMul: // Scalar multiply.
case Instruction::Add:
case Instruction::Mul:
case Instruction::Sub:
return true;
default:
return false;
}
}
/// Returns true if shape information can be used for \p V. The supported
/// instructions must match the instructions that can be lowered by this pass.
bool supportsShapeInfo(Value *V) {
Instruction *Inst = dyn_cast<Instruction>(V);
if (!Inst)
return false;
IntrinsicInst *II = dyn_cast<IntrinsicInst>(Inst);
if (II)
switch (II->getIntrinsicID()) {
case Intrinsic::matrix_multiply:
case Intrinsic::matrix_transpose:
case Intrinsic::matrix_columnwise_load:
case Intrinsic::matrix_columnwise_store:
return true;
default:
return false;
}
return isUniformShape(V) || isa<StoreInst>(V) || isa<LoadInst>(V);
}
/// Propagate the shape information of instructions to their users.
/// The work list contains instructions for which we can compute the shape,
/// either based on the information provided by matrix intrinsics or known
/// shapes of operands.
SmallVector<Instruction *, 32>
propagateShapeForward(SmallVectorImpl<Instruction *> &WorkList) {
SmallVector<Instruction *, 32> NewWorkList;
// Pop an element for which we guaranteed to have at least one of the
// operand shapes. Add the shape for this and then add users to the work
// list.
LLVM_DEBUG(dbgs() << "Forward-propagate shapes:\n");
while (!WorkList.empty()) {
Instruction *Inst = WorkList.back();
WorkList.pop_back();
// New entry, set the value and insert operands
bool Propagate = false;
Value *MatrixA;
Value *MatrixB;
Value *M;
Value *N;
Value *K;
if (match(Inst, m_Intrinsic<Intrinsic::matrix_multiply>(
m_Value(MatrixA), m_Value(MatrixB), m_Value(M),
m_Value(N), m_Value(K)))) {
Propagate = setShapeInfo(Inst, {M, K});
} else if (match(Inst, m_Intrinsic<Intrinsic::matrix_transpose>(
m_Value(MatrixA), m_Value(M), m_Value(N)))) {
// Flip dimensions.
Propagate = setShapeInfo(Inst, {N, M});
} else if (match(Inst, m_Intrinsic<Intrinsic::matrix_columnwise_store>(
m_Value(MatrixA), m_Value(), m_Value(),
m_Value(M), m_Value(N)))) {
Propagate = setShapeInfo(Inst, {N, M});
} else if (match(Inst,
m_Intrinsic<Intrinsic::matrix_columnwise_load>(
m_Value(), m_Value(), m_Value(M), m_Value(N)))) {
Propagate = setShapeInfo(Inst, {M, N});
} else if (match(Inst, m_Store(m_Value(MatrixA), m_Value()))) {
auto OpShape = ShapeMap.find(MatrixA);
if (OpShape != ShapeMap.end())
setShapeInfo(Inst, OpShape->second);
continue;
} else if (isUniformShape(Inst)) {
// Find the first operand that has a known shape and use that.
for (auto &Op : Inst->operands()) {
auto OpShape = ShapeMap.find(Op.get());
if (OpShape != ShapeMap.end()) {
Propagate |= setShapeInfo(Inst, OpShape->second);
break;
}
}
}
if (Propagate) {
NewWorkList.push_back(Inst);
for (auto *User : Inst->users())
if (ShapeMap.count(User) == 0)
WorkList.push_back(cast<Instruction>(User));
}
}
return NewWorkList;
}
/// Propagate the shape to operands of instructions with shape information.
/// \p Worklist contains the instruction for which we already know the shape.
SmallVector<Instruction *, 32>
propagateShapeBackward(SmallVectorImpl<Instruction *> &WorkList) {
SmallVector<Instruction *, 32> NewWorkList;
auto pushInstruction = [](Value *V,
SmallVectorImpl<Instruction *> &WorkList) {
Instruction *I = dyn_cast<Instruction>(V);
if (I)
WorkList.push_back(I);
};
// Pop an element with known shape. Traverse the operands, if their shape
// derives from the result shape and is unknown, add it and add them to the
// worklist.
LLVM_DEBUG(dbgs() << "Backward-propagate shapes:\n");
while (!WorkList.empty()) {
Value *V = WorkList.back();
WorkList.pop_back();
size_t BeforeProcessingV = WorkList.size();
if (!isa<Instruction>(V))
continue;
Value *MatrixA;
Value *MatrixB;
Value *M;
Value *N;
Value *K;
if (match(V, m_Intrinsic<Intrinsic::matrix_multiply>(
m_Value(MatrixA), m_Value(MatrixB), m_Value(M),
m_Value(N), m_Value(K)))) {
if (setShapeInfo(MatrixA, {M, N}))
pushInstruction(MatrixA, WorkList);
if (setShapeInfo(MatrixB, {N, K}))
pushInstruction(MatrixB, WorkList);
} else if (match(V, m_Intrinsic<Intrinsic::matrix_transpose>(
m_Value(MatrixA), m_Value(M), m_Value(N)))) {
// Flip dimensions.
if (setShapeInfo(MatrixA, {M, N}))
pushInstruction(MatrixA, WorkList);
} else if (match(V, m_Intrinsic<Intrinsic::matrix_columnwise_store>(
m_Value(MatrixA), m_Value(), m_Value(),
m_Value(M), m_Value(N)))) {
if (setShapeInfo(MatrixA, {M, N})) {
pushInstruction(MatrixA, WorkList);
}
} else if (isa<LoadInst>(V) ||
match(V, m_Intrinsic<Intrinsic::matrix_columnwise_load>())) {
// Nothing to do, no matrix input.
} else if (isa<StoreInst>(V)) {
// Nothing to do. We forward-propagated to this so we would just
// backward propagate to an instruction with an already known shape.
} else if (isUniformShape(V)) {
// Propagate to all operands.
ShapeInfo Shape = ShapeMap[V];
for (Use &U : cast<Instruction>(V)->operands()) {
if (setShapeInfo(U.get(), Shape))
pushInstruction(U.get(), WorkList);
}
}
// After we discovered new shape info for new instructions in the
// worklist, we use their users as seeds for the next round of forward
// propagation.
for (size_t I = BeforeProcessingV; I != WorkList.size(); I++)
for (User *U : WorkList[I]->users())
if (isa<Instruction>(U) && V != U)
NewWorkList.push_back(cast<Instruction>(U));
}
return NewWorkList;
}
bool Visit() {
if (EnableShapePropagation) {
SmallVector<Instruction *, 32> WorkList;
// Initially only the shape of matrix intrinsics is known.
// Initialize the work list with ops carrying shape information.
for (BasicBlock &BB : Func)
for (Instruction &Inst : BB) {
IntrinsicInst *II = dyn_cast<IntrinsicInst>(&Inst);
if (!II)
continue;
switch (II->getIntrinsicID()) {
case Intrinsic::matrix_multiply:
case Intrinsic::matrix_transpose:
case Intrinsic::matrix_columnwise_load:
case Intrinsic::matrix_columnwise_store:
WorkList.push_back(&Inst);
break;
default:
break;
}
}
// Propagate shapes until nothing changes any longer.
while (!WorkList.empty()) {
WorkList = propagateShapeForward(WorkList);
WorkList = propagateShapeBackward(WorkList);
}
}
bool Changed = false;
SmallVector<CallInst *, 16> MaybeFusableInsts;
SmallVector<Instruction *, 16> MatrixInsts;
// First, collect all instructions with shape information and candidates for
// fusion (currently only matrix multiplies).
ReversePostOrderTraversal<Function *> RPOT(&Func);
for (auto *BB : RPOT)
for (Instruction &I : *BB) {
if (ShapeMap.find(&I) == ShapeMap.end())
continue;
if (match(&I, m_Intrinsic<Intrinsic::matrix_multiply>()))
MaybeFusableInsts.push_back(cast<CallInst>(&I));
MatrixInsts.push_back(&I);
}
// Second, try to fuse candidates.
SmallPtrSet<Instruction *, 16> FusedInsts;
for (CallInst *CI : MaybeFusableInsts)
LowerMatrixMultiplyFused(CI, FusedInsts);
Changed = !FusedInsts.empty();
// Third, lower remaining instructions with shape information.
for (Instruction *Inst : MatrixInsts) {
if (FusedInsts.find(Inst) != FusedInsts.end())
continue;
IRBuilder<> Builder(Inst);
if (CallInst *CInst = dyn_cast<CallInst>(Inst))
Changed |= VisitCallInst(CInst);
Value *Op1;
Value *Op2;
if (auto *BinOp = dyn_cast<BinaryOperator>(Inst))
Changed |= VisitBinaryOperator(BinOp);
if (match(Inst, m_Load(m_Value(Op1))))
Changed |= VisitLoad(Inst, Op1, Builder);
else if (match(Inst, m_Store(m_Value(Op1), m_Value(Op2))))
Changed |= VisitStore(Inst, Op1, Op2, Builder);
}
RemarkGenerator RemarkGen(Inst2ColumnMatrix, ORE, Func);
RemarkGen.emitRemarks();
for (Instruction *Inst : reverse(ToRemove))
Inst->eraseFromParent();
return Changed;
}
LoadInst *createVectorLoad(Value *ColumnPtr, Type *EltType,
IRBuilder<> &Builder) {
return Builder.CreateAlignedLoad(
ColumnPtr, Align(DL.getABITypeAlignment(EltType)), "col.load");
}
StoreInst *createVectorStore(Value *ColumnValue, Value *ColumnPtr,
Type *EltType, IRBuilder<> &Builder) {
return Builder.CreateAlignedStore(ColumnValue, ColumnPtr,
DL.getABITypeAlign(EltType));
}
/// Turns \p BasePtr into an elementwise pointer to \p EltType.
Value *createElementPtr(Value *BasePtr, Type *EltType, IRBuilder<> &Builder) {
unsigned AS = cast<PointerType>(BasePtr->getType())->getAddressSpace();
Type *EltPtrType = PointerType::get(EltType, AS);
return Builder.CreatePointerCast(BasePtr, EltPtrType);
}
/// Replace intrinsic calls
bool VisitCallInst(CallInst *Inst) {
if (!Inst->getCalledFunction() || !Inst->getCalledFunction()->isIntrinsic())
return false;
switch (Inst->getCalledFunction()->getIntrinsicID()) {
case Intrinsic::matrix_multiply:
LowerMultiply(Inst);
break;
case Intrinsic::matrix_transpose:
LowerTranspose(Inst);
break;
case Intrinsic::matrix_columnwise_load:
LowerColumnwiseLoad(Inst);
break;
case Intrinsic::matrix_columnwise_store:
LowerColumnwiseStore(Inst);
break;
default:
return false;
}
return true;
}
/// Load a matrix with \p Shape starting at \p Ptr and using \p Stride between
/// vectors.
MatrixTy loadMatrix(Type *Ty, Value *Ptr, Value *Stride, ShapeInfo Shape,
IRBuilder<> &Builder) {
auto VType = cast<VectorType>(Ty);
Value *EltPtr = createElementPtr(Ptr, VType->getElementType(), Builder);
MatrixTy Result;
for (unsigned I = 0, E = Shape.getNumVectors(); I < E; ++I) {
Value *GEP = computeVectorAddr(EltPtr, Builder.getInt32(I), Stride,
Shape.getStride(), VType->getElementType(),
Builder);
Value *Vector = createVectorLoad(GEP, VType->getElementType(), Builder);
Result.addVector(Vector);
}
return Result.addNumLoads(getNumOps(Result.getVectorTy()) *
Result.getNumVectors());
}
/// Loads a sub-matrix with shape \p ResultShape from a \p R x \p C matrix,
/// starting at \p MatrixPtr[I][J].
MatrixTy loadMatrix(Value *MatrixPtr, ShapeInfo MatrixShape, Value *I,
Value *J, ShapeInfo ResultShape, Type *EltTy,
IRBuilder<> &Builder) {
Value *Offset = Builder.CreateAdd(
Builder.CreateMul(J, Builder.getInt32(MatrixShape.getStride())), I);
unsigned AS = cast<PointerType>(MatrixPtr->getType())->getAddressSpace();
Value *EltPtr =
Builder.CreatePointerCast(MatrixPtr, PointerType::get(EltTy, AS));
Value *TileStart = Builder.CreateGEP(EltTy, EltPtr, Offset);
Type *TileTy =
VectorType::get(EltTy, ResultShape.NumRows * ResultShape.NumColumns);
Type *TilePtrTy = PointerType::get(TileTy, AS);
Value *TilePtr =
Builder.CreatePointerCast(TileStart, TilePtrTy, "col.cast");
return loadMatrix(TileTy, TilePtr,
Builder.getInt32(MatrixShape.getStride()), ResultShape,
Builder);
}
/// Lower a load instruction with shape information.
void LowerLoad(Instruction *Inst, Value *Ptr, Value *Stride,
ShapeInfo Shape) {
IRBuilder<> Builder(Inst);
finalizeLowering(Inst,
loadMatrix(Inst->getType(), Ptr, Stride, Shape, Builder),
Builder);
}
/// Lowers llvm.matrix.columnwise.load.
///
/// The intrinsic loads a matrix from memory using a stride between columns.
void LowerColumnwiseLoad(CallInst *Inst) {
assert(MatrixLayout == MatrixLayoutTy::ColumnMajor &&
"Intrinsic only supports column-major layout!");
Value *Ptr = Inst->getArgOperand(0);
Value *Stride = Inst->getArgOperand(1);
LowerLoad(Inst, Ptr, Stride,
{Inst->getArgOperand(2), Inst->getArgOperand(3)});
}
/// Stores a sub-matrix \p StoreVal into the \p R x \p C matrix starting at \p
/// MatrixPtr[I][J].
void storeMatrix(const MatrixTy &StoreVal, Value *MatrixPtr,
ShapeInfo MatrixShape, Value *I, Value *J, Type *EltTy,
IRBuilder<> &Builder) {
Value *Offset = Builder.CreateAdd(
Builder.CreateMul(J, Builder.getInt32(MatrixShape.getStride())), I);
unsigned AS = cast<PointerType>(MatrixPtr->getType())->getAddressSpace();
Value *EltPtr =
Builder.CreatePointerCast(MatrixPtr, PointerType::get(EltTy, AS));
Value *TileStart = Builder.CreateGEP(EltTy, EltPtr, Offset);
Type *TileTy = VectorType::get(EltTy, StoreVal.getNumRows() *
StoreVal.getNumColumns());
Type *TilePtrTy = PointerType::get(TileTy, AS);
Value *TilePtr =
Builder.CreatePointerCast(TileStart, TilePtrTy, "col.cast");
storeMatrix(TileTy, StoreVal, TilePtr,
Builder.getInt32(MatrixShape.getStride()), Builder);
}
/// Store matrix \p StoreVal starting at \p Ptr and using \p Stride between
/// vectors.
MatrixTy storeMatrix(Type *Ty, MatrixTy StoreVal, Value *Ptr, Value *Stride,
IRBuilder<> &Builder) {
auto VType = cast<VectorType>(Ty);
Value *EltPtr = createElementPtr(Ptr, VType->getElementType(), Builder);
for (auto Vec : enumerate(StoreVal.vectors())) {
Value *GEP = computeVectorAddr(EltPtr, Builder.getInt32(Vec.index()),
Stride, StoreVal.getStride(),
VType->getElementType(), Builder);
createVectorStore(Vec.value(), GEP, VType->getElementType(), Builder);
}
return MatrixTy().addNumStores(getNumOps(StoreVal.getVectorTy()) *
StoreVal.getNumVectors());
}
/// Lower a store instruction with shape information.
void LowerStore(Instruction *Inst, Value *Matrix, Value *Ptr, Value *Stride,
ShapeInfo Shape) {
IRBuilder<> Builder(Inst);
auto StoreVal = getMatrix(Matrix, Shape, Builder);
finalizeLowering(
Inst, storeMatrix(Matrix->getType(), StoreVal, Ptr, Stride, Builder),
Builder);
}
/// Lowers llvm.matrix.columnwise.store.
///
/// The intrinsic store a matrix back memory using a stride between columns.
void LowerColumnwiseStore(CallInst *Inst) {
assert(MatrixLayout == MatrixLayoutTy::ColumnMajor &&
"Intrinsic only supports column-major layout!");
Value *Matrix = Inst->getArgOperand(0);
Value *Ptr = Inst->getArgOperand(1);
Value *Stride = Inst->getArgOperand(2);
LowerStore(Inst, Matrix, Ptr, Stride,
{Inst->getArgOperand(3), Inst->getArgOperand(4)});
}
// Set elements I..I+NumElts-1 to Block
Value *insertVector(Value *Col, unsigned I, Value *Block,
IRBuilder<> &Builder) {
// First, bring Block to the same size as Col
unsigned BlockNumElts =
cast<VectorType>(Block->getType())->getNumElements();
unsigned NumElts = cast<VectorType>(Col->getType())->getNumElements();
assert(NumElts >= BlockNumElts && "Too few elements for current block");
Value *ExtendMask =
createSequentialMask(Builder, 0, BlockNumElts, NumElts - BlockNumElts);
Value *Undef = UndefValue::get(Block->getType());
Block = Builder.CreateShuffleVector(Block, Undef, ExtendMask);
// If Col is 7 long and I is 2 and BlockNumElts is 2 the mask is: 0, 1, 7,
// 8, 4, 5, 6
SmallVector<Constant *, 16> Mask;
unsigned i;
for (i = 0; i < I; i++)
Mask.push_back(Builder.getInt32(i));
unsigned VecNumElts = cast<VectorType>(Col->getType())->getNumElements();
for (; i < I + BlockNumElts; i++)
Mask.push_back(Builder.getInt32(i - I + VecNumElts));
for (; i < VecNumElts; i++)
Mask.push_back(Builder.getInt32(i));
Value *MaskVal = ConstantVector::get(Mask);
return Builder.CreateShuffleVector(Col, Block, MaskVal);
}
Value *createMulAdd(Value *Sum, Value *A, Value *B, bool UseFPOp,
IRBuilder<> &Builder, bool AllowContraction,
unsigned &NumComputeOps) {
NumComputeOps += getNumOps(A->getType());
if (!Sum)
return UseFPOp ? Builder.CreateFMul(A, B) : Builder.CreateMul(A, B);
if (UseFPOp) {
if (AllowContraction) {
// Use fmuladd for floating point operations and let the backend decide
// if that's profitable.
Function *FMulAdd = Intrinsic::getDeclaration(
Func.getParent(), Intrinsic::fmuladd, A->getType());
return Builder.CreateCall(FMulAdd, {A, B, Sum});
}
NumComputeOps += getNumOps(A->getType());
Value *Mul = Builder.CreateFMul(A, B);
return Builder.CreateFAdd(Sum, Mul);
}
NumComputeOps += getNumOps(A->getType());
Value *Mul = Builder.CreateMul(A, B);
return Builder.CreateAdd(Sum, Mul);
}
/// Cache \p Matrix as result of \p Inst and update the uses of \p Inst. For
/// users with shape information, there's nothing to do: the will use the
/// cached value when they are lowered. For other users, \p Matrix is
/// flattened and the uses are updated to use it. Also marks \p Inst for
/// deletion.
void finalizeLowering(Instruction *Inst, MatrixTy Matrix,
IRBuilder<> &Builder) {
Inst2ColumnMatrix.insert(std::make_pair(Inst, Matrix));
ToRemove.push_back(Inst);
Value *Flattened = nullptr;
for (auto I = Inst->use_begin(), E = Inst->use_end(); I != E;) {
Use &U = *I++;
if (ShapeMap.find(U.getUser()) == ShapeMap.end()) {
if (!Flattened)
Flattened = Matrix.embedInVector(Builder);
U.set(Flattened);
}
}
}
/// Compute \p Result += \p A * \p B for input matrices with left-associating
/// addition.
void emitMatrixMultiply(MatrixTy &Result, const MatrixTy &A,
const MatrixTy &B, bool AllowContraction,
IRBuilder<> &Builder, bool isTiled) {
const unsigned VF = std::max<unsigned>(
TTI.getRegisterBitWidth(true) /
Result.getElementType()->getPrimitiveSizeInBits().getFixedSize(),
1U);
unsigned R = Result.getNumRows();
unsigned C = Result.getNumColumns();
unsigned M = A.getNumColumns();
bool IsFP = Result.getElementType()->isFloatingPointTy();
assert(A.isColumnMajor() == B.isColumnMajor() &&
Result.isColumnMajor() == A.isColumnMajor() &&
"operands must agree on matrix layout");
unsigned NumComputeOps = 0;
if (A.isColumnMajor()) {
// Multiply columns from the first operand with scalars from the second
// operand. Then move along the K axes and accumulate the columns. With
// this the adds can be vectorized without reassociation.
for (unsigned J = 0; J < C; ++J) {
unsigned BlockSize = VF;
// If Result is zero, we don't need to accumulate in the K==0 iteration.
bool isSumZero = isa<ConstantAggregateZero>(Result.getColumn(J));
for (unsigned I = 0; I < R; I += BlockSize) {
// Gradually lower the vectorization factor to cover the remainder.
while (I + BlockSize > R)
BlockSize /= 2;
Value *Sum = isTiled ? Result.extractVector(I, J, BlockSize, Builder)
: nullptr;
for (unsigned K = 0; K < M; ++K) {
Value *L = A.extractVector(I, K, BlockSize, Builder);
Value *RH = Builder.CreateExtractElement(B.getColumn(J), K);
Value *Splat = Builder.CreateVectorSplat(BlockSize, RH, "splat");
Sum = createMulAdd(isSumZero && K == 0 ? nullptr : Sum, L, Splat,
Result.getElementType()->isFloatingPointTy(),
Builder, AllowContraction, NumComputeOps);
}
Result.setVector(J,
insertVector(Result.getVector(J), I, Sum, Builder));
}
}
} else {
// Multiply rows from the second operand with scalars from the first
// operand. Then move along the K axes and accumulate the rows. With this
// the adds can be vectorized without reassociation.
for (unsigned I = 0; I < R; ++I) {
unsigned BlockSize = VF;
bool isSumZero = isa<ConstantAggregateZero>(Result.getRow(I));
for (unsigned J = 0; J < C; J += BlockSize) {
// Gradually lower the vectorization factor to cover the remainder.
while (J + BlockSize > C)
BlockSize /= 2;
Value *Sum = nullptr;
for (unsigned K = 0; K < M; ++K) {
Value *R = B.extractVector(K, J, BlockSize, Builder);
Value *LH = Builder.CreateExtractElement(A.getVector(I), K);
Value *Splat = Builder.CreateVectorSplat(BlockSize, LH, "splat");
Sum = createMulAdd(isSumZero && K == 0 ? nullptr : Sum, Splat, R,
IsFP, Builder, AllowContraction, NumComputeOps);
}
Result.setVector(I,
insertVector(Result.getVector(I), J, Sum, Builder));
}
}
}
Result.addNumComputeOps(NumComputeOps);
}
/// Ensure that the memory in \p Load does not alias \p Store by potentially
/// copying it to a new location. This new or otherwise the original location
/// is returned.
Value *getNonAliasingPointer(LoadInst *Load, StoreInst *Store,
CallInst *MatMul) {
MemoryLocation StoreLoc = MemoryLocation::get(Store);
MemoryLocation LoadLoc = MemoryLocation::get(Load);
AliasResult LdAliased = AA.alias(LoadLoc, StoreLoc);
// If we can statically determine noalias we're good.
if (!LdAliased)
return Load->getPointerOperand();
// Create code to check if the memory locations of the Load and Store
// overlap and if they do, copy Load's operand to a new buffer.
// First, create new blocks for 2n part of the check and the copy.
BasicBlock *Check0 = MatMul->getParent();
// FIXME: Use lazy DTU and update SplitBlock to accept a DTU instead of a
// DT. Manually collect dominator tree updates, to avoid unnecessary work,
// as we adjust Check0 and Check1's branches.
SmallVector<DominatorTree::UpdateType, 4> DTUpdates;
for (BasicBlock *Succ : successors(Check0))
DTUpdates.push_back({DT.Delete, Check0, Succ});
BasicBlock *Check1 = SplitBlock(MatMul->getParent(), MatMul, nullptr, &LI,
nullptr, "alias_cont");
BasicBlock *Copy =
SplitBlock(MatMul->getParent(), MatMul, nullptr, &LI, nullptr, "copy");
BasicBlock *Fusion = SplitBlock(MatMul->getParent(), MatMul, nullptr, &LI,
nullptr, "no_alias");
// Check if the loaded memory location begins before the end of the store
// location. If the condition holds, they might overlap, otherwise they are
// guaranteed to not overlap.
IRBuilder<> Builder(MatMul);
Check0->getTerminator()->eraseFromParent();
Builder.SetInsertPoint(Check0);
Type *IntPtrTy = Builder.getIntPtrTy(Load->getModule()->getDataLayout());
Value *StoreBegin = Builder.CreatePtrToInt(
const_cast<Value *>(StoreLoc.Ptr), IntPtrTy, "store.begin");
Value *StoreEnd = Builder.CreateAdd(
StoreBegin, ConstantInt::get(IntPtrTy, StoreLoc.Size.getValue()),
"store.end", true, true);
Value *LoadBegin = Builder.CreatePtrToInt(const_cast<Value *>(LoadLoc.Ptr),
IntPtrTy, "load.begin");
Builder.CreateCondBr(Builder.CreateICmpULT(LoadBegin, StoreEnd), Check1,
Fusion);
// Check if the store begins before the end of the load location. If the
// condition holds, they alias, otherwise they are guaranteed to not
// overlap.
Check1->getTerminator()->eraseFromParent();
Builder.SetInsertPoint(Check1, Check1->begin());
Value *LoadEnd = Builder.CreateAdd(
LoadBegin, ConstantInt::get(IntPtrTy, LoadLoc.Size.getValue()),
"load.end", true, true);
Builder.CreateCondBr(Builder.CreateICmpULT(StoreBegin, LoadEnd), Copy,
Fusion);
// Copy load operand to new alloca.
Builder.SetInsertPoint(Copy, Copy->begin());
AllocaInst *NewLd =
Builder.CreateAlloca(Load->getType(), Load->getPointerAddressSpace());
Builder.CreateMemCpy(NewLd, NewLd->getAlign(),
Load->getPointerOperand(), Load->getAlign(),
LoadLoc.Size.getValue());
Builder.SetInsertPoint(Fusion, Fusion->begin());
PHINode *PHI = Builder.CreatePHI(Load->getPointerOperandType(), 3);
PHI->addIncoming(Load->getPointerOperand(), Check0);
PHI->addIncoming(Load->getPointerOperand(), Check1);
PHI->addIncoming(NewLd, Copy);
// Adjust DT.
DTUpdates.push_back({DT.Insert, Check0, Check1});
DTUpdates.push_back({DT.Insert, Check0, Fusion});
DTUpdates.push_back({DT.Insert, Check1, Copy});
DTUpdates.push_back({DT.Insert, Check1, Fusion});
DT.applyUpdates(DTUpdates);
return PHI;
}
bool isFusionProfitable(CallInst *MatMul) {
if (ForceFusion)
return true;
ShapeInfo LShape(MatMul->getArgOperand(2), MatMul->getArgOperand(3));
ShapeInfo RShape(MatMul->getArgOperand(3), MatMul->getArgOperand(4));
const unsigned R = LShape.NumRows;
const unsigned C = RShape.NumColumns;
const unsigned M = LShape.NumColumns;
auto *EltType = cast<VectorType>(MatMul->getType())->getElementType();
const unsigned VF =
std::max<unsigned>(TTI.getRegisterBitWidth(true) /
EltType->getPrimitiveSizeInBits().getFixedSize(),
1U);
// Cost model for tiling
//
// For tiling to be beneficial, we need reuse either along the R or
// the C axis. We vectorize along the R axis so that means at least
// 3 elements.
// TODO: Also consider cost of copying if operands alias.
if (R <= VF && C == 1)
return false;
// Then we need enough elements to exceed the number of vector
// registers we have. Note that this is an oversimplification since
// fusing also takes some extra loads which may exceed the number of
// reloads necessary.
unsigned Op0Regs = (R + VF - 1) / VF * M;
unsigned Op1Regs = (M + VF - 1) / VF * C;
return Op0Regs + Op1Regs > TTI.getNumberOfRegisters(true);
}
MatrixTy getZeroMatrix(Type *EltType, unsigned R, unsigned C) {
MatrixTy Res;
Type *ColumType = VectorType::get(EltType, R);
for (unsigned I = 0; I < C; ++I)
Res.addVector(ConstantAggregateZero::get(ColumType));
return Res;
}
void emitSIMDTiling(CallInst *MatMul, LoadInst *LoadOp0, LoadInst *LoadOp1,
StoreInst *Store,
SmallPtrSetImpl<Instruction *> &FusedInsts) {
assert(MatrixLayout == MatrixLayoutTy::ColumnMajor &&
"Tiling only supported for column-major matrixes at the moment!");
if (!isFusionProfitable(MatMul))
return;
ShapeInfo LShape(MatMul->getArgOperand(2), MatMul->getArgOperand(3));
ShapeInfo RShape(MatMul->getArgOperand(3), MatMul->getArgOperand(4));
const unsigned R = LShape.NumRows;
const unsigned C = RShape.NumColumns;
const unsigned M = LShape.NumColumns;
auto *EltType = cast<VectorType>(MatMul->getType())->getElementType();
Value *APtr = getNonAliasingPointer(LoadOp0, Store, MatMul);
Value *BPtr = getNonAliasingPointer(LoadOp1, Store, MatMul);
Value *CPtr = Store->getPointerOperand();
bool AllowContract = AllowContractEnabled || (isa<FPMathOperator>(MatMul) &&
MatMul->hasAllowContract());
IRBuilder<> Builder(Store);
for (unsigned J = 0; J < C; J += TileSize)
for (unsigned I = 0; I < R; I += TileSize) {
const unsigned TileR = std::min(R - I, unsigned(TileSize));
const unsigned TileC = std::min(C - J, unsigned(TileSize));
MatrixTy Res = getZeroMatrix(EltType, TileR, TileC);
for (unsigned K = 0; K < M; K += TileSize) {
const unsigned TileM = std::min(M - K, unsigned(TileSize));
MatrixTy A =
loadMatrix(APtr, LShape, Builder.getInt32(I), Builder.getInt32(K),
{TileR, TileM}, EltType, Builder);
MatrixTy B =
loadMatrix(BPtr, RShape, Builder.getInt32(K), Builder.getInt32(J),
{TileM, TileC}, EltType, Builder);
emitMatrixMultiply(Res, A, B, AllowContract, Builder, true);
}
storeMatrix(Res, CPtr, {R, M}, Builder.getInt32(I), Builder.getInt32(J),
EltType, Builder);
}
// Mark eliminated instructions as fused and remove them.
FusedInsts.insert(Store);
FusedInsts.insert(MatMul);
Store->eraseFromParent();
MatMul->eraseFromParent();
if (LoadOp0->hasNUses(0)) {
FusedInsts.insert(LoadOp0);
LoadOp0->eraseFromParent();
}
if (LoadOp1->hasNUses(0)) {
FusedInsts.insert(LoadOp1);
LoadOp1->eraseFromParent();
}
}
/// Try to lower matrix multiply chains by fusing operations.
///
/// Currently we only lower {ld, ld} -> matmul -> st chains.
//
/// No need to return a MatrixTy object for the result of the operation, since
/// the single store user will be lowered as part of this. Instructions that
/// are completely eliminated by fusion are added to \p FusedInsts.
void LowerMatrixMultiplyFused(CallInst *MatMul,
SmallPtrSetImpl<Instruction *> &FusedInsts) {
if (!FuseMatrix || !MatMul->hasOneUse() ||
MatrixLayout != MatrixLayoutTy::ColumnMajor)
return;
auto *LoadOp0 = dyn_cast<LoadInst>(MatMul->getOperand(0));
auto *LoadOp1 = dyn_cast<LoadInst>(MatMul->getOperand(1));
auto *Store = dyn_cast<StoreInst>(*MatMul->user_begin());
if (LoadOp0 && LoadOp1 && Store) {
// The store address must dominate the MatMul instruction, otherwise
// we create invalid IR.
// FIXME: See if we can hoist the store address computation.
auto *AddrI = dyn_cast<Instruction>(Store->getOperand(1));
if (AddrI && (!DT.dominates(AddrI, MatMul)))
return;
emitSIMDTiling(MatMul, LoadOp0, LoadOp1, Store, FusedInsts);
return;
}
}
/// Lowers llvm.matrix.multiply.
void LowerMultiply(CallInst *MatMul) {
IRBuilder<> Builder(MatMul);
auto *EltType = cast<VectorType>(MatMul->getType())->getElementType();
ShapeInfo LShape(MatMul->getArgOperand(2), MatMul->getArgOperand(3));
ShapeInfo RShape(MatMul->getArgOperand(3), MatMul->getArgOperand(4));
const MatrixTy &Lhs = getMatrix(MatMul->getArgOperand(0), LShape, Builder);
const MatrixTy &Rhs = getMatrix(MatMul->getArgOperand(1), RShape, Builder);
const unsigned R = LShape.NumRows;
const unsigned C = RShape.NumColumns;
assert(LShape.NumColumns == RShape.NumRows);
// Initialize the output
MatrixTy Result(R, C, EltType);
bool AllowContract = AllowContractEnabled || (isa<FPMathOperator>(MatMul) &&
MatMul->hasAllowContract());
emitMatrixMultiply(Result, Lhs, Rhs, AllowContract, Builder, false);
finalizeLowering(MatMul, Result, Builder);
}
/// Lowers llvm.matrix.transpose.
void LowerTranspose(CallInst *Inst) {
MatrixTy Result;
IRBuilder<> Builder(Inst);
Value *InputVal = Inst->getArgOperand(0);
VectorType *VectorTy = cast<VectorType>(InputVal->getType());
ShapeInfo ArgShape(Inst->getArgOperand(1), Inst->getArgOperand(2));
MatrixTy InputMatrix = getMatrix(InputVal, ArgShape, Builder);
assert(InputMatrix.isColumnMajor() &&
"Row-major code-gen not supported yet!");
for (unsigned Row = 0; Row < ArgShape.NumRows; ++Row) {
// Build a single column vector for this row. First initialize it.
Value *ResultColumn = UndefValue::get(
VectorType::get(VectorTy->getElementType(), ArgShape.NumColumns));
// Go through the elements of this row and insert it into the resulting
// column vector.
for (auto C : enumerate(InputMatrix.columns())) {
Value *Elt = Builder.CreateExtractElement(C.value(), Row);
// We insert at index Column since that is the row index after the
// transpose.
ResultColumn =
Builder.CreateInsertElement(ResultColumn, Elt, C.index());
}
Result.addVector(ResultColumn);
}
// TODO: Improve estimate of operations needed for transposes. Currently we
// just count the insertelement/extractelement instructions, but do not
// account for later simplifications/combines.
finalizeLowering(
Inst,
Result.addNumComputeOps(2 * ArgShape.NumRows * ArgShape.NumColumns),
Builder);
}
/// Lower load instructions, if shape information is available.
bool VisitLoad(Instruction *Inst, Value *Ptr, IRBuilder<> &Builder) {
auto I = ShapeMap.find(Inst);
if (I == ShapeMap.end())
return false;
LowerLoad(Inst, Ptr, Builder.getInt32(I->second.getStride()), I->second);
return true;
}
bool VisitStore(Instruction *Inst, Value *StoredVal, Value *Ptr,
IRBuilder<> &Builder) {
auto I = ShapeMap.find(StoredVal);
if (I == ShapeMap.end())
return false;
LowerStore(Inst, StoredVal, Ptr, Builder.getInt32(I->second.getStride()),
I->second);
return true;
}
/// Lower binary operators, if shape information is available.
bool VisitBinaryOperator(BinaryOperator *Inst) {
auto I = ShapeMap.find(Inst);
if (I == ShapeMap.end())
return false;
Value *Lhs = Inst->getOperand(0);
Value *Rhs = Inst->getOperand(1);
IRBuilder<> Builder(Inst);
ShapeInfo &Shape = I->second;
MatrixTy Result;
MatrixTy A = getMatrix(Lhs, Shape, Builder);
MatrixTy B = getMatrix(Rhs, Shape, Builder);
assert(A.isColumnMajor() == B.isColumnMajor() &&
Result.isColumnMajor() == A.isColumnMajor() &&
"operands must agree on matrix layout");
// Helper to perform binary op on vectors.
auto BuildVectorOp = [&Builder, Inst](Value *LHS, Value *RHS) {
switch (Inst->getOpcode()) {
case Instruction::Add:
return Builder.CreateAdd(LHS, RHS);
case Instruction::Mul:
return Builder.CreateMul(LHS, RHS);
case Instruction::Sub:
return Builder.CreateSub(LHS, RHS);
case Instruction::FAdd:
return Builder.CreateFAdd(LHS, RHS);
case Instruction::FMul:
return Builder.CreateFMul(LHS, RHS);
case Instruction::FSub:
return Builder.CreateFSub(LHS, RHS);
default:
llvm_unreachable("Unsupported binary operator for matrix");
}
};
for (unsigned I = 0; I < Shape.getNumVectors(); ++I)
Result.addVector(BuildVectorOp(A.getVector(I), B.getVector(I)));
finalizeLowering(Inst,
Result.addNumComputeOps(getNumOps(Result.getVectorTy()) *
Result.getNumVectors()),
Builder);
return true;
}
/// Helper to linearize a matrix expression tree into a string. Currently
/// matrix expressions are linarized by starting at an expression leaf and
/// linearizing bottom up.
struct ExprLinearizer {
unsigned LengthToBreak = 100;
std::string Str;
raw_string_ostream Stream;
unsigned LineLength = 0;
const DataLayout &DL;
/// Mapping from instructions to matrixes. It is used to identify
/// matrix instructions.
const MapVector<Value *, MatrixTy> &Inst2Matrix;
/// Mapping from values to the leaves of all expressions that the value is
/// part of.
const DenseMap<Value *, SmallPtrSet<Value *, 2>> &Shared;
/// Set of matrix expressions in the scope of a given DISubprogram.
const SmallSetVector<Value *, 32> &ExprsInSubprogram;
/// Leaf node of the expression to linearize.
Value *Leaf;
/// Used to keep track of sub-expressions that get reused while linearizing
/// the expression. Re-used sub-expressions are marked as (reused).
SmallPtrSet<Value *, 8> ReusedExprs;
ExprLinearizer(const DataLayout &DL,
const MapVector<Value *, MatrixTy> &Inst2Matrix,
const DenseMap<Value *, SmallPtrSet<Value *, 2>> &Shared,
const SmallSetVector<Value *, 32> &ExprsInSubprogram,
Value *Leaf)
: Str(), Stream(Str), DL(DL), Inst2Matrix(Inst2Matrix), Shared(Shared),
ExprsInSubprogram(ExprsInSubprogram), Leaf(Leaf) {}
void indent(unsigned N) {
LineLength += N;
for (unsigned i = 0; i < N; i++)
Stream << " ";
}
void lineBreak() {
Stream << "\n";
LineLength = 0;
}
void maybeIndent(unsigned Indent) {
if (LineLength >= LengthToBreak)
lineBreak();
if (LineLength == 0)
indent(Indent);
}
void write(StringRef S) {
LineLength += S.size();
Stream << S;
}
Value *getUnderlyingObjectThroughLoads(Value *V) {
if (Value *Ptr = getPointerOperand(V))
return getUnderlyingObjectThroughLoads(Ptr);
else if (V->getType()->isPointerTy())
return GetUnderlyingObject(V, DL);
return V;
}
/// Returns true if \p V is a matrix value in the given subprogram.
bool isMatrix(Value *V) const { return ExprsInSubprogram.count(V); }
/// If \p V is a matrix value, print its shape as as NumRows x NumColumns to
/// \p SS.
void prettyPrintMatrixType(Value *V, raw_string_ostream &SS) {
auto M = Inst2Matrix.find(V);
if (M == Inst2Matrix.end())
SS << "unknown";
else {
SS << M->second.getNumRows();
SS << "x";
SS << M->second.getNumColumns();
}
}
/// Write the called function name. Handles calls to llvm.matrix.*
/// specially: we write the name, followed by the dimensions of the input
/// matrixes, followed by the scalar type name.
void writeFnName(CallInst *CI) {
if (!CI->getCalledFunction())
write("<no called fn>");
else {
StringRef Name = CI->getCalledFunction()->getName();
if (!Name.startswith("llvm.matrix")) {
write(Name);
return;
}
IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI);
write(StringRef(Intrinsic::getName(II->getIntrinsicID(), {}))
.drop_front(StringRef("llvm.matrix.").size()));
write(".");
std::string Tmp = "";
raw_string_ostream SS(Tmp);
switch (II->getIntrinsicID()) {
case Intrinsic::matrix_multiply:
prettyPrintMatrixType(II->getOperand(0), SS);
SS << ".";
prettyPrintMatrixType(II->getOperand(1), SS);
SS << "." << *II->getType()->getScalarType();
break;
case Intrinsic::matrix_transpose:
prettyPrintMatrixType(II->getOperand(0), SS);
SS << "." << *II->getType()->getScalarType();
break;
case Intrinsic::matrix_columnwise_load:
prettyPrintMatrixType(II, SS);
SS << "." << *II->getType()->getScalarType();
break;
case Intrinsic::matrix_columnwise_store:
prettyPrintMatrixType(II->getOperand(0), SS);
SS << "." << *II->getOperand(0)->getType()->getScalarType();
break;
default:
llvm_unreachable("Unhandled case");
}
SS.flush();
write(Tmp);
}
}
unsigned getNumShapeArgs(CallInst *CI) const {
if (IntrinsicInst *II = dyn_cast<IntrinsicInst>(CI)) {
switch (II->getIntrinsicID()) {
case Intrinsic::matrix_multiply:
return 3;
case Intrinsic::matrix_transpose:
case Intrinsic::matrix_columnwise_load:
case Intrinsic::matrix_columnwise_store:
return 2;
default:
return 0;
}
}
return 0;
}
/// Special printing for values: for pointers, we print if they refer to an
/// (function) external address or a stack address, for other values we
/// either print the constant or "scalar"/"matrix" for other values.
void write(Value *V) {
V = getUnderlyingObjectThroughLoads(V);
if (V->getType()->isPointerTy()) {
if (isa<AllocaInst>(V)) {
Stream << "stack addr";
LineLength += StringRef("stack addr").size();
} else {
Stream << "addr";
LineLength += StringRef("addr").size();
}
if (!V->getName().empty()) {
Stream << " %" << V->getName() << "";
LineLength += V->getName().size() + 2;
}
return;
}
std::string Tmp;
raw_string_ostream TmpStream(Tmp);
if (auto *CI = dyn_cast<ConstantInt>(V))
TmpStream << CI->getValue();
else if (isa<Constant>(V))
TmpStream << "constant";
else {
if (isMatrix(V))
TmpStream << "matrix";
else
TmpStream << "scalar";
}
TmpStream.flush();
Tmp = std::string(StringRef(Tmp).trim());
LineLength += Tmp.size();
Stream << Tmp;
}
/// Linearize expression \p Expr starting at an indentation of \p Indent.
/// Expressions that are re-used multiple times are prefixed with (reused)
/// at the re-used root instruction.
void linearizeExpr(Value *Expr, unsigned Indent, bool ParentReused,
bool ParentShared) {
auto *I = cast<Instruction>(Expr);
maybeIndent(Indent);
SmallVector<Value *, 8> Ops;
// Is Expr shared with other expression leaves?
bool ExprShared = false;
// Deal with shared subtrees. Mark them as shared, if required.
if (!ParentShared) {
auto SI = Shared.find(Expr);
assert(SI != Shared.end() && SI->second.find(Leaf) != SI->second.end());
for (Value *S : SI->second) {
if (S == Leaf)
continue;
DebugLoc DL = cast<Instruction>(S)->getDebugLoc();
write("shared with remark at line " + std::to_string(DL.getLine()) +
" column " + std::to_string(DL.getCol()) + " (");
}
ExprShared = SI->second.size() > 1;
}
bool Reused = !ReusedExprs.insert(Expr).second;
if (Reused && !ParentReused)
write("(reused) ");
if (auto *CI = dyn_cast<CallInst>(I)) {
writeFnName(CI);
Ops.append(CallSite(CI).arg_begin(),
CallSite(CI).arg_end() - getNumShapeArgs(CI));
} else if (isa<BitCastInst>(Expr)) {
// Special case bitcasts, which are used to materialize matrixes from
// non-matrix ops.
write("matrix");
return;
} else {
Ops.append(I->value_op_begin(), I->value_op_end());
write(std::string(I->getOpcodeName()));
}
write(std::string("("));
unsigned NumOpsToBreak = 1;
if (match(Expr, m_Intrinsic<Intrinsic::matrix_columnwise_load>()))
NumOpsToBreak = 2;
for (Value *Op : Ops) {
if (Ops.size() > NumOpsToBreak)
lineBreak();
maybeIndent(Indent + 1);
if (isMatrix(Op))
linearizeExpr(Op, Indent + 1, Reused, ExprShared);
else
write(Op);
if (Op != Ops.back())
write(", ");
}
write(")");
}
const std::string &getResult() {
Stream.flush();
return Str;
}
};
/// Generate remarks for matrix operations in a function. To generate remarks
/// for matrix expressions, the following approach is used:
/// 1. Use the inlined-at debug information to group matrix operations to the
/// DISubprograms they are contained in.
/// 2. Collect leaves of matrix expressions (done in
/// RemarkGenerator::getExpressionLeaves) for each subprogram - expression
// mapping. Leaves are lowered matrix instructions without other matrix
// users (like stores) in the current subprogram.
/// 3. For each leaf, create a remark containing a linearizied version of the
/// matrix expression. The expression is linearized by a recursive
/// bottom-up traversal of the matrix operands, starting at a leaf. Note
/// that multiple leaves can share sub-expressions. Shared subexpressions
/// are explicitly marked as shared().
struct RemarkGenerator {
const MapVector<Value *, MatrixTy> &Inst2Matrix;
OptimizationRemarkEmitter &ORE;
Function &Func;
const DataLayout &DL;
RemarkGenerator(const MapVector<Value *, MatrixTy> &Inst2Matrix,
OptimizationRemarkEmitter &ORE, Function &Func)
: Inst2Matrix(Inst2Matrix), ORE(ORE), Func(Func),
DL(Func.getParent()->getDataLayout()) {}
/// Return all leaves of the expressions in \p ExprsInSubprogram. Those are
/// instructions in Inst2Matrix returning void or without any users in
/// \p ExprsInSubprogram. Currently that should only include stores.
SmallVector<Value *, 4>
getExpressionLeaves(const SmallSetVector<Value *, 32> &ExprsInSubprogram) {
SmallVector<Value *, 4> Leaves;
for (auto *Expr : ExprsInSubprogram)
if (Expr->getType()->isVoidTy() ||
!any_of(Expr->users(), [&ExprsInSubprogram](User *U) {
return ExprsInSubprogram.count(U);
}))
Leaves.push_back(Expr);
return Leaves;
}
/// Recursively traverse expression \p V starting at \p Leaf and add \p Leaf
/// to all visited expressions in \p Shared. Limit the matrix operations to
/// the ones in \p ExprsInSubprogram.
void collectSharedInfo(Value *Leaf, Value *V,
const SmallSetVector<Value *, 32> &ExprsInSubprogram,
DenseMap<Value *, SmallPtrSet<Value *, 2>> &Shared) {
if (!ExprsInSubprogram.count(V))
return;
auto I = Shared.insert({V, {}});
I.first->second.insert(Leaf);
for (Value *Op : cast<Instruction>(V)->operand_values())
collectSharedInfo(Leaf, Op, ExprsInSubprogram, Shared);
return;
}
/// Calculate the number of exclusive and shared op counts for expression
/// starting at \p V. Expressions used multiple times are counted once.
/// Limit the matrix operations to the ones in \p ExprsInSubprogram.
std::pair<OpInfoTy, OpInfoTy>
sumOpInfos(Value *Root, SmallPtrSetImpl<Value *> &ReusedExprs,
const SmallSetVector<Value *, 32> &ExprsInSubprogram,
DenseMap<Value *, SmallPtrSet<Value *, 2>> &Shared) const {
if (!ExprsInSubprogram.count(Root))
return {};
// Already counted this expression. Stop.
if (!ReusedExprs.insert(Root).second)
return {};
OpInfoTy SharedCount;
OpInfoTy Count;
auto I = Shared.find(Root);
auto CM = Inst2Matrix.find(Root);
if (I->second.size() == 1)
Count = CM->second.getOpInfo();
else
SharedCount = CM->second.getOpInfo();
for (Value *Op : cast<Instruction>(Root)->operand_values()) {
auto C = sumOpInfos(Op, ReusedExprs, ExprsInSubprogram, Shared);
Count += C.first;
SharedCount += C.second;
}
return {Count, SharedCount};
}
void emitRemarks() {
if (!ORE.allowExtraAnalysis(DEBUG_TYPE))
return;
// Map matrix operations to their containting subprograms, by traversing
// the inlinedAt chain. If the function does not have a DISubprogram, we
// only map them to the containing function.
MapVector<DISubprogram *, SmallVector<Value *, 8>> Subprog2Exprs;
for (auto &KV : Inst2Matrix) {
if (Func.getSubprogram()) {
auto *I = cast<Instruction>(KV.first);
DILocation *Context = I->getDebugLoc();
while (Context) {
auto I =
Subprog2Exprs.insert({getSubprogram(Context->getScope()), {}});
I.first->second.push_back(KV.first);
Context = DebugLoc(Context).getInlinedAt();
}
} else {
auto I = Subprog2Exprs.insert({nullptr, {}});
I.first->second.push_back(KV.first);
}
}
for (auto &KV : Subprog2Exprs) {
SmallSetVector<Value *, 32> ExprsInSubprogram(KV.second.begin(),
KV.second.end());
auto Leaves = getExpressionLeaves(ExprsInSubprogram);
DenseMap<Value *, SmallPtrSet<Value *, 2>> Shared;
for (Value *Leaf : Leaves)
collectSharedInfo(Leaf, Leaf, ExprsInSubprogram, Shared);
// Generate remarks for each leaf.
for (auto *L : Leaves) {
DebugLoc Loc = cast<Instruction>(L)->getDebugLoc();
DILocation *Context = cast<Instruction>(L)->getDebugLoc();
while (Context) {
if (getSubprogram(Context->getScope()) == KV.first) {
Loc = Context;
break;
}
Context = DebugLoc(Context).getInlinedAt();
}
SmallPtrSet<Value *, 8> ReusedExprs;
OpInfoTy Counts, SharedCounts;
std::tie(Counts, SharedCounts) =
sumOpInfos(L, ReusedExprs, ExprsInSubprogram, Shared);
OptimizationRemark Rem(DEBUG_TYPE, "matrix-lowered", Loc,
cast<Instruction>(L)->getParent());
Rem << "Lowered with ";
Rem << ore::NV("NumStores", Counts.NumStores) << " stores, "
<< ore::NV("NumLoads", Counts.NumLoads) << " loads, "
<< ore::NV("NumComputeOps", Counts.NumComputeOps)
<< " compute ops";
if (SharedCounts.NumStores > 0 || SharedCounts.NumLoads > 0 ||
SharedCounts.NumComputeOps > 0) {
Rem << ",\nadditionally "
<< ore::NV("NumStores", SharedCounts.NumStores) << " stores, "
<< ore::NV("NumLoads", SharedCounts.NumLoads) << " loads, "
<< ore::NV("NumFPOps", SharedCounts.NumComputeOps)
<< " compute ops"
<< " are shared with other expressions";
}
Rem << ("\n" + linearize(L, Shared, ExprsInSubprogram, DL));
ORE.emit(Rem);
}
}
}
std::string
linearize(Value *L,
const DenseMap<Value *, SmallPtrSet<Value *, 2>> &Shared,
const SmallSetVector<Value *, 32> &ExprsInSubprogram,
const DataLayout &DL) {
ExprLinearizer Lin(DL, Inst2Matrix, Shared, ExprsInSubprogram, L);
Lin.linearizeExpr(L, 0, false, false);
return Lin.getResult();
}
};
};
} // namespace
PreservedAnalyses LowerMatrixIntrinsicsPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
auto &ORE = AM.getResult<OptimizationRemarkEmitterAnalysis>(F);
auto &AA = AM.getResult<AAManager>(F);
auto &DT = AM.getResult<DominatorTreeAnalysis>(F);
auto &LI = AM.getResult<LoopAnalysis>(F);
LowerMatrixIntrinsics LMT(F, TTI, AA, DT, LI, ORE);
if (LMT.Visit()) {
PreservedAnalyses PA;
PA.preserveSet<CFGAnalyses>();
return PA;
}
return PreservedAnalyses::all();
}
namespace {
class LowerMatrixIntrinsicsLegacyPass : public FunctionPass {
public:
static char ID;
LowerMatrixIntrinsicsLegacyPass() : FunctionPass(ID) {
initializeLowerMatrixIntrinsicsLegacyPassPass(
*PassRegistry::getPassRegistry());
}
bool runOnFunction(Function &F) override {
auto &TTI = getAnalysis<TargetTransformInfoWrapperPass>().getTTI(F);
auto &ORE = getAnalysis<OptimizationRemarkEmitterWrapperPass>().getORE();
auto &AA = getAnalysis<AAResultsWrapperPass>().getAAResults();
auto &DT = getAnalysis<DominatorTreeWrapperPass>().getDomTree();
auto &LI = getAnalysis<LoopInfoWrapperPass>().getLoopInfo();
LowerMatrixIntrinsics LMT(F, TTI, AA, DT, LI, ORE);
bool C = LMT.Visit();
return C;
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.addRequired<OptimizationRemarkEmitterWrapperPass>();
AU.addRequired<AAResultsWrapperPass>();
AU.addRequired<DominatorTreeWrapperPass>();
AU.addPreserved<DominatorTreeWrapperPass>();
AU.addRequired<LoopInfoWrapperPass>();
AU.addPreserved<LoopInfoWrapperPass>();
}
};
} // namespace
static const char pass_name[] = "Lower the matrix intrinsics";
char LowerMatrixIntrinsicsLegacyPass::ID = 0;
INITIALIZE_PASS_BEGIN(LowerMatrixIntrinsicsLegacyPass, DEBUG_TYPE, pass_name,
false, false)
INITIALIZE_PASS_DEPENDENCY(OptimizationRemarkEmitterWrapperPass)
INITIALIZE_PASS_DEPENDENCY(AAResultsWrapperPass)
INITIALIZE_PASS_DEPENDENCY(DominatorTreeWrapperPass)
INITIALIZE_PASS_DEPENDENCY(LoopInfoWrapperPass)
INITIALIZE_PASS_END(LowerMatrixIntrinsicsLegacyPass, DEBUG_TYPE, pass_name,
false, false)
Pass *llvm::createLowerMatrixIntrinsicsPass() {
return new LowerMatrixIntrinsicsLegacyPass();
}
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