//===- 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:
// * Implement multiply & add fusion
// * Add remark, summarizing the available matrix optimization opportunities.
//
//===----------------------------------------------------------------------===//
#include "llvm/Transforms/Scalar/LowerMatrixIntrinsics.h"
#include "llvm/ADT/GraphTraits.h"
#include "llvm/ADT/PostOrderIterator.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/Analysis/TargetTransformInfo.h"
#include "llvm/Analysis/VectorUtils.h"
#include "llvm/IR/CFG.h"
#include "llvm/IR/DataLayout.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"
using namespace llvm;
using namespace PatternMatch;
#define DEBUG_TYPE "lower-matrix-intrinsics"
static cl::opt<bool> EnableShapePropagation("matrix-propagate-shape",
cl::init(true));
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."));
namespace {
// Given an element poitner \p BasePtr to the start of a (sub) matrix, compute
// the start address of column \p Col with type (\p EltType x \p NumRows)
// assuming \p Stride elements between start two consecutive columns.
// \p Stride must be >= \p NumRows.
//
// Consider a 4x4 matrix 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 computeColumnAddr to compute the addresses for the columns
// of the sub-matrix.
//
// Column 0: computeColumnAddr(Base, 0 (column), 4 (stride), 2 (num rows), ..)
// -> just returns Base
// Column 1: computeColumnAddr(Base, 1 (column), 4 (stride), 2 (num rows), ..)
// -> returns Base + (1 * 4)
// Column 2: computeColumnAddr(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 *computeColumnAddr(Value *BasePtr, Value *Col, Value *Stride,
unsigned NumRows, Type *EltType,
IRBuilder<> &Builder) {
assert((!isa<ConstantInt>(Stride) ||
cast<ConstantInt>(Stride)->getZExtValue() >= NumRows) &&
"Stride must be >= the number of rows.");
unsigned AS = cast<PointerType>(BasePtr->getType())->getAddressSpace();
// Compute the start of the column with index Col as Col * Stride.
Value *ColumnStart = Builder.CreateMul(Col, Stride, "col.start");
// Get pointer to the start of the selected column. Skip GEP creation,
// if we select column 0.
if (isa<ConstantInt>(ColumnStart) && cast<ConstantInt>(ColumnStart)->isZero())
ColumnStart = BasePtr;
else
ColumnStart = Builder.CreateGEP(EltType, BasePtr, ColumnStart, "col.gep");
// Cast elementwise column start pointer to a pointer to a column
// (EltType x NumRows)*.
Type *ColumnType = VectorType::get(EltType, NumRows);
Type *ColumnPtrType = PointerType::get(ColumnType, AS);
return Builder.CreatePointerCast(ColumnStart, ColumnPtrType, "col.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.
/// 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;
/// Wrapper class representing a matrix as a set of column vectors.
/// All column vectors must have the same vector type.
class ColumnMatrixTy {
SmallVector<Value *, 16> Columns;
public:
ColumnMatrixTy() : Columns() {}
ColumnMatrixTy(ArrayRef<Value *> Cols)
: Columns(Cols.begin(), Cols.end()) {}
Value *getColumn(unsigned i) const { return Columns[i]; }
void setColumn(unsigned i, Value *V) { Columns[i] = V; }
size_t getNumColumns() const { return Columns.size(); }
size_t getNumRows() const {
assert(Columns.size() > 0 && "Cannot call getNumRows without columns");
return cast<VectorType>(Columns[0]->getType())->getNumElements();
}
const SmallVectorImpl<Value *> &getColumnVectors() const { return Columns; }
SmallVectorImpl<Value *> &getColumnVectors() { return Columns; }
void addColumn(Value *V) { Columns.push_back(V); }
iterator_range<SmallVector<Value *, 8>::iterator> columns() {
return make_range(Columns.begin(), Columns.end());
}
/// Embed the columns of the matrix into a flat vector by concatenating
/// them.
Value *embedInVector(IRBuilder<> &Builder) const {
return Columns.size() == 1 ? Columns[0]
: concatenateVectors(Builder, Columns);
}
};
struct ShapeInfo {
unsigned NumRows;
unsigned NumColumns;
ShapeInfo(unsigned NumRows = 0, unsigned NumColumns = 0)
: NumRows(NumRows), NumColumns(NumColumns) {}
ShapeInfo(Value *NumRows, Value *NumColumns)
: NumRows(cast<ConstantInt>(NumRows)->getZExtValue()),
NumColumns(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;
}
};
/// 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.
DenseMap<Value *, ColumnMatrixTy> Inst2ColumnMatrix;
public:
LowerMatrixIntrinsics(Function &F, TargetTransformInfo &TTI)
: Func(F), DL(F.getParent()->getDataLayout()), TTI(TTI) {}
/// Return the set of column vectors that a matrix value is lowered to.
///
/// If we lowered \p MatrixVal, just return the cache result column matrix.
/// Otherwie split the flat vector \p MatrixVal containing a matrix with
/// shape \p SI into column vectors.
ColumnMatrixTy 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 column 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()) {
ColumnMatrixTy &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.NumRows) {
Constant *Mask = createSequentialMask(Builder, MaskStart, SI.NumRows, 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);
}
}
ReversePostOrderTraversal<Function *> RPOT(&Func);
bool Changed = false;
for (auto *BB : RPOT) {
for (Instruction &Inst : make_early_inc_range(*BB)) {
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);
}
}
for (Instruction *Inst : reverse(ToRemove))
Inst->eraseFromParent();
return Changed;
}
LoadInst *createColumnLoad(Value *ColumnPtr, Type *EltType,
IRBuilder<> Builder) {
unsigned Align = DL.getABITypeAlignment(EltType);
return Builder.CreateAlignedLoad(ColumnPtr, Align, "col.load");
}
StoreInst *createColumnStore(Value *ColumnValue, Value *ColumnPtr,
Type *EltType, IRBuilder<> Builder) {
unsigned Align = DL.getABITypeAlignment(EltType);
return Builder.CreateAlignedStore(ColumnValue, ColumnPtr, Align);
}
/// 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;
}
void LowerLoad(Instruction *Inst, Value *Ptr, Value *Stride,
ShapeInfo Shape) {
IRBuilder<> Builder(Inst);
auto VType = cast<VectorType>(Inst->getType());
Value *EltPtr = createElementPtr(Ptr, VType->getElementType(), Builder);
ColumnMatrixTy Result;
// Distance between start of one column and the start of the next
for (unsigned C = 0, E = Shape.NumColumns; C < E; ++C) {
Value *GEP =
computeColumnAddr(EltPtr, Builder.getInt32(C), Stride, Shape.NumRows,
VType->getElementType(), Builder);
Value *Column = createColumnLoad(GEP, VType->getElementType(), Builder);
Result.addColumn(Column);
}
finalizeLowering(Inst, Result, Builder);
}
/// Lowers llvm.matrix.columnwise.load.
///
/// The intrinsic loads a matrix from memory using a stride between columns.
void LowerColumnwiseLoad(CallInst *Inst) {
Value *Ptr = Inst->getArgOperand(0);
Value *Stride = Inst->getArgOperand(1);
LowerLoad(Inst, Ptr, Stride,
{Inst->getArgOperand(2), Inst->getArgOperand(3)});
}
void LowerStore(Instruction *Inst, Value *Matrix, Value *Ptr, Value *Stride,
ShapeInfo Shape) {
IRBuilder<> Builder(Inst);
auto VType = cast<VectorType>(Matrix->getType());
Value *EltPtr = createElementPtr(Ptr, VType->getElementType(), Builder);
auto LM = getMatrix(Matrix, Shape, Builder);
for (auto C : enumerate(LM.columns())) {
Value *GEP =
computeColumnAddr(EltPtr, Builder.getInt32(C.index()), Stride,
Shape.NumRows, VType->getElementType(), Builder);
createColumnStore(C.value(), GEP, VType->getElementType(), Builder);
}
ToRemove.push_back(Inst);
}
/// Lowers llvm.matrix.columnwise.store.
///
/// The intrinsic store a matrix back memory using a stride between columns.
void LowerColumnwiseStore(CallInst *Inst) {
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)});
}
/// Extract a column vector of \p NumElts starting at index (\p I, \p J) from
/// the matrix \p LM represented as a vector of column vectors.
Value *extractVector(const ColumnMatrixTy &LM, unsigned I, unsigned J,
unsigned NumElts, IRBuilder<> Builder) {
Value *Col = LM.getColumn(J);
Value *Undef = UndefValue::get(Col->getType());
Constant *Mask = createSequentialMask(Builder, I, NumElts, 0);
return Builder.CreateShuffleVector(Col, Undef, Mask, "block");
}
// 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) {
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.
Value *FMulAdd = Intrinsic::getDeclaration(
Func.getParent(), Intrinsic::fmuladd, A->getType());
return Builder.CreateCall(FMulAdd, {A, B, Sum});
}
Value *Mul = Builder.CreateFMul(A, B);
return Builder.CreateFAdd(Sum, Mul);
}
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, ColumnMatrixTy 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);
}
}
}
/// 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 ColumnMatrixTy &Lhs =
getMatrix(MatMul->getArgOperand(0), LShape, Builder);
const ColumnMatrixTy &Rhs =
getMatrix(MatMul->getArgOperand(1), RShape, Builder);
const unsigned R = LShape.NumRows;
const unsigned M = LShape.NumColumns;
const unsigned C = RShape.NumColumns;
assert(M == RShape.NumRows);
// Initialize the output
ColumnMatrixTy Result;
for (unsigned J = 0; J < C; ++J)
Result.addColumn(UndefValue::get(VectorType::get(EltType, R)));
const unsigned VF = std::max(TTI.getRegisterBitWidth(true) /
EltType->getPrimitiveSizeInBits(),
uint64_t(1));
bool AllowContract = AllowContractEnabled || (isa<FPMathOperator>(MatMul) &&
MatMul->hasAllowContract());
// 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;
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 = nullptr;
for (unsigned K = 0; K < M; ++K) {
Value *L = extractVector(Lhs, I, K, BlockSize, Builder);
Value *RH = Builder.CreateExtractElement(Rhs.getColumn(J), K);
Value *Splat = Builder.CreateVectorSplat(BlockSize, RH, "splat");
Sum = createMulAdd(Sum, L, Splat, EltType->isFloatingPointTy(),
Builder, AllowContract);
}
Result.setColumn(J, insertVector(Result.getColumn(J), I, Sum, Builder));
}
}
finalizeLowering(MatMul, Result, Builder);
}
/// Lowers llvm.matrix.transpose.
void LowerTranspose(CallInst *Inst) {
ColumnMatrixTy Result;
IRBuilder<> Builder(Inst);
Value *InputVal = Inst->getArgOperand(0);
VectorType *VectorTy = cast<VectorType>(InputVal->getType());
ShapeInfo ArgShape(Inst->getArgOperand(1), Inst->getArgOperand(2));
ColumnMatrixTy InputMatrix = getMatrix(InputVal, ArgShape, Builder);
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.addColumn(ResultColumn);
}
finalizeLowering(Inst, Result, 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.NumRows), 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.NumRows), 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;
ColumnMatrixTy LoweredLhs = getMatrix(Lhs, Shape, Builder);
ColumnMatrixTy LoweredRhs = getMatrix(Rhs, Shape, Builder);
// Add each column and store the result back into the opmapping
ColumnMatrixTy Result;
auto BuildColumnOp = [&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 C = 0; C < Shape.NumColumns; ++C)
Result.addColumn(
BuildColumnOp(LoweredLhs.getColumn(C), LoweredRhs.getColumn(C)));
finalizeLowering(Inst, Result, Builder);
return true;
}
};
} // namespace
PreservedAnalyses LowerMatrixIntrinsicsPass::run(Function &F,
FunctionAnalysisManager &AM) {
auto &TTI = AM.getResult<TargetIRAnalysis>(F);
LowerMatrixIntrinsics LMT(F, TTI);
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);
LowerMatrixIntrinsics LMT(F, *TTI);
bool C = LMT.Visit();
return C;
}
void getAnalysisUsage(AnalysisUsage &AU) const override {
AU.addRequired<TargetTransformInfoWrapperPass>();
AU.setPreservesCFG();
}
};
} // 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_END(LowerMatrixIntrinsicsLegacyPass, DEBUG_TYPE, pass_name,
false, false)
Pass *llvm::createLowerMatrixIntrinsicsPass() {
return new LowerMatrixIntrinsicsLegacyPass();
}