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llvm-project/mlir/lib/Analysis/Utils.cpp

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//===- Utils.cpp ---- Misc utilities for analysis -------------------------===//
//
// 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
//
//===----------------------------------------------------------------------===//
//
// This file implements miscellaneous analysis routines for non-loop IR
// structures.
//
//===----------------------------------------------------------------------===//
#include "mlir/Analysis/Utils.h"
#include "mlir/Analysis/AffineAnalysis.h"
#include "mlir/Analysis/LoopAnalysis.h"
#include "mlir/Analysis/PresburgerSet.h"
#include "mlir/Dialect/Affine/IR/AffineOps.h"
#include "mlir/Dialect/Affine/IR/AffineValueMap.h"
#include "mlir/Dialect/Arithmetic/IR/Arithmetic.h"
#include "mlir/Dialect/StandardOps/IR/Ops.h"
#include "mlir/IR/IntegerSet.h"
#include "llvm/ADT/SmallPtrSet.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#define DEBUG_TYPE "analysis-utils"
using namespace mlir;
using llvm::SmallDenseMap;
/// Populates 'loops' with IVs of the loops surrounding 'op' ordered from
/// the outermost 'affine.for' operation to the innermost one.
void mlir::getLoopIVs(Operation &op, SmallVectorImpl<AffineForOp> *loops) {
auto *currOp = op.getParentOp();
AffineForOp currAffineForOp;
// Traverse up the hierarchy collecting all 'affine.for' operation while
// skipping over 'affine.if' operations.
while (currOp) {
if (AffineForOp currAffineForOp = dyn_cast<AffineForOp>(currOp))
loops->push_back(currAffineForOp);
currOp = currOp->getParentOp();
}
std::reverse(loops->begin(), loops->end());
}
/// Populates 'ops' with IVs of the loops surrounding `op`, along with
/// `affine.if` operations interleaved between these loops, ordered from the
/// outermost `affine.for` operation to the innermost one.
void mlir::getEnclosingAffineForAndIfOps(Operation &op,
SmallVectorImpl<Operation *> *ops) {
ops->clear();
Operation *currOp = op.getParentOp();
// Traverse up the hierarchy collecting all `affine.for` and `affine.if`
// operations.
while (currOp) {
if (isa<AffineIfOp, AffineForOp>(currOp))
ops->push_back(currOp);
currOp = currOp->getParentOp();
}
std::reverse(ops->begin(), ops->end());
}
// Populates 'cst' with FlatAffineValueConstraints which represent original
// domain of the loop bounds that define 'ivs'.
LogicalResult
ComputationSliceState::getSourceAsConstraints(FlatAffineValueConstraints &cst) {
assert(!ivs.empty() && "Cannot have a slice without its IVs");
cst.reset(/*numDims=*/ivs.size(), /*numSymbols=*/0, /*numLocals=*/0, ivs);
for (Value iv : ivs) {
AffineForOp loop = getForInductionVarOwner(iv);
assert(loop && "Expected affine for");
if (failed(cst.addAffineForOpDomain(loop)))
return failure();
}
return success();
}
// Populates 'cst' with FlatAffineValueConstraints which represent slice bounds.
LogicalResult
ComputationSliceState::getAsConstraints(FlatAffineValueConstraints *cst) {
assert(!lbOperands.empty());
// Adds src 'ivs' as dimension identifiers in 'cst'.
unsigned numDims = ivs.size();
// Adds operands (dst ivs and symbols) as symbols in 'cst'.
unsigned numSymbols = lbOperands[0].size();
SmallVector<Value, 4> values(ivs);
// Append 'ivs' then 'operands' to 'values'.
values.append(lbOperands[0].begin(), lbOperands[0].end());
cst->reset(numDims, numSymbols, 0, values);
// Add loop bound constraints for values which are loop IVs of the destination
// of fusion and equality constraints for symbols which are constants.
for (unsigned i = numDims, end = values.size(); i < end; ++i) {
Value value = values[i];
assert(cst->containsId(value) && "value expected to be present");
if (isValidSymbol(value)) {
// Check if the symbol is a constant.
if (auto cOp = value.getDefiningOp<arith::ConstantIndexOp>())
cst->addBound(FlatAffineConstraints::EQ, value, cOp.value());
} else if (auto loop = getForInductionVarOwner(value)) {
if (failed(cst->addAffineForOpDomain(loop)))
return failure();
}
}
// Add slices bounds on 'ivs' using maps 'lbs'/'ubs' with 'lbOperands[0]'
LogicalResult ret = cst->addSliceBounds(ivs, lbs, ubs, lbOperands[0]);
assert(succeeded(ret) &&
"should not fail as we never have semi-affine slice maps");
(void)ret;
return success();
}
// Clears state bounds and operand state.
void ComputationSliceState::clearBounds() {
lbs.clear();
ubs.clear();
lbOperands.clear();
ubOperands.clear();
}
void ComputationSliceState::dump() const {
llvm::errs() << "\tIVs:\n";
for (Value iv : ivs)
llvm::errs() << "\t\t" << iv << "\n";
llvm::errs() << "\tLBs:\n";
for (auto &en : llvm::enumerate(lbs)) {
llvm::errs() << "\t\t" << en.value() << "\n";
llvm::errs() << "\t\tOperands:\n";
for (Value lbOp : lbOperands[en.index()])
llvm::errs() << "\t\t\t" << lbOp << "\n";
}
llvm::errs() << "\tUBs:\n";
for (auto &en : llvm::enumerate(ubs)) {
llvm::errs() << "\t\t" << en.value() << "\n";
llvm::errs() << "\t\tOperands:\n";
for (Value ubOp : ubOperands[en.index()])
llvm::errs() << "\t\t\t" << ubOp << "\n";
}
}
/// Fast check to determine if the computation slice is maximal. Returns true if
/// each slice dimension maps to an existing dst dimension and both the src
/// and the dst loops for those dimensions have the same bounds. Returns false
/// if both the src and the dst loops don't have the same bounds. Returns
/// llvm::None if none of the above can be proven.
Optional<bool> ComputationSliceState::isSliceMaximalFastCheck() const {
assert(lbs.size() == ubs.size() && lbs.size() && ivs.size() &&
"Unexpected number of lbs, ubs and ivs in slice");
for (unsigned i = 0, end = lbs.size(); i < end; ++i) {
AffineMap lbMap = lbs[i];
AffineMap ubMap = ubs[i];
// Check if this slice is just an equality along this dimension.
if (!lbMap || !ubMap || lbMap.getNumResults() != 1 ||
ubMap.getNumResults() != 1 ||
lbMap.getResult(0) + 1 != ubMap.getResult(0) ||
// The condition above will be true for maps describing a single
// iteration (e.g., lbMap.getResult(0) = 0, ubMap.getResult(0) = 1).
// Make sure we skip those cases by checking that the lb result is not
// just a constant.
lbMap.getResult(0).isa<AffineConstantExpr>())
return llvm::None;
// Limited support: we expect the lb result to be just a loop dimension for
// now.
AffineDimExpr result = lbMap.getResult(0).dyn_cast<AffineDimExpr>();
if (!result)
return llvm::None;
// Retrieve dst loop bounds.
AffineForOp dstLoop =
getForInductionVarOwner(lbOperands[i][result.getPosition()]);
if (!dstLoop)
return llvm::None;
AffineMap dstLbMap = dstLoop.getLowerBoundMap();
AffineMap dstUbMap = dstLoop.getUpperBoundMap();
// Retrieve src loop bounds.
AffineForOp srcLoop = getForInductionVarOwner(ivs[i]);
assert(srcLoop && "Expected affine for");
AffineMap srcLbMap = srcLoop.getLowerBoundMap();
AffineMap srcUbMap = srcLoop.getUpperBoundMap();
// Limited support: we expect simple src and dst loops with a single
// constant component per bound for now.
if (srcLbMap.getNumResults() != 1 || srcUbMap.getNumResults() != 1 ||
dstLbMap.getNumResults() != 1 || dstUbMap.getNumResults() != 1)
return llvm::None;
AffineExpr srcLbResult = srcLbMap.getResult(0);
AffineExpr dstLbResult = dstLbMap.getResult(0);
AffineExpr srcUbResult = srcUbMap.getResult(0);
AffineExpr dstUbResult = dstUbMap.getResult(0);
if (!srcLbResult.isa<AffineConstantExpr>() ||
!srcUbResult.isa<AffineConstantExpr>() ||
!dstLbResult.isa<AffineConstantExpr>() ||
!dstUbResult.isa<AffineConstantExpr>())
return llvm::None;
// Check if src and dst loop bounds are the same. If not, we can guarantee
// that the slice is not maximal.
if (srcLbResult != dstLbResult || srcUbResult != dstUbResult ||
srcLoop.getStep() != dstLoop.getStep())
return false;
}
return true;
}
/// Returns true if it is deterministically verified that the original iteration
/// space of the slice is contained within the new iteration space that is
/// created after fusing 'this' slice into its destination.
Optional<bool> ComputationSliceState::isSliceValid() {
// Fast check to determine if the slice is valid. If the following conditions
// are verified to be true, slice is declared valid by the fast check:
// 1. Each slice loop is a single iteration loop bound in terms of a single
// destination loop IV.
// 2. Loop bounds of the destination loop IV (from above) and those of the
// source loop IV are exactly the same.
// If the fast check is inconclusive or false, we proceed with a more
// expensive analysis.
// TODO: Store the result of the fast check, as it might be used again in
// `canRemoveSrcNodeAfterFusion`.
Optional<bool> isValidFastCheck = isSliceMaximalFastCheck();
if (isValidFastCheck.hasValue() && isValidFastCheck.getValue())
return true;
// Create constraints for the source loop nest using which slice is computed.
FlatAffineValueConstraints srcConstraints;
// TODO: Store the source's domain to avoid computation at each depth.
if (failed(getSourceAsConstraints(srcConstraints))) {
LLVM_DEBUG(llvm::dbgs() << "Unable to compute source's domain\n");
return llvm::None;
}
// As the set difference utility currently cannot handle symbols in its
// operands, validity of the slice cannot be determined.
if (srcConstraints.getNumSymbolIds() > 0) {
LLVM_DEBUG(llvm::dbgs() << "Cannot handle symbols in source domain\n");
return llvm::None;
}
// TODO: Handle local ids in the source domains while using the 'projectOut'
// utility below. Currently, aligning is not done assuming that there will be
// no local ids in the source domain.
if (srcConstraints.getNumLocalIds() != 0) {
LLVM_DEBUG(llvm::dbgs() << "Cannot handle locals in source domain\n");
return llvm::None;
}
// Create constraints for the slice loop nest that would be created if the
// fusion succeeds.
FlatAffineValueConstraints sliceConstraints;
if (failed(getAsConstraints(&sliceConstraints))) {
LLVM_DEBUG(llvm::dbgs() << "Unable to compute slice's domain\n");
return llvm::None;
}
// Projecting out every dimension other than the 'ivs' to express slice's
// domain completely in terms of source's IVs.
sliceConstraints.projectOut(ivs.size(),
sliceConstraints.getNumIds() - ivs.size());
LLVM_DEBUG(llvm::dbgs() << "Domain of the source of the slice:\n");
LLVM_DEBUG(srcConstraints.dump());
LLVM_DEBUG(llvm::dbgs() << "Domain of the slice if this fusion succeeds "
"(expressed in terms of its source's IVs):\n");
LLVM_DEBUG(sliceConstraints.dump());
// TODO: Store 'srcSet' to avoid recalculating for each depth.
PresburgerSet srcSet(srcConstraints);
PresburgerSet sliceSet(sliceConstraints);
PresburgerSet diffSet = sliceSet.subtract(srcSet);
if (!diffSet.isIntegerEmpty()) {
LLVM_DEBUG(llvm::dbgs() << "Incorrect slice\n");
return false;
}
return true;
}
/// Returns true if the computation slice encloses all the iterations of the
/// sliced loop nest. Returns false if it does not. Returns llvm::None if it
/// cannot determine if the slice is maximal or not.
Optional<bool> ComputationSliceState::isMaximal() const {
// Fast check to determine if the computation slice is maximal. If the result
// is inconclusive, we proceed with a more expensive analysis.
Optional<bool> isMaximalFastCheck = isSliceMaximalFastCheck();
if (isMaximalFastCheck.hasValue())
return isMaximalFastCheck;
// Create constraints for the src loop nest being sliced.
FlatAffineValueConstraints srcConstraints;
srcConstraints.reset(/*numDims=*/ivs.size(), /*numSymbols=*/0,
/*numLocals=*/0, ivs);
for (Value iv : ivs) {
AffineForOp loop = getForInductionVarOwner(iv);
assert(loop && "Expected affine for");
if (failed(srcConstraints.addAffineForOpDomain(loop)))
return llvm::None;
}
// Create constraints for the slice using the dst loop nest information. We
// retrieve existing dst loops from the lbOperands.
SmallVector<Value, 8> consumerIVs;
for (Value lbOp : lbOperands[0])
if (getForInductionVarOwner(lbOp))
consumerIVs.push_back(lbOp);
// Add empty IV Values for those new loops that are not equalities and,
// therefore, are not yet materialized in the IR.
for (int i = consumerIVs.size(), end = ivs.size(); i < end; ++i)
consumerIVs.push_back(Value());
FlatAffineValueConstraints sliceConstraints;
sliceConstraints.reset(/*numDims=*/consumerIVs.size(), /*numSymbols=*/0,
/*numLocals=*/0, consumerIVs);
if (failed(sliceConstraints.addDomainFromSliceMaps(lbs, ubs, lbOperands[0])))
return llvm::None;
if (srcConstraints.getNumDimIds() != sliceConstraints.getNumDimIds())
// Constraint dims are different. The integer set difference can't be
// computed so we don't know if the slice is maximal.
return llvm::None;
// Compute the difference between the src loop nest and the slice integer
// sets.
PresburgerSet srcSet(srcConstraints);
PresburgerSet sliceSet(sliceConstraints);
PresburgerSet diffSet = srcSet.subtract(sliceSet);
return diffSet.isIntegerEmpty();
}
unsigned MemRefRegion::getRank() const {
return memref.getType().cast<MemRefType>().getRank();
}
Optional<int64_t> MemRefRegion::getConstantBoundingSizeAndShape(
SmallVectorImpl<int64_t> *shape, std::vector<SmallVector<int64_t, 4>> *lbs,
SmallVectorImpl<int64_t> *lbDivisors) const {
auto memRefType = memref.getType().cast<MemRefType>();
unsigned rank = memRefType.getRank();
if (shape)
shape->reserve(rank);
assert(rank == cst.getNumDimIds() && "inconsistent memref region");
// Use a copy of the region constraints that has upper/lower bounds for each
// memref dimension with static size added to guard against potential
// over-approximation from projection or union bounding box. We may not add
// this on the region itself since they might just be redundant constraints
// that will need non-trivials means to eliminate.
FlatAffineConstraints cstWithShapeBounds(cst);
for (unsigned r = 0; r < rank; r++) {
cstWithShapeBounds.addBound(FlatAffineConstraints::LB, r, 0);
int64_t dimSize = memRefType.getDimSize(r);
if (ShapedType::isDynamic(dimSize))
continue;
cstWithShapeBounds.addBound(FlatAffineConstraints::UB, r, dimSize - 1);
}
// Find a constant upper bound on the extent of this memref region along each
// dimension.
int64_t numElements = 1;
int64_t diffConstant;
int64_t lbDivisor;
for (unsigned d = 0; d < rank; d++) {
SmallVector<int64_t, 4> lb;
Optional<int64_t> diff =
cstWithShapeBounds.getConstantBoundOnDimSize(d, &lb, &lbDivisor);
if (diff.hasValue()) {
diffConstant = diff.getValue();
assert(diffConstant >= 0 && "Dim size bound can't be negative");
assert(lbDivisor > 0);
} else {
// If no constant bound is found, then it can always be bound by the
// memref's dim size if the latter has a constant size along this dim.
auto dimSize = memRefType.getDimSize(d);
if (dimSize == -1)
return None;
diffConstant = dimSize;
// Lower bound becomes 0.
lb.resize(cstWithShapeBounds.getNumSymbolIds() + 1, 0);
lbDivisor = 1;
}
numElements *= diffConstant;
if (lbs) {
lbs->push_back(lb);
assert(lbDivisors && "both lbs and lbDivisor or none");
lbDivisors->push_back(lbDivisor);
}
if (shape) {
shape->push_back(diffConstant);
}
}
return numElements;
}
void MemRefRegion::getLowerAndUpperBound(unsigned pos, AffineMap &lbMap,
AffineMap &ubMap) const {
assert(pos < cst.getNumDimIds() && "invalid position");
auto memRefType = memref.getType().cast<MemRefType>();
unsigned rank = memRefType.getRank();
assert(rank == cst.getNumDimIds() && "inconsistent memref region");
auto boundPairs = cst.getLowerAndUpperBound(
pos, /*offset=*/0, /*num=*/rank, cst.getNumDimAndSymbolIds(),
/*localExprs=*/{}, memRefType.getContext());
lbMap = boundPairs.first;
ubMap = boundPairs.second;
assert(lbMap && "lower bound for a region must exist");
assert(ubMap && "upper bound for a region must exist");
assert(lbMap.getNumInputs() == cst.getNumDimAndSymbolIds() - rank);
assert(ubMap.getNumInputs() == cst.getNumDimAndSymbolIds() - rank);
}
LogicalResult MemRefRegion::unionBoundingBox(const MemRefRegion &other) {
assert(memref == other.memref);
return cst.unionBoundingBox(*other.getConstraints());
}
/// Computes the memory region accessed by this memref with the region
/// represented as constraints symbolic/parametric in 'loopDepth' loops
/// surrounding opInst and any additional Function symbols.
// For example, the memref region for this load operation at loopDepth = 1 will
// be as below:
//
// affine.for %i = 0 to 32 {
// affine.for %ii = %i to (d0) -> (d0 + 8) (%i) {
// load %A[%ii]
// }
// }
//
// region: {memref = %A, write = false, {%i <= m0 <= %i + 7} }
// The last field is a 2-d FlatAffineConstraints symbolic in %i.
//
// TODO: extend this to any other memref dereferencing ops
// (dma_start, dma_wait).
LogicalResult MemRefRegion::compute(Operation *op, unsigned loopDepth,
const ComputationSliceState *sliceState,
bool addMemRefDimBounds) {
assert((isa<AffineReadOpInterface, AffineWriteOpInterface>(op)) &&
"affine read/write op expected");
MemRefAccess access(op);
memref = access.memref;
write = access.isStore();
unsigned rank = access.getRank();
LLVM_DEBUG(llvm::dbgs() << "MemRefRegion::compute: " << *op
<< "depth: " << loopDepth << "\n";);
// 0-d memrefs.
if (rank == 0) {
SmallVector<AffineForOp, 4> ivs;
getLoopIVs(*op, &ivs);
assert(loopDepth <= ivs.size() && "invalid 'loopDepth'");
// The first 'loopDepth' IVs are symbols for this region.
ivs.resize(loopDepth);
SmallVector<Value, 4> regionSymbols;
extractForInductionVars(ivs, &regionSymbols);
// A 0-d memref has a 0-d region.
cst.reset(rank, loopDepth, /*numLocals=*/0, regionSymbols);
return success();
}
// Build the constraints for this region.
AffineValueMap accessValueMap;
access.getAccessMap(&accessValueMap);
AffineMap accessMap = accessValueMap.getAffineMap();
unsigned numDims = accessMap.getNumDims();
unsigned numSymbols = accessMap.getNumSymbols();
unsigned numOperands = accessValueMap.getNumOperands();
// Merge operands with slice operands.
SmallVector<Value, 4> operands;
operands.resize(numOperands);
for (unsigned i = 0; i < numOperands; ++i)
operands[i] = accessValueMap.getOperand(i);
if (sliceState != nullptr) {
operands.reserve(operands.size() + sliceState->lbOperands[0].size());
// Append slice operands to 'operands' as symbols.
for (auto extraOperand : sliceState->lbOperands[0]) {
if (!llvm::is_contained(operands, extraOperand)) {
operands.push_back(extraOperand);
numSymbols++;
}
}
}
// We'll first associate the dims and symbols of the access map to the dims
// and symbols resp. of cst. This will change below once cst is
// fully constructed out.
cst.reset(numDims, numSymbols, 0, operands);
// Add equality constraints.
// Add inequalities for loop lower/upper bounds.
for (unsigned i = 0; i < numDims + numSymbols; ++i) {
auto operand = operands[i];
if (auto loop = getForInductionVarOwner(operand)) {
// Note that cst can now have more dimensions than accessMap if the
// bounds expressions involve outer loops or other symbols.
// TODO: rewrite this to use getInstIndexSet; this way
// conditionals will be handled when the latter supports it.
if (failed(cst.addAffineForOpDomain(loop)))
return failure();
} else {
// Has to be a valid symbol.
auto symbol = operand;
assert(isValidSymbol(symbol));
// Check if the symbol is a constant.
if (auto *op = symbol.getDefiningOp()) {
if (auto constOp = dyn_cast<arith::ConstantIndexOp>(op)) {
cst.addBound(FlatAffineConstraints::EQ, symbol, constOp.value());
}
}
}
}
// Add lower/upper bounds on loop IVs using bounds from 'sliceState'.
if (sliceState != nullptr) {
// Add dim and symbol slice operands.
for (auto operand : sliceState->lbOperands[0]) {
cst.addInductionVarOrTerminalSymbol(operand);
}
// Add upper/lower bounds from 'sliceState' to 'cst'.
LogicalResult ret =
cst.addSliceBounds(sliceState->ivs, sliceState->lbs, sliceState->ubs,
sliceState->lbOperands[0]);
assert(succeeded(ret) &&
"should not fail as we never have semi-affine slice maps");
(void)ret;
}
// Add access function equalities to connect loop IVs to data dimensions.
if (failed(cst.composeMap(&accessValueMap))) {
op->emitError("getMemRefRegion: compose affine map failed");
LLVM_DEBUG(accessValueMap.getAffineMap().dump());
return failure();
}
// Set all identifiers appearing after the first 'rank' identifiers as
// symbolic identifiers - so that the ones corresponding to the memref
// dimensions are the dimensional identifiers for the memref region.
cst.setDimSymbolSeparation(cst.getNumDimAndSymbolIds() - rank);
// Eliminate any loop IVs other than the outermost 'loopDepth' IVs, on which
// this memref region is symbolic.
SmallVector<AffineForOp, 4> enclosingIVs;
getLoopIVs(*op, &enclosingIVs);
assert(loopDepth <= enclosingIVs.size() && "invalid loop depth");
enclosingIVs.resize(loopDepth);
SmallVector<Value, 4> ids;
cst.getValues(cst.getNumDimIds(), cst.getNumDimAndSymbolIds(), &ids);
for (auto id : ids) {
AffineForOp iv;
if ((iv = getForInductionVarOwner(id)) &&
llvm::is_contained(enclosingIVs, iv) == false) {
cst.projectOut(id);
}
}
// Project out any local variables (these would have been added for any
// mod/divs).
cst.projectOut(cst.getNumDimAndSymbolIds(), cst.getNumLocalIds());
// Constant fold any symbolic identifiers.
cst.constantFoldIdRange(/*pos=*/cst.getNumDimIds(),
/*num=*/cst.getNumSymbolIds());
assert(cst.getNumDimIds() == rank && "unexpected MemRefRegion format");
// Add upper/lower bounds for each memref dimension with static size
// to guard against potential over-approximation from projection.
// TODO: Support dynamic memref dimensions.
if (addMemRefDimBounds) {
auto memRefType = memref.getType().cast<MemRefType>();
for (unsigned r = 0; r < rank; r++) {
cst.addBound(FlatAffineConstraints::LB, /*pos=*/r, /*value=*/0);
if (memRefType.isDynamicDim(r))
continue;
cst.addBound(FlatAffineConstraints::UB, /*pos=*/r,
memRefType.getDimSize(r) - 1);
}
}
cst.removeTrivialRedundancy();
LLVM_DEBUG(llvm::dbgs() << "Memory region:\n");
LLVM_DEBUG(cst.dump());
return success();
}
static unsigned getMemRefEltSizeInBytes(MemRefType memRefType) {
auto elementType = memRefType.getElementType();
unsigned sizeInBits;
if (elementType.isIntOrFloat()) {
sizeInBits = elementType.getIntOrFloatBitWidth();
} else {
auto vectorType = elementType.cast<VectorType>();
sizeInBits =
vectorType.getElementTypeBitWidth() * vectorType.getNumElements();
}
return llvm::divideCeil(sizeInBits, 8);
}
// Returns the size of the region.
Optional<int64_t> MemRefRegion::getRegionSize() {
auto memRefType = memref.getType().cast<MemRefType>();
if (!memRefType.getLayout().isIdentity()) {
LLVM_DEBUG(llvm::dbgs() << "Non-identity layout map not yet supported\n");
return false;
}
// Indices to use for the DmaStart op.
// Indices for the original memref being DMAed from/to.
SmallVector<Value, 4> memIndices;
// Indices for the faster buffer being DMAed into/from.
SmallVector<Value, 4> bufIndices;
// Compute the extents of the buffer.
Optional<int64_t> numElements = getConstantBoundingSizeAndShape();
if (!numElements.hasValue()) {
LLVM_DEBUG(llvm::dbgs() << "Dynamic shapes not yet supported\n");
return None;
}
return getMemRefEltSizeInBytes(memRefType) * numElements.getValue();
}
/// Returns the size of memref data in bytes if it's statically shaped, None
/// otherwise. If the element of the memref has vector type, takes into account
/// size of the vector as well.
// TODO: improve/complete this when we have target data.
Optional<uint64_t> mlir::getMemRefSizeInBytes(MemRefType memRefType) {
if (!memRefType.hasStaticShape())
return None;
auto elementType = memRefType.getElementType();
if (!elementType.isIntOrFloat() && !elementType.isa<VectorType>())
return None;
uint64_t sizeInBytes = getMemRefEltSizeInBytes(memRefType);
for (unsigned i = 0, e = memRefType.getRank(); i < e; i++) {
sizeInBytes = sizeInBytes * memRefType.getDimSize(i);
}
return sizeInBytes;
}
template <typename LoadOrStoreOp>
LogicalResult mlir::boundCheckLoadOrStoreOp(LoadOrStoreOp loadOrStoreOp,
bool emitError) {
static_assert(llvm::is_one_of<LoadOrStoreOp, AffineReadOpInterface,
AffineWriteOpInterface>::value,
"argument should be either a AffineReadOpInterface or a "
"AffineWriteOpInterface");
Operation *op = loadOrStoreOp.getOperation();
MemRefRegion region(op->getLoc());
if (failed(region.compute(op, /*loopDepth=*/0, /*sliceState=*/nullptr,
/*addMemRefDimBounds=*/false)))
return success();
LLVM_DEBUG(llvm::dbgs() << "Memory region");
LLVM_DEBUG(region.getConstraints()->dump());
bool outOfBounds = false;
unsigned rank = loadOrStoreOp.getMemRefType().getRank();
// For each dimension, check for out of bounds.
for (unsigned r = 0; r < rank; r++) {
FlatAffineConstraints ucst(*region.getConstraints());
// Intersect memory region with constraint capturing out of bounds (both out
// of upper and out of lower), and check if the constraint system is
// feasible. If it is, there is at least one point out of bounds.
SmallVector<int64_t, 4> ineq(rank + 1, 0);
int64_t dimSize = loadOrStoreOp.getMemRefType().getDimSize(r);
// TODO: handle dynamic dim sizes.
if (dimSize == -1)
continue;
// Check for overflow: d_i >= memref dim size.
ucst.addBound(FlatAffineConstraints::LB, r, dimSize);
outOfBounds = !ucst.isEmpty();
if (outOfBounds && emitError) {
loadOrStoreOp.emitOpError()
<< "memref out of upper bound access along dimension #" << (r + 1);
}
// Check for a negative index.
FlatAffineConstraints lcst(*region.getConstraints());
std::fill(ineq.begin(), ineq.end(), 0);
// d_i <= -1;
lcst.addBound(FlatAffineConstraints::UB, r, -1);
outOfBounds = !lcst.isEmpty();
if (outOfBounds && emitError) {
loadOrStoreOp.emitOpError()
<< "memref out of lower bound access along dimension #" << (r + 1);
}
}
return failure(outOfBounds);
}
// Explicitly instantiate the template so that the compiler knows we need them!
template LogicalResult
mlir::boundCheckLoadOrStoreOp(AffineReadOpInterface loadOp, bool emitError);
template LogicalResult
mlir::boundCheckLoadOrStoreOp(AffineWriteOpInterface storeOp, bool emitError);
// Returns in 'positions' the Block positions of 'op' in each ancestor
// Block from the Block containing operation, stopping at 'limitBlock'.
static void findInstPosition(Operation *op, Block *limitBlock,
SmallVectorImpl<unsigned> *positions) {
Block *block = op->getBlock();
while (block != limitBlock) {
// FIXME: This algorithm is unnecessarily O(n) and should be improved to not
// rely on linear scans.
int instPosInBlock = std::distance(block->begin(), op->getIterator());
positions->push_back(instPosInBlock);
op = block->getParentOp();
block = op->getBlock();
}
std::reverse(positions->begin(), positions->end());
}
// Returns the Operation in a possibly nested set of Blocks, where the
// position of the operation is represented by 'positions', which has a
// Block position for each level of nesting.
static Operation *getInstAtPosition(ArrayRef<unsigned> positions,
unsigned level, Block *block) {
unsigned i = 0;
for (auto &op : *block) {
if (i != positions[level]) {
++i;
continue;
}
if (level == positions.size() - 1)
return &op;
if (auto childAffineForOp = dyn_cast<AffineForOp>(op))
return getInstAtPosition(positions, level + 1,
childAffineForOp.getBody());
for (auto &region : op.getRegions()) {
for (auto &b : region)
if (auto *ret = getInstAtPosition(positions, level + 1, &b))
return ret;
}
return nullptr;
}
return nullptr;
}
// Adds loop IV bounds to 'cst' for loop IVs not found in 'ivs'.
static LogicalResult addMissingLoopIVBounds(SmallPtrSet<Value, 8> &ivs,
FlatAffineValueConstraints *cst) {
for (unsigned i = 0, e = cst->getNumDimIds(); i < e; ++i) {
auto value = cst->getValue(i);
if (ivs.count(value) == 0) {
assert(isForInductionVar(value));
auto loop = getForInductionVarOwner(value);
if (failed(cst->addAffineForOpDomain(loop)))
return failure();
}
}
return success();
}
/// Returns the innermost common loop depth for the set of operations in 'ops'.
// TODO: Move this to LoopUtils.
unsigned mlir::getInnermostCommonLoopDepth(
ArrayRef<Operation *> ops, SmallVectorImpl<AffineForOp> *surroundingLoops) {
unsigned numOps = ops.size();
assert(numOps > 0 && "Expected at least one operation");
std::vector<SmallVector<AffineForOp, 4>> loops(numOps);
unsigned loopDepthLimit = std::numeric_limits<unsigned>::max();
for (unsigned i = 0; i < numOps; ++i) {
getLoopIVs(*ops[i], &loops[i]);
loopDepthLimit =
std::min(loopDepthLimit, static_cast<unsigned>(loops[i].size()));
}
unsigned loopDepth = 0;
for (unsigned d = 0; d < loopDepthLimit; ++d) {
unsigned i;
for (i = 1; i < numOps; ++i) {
if (loops[i - 1][d] != loops[i][d])
return loopDepth;
}
if (surroundingLoops)
surroundingLoops->push_back(loops[i - 1][d]);
++loopDepth;
}
return loopDepth;
}
/// Computes in 'sliceUnion' the union of all slice bounds computed at
/// 'loopDepth' between all dependent pairs of ops in 'opsA' and 'opsB', and
/// then verifies if it is valid. Returns 'SliceComputationResult::Success' if
/// union was computed correctly, an appropriate failure otherwise.
SliceComputationResult
mlir::computeSliceUnion(ArrayRef<Operation *> opsA, ArrayRef<Operation *> opsB,
unsigned loopDepth, unsigned numCommonLoops,
bool isBackwardSlice,
ComputationSliceState *sliceUnion) {
// Compute the union of slice bounds between all pairs in 'opsA' and
// 'opsB' in 'sliceUnionCst'.
FlatAffineValueConstraints sliceUnionCst;
assert(sliceUnionCst.getNumDimAndSymbolIds() == 0);
std::vector<std::pair<Operation *, Operation *>> dependentOpPairs;
for (unsigned i = 0, numOpsA = opsA.size(); i < numOpsA; ++i) {
MemRefAccess srcAccess(opsA[i]);
for (unsigned j = 0, numOpsB = opsB.size(); j < numOpsB; ++j) {
MemRefAccess dstAccess(opsB[j]);
if (srcAccess.memref != dstAccess.memref)
continue;
// Check if 'loopDepth' exceeds nesting depth of src/dst ops.
if ((!isBackwardSlice && loopDepth > getNestingDepth(opsA[i])) ||
(isBackwardSlice && loopDepth > getNestingDepth(opsB[j]))) {
LLVM_DEBUG(llvm::dbgs() << "Invalid loop depth\n");
return SliceComputationResult::GenericFailure;
}
bool readReadAccesses = isa<AffineReadOpInterface>(srcAccess.opInst) &&
isa<AffineReadOpInterface>(dstAccess.opInst);
FlatAffineValueConstraints dependenceConstraints;
// Check dependence between 'srcAccess' and 'dstAccess'.
DependenceResult result = checkMemrefAccessDependence(
srcAccess, dstAccess, /*loopDepth=*/numCommonLoops + 1,
&dependenceConstraints, /*dependenceComponents=*/nullptr,
/*allowRAR=*/readReadAccesses);
if (result.value == DependenceResult::Failure) {
LLVM_DEBUG(llvm::dbgs() << "Dependence check failed\n");
return SliceComputationResult::GenericFailure;
}
if (result.value == DependenceResult::NoDependence)
continue;
dependentOpPairs.push_back({opsA[i], opsB[j]});
// Compute slice bounds for 'srcAccess' and 'dstAccess'.
ComputationSliceState tmpSliceState;
mlir::getComputationSliceState(opsA[i], opsB[j], &dependenceConstraints,
loopDepth, isBackwardSlice,
&tmpSliceState);
if (sliceUnionCst.getNumDimAndSymbolIds() == 0) {
// Initialize 'sliceUnionCst' with the bounds computed in previous step.
if (failed(tmpSliceState.getAsConstraints(&sliceUnionCst))) {
LLVM_DEBUG(llvm::dbgs()
<< "Unable to compute slice bound constraints\n");
return SliceComputationResult::GenericFailure;
}
assert(sliceUnionCst.getNumDimAndSymbolIds() > 0);
continue;
}
// Compute constraints for 'tmpSliceState' in 'tmpSliceCst'.
FlatAffineValueConstraints tmpSliceCst;
if (failed(tmpSliceState.getAsConstraints(&tmpSliceCst))) {
LLVM_DEBUG(llvm::dbgs()
<< "Unable to compute slice bound constraints\n");
return SliceComputationResult::GenericFailure;
}
// Align coordinate spaces of 'sliceUnionCst' and 'tmpSliceCst' if needed.
if (!sliceUnionCst.areIdsAlignedWithOther(tmpSliceCst)) {
// Pre-constraint id alignment: record loop IVs used in each constraint
// system.
SmallPtrSet<Value, 8> sliceUnionIVs;
for (unsigned k = 0, l = sliceUnionCst.getNumDimIds(); k < l; ++k)
sliceUnionIVs.insert(sliceUnionCst.getValue(k));
SmallPtrSet<Value, 8> tmpSliceIVs;
for (unsigned k = 0, l = tmpSliceCst.getNumDimIds(); k < l; ++k)
tmpSliceIVs.insert(tmpSliceCst.getValue(k));
sliceUnionCst.mergeAndAlignIdsWithOther(/*offset=*/0, &tmpSliceCst);
// Post-constraint id alignment: add loop IV bounds missing after
// id alignment to constraint systems. This can occur if one constraint
// system uses an loop IV that is not used by the other. The call
// to unionBoundingBox below expects constraints for each Loop IV, even
// if they are the unsliced full loop bounds added here.
if (failed(addMissingLoopIVBounds(sliceUnionIVs, &sliceUnionCst)))
return SliceComputationResult::GenericFailure;
if (failed(addMissingLoopIVBounds(tmpSliceIVs, &tmpSliceCst)))
return SliceComputationResult::GenericFailure;
}
// Compute union bounding box of 'sliceUnionCst' and 'tmpSliceCst'.
if (sliceUnionCst.getNumLocalIds() > 0 ||
tmpSliceCst.getNumLocalIds() > 0 ||
failed(sliceUnionCst.unionBoundingBox(tmpSliceCst))) {
LLVM_DEBUG(llvm::dbgs()
<< "Unable to compute union bounding box of slice bounds\n");
return SliceComputationResult::GenericFailure;
}
}
}
// Empty union.
if (sliceUnionCst.getNumDimAndSymbolIds() == 0)
return SliceComputationResult::GenericFailure;
// Gather loops surrounding ops from loop nest where slice will be inserted.
SmallVector<Operation *, 4> ops;
for (auto &dep : dependentOpPairs) {
ops.push_back(isBackwardSlice ? dep.second : dep.first);
}
SmallVector<AffineForOp, 4> surroundingLoops;
unsigned innermostCommonLoopDepth =
getInnermostCommonLoopDepth(ops, &surroundingLoops);
if (loopDepth > innermostCommonLoopDepth) {
LLVM_DEBUG(llvm::dbgs() << "Exceeds max loop depth\n");
return SliceComputationResult::GenericFailure;
}
// Store 'numSliceLoopIVs' before converting dst loop IVs to dims.
unsigned numSliceLoopIVs = sliceUnionCst.getNumDimIds();
// Convert any dst loop IVs which are symbol identifiers to dim identifiers.
sliceUnionCst.convertLoopIVSymbolsToDims();
sliceUnion->clearBounds();
sliceUnion->lbs.resize(numSliceLoopIVs, AffineMap());
sliceUnion->ubs.resize(numSliceLoopIVs, AffineMap());
// Get slice bounds from slice union constraints 'sliceUnionCst'.
sliceUnionCst.getSliceBounds(/*offset=*/0, numSliceLoopIVs,
opsA[0]->getContext(), &sliceUnion->lbs,
&sliceUnion->ubs);
// Add slice bound operands of union.
SmallVector<Value, 4> sliceBoundOperands;
sliceUnionCst.getValues(numSliceLoopIVs,
sliceUnionCst.getNumDimAndSymbolIds(),
&sliceBoundOperands);
// Copy src loop IVs from 'sliceUnionCst' to 'sliceUnion'.
sliceUnion->ivs.clear();
sliceUnionCst.getValues(0, numSliceLoopIVs, &sliceUnion->ivs);
// Set loop nest insertion point to block start at 'loopDepth'.
sliceUnion->insertPoint =
isBackwardSlice
? surroundingLoops[loopDepth - 1].getBody()->begin()
: std::prev(surroundingLoops[loopDepth - 1].getBody()->end());
// Give each bound its own copy of 'sliceBoundOperands' for subsequent
// canonicalization.
sliceUnion->lbOperands.resize(numSliceLoopIVs, sliceBoundOperands);
sliceUnion->ubOperands.resize(numSliceLoopIVs, sliceBoundOperands);
// Check if the slice computed is valid. Return success only if it is verified
// that the slice is valid, otherwise return appropriate failure status.
Optional<bool> isSliceValid = sliceUnion->isSliceValid();
if (!isSliceValid.hasValue()) {
LLVM_DEBUG(llvm::dbgs() << "Cannot determine if the slice is valid\n");
return SliceComputationResult::GenericFailure;
}
if (!isSliceValid.getValue())
return SliceComputationResult::IncorrectSliceFailure;
return SliceComputationResult::Success;
}
// TODO: extend this to handle multiple result maps.
static Optional<uint64_t> getConstDifference(AffineMap lbMap, AffineMap ubMap) {
assert(lbMap.getNumResults() == 1 && "expected single result bound map");
assert(ubMap.getNumResults() == 1 && "expected single result bound map");
assert(lbMap.getNumDims() == ubMap.getNumDims());
assert(lbMap.getNumSymbols() == ubMap.getNumSymbols());
AffineExpr lbExpr(lbMap.getResult(0));
AffineExpr ubExpr(ubMap.getResult(0));
auto loopSpanExpr = simplifyAffineExpr(ubExpr - lbExpr, lbMap.getNumDims(),
lbMap.getNumSymbols());
auto cExpr = loopSpanExpr.dyn_cast<AffineConstantExpr>();
if (!cExpr)
return None;
return cExpr.getValue();
}
// Builds a map 'tripCountMap' from AffineForOp to constant trip count for loop
// nest surrounding represented by slice loop bounds in 'slice'. Returns true
// on success, false otherwise (if a non-constant trip count was encountered).
// TODO: Make this work with non-unit step loops.
bool mlir::buildSliceTripCountMap(
const ComputationSliceState &slice,
llvm::SmallDenseMap<Operation *, uint64_t, 8> *tripCountMap) {
unsigned numSrcLoopIVs = slice.ivs.size();
// Populate map from AffineForOp -> trip count
for (unsigned i = 0; i < numSrcLoopIVs; ++i) {
AffineForOp forOp = getForInductionVarOwner(slice.ivs[i]);
auto *op = forOp.getOperation();
AffineMap lbMap = slice.lbs[i];
AffineMap ubMap = slice.ubs[i];
// If lower or upper bound maps are null or provide no results, it implies
// that source loop was not at all sliced, and the entire loop will be a
// part of the slice.
if (!lbMap || lbMap.getNumResults() == 0 || !ubMap ||
ubMap.getNumResults() == 0) {
// The iteration of src loop IV 'i' was not sliced. Use full loop bounds.
if (forOp.hasConstantLowerBound() && forOp.hasConstantUpperBound()) {
(*tripCountMap)[op] =
forOp.getConstantUpperBound() - forOp.getConstantLowerBound();
continue;
}
Optional<uint64_t> maybeConstTripCount = getConstantTripCount(forOp);
if (maybeConstTripCount.hasValue()) {
(*tripCountMap)[op] = maybeConstTripCount.getValue();
continue;
}
return false;
}
Optional<uint64_t> tripCount = getConstDifference(lbMap, ubMap);
// Slice bounds are created with a constant ub - lb difference.
if (!tripCount.hasValue())
return false;
(*tripCountMap)[op] = tripCount.getValue();
}
return true;
}
// Return the number of iterations in the given slice.
uint64_t mlir::getSliceIterationCount(
const llvm::SmallDenseMap<Operation *, uint64_t, 8> &sliceTripCountMap) {
uint64_t iterCount = 1;
for (const auto &count : sliceTripCountMap) {
iterCount *= count.second;
}
return iterCount;
}
const char *const kSliceFusionBarrierAttrName = "slice_fusion_barrier";
// Computes slice bounds by projecting out any loop IVs from
// 'dependenceConstraints' at depth greater than 'loopDepth', and computes slice
// bounds in 'sliceState' which represent the one loop nest's IVs in terms of
// the other loop nest's IVs, symbols and constants (using 'isBackwardsSlice').
void mlir::getComputationSliceState(
Operation *depSourceOp, Operation *depSinkOp,
FlatAffineValueConstraints *dependenceConstraints, unsigned loopDepth,
bool isBackwardSlice, ComputationSliceState *sliceState) {
// Get loop nest surrounding src operation.
SmallVector<AffineForOp, 4> srcLoopIVs;
getLoopIVs(*depSourceOp, &srcLoopIVs);
unsigned numSrcLoopIVs = srcLoopIVs.size();
// Get loop nest surrounding dst operation.
SmallVector<AffineForOp, 4> dstLoopIVs;
getLoopIVs(*depSinkOp, &dstLoopIVs);
unsigned numDstLoopIVs = dstLoopIVs.size();
assert((!isBackwardSlice && loopDepth <= numSrcLoopIVs) ||
(isBackwardSlice && loopDepth <= numDstLoopIVs));
// Project out dimensions other than those up to 'loopDepth'.
unsigned pos = isBackwardSlice ? numSrcLoopIVs + loopDepth : loopDepth;
unsigned num =
isBackwardSlice ? numDstLoopIVs - loopDepth : numSrcLoopIVs - loopDepth;
dependenceConstraints->projectOut(pos, num);
// Add slice loop IV values to 'sliceState'.
unsigned offset = isBackwardSlice ? 0 : loopDepth;
unsigned numSliceLoopIVs = isBackwardSlice ? numSrcLoopIVs : numDstLoopIVs;
dependenceConstraints->getValues(offset, offset + numSliceLoopIVs,
&sliceState->ivs);
// Set up lower/upper bound affine maps for the slice.
sliceState->lbs.resize(numSliceLoopIVs, AffineMap());
sliceState->ubs.resize(numSliceLoopIVs, AffineMap());
// Get bounds for slice IVs in terms of other IVs, symbols, and constants.
dependenceConstraints->getSliceBounds(offset, numSliceLoopIVs,
depSourceOp->getContext(),
&sliceState->lbs, &sliceState->ubs);
// Set up bound operands for the slice's lower and upper bounds.
SmallVector<Value, 4> sliceBoundOperands;
unsigned numDimsAndSymbols = dependenceConstraints->getNumDimAndSymbolIds();
for (unsigned i = 0; i < numDimsAndSymbols; ++i) {
if (i < offset || i >= offset + numSliceLoopIVs) {
sliceBoundOperands.push_back(dependenceConstraints->getValue(i));
}
}
// Give each bound its own copy of 'sliceBoundOperands' for subsequent
// canonicalization.
sliceState->lbOperands.resize(numSliceLoopIVs, sliceBoundOperands);
sliceState->ubOperands.resize(numSliceLoopIVs, sliceBoundOperands);
// Set destination loop nest insertion point to block start at 'dstLoopDepth'.
sliceState->insertPoint =
isBackwardSlice ? dstLoopIVs[loopDepth - 1].getBody()->begin()
: std::prev(srcLoopIVs[loopDepth - 1].getBody()->end());
llvm::SmallDenseSet<Value, 8> sequentialLoops;
if (isa<AffineReadOpInterface>(depSourceOp) &&
isa<AffineReadOpInterface>(depSinkOp)) {
// For read-read access pairs, clear any slice bounds on sequential loops.
// Get sequential loops in loop nest rooted at 'srcLoopIVs[0]'.
getSequentialLoops(isBackwardSlice ? srcLoopIVs[0] : dstLoopIVs[0],
&sequentialLoops);
}
auto getSliceLoop = [&](unsigned i) {
return isBackwardSlice ? srcLoopIVs[i] : dstLoopIVs[i];
};
auto isInnermostInsertion = [&]() {
return (isBackwardSlice ? loopDepth >= srcLoopIVs.size()
: loopDepth >= dstLoopIVs.size());
};
llvm::SmallDenseMap<Operation *, uint64_t, 8> sliceTripCountMap;
auto srcIsUnitSlice = [&]() {
return (buildSliceTripCountMap(*sliceState, &sliceTripCountMap) &&
(getSliceIterationCount(sliceTripCountMap) == 1));
};
// Clear all sliced loop bounds beginning at the first sequential loop, or
// first loop with a slice fusion barrier attribute..
for (unsigned i = 0; i < numSliceLoopIVs; ++i) {
Value iv = getSliceLoop(i).getInductionVar();
if (sequentialLoops.count(iv) == 0 &&
getSliceLoop(i)->getAttr(kSliceFusionBarrierAttrName) == nullptr)
continue;
// Skip reset of bounds of reduction loop inserted in the destination loop
// that meets the following conditions:
// 1. Slice is single trip count.
// 2. Loop bounds of the source and destination match.
// 3. Is being inserted at the innermost insertion point.
Optional<bool> isMaximal = sliceState->isMaximal();
if (isLoopParallelAndContainsReduction(getSliceLoop(i)) &&
isInnermostInsertion() && srcIsUnitSlice() && isMaximal.hasValue() &&
isMaximal.getValue())
continue;
for (unsigned j = i; j < numSliceLoopIVs; ++j) {
sliceState->lbs[j] = AffineMap();
sliceState->ubs[j] = AffineMap();
}
break;
}
}
/// Creates a computation slice of the loop nest surrounding 'srcOpInst',
/// updates the slice loop bounds with any non-null bound maps specified in
/// 'sliceState', and inserts this slice into the loop nest surrounding
/// 'dstOpInst' at loop depth 'dstLoopDepth'.
// TODO: extend the slicing utility to compute slices that
// aren't necessarily a one-to-one relation b/w the source and destination. The
// relation between the source and destination could be many-to-many in general.
// TODO: the slice computation is incorrect in the cases
// where the dependence from the source to the destination does not cover the
// entire destination index set. Subtract out the dependent destination
// iterations from destination index set and check for emptiness --- this is one
// solution.
AffineForOp
mlir::insertBackwardComputationSlice(Operation *srcOpInst, Operation *dstOpInst,
unsigned dstLoopDepth,
ComputationSliceState *sliceState) {
// Get loop nest surrounding src operation.
SmallVector<AffineForOp, 4> srcLoopIVs;
getLoopIVs(*srcOpInst, &srcLoopIVs);
unsigned numSrcLoopIVs = srcLoopIVs.size();
// Get loop nest surrounding dst operation.
SmallVector<AffineForOp, 4> dstLoopIVs;
getLoopIVs(*dstOpInst, &dstLoopIVs);
unsigned dstLoopIVsSize = dstLoopIVs.size();
if (dstLoopDepth > dstLoopIVsSize) {
dstOpInst->emitError("invalid destination loop depth");
return AffineForOp();
}
// Find the op block positions of 'srcOpInst' within 'srcLoopIVs'.
SmallVector<unsigned, 4> positions;
// TODO: This code is incorrect since srcLoopIVs can be 0-d.
findInstPosition(srcOpInst, srcLoopIVs[0]->getBlock(), &positions);
// Clone src loop nest and insert it a the beginning of the operation block
// of the loop at 'dstLoopDepth' in 'dstLoopIVs'.
auto dstAffineForOp = dstLoopIVs[dstLoopDepth - 1];
OpBuilder b(dstAffineForOp.getBody(), dstAffineForOp.getBody()->begin());
auto sliceLoopNest =
cast<AffineForOp>(b.clone(*srcLoopIVs[0].getOperation()));
Operation *sliceInst =
getInstAtPosition(positions, /*level=*/0, sliceLoopNest.getBody());
// Get loop nest surrounding 'sliceInst'.
SmallVector<AffineForOp, 4> sliceSurroundingLoops;
getLoopIVs(*sliceInst, &sliceSurroundingLoops);
// Sanity check.
unsigned sliceSurroundingLoopsSize = sliceSurroundingLoops.size();
(void)sliceSurroundingLoopsSize;
assert(dstLoopDepth + numSrcLoopIVs >= sliceSurroundingLoopsSize);
unsigned sliceLoopLimit = dstLoopDepth + numSrcLoopIVs;
(void)sliceLoopLimit;
assert(sliceLoopLimit >= sliceSurroundingLoopsSize);
// Update loop bounds for loops in 'sliceLoopNest'.
for (unsigned i = 0; i < numSrcLoopIVs; ++i) {
auto forOp = sliceSurroundingLoops[dstLoopDepth + i];
if (AffineMap lbMap = sliceState->lbs[i])
forOp.setLowerBound(sliceState->lbOperands[i], lbMap);
if (AffineMap ubMap = sliceState->ubs[i])
forOp.setUpperBound(sliceState->ubOperands[i], ubMap);
}
return sliceLoopNest;
}
// Constructs MemRefAccess populating it with the memref, its indices and
// opinst from 'loadOrStoreOpInst'.
MemRefAccess::MemRefAccess(Operation *loadOrStoreOpInst) {
if (auto loadOp = dyn_cast<AffineReadOpInterface>(loadOrStoreOpInst)) {
memref = loadOp.getMemRef();
opInst = loadOrStoreOpInst;
auto loadMemrefType = loadOp.getMemRefType();
indices.reserve(loadMemrefType.getRank());
for (auto index : loadOp.getMapOperands()) {
indices.push_back(index);
}
} else {
assert(isa<AffineWriteOpInterface>(loadOrStoreOpInst) &&
"Affine read/write op expected");
auto storeOp = cast<AffineWriteOpInterface>(loadOrStoreOpInst);
opInst = loadOrStoreOpInst;
memref = storeOp.getMemRef();
auto storeMemrefType = storeOp.getMemRefType();
indices.reserve(storeMemrefType.getRank());
for (auto index : storeOp.getMapOperands()) {
indices.push_back(index);
}
}
}
unsigned MemRefAccess::getRank() const {
return memref.getType().cast<MemRefType>().getRank();
}
bool MemRefAccess::isStore() const {
return isa<AffineWriteOpInterface>(opInst);
}
/// Returns the nesting depth of this statement, i.e., the number of loops
/// surrounding this statement.
unsigned mlir::getNestingDepth(Operation *op) {
Operation *currOp = op;
unsigned depth = 0;
while ((currOp = currOp->getParentOp())) {
if (isa<AffineForOp>(currOp))
depth++;
}
return depth;
}
/// Equal if both affine accesses are provably equivalent (at compile
/// time) when considering the memref, the affine maps and their respective
/// operands. The equality of access functions + operands is checked by
/// subtracting fully composed value maps, and then simplifying the difference
/// using the expression flattener.
/// TODO: this does not account for aliasing of memrefs.
bool MemRefAccess::operator==(const MemRefAccess &rhs) const {
if (memref != rhs.memref)
return false;
AffineValueMap diff, thisMap, rhsMap;
getAccessMap(&thisMap);
rhs.getAccessMap(&rhsMap);
AffineValueMap::difference(thisMap, rhsMap, &diff);
return llvm::all_of(diff.getAffineMap().getResults(),
[](AffineExpr e) { return e == 0; });
}
/// Returns the number of surrounding loops common to 'loopsA' and 'loopsB',
/// where each lists loops from outer-most to inner-most in loop nest.
unsigned mlir::getNumCommonSurroundingLoops(Operation &A, Operation &B) {
SmallVector<AffineForOp, 4> loopsA, loopsB;
getLoopIVs(A, &loopsA);
getLoopIVs(B, &loopsB);
unsigned minNumLoops = std::min(loopsA.size(), loopsB.size());
unsigned numCommonLoops = 0;
for (unsigned i = 0; i < minNumLoops; ++i) {
if (loopsA[i].getOperation() != loopsB[i].getOperation())
break;
++numCommonLoops;
}
return numCommonLoops;
}
static Optional<int64_t> getMemoryFootprintBytes(Block &block,
Block::iterator start,
Block::iterator end,
int memorySpace) {
SmallDenseMap<Value, std::unique_ptr<MemRefRegion>, 4> regions;
// Walk this 'affine.for' operation to gather all memory regions.
auto result = block.walk(start, end, [&](Operation *opInst) -> WalkResult {
if (!isa<AffineReadOpInterface, AffineWriteOpInterface>(opInst)) {
// Neither load nor a store op.
return WalkResult::advance();
}
// Compute the memref region symbolic in any IVs enclosing this block.
auto region = std::make_unique<MemRefRegion>(opInst->getLoc());
if (failed(
region->compute(opInst,
/*loopDepth=*/getNestingDepth(&*block.begin())))) {
return opInst->emitError("error obtaining memory region\n");
}
auto it = regions.find(region->memref);
if (it == regions.end()) {
regions[region->memref] = std::move(region);
} else if (failed(it->second->unionBoundingBox(*region))) {
return opInst->emitWarning(
"getMemoryFootprintBytes: unable to perform a union on a memory "
"region");
}
return WalkResult::advance();
});
if (result.wasInterrupted())
return None;
int64_t totalSizeInBytes = 0;
for (const auto &region : regions) {
Optional<int64_t> size = region.second->getRegionSize();
if (!size.hasValue())
return None;
totalSizeInBytes += size.getValue();
}
return totalSizeInBytes;
}
Optional<int64_t> mlir::getMemoryFootprintBytes(AffineForOp forOp,
int memorySpace) {
auto *forInst = forOp.getOperation();
return ::getMemoryFootprintBytes(
*forInst->getBlock(), Block::iterator(forInst),
std::next(Block::iterator(forInst)), memorySpace);
}
/// Returns whether a loop is parallel and contains a reduction loop.
bool mlir::isLoopParallelAndContainsReduction(AffineForOp forOp) {
SmallVector<LoopReduction> reductions;
if (!isLoopParallel(forOp, &reductions))
return false;
return !reductions.empty();
}
/// Returns in 'sequentialLoops' all sequential loops in loop nest rooted
/// at 'forOp'.
void mlir::getSequentialLoops(AffineForOp forOp,
llvm::SmallDenseSet<Value, 8> *sequentialLoops) {
forOp->walk([&](Operation *op) {
if (auto innerFor = dyn_cast<AffineForOp>(op))
if (!isLoopParallel(innerFor))
sequentialLoops->insert(innerFor.getInductionVar());
});
}
IntegerSet mlir::simplifyIntegerSet(IntegerSet set) {
FlatAffineConstraints fac(set);
if (fac.isEmpty())
return IntegerSet::getEmptySet(set.getNumDims(), set.getNumSymbols(),
set.getContext());
fac.removeTrivialRedundancy();
auto simplifiedSet = fac.getAsIntegerSet(set.getContext());
assert(simplifiedSet && "guaranteed to succeed while roundtripping");
return simplifiedSet;
}
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