MLIR  22.0.0git
IndependenceTransforms.cpp
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1 //===- IndependenceTransforms.cpp - Make ops independent of values --------===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 
10 
14 
15 using namespace mlir;
16 using namespace mlir::memref;
17 
18 /// Make the given OpFoldResult independent of all independencies.
19 static FailureOr<OpFoldResult> makeIndependent(OpBuilder &b, Location loc,
20  OpFoldResult ofr,
21  ValueRange independencies) {
22  if (isa<Attribute>(ofr))
23  return ofr;
24  AffineMap boundMap;
25  ValueDimList mapOperands;
27  boundMap, mapOperands, presburger::BoundType::UB, ofr, independencies,
28  /*closedUB=*/true)))
29  return failure();
30  return affine::materializeComputedBound(b, loc, boundMap, mapOperands);
31 }
32 
33 FailureOr<Value> memref::buildIndependentOp(OpBuilder &b,
34  memref::AllocaOp allocaOp,
35  ValueRange independencies) {
37  b.setInsertionPoint(allocaOp);
38  Location loc = allocaOp.getLoc();
39 
41  for (OpFoldResult ofr : allocaOp.getMixedSizes()) {
42  auto ub = makeIndependent(b, loc, ofr, independencies);
43  if (failed(ub))
44  return failure();
45  newSizes.push_back(*ub);
46  }
47 
48  // Return existing memref::AllocaOp if nothing has changed.
49  if (llvm::equal(allocaOp.getMixedSizes(), newSizes))
50  return allocaOp.getResult();
51 
52  // Create a new memref::AllocaOp.
53  Value newAllocaOp =
54  AllocaOp::create(b, loc, newSizes, allocaOp.getType().getElementType());
55 
56  // Create a memref::SubViewOp.
57  SmallVector<OpFoldResult> offsets(newSizes.size(), b.getIndexAttr(0));
58  SmallVector<OpFoldResult> strides(newSizes.size(), b.getIndexAttr(1));
59  return SubViewOp::create(b, loc, newAllocaOp, offsets,
60  allocaOp.getMixedSizes(), strides)
61  .getResult();
62 }
63 
64 /// Push down an UnrealizedConversionCastOp past a SubViewOp.
65 static UnrealizedConversionCastOp
67  UnrealizedConversionCastOp conversionOp, SubViewOp op) {
68  OpBuilder::InsertionGuard g(rewriter);
69  rewriter.setInsertionPoint(op);
70  MemRefType newResultType = SubViewOp::inferRankReducedResultType(
71  op.getType().getShape(), op.getSourceType(), op.getMixedOffsets(),
72  op.getMixedSizes(), op.getMixedStrides());
73  Value newSubview = SubViewOp::create(
74  rewriter, op.getLoc(), newResultType, conversionOp.getOperand(0),
75  op.getMixedOffsets(), op.getMixedSizes(), op.getMixedStrides());
76  auto newConversionOp = UnrealizedConversionCastOp::create(
77  rewriter, op.getLoc(), op.getType(), newSubview);
78  rewriter.replaceAllUsesWith(op.getResult(), newConversionOp->getResult(0));
79  return newConversionOp;
80 }
81 
82 /// Given an original op and a new, modified op with the same number of results,
83 /// whose memref return types may differ, replace all uses of the original op
84 /// with the new op and propagate the new memref types through the IR.
85 ///
86 /// Example:
87 /// %from = memref.alloca(%sz) : memref<?xf32>
88 /// %to = memref.subview ... : ... to memref<?xf32, strided<[1], offset: ?>>
89 /// memref.store %cst, %from[%c0] : memref<?xf32>
90 ///
91 /// In the above example, all uses of %from are replaced with %to. This can be
92 /// done directly for ops such as memref.store. For ops that have memref results
93 /// (e.g., memref.subview), the result type may depend on the operand type, so
94 /// we cannot just replace all uses. There is special handling for common memref
95 /// ops. For all other ops, unrealized_conversion_cast is inserted.
97  Operation *from, Operation *to) {
98  assert(from->getNumResults() == to->getNumResults() &&
99  "expected same number of results");
100  OpBuilder::InsertionGuard g(rewriter);
101  rewriter.setInsertionPointAfter(to);
102 
103  // Wrap new results in unrealized_conversion_cast and replace all uses of the
104  // original op.
105  SmallVector<UnrealizedConversionCastOp> unrealizedConversions;
106  for (const auto &it :
107  llvm::enumerate(llvm::zip(from->getResults(), to->getResults()))) {
108  unrealizedConversions.push_back(UnrealizedConversionCastOp::create(
109  rewriter, to->getLoc(), std::get<0>(it.value()).getType(),
110  std::get<1>(it.value())));
111  rewriter.replaceAllUsesWith(from->getResult(it.index()),
112  unrealizedConversions.back()->getResult(0));
113  }
114 
115  // Push unrealized_conversion_cast ops further down in the IR. I.e., try to
116  // wrap results instead of operands in a cast.
117  for (int i = 0; i < static_cast<int>(unrealizedConversions.size()); ++i) {
118  UnrealizedConversionCastOp conversion = unrealizedConversions[i];
119  assert(conversion->getNumOperands() == 1 &&
120  conversion->getNumResults() == 1 &&
121  "expected single operand and single result");
122  SmallVector<Operation *> users = llvm::to_vector(conversion->getUsers());
123  for (Operation *user : users) {
124  // Handle common memref dialect ops that produce new memrefs and must
125  // be recreated with the new result type.
126  if (auto subviewOp = dyn_cast<SubViewOp>(user)) {
127  unrealizedConversions.push_back(
128  propagateSubViewOp(rewriter, conversion, subviewOp));
129  continue;
130  }
131 
132  // TODO: Other memref ops such as memref.collapse_shape/expand_shape
133  // should also be handled here.
134 
135  // Skip any ops that produce MemRef result or have MemRef region block
136  // arguments. These may need special handling (e.g., scf.for).
137  if (llvm::any_of(user->getResultTypes(),
138  [](Type t) { return isa<MemRefType>(t); }))
139  continue;
140  if (llvm::any_of(user->getRegions(), [](Region &r) {
141  return llvm::any_of(r.getArguments(), [](BlockArgument bbArg) {
142  return isa<MemRefType>(bbArg.getType());
143  });
144  }))
145  continue;
146 
147  // For all other ops, we assume that we can directly replace the operand.
148  // This may have to be revised in the future; e.g., there may be ops that
149  // do not support non-identity layout maps.
150  for (OpOperand &operand : user->getOpOperands()) {
151  if ([[maybe_unused]] auto castOp =
152  operand.get().getDefiningOp<UnrealizedConversionCastOp>()) {
153  rewriter.modifyOpInPlace(
154  user, [&]() { operand.set(conversion->getOperand(0)); });
155  }
156  }
157  }
158  }
159 
160  // Erase all unrealized_conversion_cast ops without uses.
161  for (auto op : unrealizedConversions)
162  if (op->getUses().empty())
163  rewriter.eraseOp(op);
164 }
165 
167  memref::AllocaOp allocaOp,
168  ValueRange independencies) {
169  auto replacement =
170  memref::buildIndependentOp(rewriter, allocaOp, independencies);
171  if (failed(replacement))
172  return failure();
173  replaceAndPropagateMemRefType(rewriter, allocaOp,
174  replacement->getDefiningOp());
175  return replacement;
176 }
177 
178 memref::AllocaOp memref::allocToAlloca(
179  RewriterBase &rewriter, memref::AllocOp alloc,
180  function_ref<bool(memref::AllocOp, memref::DeallocOp)> filter) {
181  memref::DeallocOp dealloc = nullptr;
182  for (Operation &candidate :
183  llvm::make_range(alloc->getIterator(), alloc->getBlock()->end())) {
184  dealloc = dyn_cast<memref::DeallocOp>(candidate);
185  if (dealloc && dealloc.getMemref() == alloc.getMemref() &&
186  (!filter || filter(alloc, dealloc))) {
187  break;
188  }
189  }
190 
191  if (!dealloc)
192  return nullptr;
193 
194  OpBuilder::InsertionGuard guard(rewriter);
195  rewriter.setInsertionPoint(alloc);
196  auto alloca = rewriter.replaceOpWithNewOp<memref::AllocaOp>(
197  alloc, alloc.getMemref().getType(), alloc.getOperands());
198  rewriter.eraseOp(dealloc);
199  return alloca;
200 }
static void replaceAndPropagateMemRefType(RewriterBase &rewriter, Operation *from, Operation *to)
Given an original op and a new, modified op with the same number of results, whose memref return type...
static FailureOr< OpFoldResult > makeIndependent(OpBuilder &b, Location loc, OpFoldResult ofr, ValueRange independencies)
Make the given OpFoldResult independent of all independencies.
static UnrealizedConversionCastOp propagateSubViewOp(RewriterBase &rewriter, UnrealizedConversionCastOp conversionOp, SubViewOp op)
Push down an UnrealizedConversionCastOp past a SubViewOp.
A multi-dimensional affine map Affine map's are immutable like Type's, and they are uniqued.
Definition: AffineMap.h:46
IntegerAttr getIndexAttr(int64_t value)
Definition: Builders.cpp:107
Ty getType(Args &&...args)
Get or construct an instance of the type Ty with provided arguments.
Definition: Builders.h:91
This class defines the main interface for locations in MLIR and acts as a non-nullable wrapper around...
Definition: Location.h:76
RAII guard to reset the insertion point of the builder when destroyed.
Definition: Builders.h:348
This class helps build Operations.
Definition: Builders.h:207
void setInsertionPoint(Block *block, Block::iterator insertPoint)
Set the insertion point to the specified location.
Definition: Builders.h:398
void setInsertionPointAfter(Operation *op)
Sets the insertion point to the node after the specified operation, which will cause subsequent inser...
Definition: Builders.h:412
This class represents a single result from folding an operation.
Definition: OpDefinition.h:272
This class represents an operand of an operation.
Definition: Value.h:257
Operation is the basic unit of execution within MLIR.
Definition: Operation.h:88
OpResult getResult(unsigned idx)
Get the 'idx'th result of this operation.
Definition: Operation.h:407
Location getLoc()
The source location the operation was defined or derived from.
Definition: Operation.h:223
result_range getResults()
Definition: Operation.h:415
unsigned getNumResults()
Return the number of results held by this operation.
Definition: Operation.h:404
This class contains a list of basic blocks and a link to the parent operation it is attached to.
Definition: Region.h:26
This class coordinates the application of a rewrite on a set of IR, providing a way for clients to tr...
Definition: PatternMatch.h:358
void replaceAllUsesWith(Value from, Value to)
Find uses of from and replace them with to.
Definition: PatternMatch.h:636
virtual void eraseOp(Operation *op)
This method erases an operation that is known to have no uses.
void modifyOpInPlace(Operation *root, CallableT &&callable)
This method is a utility wrapper around an in-place modification of an operation.
Definition: PatternMatch.h:628
OpTy replaceOpWithNewOp(Operation *op, Args &&...args)
Replace the results of the given (original) op with a new op that is created without verification (re...
Definition: PatternMatch.h:519
Instances of the Type class are uniqued, have an immutable identifier and an optional mutable compone...
Definition: Types.h:74
static LogicalResult computeIndependentBound(AffineMap &resultMap, ValueDimList &mapOperands, presburger::BoundType type, const Variable &var, ValueRange independencies, bool closedUB=false)
Compute a bound in that is independent of all values in independencies.
This class provides an abstraction over the different types of ranges over Values.
Definition: ValueRange.h:387
This class represents an instance of an SSA value in the MLIR system, representing a computable value...
Definition: Value.h:96
OpFoldResult materializeComputedBound(OpBuilder &b, Location loc, AffineMap boundMap, ArrayRef< std::pair< Value, std::optional< int64_t >>> mapOperands)
Materialize an already computed bound with Affine dialect ops.
constexpr void enumerate(std::tuple< Tys... > &tuple, CallbackT &&callback)
Definition: Matchers.h:344
FailureOr< Value > buildIndependentOp(OpBuilder &b, AllocaOp allocaOp, ValueRange independencies)
Build a new memref::AllocaOp whose dynamic sizes are independent of all given independencies.
FailureOr< Value > replaceWithIndependentOp(RewriterBase &rewriter, memref::AllocaOp allocaOp, ValueRange independencies)
Build a new memref::AllocaOp whose dynamic sizes are independent of all given independencies.
memref::AllocaOp allocToAlloca(RewriterBase &rewriter, memref::AllocOp alloc, function_ref< bool(memref::AllocOp, memref::DeallocOp)> filter=nullptr)
Replaces the given alloc with the corresponding alloca and returns it if the following conditions are...
detail::InFlightRemark failed(Location loc, RemarkOpts opts)
Report an optimization remark that failed.
Definition: Remarks.h:491
Include the generated interface declarations.
SmallVector< std::pair< Value, std::optional< int64_t > >> ValueDimList