MLIR  22.0.0git
Utils.cpp
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1 //===- Utils.cpp - Utils related to the transform dialect -------*- C++ -*-===//
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 
11 #include "mlir/IR/Verifier.h"
13 #include "llvm/Support/Debug.h"
14 #include "llvm/Support/DebugLog.h"
15 
16 using namespace mlir;
17 
18 #define DEBUG_TYPE "transform-dialect-utils"
19 #define DBGS() (llvm::dbgs() << "[" DEBUG_TYPE << "]: ")
20 
21 /// Return whether `func1` can be merged into `func2`. For that to work
22 /// `func1` has to be a declaration (aka has to be external) and `func2`
23 /// either has to be a declaration as well, or it has to be public (otherwise,
24 /// it wouldn't be visible by `func1`).
25 static bool canMergeInto(FunctionOpInterface func1, FunctionOpInterface func2) {
26  return func1.isExternal() && (func2.isPublic() || func2.isExternal());
27 }
28 
29 /// Merge `func1` into `func2`. The two ops must be inside the same parent op
30 /// and mergable according to `canMergeInto`. The function erases `func1` such
31 /// that only `func2` exists when the function returns.
32 static InFlightDiagnostic mergeInto(FunctionOpInterface func1,
33  FunctionOpInterface func2) {
34  assert(canMergeInto(func1, func2));
35  assert(func1->getParentOp() == func2->getParentOp() &&
36  "expected func1 and func2 to be in the same parent op");
37 
38  // Check that function signatures match.
39  if (func1.getFunctionType() != func2.getFunctionType()) {
40  return func1.emitError()
41  << "external definition has a mismatching signature ("
42  << func2.getFunctionType() << ")";
43  }
44 
45  // Check and merge argument attributes.
46  MLIRContext *context = func1->getContext();
47  auto *td = context->getLoadedDialect<transform::TransformDialect>();
48  StringAttr consumedName = td->getConsumedAttrName();
49  StringAttr readOnlyName = td->getReadOnlyAttrName();
50  for (unsigned i = 0, e = func1.getNumArguments(); i < e; ++i) {
51  bool isExternalConsumed = func2.getArgAttr(i, consumedName) != nullptr;
52  bool isExternalReadonly = func2.getArgAttr(i, readOnlyName) != nullptr;
53  bool isConsumed = func1.getArgAttr(i, consumedName) != nullptr;
54  bool isReadonly = func1.getArgAttr(i, readOnlyName) != nullptr;
55  if (!isExternalConsumed && !isExternalReadonly) {
56  if (isConsumed)
57  func2.setArgAttr(i, consumedName, UnitAttr::get(context));
58  else if (isReadonly)
59  func2.setArgAttr(i, readOnlyName, UnitAttr::get(context));
60  continue;
61  }
62 
63  if ((isExternalConsumed && !isConsumed) ||
64  (isExternalReadonly && !isReadonly)) {
65  return func1.emitError()
66  << "external definition has mismatching consumption "
67  "annotations for argument #"
68  << i;
69  }
70  }
71 
72  // `func1` is the external one, so we can remove it.
73  assert(func1.isExternal());
74  func1->erase();
75 
76  return InFlightDiagnostic();
77 }
78 
82  assert(target->hasTrait<OpTrait::SymbolTable>() &&
83  "requires target to implement the 'SymbolTable' trait");
84  assert(other->hasTrait<OpTrait::SymbolTable>() &&
85  "requires target to implement the 'SymbolTable' trait");
86 
87  SymbolTable targetSymbolTable(target);
88  SymbolTable otherSymbolTable(*other);
89 
90  // Step 1:
91  //
92  // Rename private symbols in both ops in order to resolve conflicts that can
93  // be resolved that way.
94  LDBG() << "renaming private symbols to resolve conflicts:";
95  // TODO: Do we *actually* need to test in both directions?
96  for (auto &&[symbolTable, otherSymbolTable] : llvm::zip(
97  SmallVector<SymbolTable *, 2>{&targetSymbolTable, &otherSymbolTable},
98  SmallVector<SymbolTable *, 2>{&otherSymbolTable,
99  &targetSymbolTable})) {
100  Operation *symbolTableOp = symbolTable->getOp();
101  for (Operation &op : symbolTableOp->getRegion(0).front()) {
102  auto symbolOp = dyn_cast<SymbolOpInterface>(op);
103  if (!symbolOp)
104  continue;
105  StringAttr name = symbolOp.getNameAttr();
106  LDBG() << " found @" << name.getValue();
107 
108  // Check if there is a colliding op in the other module.
109  auto collidingOp =
110  cast_or_null<SymbolOpInterface>(otherSymbolTable->lookup(name));
111  if (!collidingOp)
112  continue;
113 
114  LDBG() << " collision found for @" << name.getValue();
115 
116  // Collisions are fine if both opt are functions and can be merged.
117  if (auto funcOp = dyn_cast<FunctionOpInterface>(op),
118  collidingFuncOp =
119  dyn_cast<FunctionOpInterface>(collidingOp.getOperation());
120  funcOp && collidingFuncOp) {
121  if (canMergeInto(funcOp, collidingFuncOp) ||
122  canMergeInto(collidingFuncOp, funcOp)) {
123  LDBG() << " but both ops are functions and will be merged";
124  continue;
125  }
126 
127  // If they can't be merged, proceed like any other collision.
128  LDBG() << " and both ops are function definitions";
129  }
130 
131  // Collision can be resolved by renaming if one of the ops is private.
132  auto renameToUnique =
133  [&](SymbolOpInterface op, SymbolOpInterface otherOp,
134  SymbolTable &symbolTable,
135  SymbolTable &otherSymbolTable) -> InFlightDiagnostic {
136  LDBG() << ", renaming";
137  FailureOr<StringAttr> maybeNewName =
138  symbolTable.renameToUnique(op, {&otherSymbolTable});
139  if (failed(maybeNewName)) {
140  InFlightDiagnostic diag = op->emitError("failed to rename symbol");
141  diag.attachNote(otherOp->getLoc())
142  << "attempted renaming due to collision with this op";
143  return diag;
144  }
145  LDBG() << " renamed to @" << maybeNewName->getValue();
146  return InFlightDiagnostic();
147  };
148 
149  if (symbolOp.isPrivate()) {
150  InFlightDiagnostic diag = renameToUnique(
151  symbolOp, collidingOp, *symbolTable, *otherSymbolTable);
152  if (failed(diag))
153  return diag;
154  continue;
155  }
156  if (collidingOp.isPrivate()) {
157  InFlightDiagnostic diag = renameToUnique(
158  collidingOp, symbolOp, *otherSymbolTable, *symbolTable);
159  if (failed(diag))
160  return diag;
161  continue;
162  }
163  LDBG() << ", emitting error";
164  InFlightDiagnostic diag = symbolOp.emitError()
165  << "doubly defined symbol @" << name.getValue();
166  diag.attachNote(collidingOp->getLoc()) << "previously defined here";
167  return diag;
168  }
169  }
170 
171  // TODO: This duplicates pass infrastructure. We should split this pass into
172  // several and let the pass infrastructure do the verification.
173  for (auto *op : SmallVector<Operation *>{target, *other}) {
174  if (failed(mlir::verify(op)))
175  return op->emitError() << "failed to verify input op after renaming";
176  }
177 
178  // Step 2:
179  //
180  // Move all ops from `other` into target and merge public symbols.
181  LDBG() << "moving all symbols into target";
182  {
184  for (Operation &op : other->getRegion(0).front()) {
185  if (auto symbol = dyn_cast<SymbolOpInterface>(op))
186  opsToMove.push_back(symbol);
187  }
188 
189  for (SymbolOpInterface op : opsToMove) {
190  // Remember potentially colliding op in the target module.
191  auto collidingOp = cast_or_null<SymbolOpInterface>(
192  targetSymbolTable.lookup(op.getNameAttr()));
193 
194  // Move op even if we get a collision.
195  LDBG() << " moving @" << op.getName();
196  op->moveBefore(&target->getRegion(0).front(),
197  target->getRegion(0).front().end());
198 
199  // If there is no collision, we are done.
200  if (!collidingOp) {
201  LDBG() << " without collision";
202  continue;
203  }
204 
205  // The two colliding ops must both be functions because we have already
206  // emitted errors otherwise earlier.
207  auto funcOp = cast<FunctionOpInterface>(op.getOperation());
208  auto collidingFuncOp =
209  cast<FunctionOpInterface>(collidingOp.getOperation());
210 
211  // Both ops are in the target module now and can be treated
212  // symmetrically, so w.l.o.g. we can reduce to merging `funcOp` into
213  // `collidingFuncOp`.
214  if (!canMergeInto(funcOp, collidingFuncOp)) {
215  std::swap(funcOp, collidingFuncOp);
216  }
217  assert(canMergeInto(funcOp, collidingFuncOp));
218 
219  LDBG() << " with collision, trying to keep op at "
220  << collidingFuncOp.getLoc() << ":\n"
221  << collidingFuncOp;
222 
223  // Update symbol table. This works with or without the previous `swap`.
224  targetSymbolTable.remove(funcOp);
225  targetSymbolTable.insert(collidingFuncOp);
226  assert(targetSymbolTable.lookup(funcOp.getName()) == collidingFuncOp);
227 
228  // Do the actual merging.
229  {
230  InFlightDiagnostic diag = mergeInto(funcOp, collidingFuncOp);
231  if (failed(diag))
232  return diag;
233  }
234  }
235  }
236 
237  if (failed(mlir::verify(target)))
238  return target->emitError()
239  << "failed to verify target op after merging symbols";
240 
241  LDBG() << "done merging ops";
242  return InFlightDiagnostic();
243 }
static bool canMergeInto(FunctionOpInterface func1, FunctionOpInterface func2)
Return whether func1 can be merged into func2.
Definition: Utils.cpp:25
static InFlightDiagnostic mergeInto(FunctionOpInterface func1, FunctionOpInterface func2)
Merge func1 into func2.
Definition: Utils.cpp:32
static std::string diag(const llvm::Value &value)
iterator end()
Definition: Block.h:144
This class represents a diagnostic that is inflight and set to be reported.
Definition: Diagnostics.h:314
MLIRContext is the top-level object for a collection of MLIR operations.
Definition: MLIRContext.h:63
Dialect * getLoadedDialect(StringRef name)
Get a registered IR dialect with the given namespace.
A trait used to provide symbol table functionalities to a region operation.
Definition: SymbolTable.h:452
Operation is the basic unit of execution within MLIR.
Definition: Operation.h:88
bool hasTrait()
Returns true if the operation was registered with a particular trait, e.g.
Definition: Operation.h:749
InFlightDiagnostic emitError(const Twine &message={})
Emit an error about fatal conditions with this operation, reporting up to any diagnostic handlers tha...
Definition: Operation.cpp:267
Region & getRegion(unsigned index)
Returns the region held by this operation at position 'index'.
Definition: Operation.h:686
This class acts as an owning reference to an op, and will automatically destroy the held op on destru...
Definition: OwningOpRef.h:29
Block & front()
Definition: Region.h:65
This class allows for representing and managing the symbol table used by operations with the 'SymbolT...
Definition: SymbolTable.h:24
Operation * lookup(StringRef name) const
Look up a symbol with the specified name, returning null if no such name exists.
StringAttr insert(Operation *symbol, Block::iterator insertPt={})
Insert a new symbol into the table, and rename it as necessary to avoid collisions.
void remove(Operation *op)
Remove the given symbol from the table, without deleting it.
detail::InFlightRemark failed(Location loc, RemarkOpts opts)
Report an optimization remark that failed.
Definition: Remarks.h:491
InFlightDiagnostic mergeSymbolsInto(Operation *target, OwningOpRef< Operation * > other)
Merge all symbols from other into target.
Definition: Utils.cpp:80
Include the generated interface declarations.
auto get(MLIRContext *context, Ts &&...params)
Helper method that injects context only if needed, this helps unify some of the attribute constructio...
LogicalResult verify(Operation *op, bool verifyRecursively=true)
Perform (potentially expensive) checks of invariants, used to detect compiler bugs,...
Definition: Verifier.cpp:423