b55b407601
This CL starts by replacing AffineExpr* with value-type AffineExprRef in a few places in the IR. By a domino effect that is pretty telling of the inconsistencies in the codebase, const is removed where it makes sense. The rationale is that the decision was concisously made that unique'd types have pointer semantics without const specifier. This is fine but we should be consistent. In the end, the only logical invariant is that there should never be such a thing as a const AffineExpr*, const AffineMap* or const IntegerSet* in our codebase. This CL takes a number of shortcuts to killing const with fire, in particular forcing const AffineExprRef to return the underlying non-const AffineExpr*. This will be removed once AffineExpr* has disappeared in containers but for now such shortcuts allow a bit of sanity in this long quest for cleanups. The **only** places where const AffineExpr*, const AffineMap* or const IntegerSet* may still appear is by transitive needs from containers, comparison operators etc. There is still one major thing remaining here: figure out why cast/dyn_cast return me a const AffineXXX*, which in turn requires a bunch of ugly const_casts. I suspect this is due to the classof taking const AffineXXXExpr*. I wonder whether this is a side effect of 1., if it is coming from llvm itself (I'd doubt it) or something else (clattner@?) In light of this, the whole discussion about const makes total sense to me now and I would systematically apply the rule that in the end, we should never have any const XXX in our codebase for unique'd types (assuming we can remove them all in containers and no additional constness constraint is added on us from the outside world). PiperOrigin-RevId: 215811554
79 lines
2.7 KiB
C++
79 lines
2.7 KiB
C++
//===- SimplifyAffineExpr.cpp - MLIR Affine Structures Class-----*- C++ -*-===//
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//
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// Copyright 2019 The MLIR Authors.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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// =============================================================================
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//
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// This file implements a pass to simplify affine expressions.
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//
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//===----------------------------------------------------------------------===//
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#include "mlir/Analysis/AffineStructures.h"
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#include "mlir/IR/AffineMap.h"
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#include "mlir/IR/Attributes.h"
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#include "mlir/IR/StmtVisitor.h"
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#include "mlir/Transforms/Pass.h"
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#include "mlir/Transforms/Passes.h"
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using namespace mlir;
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using llvm::report_fatal_error;
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namespace {
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/// Simplifies all affine expressions appearing in the operation statements of
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/// the MLFunction. This is mainly to test the simplifyAffineExpr method.
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// TODO(someone): Gradually, extend this to all affine map references found in
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// ML functions and CFG functions.
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struct SimplifyAffineExpr : public FunctionPass {
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explicit SimplifyAffineExpr() {}
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PassResult runOnMLFunction(MLFunction *f);
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// Does nothing on CFG functions for now. No reusable walkers/visitors exist
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// for this yet? TODO(someone).
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PassResult runOnCFGFunction(CFGFunction *f) { return success(); }
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};
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} // end anonymous namespace
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FunctionPass *mlir::createSimplifyAffineExprPass() {
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return new SimplifyAffineExpr();
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}
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AffineMap *MutableAffineMap::getAffineMap() {
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return AffineMap::get(numDims, numSymbols, results, rangeSizes, context);
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}
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PassResult SimplifyAffineExpr::runOnMLFunction(MLFunction *f) {
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struct MapSimplifier : public StmtWalker<MapSimplifier> {
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MLIRContext *context;
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MapSimplifier(MLIRContext *context) : context(context) {}
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void visitOperationStmt(OperationStmt *opStmt) {
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for (auto attr : opStmt->getAttrs()) {
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if (auto *mapAttr = dyn_cast<AffineMapAttr>(attr.second)) {
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MutableAffineMap mMap(mapAttr->getValue(), context);
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mMap.simplify();
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auto *map = mMap.getAffineMap();
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opStmt->setAttr(attr.first, AffineMapAttr::get(map, context));
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}
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}
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}
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};
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MapSimplifier v(f->getContext());
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v.walkPostOrder(f);
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return success();
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}
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