forked from OSchip/llvm-project
109 lines
3.7 KiB
C++
109 lines
3.7 KiB
C++
//===- SimplifyAffineStructures.cpp ---------------------------------------===//
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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 structures.
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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/Function.h"
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#include "mlir/IR/IntegerSet.h"
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#include "mlir/IR/Operation.h"
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#include "mlir/Pass/Pass.h"
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#include "mlir/Transforms/Passes.h"
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#define DEBUG_TYPE "simplify-affine-structure"
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using namespace mlir;
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namespace {
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/// Simplifies all affine expressions appearing in the operations of
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/// the Function. This is mainly to test the simplifyAffineExpr method.
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/// TODO(someone): This should just be defined as a canonicalization pattern
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/// on AffineMap and driven from the existing canonicalization pass.
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struct SimplifyAffineStructures
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: public FunctionPass<SimplifyAffineStructures> {
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void runOnFunction() override;
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/// Utility to simplify an affine attribute and update its entry in the parent
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/// operation if necessary.
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template <typename AttributeT>
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void simplifyAndUpdateAttribute(Operation *op, Identifier name,
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AttributeT attr) {
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auto &simplified = simplifiedAttributes[attr];
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if (simplified == attr)
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return;
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// This is a newly encountered attribute.
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if (!simplified) {
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// Try to simplify the value of the attribute.
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auto value = attr.getValue();
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auto simplifiedValue = simplify(value);
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if (simplifiedValue == value) {
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simplified = attr;
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return;
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}
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simplified = AttributeT::get(simplifiedValue);
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}
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// Simplification was successful, so update the attribute.
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op->setAttr(name, simplified);
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}
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/// Performs basic integer set simplifications. Checks if it's empty, and
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/// replaces it with the canonical empty set if it is.
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IntegerSet simplify(IntegerSet set) {
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FlatAffineConstraints fac(set);
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if (fac.isEmpty())
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return IntegerSet::getEmptySet(set.getNumDims(), set.getNumSymbols(),
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&getContext());
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return set;
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}
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/// Performs basic affine map simplifications.
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AffineMap simplify(AffineMap map) {
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MutableAffineMap mMap(map);
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mMap.simplify();
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return mMap.getAffineMap();
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}
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DenseMap<Attribute, Attribute> simplifiedAttributes;
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};
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} // end anonymous namespace
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FunctionPassBase *mlir::createSimplifyAffineStructuresPass() {
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return new SimplifyAffineStructures();
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}
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void SimplifyAffineStructures::runOnFunction() {
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simplifiedAttributes.clear();
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getFunction().walk([&](Operation *opInst) {
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for (auto attr : opInst->getAttrs()) {
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if (auto mapAttr = attr.second.dyn_cast<AffineMapAttr>())
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simplifyAndUpdateAttribute(opInst, attr.first, mapAttr);
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else if (auto setAttr = attr.second.dyn_cast<IntegerSetAttr>())
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simplifyAndUpdateAttribute(opInst, attr.first, setAttr);
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}
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});
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}
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static PassRegistration<SimplifyAffineStructures>
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pass("simplify-affine-structures", "Simplify affine expressions");
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