b934d75b8f
- Detect 'mod' to replace the combination of floordiv, mul, and subtract when
possible at construction time; when 'c' is a power of two, this reduces the number of
operations; also more compact and readable. Update simplifyAdd for this.
On a side note:
- with the affine expr flattening we have, a mod expression like d0 mod c
would be flattened into d0 - c * q, c * q <= d0 <= c*q + c - 1, with 'q'
being added as the local variable (q = d0 floordiv c); as a result, a mod
was turned into a floordiv whenever the expression was reconstructed back,
i.e., as d0 - c * (d0 floordiv c); as a result of this change, we recover
the mod back.
- rename SimplifyAffineExpr -> SimplifyAffineStructures (pass had been renamed but
the file hadn't been).
PiperOrigin-RevId: 228258120
98 lines
3.2 KiB
C++
98 lines
3.2 KiB
C++
//===- SimplifyAffineStructures.cpp - ---------------------------*- 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 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/Function.h"
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#include "mlir/IR/Instructions.h"
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#include "mlir/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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using llvm::report_fatal_error;
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namespace {
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/// Simplifies all affine expressions appearing in the operation instructions 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 : public FunctionPass {
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explicit SimplifyAffineStructures()
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: FunctionPass(&SimplifyAffineStructures::passID) {}
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PassResult runOnFunction(Function *f) override;
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void visitIfInst(IfInst *ifInst);
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void visitOperationInst(OperationInst *opInst);
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static char passID;
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};
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} // end anonymous namespace
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char SimplifyAffineStructures::passID = 0;
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FunctionPass *mlir::createSimplifyAffineStructuresPass() {
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return new SimplifyAffineStructures();
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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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static IntegerSet simplifyIntegerSet(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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set.getContext());
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return set;
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}
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void SimplifyAffineStructures::visitIfInst(IfInst *ifInst) {
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auto set = ifInst->getCondition().getIntegerSet();
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ifInst->setIntegerSet(simplifyIntegerSet(set));
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}
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void SimplifyAffineStructures::visitOperationInst(OperationInst *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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MutableAffineMap mMap(mapAttr.getValue());
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mMap.simplify();
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auto map = mMap.getAffineMap();
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opInst->setAttr(attr.first, AffineMapAttr::get(map));
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}
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}
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}
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PassResult SimplifyAffineStructures::runOnFunction(Function *f) {
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f->walkInsts([&](Instruction *inst) {
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if (auto *opInst = dyn_cast<OperationInst>(inst))
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visitOperationInst(opInst);
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if (auto *ifInst = dyn_cast<IfInst>(inst))
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visitIfInst(ifInst);
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});
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return success();
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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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