09ae1bf8b7
In #173438 I added a FIR specific loop invariant code motion pass. During the review, Tom pointed out certain limitations about OpenMP dialect operations that should be taken into consideration during transformations such as LICM: https://github.com/llvm/llvm-project/pull/173438#discussion_r2657612148 I also found issues with hoisting operations out of `acc.loop` operations in certain conditions (see the added test in `licm.fir`). I am proposing a new operation interface that will allow to control movement of operations during MLIR transformations. In particular, I propose two methods (there might be more): * op.canMoveOutOf(cand) - returns true, if it is allowed to move 'cand' operation out of 'op'. * op.canMoveFromDescendant(descendant, cand) - return true, if it is allowed to move 'cand' out of 'descendant' and into 'op'. I used the new interface to get rid of explicit OpenMP interfaces checks in Flang's LICM, and I also used it for `acc.loop` operation (though, I provided conservative initial implementation). The new interface is part of FIR dialect, but I think it would better fit into the core MLIR set of interfaces so that the checks that I make in Flang's LICM are actually done in `mlir::moveLoopInvariantCode`. Moreover, other code movement transformations that may appear in MLIR may also need to use such an interface. I would like to get some feedback on whether it is reasonable to move the interface to core MLIR.
50 lines
1.8 KiB
C++
50 lines
1.8 KiB
C++
//===-- FIROperationMoveOpInterface.cpp -----------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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//
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// Coding style: https://mlir.llvm.org/getting_started/DeveloperGuide/
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//
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//===----------------------------------------------------------------------===//
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#include "flang/Optimizer/Dialect/FIROperationMoveOpInterface.h"
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#include "flang/Optimizer/Dialect/FIROperationMoveOpInterface.cpp.inc"
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llvm::LogicalResult
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fir::detail::verifyOperationMoveOpInterface(mlir::Operation *op) {
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// It does not make sense to use this interface for operations
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// without any regions.
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if (op->getNumRegions() == 0)
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return op->emitOpError("must contain at least one region");
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return llvm::success();
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}
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bool fir::canMoveFromDescendant(mlir::Operation *op,
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mlir::Operation *descendant,
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mlir::Operation *candidate) {
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// Perform some sanity checks.
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assert(op->isProperAncestor(descendant) &&
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"op must be an ancestor of descendant");
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if (candidate)
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assert(descendant->isProperAncestor(candidate) &&
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"descendant must be an ancestor of candidate");
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if (auto iface = mlir::dyn_cast<OperationMoveOpInterface>(op))
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return iface.canMoveFromDescendant(descendant, candidate);
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return true;
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}
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bool fir::canMoveOutOf(mlir::Operation *op, mlir::Operation *candidate) {
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if (candidate)
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assert(op->isProperAncestor(candidate) &&
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"op must be an ancestor of candidate");
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if (auto iface = mlir::dyn_cast<OperationMoveOpInterface>(op))
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return iface.canMoveOutOf(candidate);
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return true;
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}
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