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//===- RotateWhileLoop.cpp - scf.while loop rotation ----------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
//
// Rotates `scf.while` loops.
//
//===----------------------------------------------------------------------===//
#include "mlir/Dialect/SCF/Transforms/Patterns.h"
#include "mlir/Dialect/SCF/IR/SCF.h"
using namespace mlir;
namespace {
struct RotateWhileLoopPattern : OpRewritePattern<scf::WhileOp> {
using OpRewritePattern<scf::WhileOp>::OpRewritePattern;
LogicalResult matchAndRewrite(scf::WhileOp whileOp,
PatternRewriter &rewriter) const final {
// Setting this option would lead to infinite recursion on a greedy driver
// as 'do-while' loops wouldn't be skipped.
constexpr bool forceCreateCheck = false;
FailureOr<scf::WhileOp> result =
scf::wrapWhileLoopInZeroTripCheck(whileOp, rewriter, forceCreateCheck);
// scf::wrapWhileLoopInZeroTripCheck hasn't yet implemented a failure
// mechanism. 'do-while' loops are simply returned unmodified. In order to
// stop recursion, we check input and output operations differ.
return success(succeeded(result) && *result != whileOp);
}
};
} // namespace
namespace mlir {
namespace scf {
void populateSCFRotateWhileLoopPatterns(RewritePatternSet &patterns) {
patterns.add<RotateWhileLoopPattern>(patterns.getContext());
}
} // namespace scf
} // namespace mlir
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