| 1 | //===- ReconcileUnrealizedCasts.cpp - Eliminate noop unrealized casts -----===// |
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| 2 | // |
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| 3 | // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. |
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| 4 | // See https://llvm.org/LICENSE.txt for license information. |
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| 5 | // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception |
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| 6 | // |
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| 7 | //===----------------------------------------------------------------------===// |
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| 8 | |
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| 9 | #include "mlir/Conversion/ReconcileUnrealizedCasts/ReconcileUnrealizedCasts.h" |
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| 10 | |
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| 11 | #include "mlir/IR/BuiltinOps.h" |
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| 12 | #include "mlir/Pass/Pass.h" |
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| 13 | #include "mlir/Transforms/DialectConversion.h" |
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| 14 | |
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| 15 | namespace mlir { |
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| 16 | #define GEN_PASS_DEF_RECONCILEUNREALIZEDCASTSPASS |
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| 17 | #include "mlir/Conversion/Passes.h.inc" |
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| 18 | } // namespace mlir |
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| 19 | |
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| 20 | using namespace mlir; |
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| 21 | |
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| 22 | namespace { |
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| 23 | |
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| 24 | /// Pass to simplify and eliminate unrealized conversion casts. |
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| 25 | /// |
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| 26 | /// This pass processes unrealized_conversion_cast ops in a worklist-driven |
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| 27 | /// fashion. For each matched cast op, if the chain of input casts eventually |
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| 28 | /// reaches a cast op where the input types match the output types of the |
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| 29 | /// matched op, replace the matched op with the inputs. |
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| 30 | /// |
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| 31 | /// Example: |
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| 32 | /// %1 = unrealized_conversion_cast %0 : !A to !B |
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| 33 | /// %2 = unrealized_conversion_cast %1 : !B to !C |
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| 34 | /// %3 = unrealized_conversion_cast %2 : !C to !A |
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| 35 | /// |
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| 36 | /// In the above example, %0 can be used instead of %3 and all cast ops are |
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| 37 | /// folded away. |
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| 38 | struct ReconcileUnrealizedCasts |
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| 39 | : public impl::ReconcileUnrealizedCastsPassBase<ReconcileUnrealizedCasts> { |
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| 40 | ReconcileUnrealizedCasts() = default; |
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| 41 | |
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| 42 | void runOnOperation() override { |
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| 43 | SmallVector<UnrealizedConversionCastOp> ops; |
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| 44 | getOperation()->walk( |
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| 45 | [&](UnrealizedConversionCastOp castOp) { ops.push_back(castOp); }); |
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| 46 | reconcileUnrealizedCasts(ops); |
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| 47 | } |
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| 48 | }; |
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| 49 | |
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| 50 | } // namespace |
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| 51 | |
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