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1 //===-- MakeGuardsExplicit.h - Turn guard intrinsics into guard branches --===//
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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 // This pass lowers the @llvm.experimental.guard intrinsic to the new form of
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10 // guard represented as widenable explicit branch to the deopt block. The
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11 // difference between this pass and LowerGuardIntrinsic is that after this pass
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12 // the guard represented as intrinsic:
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13 //
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14 // call void(i1, ...) @llvm.experimental.guard(i1 %old_cond) [ "deopt"() ]
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15 //
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16 // transforms to a guard represented as widenable explicit branch:
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17 //
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18 // %widenable_cond = call i1 @llvm.experimental.widenable.condition()
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19 // br i1 (%old_cond & %widenable_cond), label %guarded, label %deopt
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20 //
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21 // Here:
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22 // - The semantics of @llvm.experimental.widenable.condition allows to replace
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23 // %widenable_cond with the construction (%widenable_cond & %any_other_cond)
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24 // without loss of correctness;
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25 // - %guarded is the lower part of old guard intrinsic's parent block split by
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26 // the intrinsic call;
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27 // - %deopt is a block containing a sole call to @llvm.experimental.deoptimize
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28 // intrinsic.
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29 //
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30 // Therefore, this branch preserves the property of widenability.
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31 //
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32 //===----------------------------------------------------------------------===//
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33 #ifndef LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
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34 #define LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
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35
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36 #include "llvm/IR/PassManager.h"
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37
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38 namespace llvm {
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39
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40 struct MakeGuardsExplicitPass : public PassInfoMixin<MakeGuardsExplicitPass> {
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41 PreservedAnalyses run(Function &F, FunctionAnalysisManager &AM);
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42 };
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43
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44 } // namespace llvm
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45
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46 #endif //LLVM_TRANSFORMS_SCALAR_MAKEGUARDSEXPLICIT_H
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