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| Rev | Author | Line No. | Line |
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| 14 | pmbaty | 1 | //===-- RelLookupTableConverterPass.h - Rel Table Conv ----------*- C++ -*-===// |
| 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 | /// \file |
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| 10 | /// This file implements relative lookup table converter that converts |
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| 11 | /// lookup tables to relative lookup tables to make them PIC-friendly. |
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| 12 | /// |
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| 13 | /// Switch lookup table example: |
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| 14 | /// @switch.table.foo = private unnamed_addr constant [3 x i8*] |
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| 15 | /// [ |
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| 16 | /// i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i64 0, i64 0), |
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| 17 | /// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.1, i64 0, i64 0), |
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| 18 | /// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0) |
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| 19 | /// ], align 8 |
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| 20 | /// |
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| 21 | /// switch.lookup: |
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| 22 | /// %1 = sext i32 %cond to i64 |
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| 23 | /// %switch.gep = getelementptr inbounds [3 x i8*], |
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| 24 | /// [3 x i8*]* @switch.table.foo, i64 0, i64 %1 |
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| 25 | /// %switch.load = load i8*, i8** %switch.gep, align 8 |
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| 26 | /// ret i8* %switch.load |
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| 27 | /// |
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| 28 | /// Switch lookup table will become a relative lookup table that |
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| 29 | /// consists of relative offsets. |
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| 30 | /// |
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| 31 | /// @reltable.foo = private unnamed_addr constant [3 x i32] |
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| 32 | /// [ |
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| 33 | /// i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str to i64), |
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| 34 | /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32), |
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| 35 | /// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.1 to i64), |
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| 36 | /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32), |
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| 37 | /// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.2 to i64), |
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| 38 | /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32) |
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| 39 | /// ], align 4 |
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| 40 | /// |
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| 41 | /// IR after converting to a relative lookup table: |
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| 42 | /// switch.lookup: |
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| 43 | /// %1 = sext i32 %cond to i64 |
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| 44 | /// %reltable.shift = shl i64 %1, 2 |
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| 45 | /// %reltable.intrinsic = call i8* @llvm.load.relative.i64( |
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| 46 | /// i8* bitcast ([3 x i32]* @reltable.foo to i8*), |
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| 47 | /// i64 %reltable.shift) |
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| 48 | /// ret i8* %reltable.intrinsic |
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| 49 | //===----------------------------------------------------------------------===// |
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| 50 | |||
| 51 | #ifndef LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H |
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| 52 | #define LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H |
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| 53 | |||
| 54 | #include "llvm/IR/PassManager.h" |
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| 55 | |||
| 56 | namespace llvm { |
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| 57 | |||
| 58 | class Module; |
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| 59 | |||
| 60 | // Pass that converts lookup tables to relative lookup tables. |
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| 61 | class RelLookupTableConverterPass |
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| 62 | : public PassInfoMixin<RelLookupTableConverterPass> { |
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| 63 | public: |
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| 64 | RelLookupTableConverterPass() = default; |
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| 65 | |||
| 66 | PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM); |
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| 67 | }; |
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| 68 | |||
| 69 | } // end namespace llvm |
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| 70 | |||
| 71 | #endif // LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H |