6024e5c395
clang 20.0.0 (based on r547379) from build 12806354. Bug: http://b/379133546 Test: N/A Change-Id: I2eb8938af55d809de674be63cb30cf27e801862b Upstream-Commit: ad834e67b1105d15ef907f6255d4c96e8e733f57
72 lines
2.7 KiB
C++
72 lines
2.7 KiB
C++
//===-- RelLookupTableConverterPass.h - Rel Table Conv ----------*- C++ -*-===//
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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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/// \file
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/// This file implements relative lookup table converter that converts
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/// lookup tables to relative lookup tables to make them PIC-friendly.
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///
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/// Switch lookup table example:
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/// @switch.table.foo = private unnamed_addr constant [3 x i8*]
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/// [
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/// i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i64 0, i64 0),
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/// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.1, i64 0, i64 0),
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/// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0)
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/// ], align 8
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///
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/// switch.lookup:
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/// %1 = sext i32 %cond to i64
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/// %switch.gep = getelementptr inbounds [3 x i8*],
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/// [3 x i8*]* @switch.table.foo, i64 0, i64 %1
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/// %switch.load = load i8*, i8** %switch.gep, align 8
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/// ret i8* %switch.load
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///
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/// Switch lookup table will become a relative lookup table that
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/// consists of relative offsets.
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///
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/// @reltable.foo = private unnamed_addr constant [3 x i32]
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/// [
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/// i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str to i64),
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/// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32),
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/// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.1 to i64),
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/// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32),
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/// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.2 to i64),
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/// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32)
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/// ], align 4
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///
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/// IR after converting to a relative lookup table:
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/// switch.lookup:
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/// %1 = sext i32 %cond to i64
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/// %reltable.shift = shl i64 %1, 2
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/// %reltable.intrinsic = call i8* @llvm.load.relative.i64(
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/// i8* bitcast ([3 x i32]* @reltable.foo to i8*),
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/// i64 %reltable.shift)
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/// ret i8* %reltable.intrinsic
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H
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#define LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H
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#include "llvm/IR/PassManager.h"
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namespace llvm {
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class Module;
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// Pass that converts lookup tables to relative lookup tables.
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class RelLookupTableConverterPass
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: public PassInfoMixin<RelLookupTableConverterPass> {
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public:
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RelLookupTableConverterPass() = default;
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PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
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};
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} // end namespace llvm
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#endif // LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H
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