//===-- RelLookupTableConverterPass.h - Rel Table Conv ----------*- C++ -*-===// // // 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 // //===----------------------------------------------------------------------===// // /// \file /// This file implements relative lookup table converter that converts /// lookup tables to relative lookup tables to make them PIC-friendly. /// /// Switch lookup table example: /// @switch.table.foo = private unnamed_addr constant [3 x i8*] /// [ /// i8* getelementptr inbounds ([5 x i8], [5 x i8]* @.str, i64 0, i64 0), /// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.1, i64 0, i64 0), /// i8* getelementptr inbounds ([4 x i8], [4 x i8]* @.str.2, i64 0, i64 0) /// ], align 8 /// /// switch.lookup: /// %1 = sext i32 %cond to i64 /// %switch.gep = getelementptr inbounds [3 x i8*], /// [3 x i8*]* @switch.table.foo, i64 0, i64 %1 /// %switch.load = load i8*, i8** %switch.gep, align 8 /// ret i8* %switch.load /// /// Switch lookup table will become a relative lookup table that /// consists of relative offsets. /// /// @reltable.foo = private unnamed_addr constant [3 x i32] /// [ /// i32 trunc (i64 sub (i64 ptrtoint ([5 x i8]* @.str to i64), /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32), /// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.1 to i64), /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32), /// i32 trunc (i64 sub (i64 ptrtoint ([4 x i8]* @.str.2 to i64), /// i64 ptrtoint ([3 x i32]* @reltable.foo to i64)) to i32) /// ], align 4 /// /// IR after converting to a relative lookup table: /// switch.lookup: /// %1 = sext i32 %cond to i64 /// %reltable.shift = shl i64 %1, 2 /// %reltable.intrinsic = call i8* @llvm.load.relative.i64( /// i8* bitcast ([3 x i32]* @reltable.foo to i8*), /// i64 %reltable.shift) /// ret i8* %reltable.intrinsic //===----------------------------------------------------------------------===// #ifndef LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H #define LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H #include "llvm/IR/PassManager.h" namespace llvm { class Module; // Pass that converts lookup tables to relative lookup tables. class RelLookupTableConverterPass : public PassInfoMixin<RelLookupTableConverterPass> { … }; } // end namespace llvm #endif // LLVM_TRANSFORMS_UTILS_RELLOOKUPTABLECONVERTER_H