1 //===- llvm/MC/MCLinkerOptimizationHint.cpp ----- LOH handling ------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 9 #include "llvm/MC/MCLinkerOptimizationHint.h" 10 #include "llvm/MC/MCAsmLayout.h" 11 #include "llvm/MC/MCMachObjectWriter.h" 12 #include "llvm/Support/LEB128.h" 13 #include "llvm/Support/raw_ostream.h" 14 #include <cstddef> 15 #include <cstdint> 16 17 using namespace llvm; 18 19 // Each LOH is composed by, in this order (each field is encoded using ULEB128): 20 // - Its kind. 21 // - Its number of arguments (let say N). 22 // - Its arg1. 23 // - ... 24 // - Its argN. 25 // <arg1> to <argN> are absolute addresses in the object file, i.e., 26 // relative addresses from the beginning of the object file. 27 void MCLOHDirective::emit_impl(raw_ostream &OutStream, 28 const MachObjectWriter &ObjWriter, 29 const MCAsmLayout &Layout) const { 30 encodeULEB128(Kind, OutStream); 31 encodeULEB128(Args.size(), OutStream); 32 for (const MCSymbol *Arg : Args) 33 encodeULEB128(ObjWriter.getSymbolAddress(*Arg, Layout), OutStream); 34 } 35 36 void MCLOHDirective::emit(MachObjectWriter &ObjWriter, 37 const MCAsmLayout &Layout) const { 38 raw_ostream &OutStream = ObjWriter.W.OS; 39 emit_impl(OutStream, ObjWriter, Layout); 40 } 41 42 uint64_t MCLOHDirective::getEmitSize(const MachObjectWriter &ObjWriter, 43 const MCAsmLayout &Layout) const { 44 class raw_counting_ostream : public raw_ostream { 45 uint64_t Count = 0; 46 47 void write_impl(const char *, size_t size) override { Count += size; } 48 49 uint64_t current_pos() const override { return Count; } 50 51 public: 52 raw_counting_ostream() = default; 53 ~raw_counting_ostream() override { flush(); } 54 }; 55 56 raw_counting_ostream OutStream; 57 emit_impl(OutStream, ObjWriter, Layout); 58 return OutStream.tell(); 59 } 60