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