1 //===- llvm/MC/MCLinkerOptimizationHint.cpp ----- LOH handling ------------===// 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/MCMachObjectWriter.h" 13 #include "llvm/Support/LEB128.h" 14 #include "llvm/Support/raw_ostream.h" 15 #include <cstddef> 16 #include <cstdint> 17 18 using namespace llvm; 19 20 // Each LOH is composed by, in this order (each field is encoded using ULEB128): 21 // - Its kind. 22 // - Its number of arguments (let say N). 23 // - Its arg1. 24 // - ... 25 // - Its argN. 26 // <arg1> to <argN> are absolute addresses in the object file, i.e., 27 // relative addresses from the beginning of the object file. 28 void MCLOHDirective::emit_impl(raw_ostream &OutStream, 29 const MachObjectWriter &ObjWriter, 30 const MCAsmLayout &Layout) const { 31 encodeULEB128(Kind, OutStream); 32 encodeULEB128(Args.size(), OutStream); 33 for (const MCSymbol *Arg : Args) 34 encodeULEB128(ObjWriter.getSymbolAddress(*Arg, Layout), OutStream); 35 } 36 37 void MCLOHDirective::emit(MachObjectWriter &ObjWriter, 38 const MCAsmLayout &Layout) const { 39 raw_ostream &OutStream = ObjWriter.getStream(); 40 emit_impl(OutStream, ObjWriter, Layout); 41 } 42 43 uint64_t MCLOHDirective::getEmitSize(const MachObjectWriter &ObjWriter, 44 const MCAsmLayout &Layout) const { 45 class raw_counting_ostream : public raw_ostream { 46 uint64_t Count = 0; 47 48 void write_impl(const char *, size_t size) override { Count += size; } 49 50 uint64_t current_pos() const override { return Count; } 51 52 public: 53 raw_counting_ostream() = default; 54 ~raw_counting_ostream() override { flush(); } 55 }; 56 57 raw_counting_ostream OutStream; 58 emit_impl(OutStream, ObjWriter, Layout); 59 return OutStream.tell(); 60 } 61