60 lines · cpp
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-exception6//7//===----------------------------------------------------------------------===//8 9#include "llvm/MC/MCLinkerOptimizationHint.h"10#include "llvm/MC/MCMachObjectWriter.h"11#include "llvm/Support/LEB128.h"12#include "llvm/Support/raw_ostream.h"13#include <cstddef>14#include <cstdint>15 16using 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.26void MCLOHDirective::emit_impl(raw_ostream &OutStream,27 const MachObjectWriter &ObjWriter28 29) const {30 encodeULEB128(Kind, OutStream);31 encodeULEB128(Args.size(), OutStream);32 for (const MCSymbol *Arg : Args)33 encodeULEB128(ObjWriter.getSymbolAddress(*Arg), OutStream);34}35 36void MCLOHDirective::emit(const MCAssembler &Asm,37 MachObjectWriter &ObjWriter) const {38 raw_ostream &OutStream = ObjWriter.W.OS;39 emit_impl(OutStream, ObjWriter);40}41 42uint64_t MCLOHDirective::getEmitSize(const MCAssembler &Asm,43 const MachObjectWriter &ObjWriter) 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);58 return OutStream.tell();59}60