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
17using 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.
27void 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
36void MCLOHDirective::emit(MachObjectWriter &ObjWriter,
37                          const MCAsmLayout &Layout) const {
38  raw_ostream &OutStream = ObjWriter.W.OS;
39  emit_impl(OutStream, ObjWriter, Layout);
40}
41
42uint64_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