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
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 &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
35void MCLOHDirective::emit(MachObjectWriter &ObjWriter,
36                          const MCAsmLayout &Layout) const {
37  raw_ostream &OutStream = ObjWriter.getStream();
38  emit_impl(OutStream, ObjWriter, Layout);
39}
40
41uint64_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