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/MCMachObjectWriter.h"
11 #include "llvm/Support/LEB128.h"
12 #include "llvm/Support/raw_ostream.h"
13 #include <cstddef>
14 #include <cstdint>
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.
emit_impl(const MCAssembler & Asm,raw_ostream & OutStream,const MachObjectWriter & ObjWriter) const26 void MCLOHDirective::emit_impl(const MCAssembler &Asm, raw_ostream &OutStream,
27 const MachObjectWriter &ObjWriter
28
29 ) const {
30 encodeULEB128(Kind, OutStream);
31 encodeULEB128(Args.size(), OutStream);
32 for (const MCSymbol *Arg : Args)
33 encodeULEB128(ObjWriter.getSymbolAddress(*Arg, Asm), OutStream);
34 }
35
emit(const MCAssembler & Asm,MachObjectWriter & ObjWriter) const36 void MCLOHDirective::emit(const MCAssembler &Asm,
37 MachObjectWriter &ObjWriter) const {
38 raw_ostream &OutStream = ObjWriter.W.OS;
39 emit_impl(Asm, OutStream, ObjWriter);
40 }
41
getEmitSize(const MCAssembler & Asm,const MachObjectWriter & ObjWriter) const42 uint64_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(Asm, OutStream, ObjWriter);
58 return OutStream.tell();
59 }
60