LLVM 18.0.0git
MCLinkerOptimizationHint.cpp
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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
10#include "llvm/MC/MCAsmLayout.h"
12#include "llvm/Support/LEB128.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
37 const MCAsmLayout &Layout) const {
38 raw_ostream &OutStream = ObjWriter.W.OS;
39 emit_impl(OutStream, ObjWriter, Layout);
40}
41
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}
Encapsulates the layout of an assembly file at a particular point in time.
Definition: MCAsmLayout.h:28
uint64_t getEmitSize(const MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const
Get the size in bytes of this directive if emitted in ObjWriter with the given Layout.
void emit(MachObjectWriter &ObjWriter, const MCAsmLayout &Layout) const
Emit this directive as: <kind, numArgs, addr1, ..., addrN>
MCSymbol - Instances of this class represent a symbol name in the MC file, and MCSymbols are created ...
Definition: MCSymbol.h:41
uint64_t getSymbolAddress(const MCSymbol &S, const MCAsmLayout &Layout) const
support::endian::Writer W
This class implements an extremely fast bulk output stream that can only output to a stream.
Definition: raw_ostream.h:52
This is an optimization pass for GlobalISel generic memory operations.
Definition: AddressRanges.h:18
auto size(R &&Range, std::enable_if_t< std::is_base_of< std::random_access_iterator_tag, typename std::iterator_traits< decltype(Range.begin())>::iterator_category >::value, void > *=nullptr)
Get the size of a range.
Definition: STLExtras.h:1685
unsigned encodeULEB128(uint64_t Value, raw_ostream &OS, unsigned PadTo=0)
Utility function to encode a ULEB128 value to an output stream.
Definition: LEB128.h:80