1//===- llvm/CodeGen/AddressPool.cpp - Dwarf Debug Framework ---------------===//
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 "AddressPool.h"
10#include "llvm/ADT/SmallVector.h"
11#include "llvm/CodeGen/AsmPrinter.h"
12#include "llvm/MC/MCAsmInfo.h"
13#include "llvm/MC/MCStreamer.h"
14#include "llvm/Target/TargetLoweringObjectFile.h"
15#include <utility>
16
17using namespace llvm;
18
19unsigned AddressPool::getIndex(const MCSymbol *Sym, bool TLS) {
20 resetUsedFlag(HasBeenUsed: true);
21 auto IterBool =
22 Pool.insert(KV: std::make_pair(x&: Sym, y: AddressPoolEntry(Pool.size(), TLS)));
23 return IterBool.first->second.Number;
24}
25
26MCSymbol *AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) {
27 static const uint8_t AddrSize = Asm.MAI->getCodePointerSize();
28
29 MCSymbol *EndLabel =
30 Asm.emitDwarfUnitLength(Prefix: "debug_addr", Comment: "Length of contribution");
31 Asm.OutStreamer->AddComment(T: "DWARF version number");
32 Asm.emitInt16(Value: Asm.getDwarfVersion());
33 Asm.OutStreamer->AddComment(T: "Address size");
34 Asm.emitInt8(Value: AddrSize);
35 Asm.OutStreamer->AddComment(T: "Segment selector size");
36 Asm.emitInt8(Value: 0); // TODO: Support non-zero segment_selector_size.
37
38 return EndLabel;
39}
40
41// Emit addresses into the section given.
42void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) {
43 if (isEmpty())
44 return;
45
46 // Start the dwarf addr section.
47 Asm.OutStreamer->switchSection(Section: AddrSection);
48
49 MCSymbol *EndLabel = nullptr;
50
51 if (Asm.getDwarfVersion() >= 5)
52 EndLabel = emitHeader(Asm, Section: AddrSection);
53
54 // Define the symbol that marks the start of the contribution.
55 // It is referenced via DW_AT_addr_base.
56 Asm.OutStreamer->emitLabel(Symbol: AddressTableBaseSym);
57
58 // Order the address pool entries by ID
59 SmallVector<const MCExpr *, 64> Entries(Pool.size());
60
61 for (const auto &I : Pool)
62 Entries[I.second.Number] =
63 I.second.TLS
64 ? Asm.getObjFileLowering().getDebugThreadLocalSymbol(Sym: I.first)
65 : MCSymbolRefExpr::create(Symbol: I.first, Ctx&: Asm.OutContext);
66
67 for (const MCExpr *Entry : Entries)
68 Asm.OutStreamer->emitValue(Value: Entry, Size: Asm.MAI->getCodePointerSize());
69
70 if (EndLabel)
71 Asm.OutStreamer->emitLabel(Symbol: EndLabel);
72}
73