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/IR/DataLayout.h"
13 #include "llvm/MC/MCAsmInfo.h"
14 #include "llvm/MC/MCStreamer.h"
15 #include "llvm/Target/TargetLoweringObjectFile.h"
16 #include <utility>
17
18 using namespace llvm;
19
getIndex(const MCSymbol * Sym,bool TLS)20 unsigned AddressPool::getIndex(const MCSymbol *Sym, bool TLS) {
21 resetUsedFlag(true);
22 auto IterBool =
23 Pool.insert(std::make_pair(Sym, AddressPoolEntry(Pool.size(), TLS)));
24 return IterBool.first->second.Number;
25 }
26
emitHeader(AsmPrinter & Asm,MCSection * Section)27 MCSymbol *AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) {
28 static const uint8_t AddrSize = Asm.MAI->getCodePointerSize();
29
30 MCSymbol *EndLabel =
31 Asm.emitDwarfUnitLength("debug_addr", "Length of contribution");
32 Asm.OutStreamer->AddComment("DWARF version number");
33 Asm.emitInt16(Asm.getDwarfVersion());
34 Asm.OutStreamer->AddComment("Address size");
35 Asm.emitInt8(AddrSize);
36 Asm.OutStreamer->AddComment("Segment selector size");
37 Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size.
38
39 return EndLabel;
40 }
41
42 // Emit addresses into the section given.
emit(AsmPrinter & Asm,MCSection * AddrSection)43 void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) {
44 if (isEmpty())
45 return;
46
47 // Start the dwarf addr section.
48 Asm.OutStreamer->switchSection(AddrSection);
49
50 MCSymbol *EndLabel = nullptr;
51
52 if (Asm.getDwarfVersion() >= 5)
53 EndLabel = emitHeader(Asm, AddrSection);
54
55 // Define the symbol that marks the start of the contribution.
56 // It is referenced via DW_AT_addr_base.
57 Asm.OutStreamer->emitLabel(AddressTableBaseSym);
58
59 // Order the address pool entries by ID
60 SmallVector<const MCExpr *, 64> Entries(Pool.size());
61
62 for (const auto &I : Pool)
63 Entries[I.second.Number] =
64 I.second.TLS
65 ? Asm.getObjFileLowering().getDebugThreadLocalSymbol(I.first)
66 : MCSymbolRefExpr::create(I.first, Asm.OutContext);
67
68 for (const MCExpr *Entry : Entries)
69 Asm.OutStreamer->emitValue(Entry, Asm.MAI->getCodePointerSize());
70
71 if (EndLabel)
72 Asm.OutStreamer->emitLabel(EndLabel);
73 }
74