1 //===- llvm/CodeGen/AddressPool.cpp - Dwarf Debug Framework ---------------===//
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 "AddressPool.h"
11 #include "llvm/ADT/SmallVector.h"
12 #include "llvm/CodeGen/AsmPrinter.h"
13 #include "llvm/IR/DataLayout.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 HasBeenUsed = true;
22 auto IterBool =
23 Pool.insert(std::make_pair(Sym, AddressPoolEntry(Pool.size(), TLS)));
24 return IterBool.first->second.Number;
25 }
26
27
emitHeader(AsmPrinter & Asm,MCSection * Section)28 void AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) {
29 static const uint8_t AddrSize = Asm.getDataLayout().getPointerSize();
30 uint64_t Length = sizeof(uint16_t) // version
31 + sizeof(uint8_t) // address_size
32 + sizeof(uint8_t) // segment_selector_size
33 + AddrSize * Pool.size(); // entries
34 Asm.OutStreamer->AddComment("Length of contribution");
35 Asm.emitInt32(Length); // TODO: Support DWARF64 format.
36 Asm.OutStreamer->AddComment("DWARF version number");
37 Asm.emitInt16(Asm.getDwarfVersion());
38 Asm.OutStreamer->AddComment("Address size");
39 Asm.emitInt8(AddrSize);
40 Asm.OutStreamer->AddComment("Segment selector size");
41 Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size.
42 }
43
44 // Emit addresses into the section given.
emit(AsmPrinter & Asm,MCSection * AddrSection)45 void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) {
46 if (isEmpty())
47 return;
48
49 // Start the dwarf addr section.
50 Asm.OutStreamer->SwitchSection(AddrSection);
51
52 if (Asm.getDwarfVersion() >= 5)
53 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.getDataLayout().getPointerSize());
70 }
71