llvm/lib/CodeGen/AsmPrinter/AddressPool.cpp

   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
  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
  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.
  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 }