AddressPool.cpp
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//===- llvm/CodeGen/AddressPool.cpp - Dwarf Debug Framework ---------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "AddressPool.h"
#include "llvm/ADT/SmallVector.h"
#include "llvm/CodeGen/AsmPrinter.h"
#include "llvm/IR/DataLayout.h"
#include "llvm/MC/MCStreamer.h"
#include "llvm/Target/TargetLoweringObjectFile.h"
#include <utility>
using namespace llvm;
unsigned AddressPool::getIndex(const MCSymbol *Sym, bool TLS) {
HasBeenUsed = true;
auto IterBool =
Pool.insert(std::make_pair(Sym, AddressPoolEntry(Pool.size(), TLS)));
return IterBool.first->second.Number;
}
MCSymbol *AddressPool::emitHeader(AsmPrinter &Asm, MCSection *Section) {
static const uint8_t AddrSize = Asm.getDataLayout().getPointerSize();
StringRef Prefix = "debug_addr_";
MCSymbol *BeginLabel = Asm.createTempSymbol(Prefix + "start");
MCSymbol *EndLabel = Asm.createTempSymbol(Prefix + "end");
Asm.OutStreamer->AddComment("Length of contribution");
Asm.EmitLabelDifference(EndLabel, BeginLabel,
4); // TODO: Support DWARF64 format.
Asm.OutStreamer->EmitLabel(BeginLabel);
Asm.OutStreamer->AddComment("DWARF version number");
Asm.emitInt16(Asm.getDwarfVersion());
Asm.OutStreamer->AddComment("Address size");
Asm.emitInt8(AddrSize);
Asm.OutStreamer->AddComment("Segment selector size");
Asm.emitInt8(0); // TODO: Support non-zero segment_selector_size.
return EndLabel;
}
// Emit addresses into the section given.
void AddressPool::emit(AsmPrinter &Asm, MCSection *AddrSection) {
if (isEmpty())
return;
// Start the dwarf addr section.
Asm.OutStreamer->SwitchSection(AddrSection);
MCSymbol *EndLabel = nullptr;
if (Asm.getDwarfVersion() >= 5)
EndLabel = emitHeader(Asm, AddrSection);
// Define the symbol that marks the start of the contribution.
// It is referenced via DW_AT_addr_base.
Asm.OutStreamer->EmitLabel(AddressTableBaseSym);
// Order the address pool entries by ID
SmallVector<const MCExpr *, 64> Entries(Pool.size());
for (const auto &I : Pool)
Entries[I.second.Number] =
I.second.TLS
? Asm.getObjFileLowering().getDebugThreadLocalSymbol(I.first)
: MCSymbolRefExpr::create(I.first, Asm.OutContext);
for (const MCExpr *Entry : Entries)
Asm.OutStreamer->EmitValue(Entry, Asm.getDataLayout().getPointerSize());
if (EndLabel)
Asm.OutStreamer->EmitLabel(EndLabel);
}