1//===- lib/MC/MCSection.cpp - Machine Code Section Representation ---------===//
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 "llvm/MC/MCSection.h"
10#include "llvm/ADT/STLExtras.h"
11#include "llvm/ADT/SmallVector.h"
12#include "llvm/Config/llvm-config.h"
13#include "llvm/MC/MCContext.h"
14#include "llvm/MC/MCFragment.h"
15#include "llvm/MC/MCSymbol.h"
16#include "llvm/Support/Compiler.h"
17#include "llvm/Support/ErrorHandling.h"
18#include "llvm/Support/raw_ostream.h"
19#include <utility>
20
21using namespace llvm;
22
23MCSection::MCSection(SectionVariant V, StringRef Name, SectionKind K,
24                     MCSymbol *Begin)
25    : Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
26      IsRegistered(false), DummyFragment(this), Name(Name), Variant(V),
27      Kind(K) {}
28
29MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
30  if (!End)
31    End = Ctx.createTempSymbol("sec_end");
32  return End;
33}
34
35bool MCSection::hasEnded() const { return End && End->isInSection(); }
36
37MCSection::~MCSection() = default;
38
39void MCSection::setBundleLockState(BundleLockStateType NewState) {
40  if (NewState == NotBundleLocked) {
41    if (BundleLockNestingDepth == 0) {
42      report_fatal_error("Mismatched bundle_lock/unlock directives");
43    }
44    if (--BundleLockNestingDepth == 0) {
45      BundleLockState = NotBundleLocked;
46    }
47    return;
48  }
49
50  // If any of the directives is an align_to_end directive, the whole nested
51  // group is align_to_end. So don't downgrade from align_to_end to just locked.
52  if (BundleLockState != BundleLockedAlignToEnd) {
53    BundleLockState = NewState;
54  }
55  ++BundleLockNestingDepth;
56}
57
58MCSection::iterator
59MCSection::getSubsectionInsertionPoint(unsigned Subsection) {
60  if (Subsection == 0 && SubsectionFragmentMap.empty())
61    return end();
62
63  SmallVectorImpl<std::pair<unsigned, MCFragment *>>::iterator MI = lower_bound(
64      SubsectionFragmentMap, std::make_pair(Subsection, (MCFragment *)nullptr));
65  bool ExactMatch = false;
66  if (MI != SubsectionFragmentMap.end()) {
67    ExactMatch = MI->first == Subsection;
68    if (ExactMatch)
69      ++MI;
70  }
71  iterator IP;
72  if (MI == SubsectionFragmentMap.end())
73    IP = end();
74  else
75    IP = MI->second->getIterator();
76  if (!ExactMatch && Subsection != 0) {
77    // The GNU as documentation claims that subsections have an alignment of 4,
78    // although this appears not to be the case.
79    MCFragment *F = new MCDataFragment();
80    SubsectionFragmentMap.insert(MI, std::make_pair(Subsection, F));
81    getFragmentList().insert(IP, F);
82    F->setParent(this);
83    F->setSubsectionNumber(Subsection);
84  }
85
86  return IP;
87}
88
89StringRef MCSection::getVirtualSectionKind() const { return "virtual"; }
90
91void MCSection::addPendingLabel(MCSymbol *label, unsigned Subsection) {
92  PendingLabels.push_back(PendingLabel(label, Subsection));
93}
94
95void MCSection::flushPendingLabels(MCFragment *F, uint64_t FOffset,
96				   unsigned Subsection) {
97  if (PendingLabels.empty())
98    return;
99
100  // Set the fragment and fragment offset for all pending symbols in the
101  // specified Subsection, and remove those symbols from the pending list.
102  for (auto It = PendingLabels.begin(); It != PendingLabels.end(); ++It) {
103    PendingLabel& Label = *It;
104    if (Label.Subsection == Subsection) {
105      Label.Sym->setFragment(F);
106      Label.Sym->setOffset(FOffset);
107      PendingLabels.erase(It--);
108    }
109  }
110}
111
112void MCSection::flushPendingLabels() {
113  // Make sure all remaining pending labels point to data fragments, by
114  // creating new empty data fragments for each Subsection with labels pending.
115  while (!PendingLabels.empty()) {
116    PendingLabel& Label = PendingLabels[0];
117    iterator CurInsertionPoint =
118      this->getSubsectionInsertionPoint(Label.Subsection);
119    MCFragment *F = new MCDataFragment();
120    getFragmentList().insert(CurInsertionPoint, F);
121    F->setParent(this);
122    flushPendingLabels(F, 0, Label.Subsection);
123  }
124}
125
126#if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
127LLVM_DUMP_METHOD void MCSection::dump() const {
128  raw_ostream &OS = errs();
129
130  OS << "<MCSection";
131  OS << " Fragments:[\n      ";
132  for (auto it = begin(), ie = end(); it != ie; ++it) {
133    if (it != begin())
134      OS << ",\n      ";
135    it->dump();
136  }
137  OS << "]>";
138}
139#endif
140