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/SmallVector.h"
11 #include "llvm/Config/llvm-config.h"
12 #include "llvm/MC/MCContext.h"
13 #include "llvm/MC/MCFragment.h"
14 #include "llvm/MC/MCSymbol.h"
15 #include "llvm/Support/Compiler.h"
16 #include "llvm/Support/ErrorHandling.h"
17 #include "llvm/Support/raw_ostream.h"
18 #include <algorithm>
19 #include <utility>
20
21 using namespace llvm;
22
MCSection(SectionVariant V,StringRef Name,SectionKind K,MCSymbol * Begin)23 MCSection::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
getEndSymbol(MCContext & Ctx)29 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
30 if (!End)
31 End = Ctx.createTempSymbol("sec_end");
32 return End;
33 }
34
hasEnded() const35 bool MCSection::hasEnded() const { return End && End->isInSection(); }
36
37 MCSection::~MCSection() = default;
38
setBundleLockState(BundleLockStateType NewState)39 void 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
58 MCSection::iterator
getSubsectionInsertionPoint(unsigned Subsection)59 MCSection::getSubsectionInsertionPoint(unsigned Subsection) {
60 if (Subsection == 0 && SubsectionFragmentMap.empty())
61 return end();
62
63 SmallVectorImpl<std::pair<unsigned, MCFragment *>>::iterator MI =
64 std::lower_bound(SubsectionFragmentMap.begin(),
65 SubsectionFragmentMap.end(),
66 std::make_pair(Subsection, (MCFragment *)nullptr));
67 bool ExactMatch = false;
68 if (MI != SubsectionFragmentMap.end()) {
69 ExactMatch = MI->first == Subsection;
70 if (ExactMatch)
71 ++MI;
72 }
73 iterator IP;
74 if (MI == SubsectionFragmentMap.end())
75 IP = end();
76 else
77 IP = MI->second->getIterator();
78 if (!ExactMatch && Subsection != 0) {
79 // The GNU as documentation claims that subsections have an alignment of 4,
80 // although this appears not to be the case.
81 MCFragment *F = new MCDataFragment();
82 SubsectionFragmentMap.insert(MI, std::make_pair(Subsection, F));
83 getFragmentList().insert(IP, F);
84 F->setParent(this);
85 F->setSubsectionNumber(Subsection);
86 }
87
88 return IP;
89 }
90
getVirtualSectionKind() const91 StringRef MCSection::getVirtualSectionKind() const { return "virtual"; }
92
addPendingLabel(MCSymbol * label,unsigned Subsection)93 void MCSection::addPendingLabel(MCSymbol *label, unsigned Subsection) {
94 PendingLabels.push_back(PendingLabel(label, Subsection));
95 }
96
flushPendingLabels(MCFragment * F,uint64_t FOffset,unsigned Subsection)97 void MCSection::flushPendingLabels(MCFragment *F, uint64_t FOffset,
98 unsigned Subsection) {
99 if (PendingLabels.empty())
100 return;
101
102 // Set the fragment and fragment offset for all pending symbols in the
103 // specified Subsection, and remove those symbols from the pending list.
104 for (auto It = PendingLabels.begin(); It != PendingLabels.end(); ++It) {
105 PendingLabel& Label = *It;
106 if (Label.Subsection == Subsection) {
107 Label.Sym->setFragment(F);
108 Label.Sym->setOffset(FOffset);
109 PendingLabels.erase(It--);
110 }
111 }
112 }
113
flushPendingLabels()114 void MCSection::flushPendingLabels() {
115 // Make sure all remaining pending labels point to data fragments, by
116 // creating new empty data fragments for each Subsection with labels pending.
117 while (!PendingLabels.empty()) {
118 PendingLabel& Label = PendingLabels[0];
119 iterator CurInsertionPoint =
120 this->getSubsectionInsertionPoint(Label.Subsection);
121 MCFragment *F = new MCDataFragment();
122 getFragmentList().insert(CurInsertionPoint, F);
123 F->setParent(this);
124 flushPendingLabels(F, 0, Label.Subsection);
125 }
126 }
127
128 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump() const129 LLVM_DUMP_METHOD void MCSection::dump() const {
130 raw_ostream &OS = errs();
131
132 OS << "<MCSection";
133 OS << " Fragments:[\n ";
134 for (auto it = begin(), ie = end(); it != ie; ++it) {
135 if (it != begin())
136 OS << ",\n ";
137 it->dump();
138 }
139 OS << "]>";
140 }
141 #endif
142