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 | |
21 | using namespace llvm; |
22 | |
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 | |
29 | MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) { |
30 | if (!End) |
31 | End = Ctx.createTempSymbol(Name: "sec_end" ); |
32 | return End; |
33 | } |
34 | |
35 | bool MCSection::hasEnded() const { return End && End->isInSection(); } |
36 | |
37 | MCSection::~MCSection() = default; |
38 | |
39 | void MCSection::setBundleLockState(BundleLockStateType NewState) { |
40 | if (NewState == NotBundleLocked) { |
41 | if (BundleLockNestingDepth == 0) { |
42 | report_fatal_error(reason: "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 |
59 | MCSection::getSubsectionInsertionPoint(unsigned Subsection) { |
60 | if (Subsection == 0 && SubsectionFragmentMap.empty()) |
61 | return end(); |
62 | |
63 | SmallVectorImpl<std::pair<unsigned, MCFragment *>>::iterator MI = lower_bound( |
64 | Range&: SubsectionFragmentMap, Value: std::make_pair(x&: Subsection, y: (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(I: MI, Elt: std::make_pair(x&: Subsection, y&: F)); |
81 | getFragmentList().insert(where: IP, New: F); |
82 | F->setParent(this); |
83 | F->setSubsectionNumber(Subsection); |
84 | } |
85 | |
86 | return IP; |
87 | } |
88 | |
89 | StringRef MCSection::getVirtualSectionKind() const { return "virtual" ; } |
90 | |
91 | void MCSection::addPendingLabel(MCSymbol *label, unsigned Subsection) { |
92 | PendingLabels.push_back(Elt: PendingLabel(label, Subsection)); |
93 | } |
94 | |
95 | void MCSection::flushPendingLabels(MCFragment *F, uint64_t FOffset, |
96 | unsigned Subsection) { |
97 | // Set the fragment and fragment offset for all pending symbols in the |
98 | // specified Subsection, and remove those symbols from the pending list. |
99 | for (auto It = PendingLabels.begin(); It != PendingLabels.end(); ++It) { |
100 | PendingLabel& Label = *It; |
101 | if (Label.Subsection == Subsection) { |
102 | Label.Sym->setFragment(F); |
103 | Label.Sym->setOffset(FOffset); |
104 | PendingLabels.erase(CI: It--); |
105 | } |
106 | } |
107 | } |
108 | |
109 | void MCSection::flushPendingLabels() { |
110 | // Make sure all remaining pending labels point to data fragments, by |
111 | // creating new empty data fragments for each Subsection with labels pending. |
112 | while (!PendingLabels.empty()) { |
113 | PendingLabel& Label = PendingLabels[0]; |
114 | iterator CurInsertionPoint = |
115 | this->getSubsectionInsertionPoint(Subsection: Label.Subsection); |
116 | const MCSymbol *Atom = nullptr; |
117 | if (CurInsertionPoint != begin()) |
118 | Atom = std::prev(x: CurInsertionPoint)->getAtom(); |
119 | MCFragment *F = new MCDataFragment(); |
120 | getFragmentList().insert(where: CurInsertionPoint, New: F); |
121 | F->setParent(this); |
122 | F->setAtom(Atom); |
123 | flushPendingLabels(F, FOffset: 0, Subsection: Label.Subsection); |
124 | } |
125 | } |
126 | |
127 | #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) |
128 | LLVM_DUMP_METHOD void MCSection::dump() const { |
129 | raw_ostream &OS = errs(); |
130 | |
131 | OS << "<MCSection" ; |
132 | OS << " Fragments:[\n " ; |
133 | for (auto it = begin(), ie = end(); it != ie; ++it) { |
134 | if (it != begin()) |
135 | OS << ",\n " ; |
136 | it->dump(); |
137 | } |
138 | OS << "]>" ; |
139 | } |
140 | #endif |
141 | |