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,SectionKind K,MCSymbol * Begin)23 MCSection::MCSection(SectionVariant V, SectionKind K, MCSymbol *Begin)
24 : Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false),
25 IsRegistered(false), DummyFragment(this), Variant(V), Kind(K) {}
26
getEndSymbol(MCContext & Ctx)27 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) {
28 if (!End)
29 End = Ctx.createTempSymbol("sec_end", true);
30 return End;
31 }
32
hasEnded() const33 bool MCSection::hasEnded() const { return End && End->isInSection(); }
34
35 MCSection::~MCSection() = default;
36
setBundleLockState(BundleLockStateType NewState)37 void MCSection::setBundleLockState(BundleLockStateType NewState) {
38 if (NewState == NotBundleLocked) {
39 if (BundleLockNestingDepth == 0) {
40 report_fatal_error("Mismatched bundle_lock/unlock directives");
41 }
42 if (--BundleLockNestingDepth == 0) {
43 BundleLockState = NotBundleLocked;
44 }
45 return;
46 }
47
48 // If any of the directives is an align_to_end directive, the whole nested
49 // group is align_to_end. So don't downgrade from align_to_end to just locked.
50 if (BundleLockState != BundleLockedAlignToEnd) {
51 BundleLockState = NewState;
52 }
53 ++BundleLockNestingDepth;
54 }
55
56 MCSection::iterator
getSubsectionInsertionPoint(unsigned Subsection)57 MCSection::getSubsectionInsertionPoint(unsigned Subsection) {
58 if (Subsection == 0 && SubsectionFragmentMap.empty())
59 return end();
60
61 SmallVectorImpl<std::pair<unsigned, MCFragment *>>::iterator MI =
62 std::lower_bound(SubsectionFragmentMap.begin(),
63 SubsectionFragmentMap.end(),
64 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 }
84
85 return IP;
86 }
87
addPendingLabel(MCSymbol * label,unsigned Subsection)88 void MCSection::addPendingLabel(MCSymbol* label, unsigned Subsection) {
89 PendingLabels.push_back(PendingLabel(label, Subsection));
90 }
91
flushPendingLabels(MCFragment * F,uint64_t FOffset,unsigned Subsection)92 void MCSection::flushPendingLabels(MCFragment *F, uint64_t FOffset,
93 unsigned Subsection) {
94 if (PendingLabels.empty())
95 return;
96
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(It--);
105 }
106 }
107 }
108
flushPendingLabels()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(Label.Subsection);
116 MCFragment *F = new MCDataFragment();
117 getFragmentList().insert(CurInsertionPoint, F);
118 F->setParent(this);
119 flushPendingLabels(F, 0, Label.Subsection);
120 }
121 }
122
123 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
dump() const124 LLVM_DUMP_METHOD void MCSection::dump() const {
125 raw_ostream &OS = errs();
126
127 OS << "<MCSection";
128 OS << " Fragments:[\n ";
129 for (auto it = begin(), ie = end(); it != ie; ++it) {
130 if (it != begin())
131 OS << ",\n ";
132 it->dump();
133 }
134 OS << "]>";
135 }
136 #endif
137