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 HasLayout(false), IsRegistered(false), DummyFragment(this), Name(Name), 27 Variant(V), Kind(K) { 28 // The initial subsection number is 0. Create a fragment list. 29 CurFragList = &Subsections.emplace_back(0u, FragList{}).second; 30 } 31 32 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) { 33 if (!End) 34 End = Ctx.createTempSymbol("sec_end"); 35 return End; 36 } 37 38 bool MCSection::hasEnded() const { return End && End->isInSection(); } 39 40 MCSection::~MCSection() { 41 for (auto &[_, Chain] : Subsections) { 42 for (MCFragment *X = Chain.Head, *Y; X; X = Y) { 43 Y = X->Next; 44 X->destroy(); 45 } 46 } 47 } 48 49 void MCSection::setBundleLockState(BundleLockStateType NewState) { 50 if (NewState == NotBundleLocked) { 51 if (BundleLockNestingDepth == 0) { 52 report_fatal_error("Mismatched bundle_lock/unlock directives"); 53 } 54 if (--BundleLockNestingDepth == 0) { 55 BundleLockState = NotBundleLocked; 56 } 57 return; 58 } 59 60 // If any of the directives is an align_to_end directive, the whole nested 61 // group is align_to_end. So don't downgrade from align_to_end to just locked. 62 if (BundleLockState != BundleLockedAlignToEnd) { 63 BundleLockState = NewState; 64 } 65 ++BundleLockNestingDepth; 66 } 67 68 void MCSection::switchSubsection(unsigned Subsection) { 69 size_t I = 0, E = Subsections.size(); 70 while (I != E && Subsections[I].first < Subsection) 71 ++I; 72 // If the subsection number is not in the sorted Subsections list, create a 73 // new fragment list. 74 if (I == E || Subsections[I].first != Subsection) 75 Subsections.insert(Subsections.begin() + I, {Subsection, FragList{}}); 76 CurFragList = &Subsections[I].second; 77 } 78 79 StringRef MCSection::getVirtualSectionKind() const { return "virtual"; } 80 81 void MCSection::addPendingLabel(MCSymbol *label, unsigned Subsection) { 82 PendingLabels.push_back(PendingLabel(label, Subsection)); 83 } 84 85 void MCSection::flushPendingLabels(MCFragment *F, unsigned Subsection) { 86 // Set the fragment and fragment offset for all pending symbols in the 87 // specified Subsection, and remove those symbols from the pending list. 88 for (auto It = PendingLabels.begin(); It != PendingLabels.end(); ++It) { 89 PendingLabel& Label = *It; 90 if (Label.Subsection == Subsection) { 91 Label.Sym->setFragment(F); 92 assert(Label.Sym->getOffset() == 0); 93 PendingLabels.erase(It--); 94 } 95 } 96 } 97 98 void MCSection::flushPendingLabels() { 99 // Make sure all remaining pending labels point to data fragments, by 100 // creating new empty data fragments for each Subsection with labels pending. 101 while (!PendingLabels.empty()) { 102 PendingLabel& Label = PendingLabels[0]; 103 switchSubsection(Label.Subsection); 104 MCFragment *F = new MCDataFragment(); 105 addFragment(*F); 106 F->setParent(this); 107 flushPendingLabels(F, Label.Subsection); 108 } 109 } 110 111 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 112 LLVM_DUMP_METHOD void MCSection::dump() const { 113 raw_ostream &OS = errs(); 114 115 OS << "<MCSection Name:" << getName(); 116 OS << " Fragments:[\n "; 117 bool First = true; 118 for (auto &F : *this) { 119 if (First) 120 First = false; 121 else 122 OS << ",\n "; 123 F.dump(); 124 } 125 OS << "]>"; 126 } 127 #endif 128