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("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("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 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 89 StringRef MCSection::getVirtualSectionKind() const { return "virtual"; } 90 91 void MCSection::addPendingLabel(MCSymbol *label, unsigned Subsection) { 92 PendingLabels.push_back(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(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(Label.Subsection); 116 const MCSymbol *Atom = nullptr; 117 if (CurInsertionPoint != begin()) 118 Atom = std::prev(CurInsertionPoint)->getAtom(); 119 MCFragment *F = new MCDataFragment(); 120 getFragmentList().insert(CurInsertionPoint, F); 121 F->setParent(this); 122 F->setAtom(Atom); 123 flushPendingLabels(F, 0, 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