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 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 27 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) { 28 if (!End) 29 End = Ctx.createTempSymbol("sec_end", true); 30 return End; 31 } 32 33 bool MCSection::hasEnded() const { return End && End->isInSection(); } 34 35 MCSection::~MCSection() = default; 36 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 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 88 void MCSection::addPendingLabel(MCSymbol* label, unsigned Subsection) { 89 PendingLabels.push_back(PendingLabel(label, Subsection)); 90 } 91 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 } 108 109 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) 124 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