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/MCSymbol.h" 14 #include "llvm/Support/Compiler.h" 15 #include "llvm/Support/ErrorHandling.h" 16 #include "llvm/Support/raw_ostream.h" 17 #include <utility> 18 19 using namespace llvm; 20 21 MCSection::MCSection(SectionVariant V, StringRef Name, bool IsText, 22 bool IsVirtual, MCSymbol *Begin) 23 : Begin(Begin), BundleGroupBeforeFirstInst(false), HasInstructions(false), 24 IsRegistered(false), IsText(IsText), IsVirtual(IsVirtual), 25 LinkerRelaxable(false), Name(Name), Variant(V) { 26 // The initial subsection number is 0. Create a fragment list. 27 CurFragList = &Subsections.emplace_back(0u, FragList{}).second; 28 } 29 30 MCSymbol *MCSection::getEndSymbol(MCContext &Ctx) { 31 if (!End) 32 End = Ctx.createTempSymbol("sec_end"); 33 return End; 34 } 35 36 bool MCSection::hasEnded() const { return End && End->isInSection(); } 37 38 void MCSection::setBundleLockState(BundleLockStateType NewState) { 39 if (NewState == NotBundleLocked) { 40 if (BundleLockNestingDepth == 0) { 41 report_fatal_error("Mismatched bundle_lock/unlock directives"); 42 } 43 if (--BundleLockNestingDepth == 0) { 44 BundleLockState = NotBundleLocked; 45 } 46 return; 47 } 48 49 // If any of the directives is an align_to_end directive, the whole nested 50 // group is align_to_end. So don't downgrade from align_to_end to just locked. 51 if (BundleLockState != BundleLockedAlignToEnd) { 52 BundleLockState = NewState; 53 } 54 ++BundleLockNestingDepth; 55 } 56 57 StringRef MCSection::getVirtualSectionKind() const { return "virtual"; } 58 59 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) 60 LLVM_DUMP_METHOD void MCSection::dump( 61 DenseMap<const MCFragment *, SmallVector<const MCSymbol *, 0>> *FragToSyms) 62 const { 63 raw_ostream &OS = errs(); 64 65 OS << "MCSection Name:" << getName(); 66 if (isLinkerRelaxable()) 67 OS << " LinkerRelaxable"; 68 for (auto &F : *this) { 69 OS << '\n'; 70 F.dump(); 71 if (!FragToSyms) 72 continue; 73 auto It = FragToSyms->find(&F); 74 if (It == FragToSyms->end()) 75 continue; 76 for (auto *Sym : It->second) { 77 OS << "\n Symbol @" << Sym->getOffset() << ' ' << Sym->getName(); 78 if (Sym->isTemporary()) 79 OS << " Temporary"; 80 } 81 } 82 } 83 #endif 84 85 void MCEncodedFragment::setContents(ArrayRef<char> Contents) { 86 auto &S = getParent()->ContentStorage; 87 if (Contents.size() > ContentSize) { 88 ContentStart = S.size(); 89 S.resize_for_overwrite(S.size() + Contents.size()); 90 } 91 ContentSize = Contents.size(); 92 llvm::copy(Contents, S.begin() + ContentStart); 93 } 94 95 void MCEncodedFragment::addFixup(MCFixup Fixup) { appendFixups({Fixup}); } 96 97 void MCEncodedFragment::appendFixups(ArrayRef<MCFixup> Fixups) { 98 auto &S = getParent()->FixupStorage; 99 if (LLVM_UNLIKELY(FixupEnd != S.size())) { 100 // Move the elements to the end. Reserve space to avoid invalidating 101 // S.begin()+I for `append`. 102 auto Size = FixupEnd - FixupStart; 103 auto I = std::exchange(FixupStart, S.size()); 104 S.reserve(S.size() + Size); 105 S.append(S.begin() + I, S.begin() + I + Size); 106 } 107 S.append(Fixups.begin(), Fixups.end()); 108 FixupEnd = S.size(); 109 } 110 111 void MCEncodedFragment::setFixups(ArrayRef<MCFixup> Fixups) { 112 auto &S = getParent()->FixupStorage; 113 if (FixupStart + Fixups.size() > FixupEnd) { 114 FixupStart = S.size(); 115 S.resize_for_overwrite(S.size() + Fixups.size()); 116 } 117 FixupEnd = FixupStart + Fixups.size(); 118 llvm::copy(Fixups, S.begin() + FixupStart); 119 } 120