llvm/lib/MC/MCXCOFFStreamer.cpp

   1 //===- lib/MC/MCXCOFFStreamer.cpp - XCOFF Object Output -------------------===//
   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 // This file assembles .s files and emits XCOFF .o object files.
  10 //
  11 //===----------------------------------------------------------------------===//
  12
  13 #include "llvm/MC/MCXCOFFStreamer.h"
  14 #include "llvm/BinaryFormat/XCOFF.h"
  15 #include "llvm/MC/MCAsmBackend.h"
  16 #include "llvm/MC/MCAssembler.h"
  17 #include "llvm/MC/MCCodeEmitter.h"
  18 #include "llvm/MC/MCDirectives.h"
  19 #include "llvm/MC/MCObjectWriter.h"
  20 #include "llvm/MC/MCSectionXCOFF.h"
  21 #include "llvm/MC/MCSymbolXCOFF.h"
  22 #include "llvm/MC/TargetRegistry.h"
  23 #include "llvm/Support/Casting.h"
  24
  25 using namespace llvm;
  26
  27 MCXCOFFStreamer::MCXCOFFStreamer(MCContext &Context,
  28                                  std::unique_ptr<MCAsmBackend> MAB,
  29                                  std::unique_ptr<MCObjectWriter> OW,
  30                                  std::unique_ptr<MCCodeEmitter> Emitter)
  31     : MCObjectStreamer(Context, std::move(MAB), std::move(OW),
  32                        std::move(Emitter)) {}
  33
  34 bool MCXCOFFStreamer::emitSymbolAttribute(MCSymbol *Sym,
  35                                           MCSymbolAttr Attribute) {
  36   auto *Symbol = cast<MCSymbolXCOFF>(Sym);
  37   getAssembler().registerSymbol(*Symbol);
  38
  39   switch (Attribute) {
  40   // XCOFF doesn't support the cold feature.
  41   case MCSA_Cold:
  42     return false;
  43
  44   case MCSA_Global:
  45   case MCSA_Extern:
  46     Symbol->setStorageClass(XCOFF::C_EXT);
  47     Symbol->setExternal(true);
  48     break;
  49   case MCSA_LGlobal:
  50     Symbol->setStorageClass(XCOFF::C_HIDEXT);
  51     Symbol->setExternal(true);
  52     break;
  53   case llvm::MCSA_Weak:
  54     Symbol->setStorageClass(XCOFF::C_WEAKEXT);
  55     Symbol->setExternal(true);
  56     break;
  57   case llvm::MCSA_Hidden:
  58     Symbol->setVisibilityType(XCOFF::SYM_V_HIDDEN);
  59     break;
  60   case llvm::MCSA_Protected:
  61     Symbol->setVisibilityType(XCOFF::SYM_V_PROTECTED);
  62     break;
  63   case llvm::MCSA_Exported:
  64     Symbol->setVisibilityType(XCOFF::SYM_V_EXPORTED);
  65     break;
  66   default:
  67     report_fatal_error("Not implemented yet.");
  68   }
  69   return true;
  70 }
  71
  72 void MCXCOFFStreamer::emitXCOFFSymbolLinkageWithVisibility(
  73     MCSymbol *Symbol, MCSymbolAttr Linkage, MCSymbolAttr Visibility) {
  74
  75   emitSymbolAttribute(Symbol, Linkage);
  76
  77   // When the caller passes `MCSA_Invalid` for the visibility, do not emit one.
  78   if (Visibility == MCSA_Invalid)
  79     return;
  80
  81   emitSymbolAttribute(Symbol, Visibility);
  82 }
  83
  84 void MCXCOFFStreamer::emitXCOFFRefDirective(const MCSymbol *Symbol) {
  85   // Add a Fixup here to later record a relocation of type R_REF to prevent the
  86   // ref symbol from being garbage collected (by the binder).
  87   MCDataFragment *DF = getOrCreateDataFragment();
  88   const MCSymbolRefExpr *SRE = MCSymbolRefExpr::create(Symbol, getContext());
  89   std::optional<MCFixupKind> MaybeKind =
  90       getAssembler().getBackend().getFixupKind("R_REF");
  91   if (!MaybeKind)
  92     report_fatal_error("failed to get fixup kind for R_REF relocation");
  93
  94   MCFixupKind Kind = *MaybeKind;
  95   MCFixup Fixup = MCFixup::create(DF->getContents().size(), SRE, Kind);
  96   DF->getFixups().push_back(Fixup);
  97 }
  98
  99 void MCXCOFFStreamer::emitXCOFFExceptDirective(const MCSymbol *Symbol,
 100                                                const MCSymbol *Trap,
 101                                                unsigned Lang, unsigned Reason,
 102                                                unsigned FunctionSize,
 103                                                bool hasDebug) {
 104   getAssembler().getWriter().addExceptionEntry(Symbol, Trap, Lang, Reason,
 105                                                FunctionSize, hasDebug);
 106 }
 107
 108 void MCXCOFFStreamer::emitXCOFFCInfoSym(StringRef Name, StringRef Metadata) {
 109   getAssembler().getWriter().addCInfoSymEntry(Name, Metadata);
 110 }
 111
 112 void MCXCOFFStreamer::emitCommonSymbol(MCSymbol *Symbol, uint64_t Size,
 113                                        Align ByteAlignment) {
 114   getAssembler().registerSymbol(*Symbol);
 115   Symbol->setExternal(cast<MCSymbolXCOFF>(Symbol)->getStorageClass() !=
 116                       XCOFF::C_HIDEXT);
 117   Symbol->setCommon(Size, ByteAlignment);
 118
 119   // Default csect align is 4, but common symbols have explicit alignment values
 120   // and we should honor it.
 121   cast<MCSymbolXCOFF>(Symbol)->getRepresentedCsect()->setAlignment(
 122       ByteAlignment);
 123
 124   // Emit the alignment and storage for the variable to the section.
 125   emitValueToAlignment(ByteAlignment);
 126   emitZeros(Size);
 127 }
 128
 129 void MCXCOFFStreamer::emitZerofill(MCSection *Section, MCSymbol *Symbol,
 130                                    uint64_t Size, Align ByteAlignment,
 131                                    SMLoc Loc) {
 132   report_fatal_error("Zero fill not implemented for XCOFF.");
 133 }
 134
 135 void MCXCOFFStreamer::emitInstToData(const MCInst &Inst,
 136                                      const MCSubtargetInfo &STI) {
 137   MCAssembler &Assembler = getAssembler();
 138   SmallVector<MCFixup, 4> Fixups;
 139   SmallString<256> Code;
 140   Assembler.getEmitter().encodeInstruction(Inst, Code, Fixups, STI);
 141
 142   // Add the fixups and data.
 143   MCDataFragment *DF = getOrCreateDataFragment(&STI);
 144   const size_t ContentsSize = DF->getContents().size();
 145   auto &DataFragmentFixups = DF->getFixups();
 146   for (auto &Fixup : Fixups) {
 147     Fixup.setOffset(Fixup.getOffset() + ContentsSize);
 148     DataFragmentFixups.push_back(Fixup);
 149   }
 150
 151   DF->setHasInstructions(STI);
 152   DF->getContents().append(Code.begin(), Code.end());
 153 }
 154
 155 MCStreamer *llvm::createXCOFFStreamer(MCContext &Context,
 156                                       std::unique_ptr<MCAsmBackend> &&MAB,
 157                                       std::unique_ptr<MCObjectWriter> &&OW,
 158                                       std::unique_ptr<MCCodeEmitter> &&CE,
 159                                       bool RelaxAll) {
 160   MCXCOFFStreamer *S = new MCXCOFFStreamer(Context, std::move(MAB),
 161                                            std::move(OW), std::move(CE));
 162   if (RelaxAll)
 163     S->getAssembler().setRelaxAll(true);
 164   return S;
 165 }
 166
 167 void MCXCOFFStreamer::emitXCOFFLocalCommonSymbol(MCSymbol *LabelSym,
 168                                                  uint64_t Size,
 169                                                  MCSymbol *CsectSym,
 170                                                  Align Alignment) {
 171   emitCommonSymbol(CsectSym, Size, Alignment);
 172 }