llvm/lib/Target/Hexagon/MCTargetDesc/HexagonMCELFStreamer.cpp

   1 //=== HexagonMCELFStreamer.cpp - Hexagon subclass of MCELFStreamer -------===//
   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 is a stub that parses a MCInst bundle and passes the
  10 // instructions on to the real streamer.
  11 //
  12 //===----------------------------------------------------------------------===//
  13
  14 #include "MCTargetDesc/HexagonMCELFStreamer.h"
  15 #include "MCTargetDesc/HexagonMCInstrInfo.h"
  16 #include "MCTargetDesc/HexagonMCShuffler.h"
  17 #include "llvm/ADT/StringRef.h"
  18 #include "llvm/BinaryFormat/ELF.h"
  19 #include "llvm/MC/MCAsmBackend.h"
  20 #include "llvm/MC/MCAssembler.h"
  21 #include "llvm/MC/MCCodeEmitter.h"
  22 #include "llvm/MC/MCContext.h"
  23 #include "llvm/MC/MCExpr.h"
  24 #include "llvm/MC/MCInst.h"
  25 #include "llvm/MC/MCObjectStreamer.h"
  26 #include "llvm/MC/MCObjectWriter.h"
  27 #include "llvm/MC/MCSection.h"
  28 #include "llvm/MC/MCSectionELF.h"
  29 #include "llvm/MC/MCStreamer.h"
  30 #include "llvm/MC/MCSymbol.h"
  31 #include "llvm/MC/MCSymbolELF.h"
  32 #include "llvm/Support/Casting.h"
  33 #include "llvm/Support/CommandLine.h"
  34 #include "llvm/Support/ErrorHandling.h"
  35 #include "llvm/Support/MathExtras.h"
  36 #include <cassert>
  37 #include <cstdint>
  38
  39 #define DEBUG_TYPE "hexagonmcelfstreamer"
  40
  41 using namespace llvm;
  42
  43 static cl::opt<unsigned> GPSize
  44   ("gpsize", cl::NotHidden,
  45    cl::desc("Global Pointer Addressing Size.  The default size is 8."),
  46    cl::Prefix,
  47    cl::init(8));
  48
  49 HexagonMCELFStreamer::HexagonMCELFStreamer(
  50     MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
  51     std::unique_ptr<MCObjectWriter> OW, std::unique_ptr<MCCodeEmitter> Emitter)
  52     : MCELFStreamer(Context, std::move(TAB), std::move(OW), std::move(Emitter)),
  53       MCII(createHexagonMCInstrInfo()) {}
  54
  55 HexagonMCELFStreamer::HexagonMCELFStreamer(
  56     MCContext &Context, std::unique_ptr<MCAsmBackend> TAB,
  57     std::unique_ptr<MCObjectWriter> OW, std::unique_ptr<MCCodeEmitter> Emitter,
  58     MCAssembler *Assembler)
  59     : MCELFStreamer(Context, std::move(TAB), std::move(OW), std::move(Emitter)),
  60       MCII(createHexagonMCInstrInfo()) {}
  61
  62 void HexagonMCELFStreamer::emitInstruction(const MCInst &MCB,
  63                                            const MCSubtargetInfo &STI) {
  64   assert(MCB.getOpcode() == Hexagon::BUNDLE);
  65   assert(HexagonMCInstrInfo::bundleSize(MCB) <= HEXAGON_PACKET_SIZE);
  66   assert(HexagonMCInstrInfo::bundleSize(MCB) > 0);
  67
  68   // At this point, MCB is a bundle
  69   // Iterate through the bundle and assign addends for the instructions
  70   for (auto const &I : HexagonMCInstrInfo::bundleInstructions(MCB)) {
  71     MCInst *MCI = const_cast<MCInst *>(I.getInst());
  72     EmitSymbol(*MCI);
  73   }
  74
  75   MCObjectStreamer::emitInstruction(MCB, STI);
  76 }
  77
  78 void HexagonMCELFStreamer::EmitSymbol(const MCInst &Inst) {
  79   // Scan for values.
  80   for (unsigned i = Inst.getNumOperands(); i--;)
  81     if (Inst.getOperand(i).isExpr())
  82       visitUsedExpr(*Inst.getOperand(i).getExpr());
  83 }
  84
  85 // EmitCommonSymbol and EmitLocalCommonSymbol are extended versions of the
  86 // functions found in MCELFStreamer.cpp taking AccessSize as an additional
  87 // parameter.
  88 void HexagonMCELFStreamer::HexagonMCEmitCommonSymbol(MCSymbol *Symbol,
  89                                                      uint64_t Size,
  90                                                      unsigned ByteAlignment,
  91                                                      unsigned AccessSize) {
  92   getAssembler().registerSymbol(*Symbol);
  93   StringRef sbss[4] = {".sbss.1", ".sbss.2", ".sbss.4", ".sbss.8"};
  94
  95   auto ELFSymbol = cast<MCSymbolELF>(Symbol);
  96   if (!ELFSymbol->isBindingSet()) {
  97     ELFSymbol->setBinding(ELF::STB_GLOBAL);
  98     ELFSymbol->setExternal(true);
  99   }
 100
 101   ELFSymbol->setType(ELF::STT_OBJECT);
 102
 103   if (ELFSymbol->getBinding() == ELF::STB_LOCAL) {
 104     StringRef SectionName =
 105         ((AccessSize == 0) || (Size == 0) || (Size > GPSize))
 106             ? ".bss"
 107             : sbss[(Log2_64(AccessSize))];
 108     MCSection &Section = *getAssembler().getContext().getELFSection(
 109         SectionName, ELF::SHT_NOBITS, ELF::SHF_WRITE | ELF::SHF_ALLOC);
 110     MCSectionSubPair P = getCurrentSection();
 111     SwitchSection(&Section);
 112
 113     if (ELFSymbol->isUndefined()) {
 114       emitValueToAlignment(ByteAlignment, 0, 1, 0);
 115       emitLabel(Symbol);
 116       emitZeros(Size);
 117     }
 118
 119     // Update the maximum alignment of the section if necessary.
 120     if (Align(ByteAlignment) > Section.getAlignment())
 121       Section.setAlignment(Align(ByteAlignment));
 122
 123     SwitchSection(P.first, P.second);
 124   } else {
 125     if (ELFSymbol->declareCommon(Size, ByteAlignment))
 126       report_fatal_error("Symbol: " + Symbol->getName() +
 127                          " redeclared as different type");
 128     if ((AccessSize) && (Size <= GPSize)) {
 129       uint64_t SectionIndex =
 130           (AccessSize <= GPSize)
 131               ? ELF::SHN_HEXAGON_SCOMMON + (Log2_64(AccessSize) + 1)
 132               : (unsigned)ELF::SHN_HEXAGON_SCOMMON;
 133       ELFSymbol->setIndex(SectionIndex);
 134     }
 135   }
 136
 137   ELFSymbol->setSize(MCConstantExpr::create(Size, getContext()));
 138 }
 139
 140 void HexagonMCELFStreamer::HexagonMCEmitLocalCommonSymbol(MCSymbol *Symbol,
 141                                                          uint64_t Size,
 142                                                          unsigned ByteAlignment,
 143                                                          unsigned AccessSize) {
 144   getAssembler().registerSymbol(*Symbol);
 145   auto ELFSymbol = cast<MCSymbolELF>(Symbol);
 146   ELFSymbol->setBinding(ELF::STB_LOCAL);
 147   ELFSymbol->setExternal(false);
 148   HexagonMCEmitCommonSymbol(Symbol, Size, ByteAlignment, AccessSize);
 149 }
 150
 151
 152 namespace llvm {
 153 MCStreamer *createHexagonELFStreamer(Triple const &TT, MCContext &Context,
 154                                      std::unique_ptr<MCAsmBackend> MAB,
 155                                      std::unique_ptr<MCObjectWriter> OW,
 156                                      std::unique_ptr<MCCodeEmitter> CE) {
 157   return new HexagonMCELFStreamer(Context, std::move(MAB), std::move(OW),
 158                                   std::move(CE));
 159   }
 160
 161 } // end namespace llvm