llvm/lib/Target/VE/MCTargetDesc/VEAsmBackend.cpp

   1 //===-- VEAsmBackend.cpp - VE Assembler Backend ---------------------------===//
   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 "MCTargetDesc/VEFixupKinds.h"
  10 #include "MCTargetDesc/VEMCTargetDesc.h"
  11 #include "llvm/MC/MCAsmBackend.h"
  12 #include "llvm/MC/MCELFObjectWriter.h"
  13 #include "llvm/MC/MCExpr.h"
  14 #include "llvm/MC/MCFixupKindInfo.h"
  15 #include "llvm/MC/MCObjectWriter.h"
  16 #include "llvm/MC/MCSubtargetInfo.h"
  17 #include "llvm/MC/MCValue.h"
  18 #include "llvm/MC/TargetRegistry.h"
  19 #include "llvm/Support/EndianStream.h"
  20
  21 using namespace llvm;
  22
  23 static uint64_t adjustFixupValue(unsigned Kind, uint64_t Value) {
  24   switch (Kind) {
  25   default:
  26     llvm_unreachable("Unknown fixup kind!");
  27   case FK_Data_1:
  28   case FK_Data_2:
  29   case FK_Data_4:
  30   case FK_Data_8:
  31   case FK_PCRel_1:
  32   case FK_PCRel_2:
  33   case FK_PCRel_4:
  34   case FK_PCRel_8:
  35     return Value;
  36   case VE::fixup_ve_hi32:
  37   case VE::fixup_ve_pc_hi32:
  38   case VE::fixup_ve_got_hi32:
  39   case VE::fixup_ve_gotoff_hi32:
  40   case VE::fixup_ve_plt_hi32:
  41   case VE::fixup_ve_tls_gd_hi32:
  42   case VE::fixup_ve_tpoff_hi32:
  43     return (Value >> 32) & 0xffffffff;
  44   case VE::fixup_ve_reflong:
  45   case VE::fixup_ve_srel32:
  46   case VE::fixup_ve_lo32:
  47   case VE::fixup_ve_pc_lo32:
  48   case VE::fixup_ve_got_lo32:
  49   case VE::fixup_ve_gotoff_lo32:
  50   case VE::fixup_ve_plt_lo32:
  51   case VE::fixup_ve_tls_gd_lo32:
  52   case VE::fixup_ve_tpoff_lo32:
  53     return Value & 0xffffffff;
  54   }
  55 }
  56
  57 /// getFixupKindNumBytes - The number of bytes the fixup may change.
  58 static unsigned getFixupKindNumBytes(unsigned Kind) {
  59   switch (Kind) {
  60   default:
  61     llvm_unreachable("Unknown fixup kind!");
  62   case FK_Data_1:
  63   case FK_PCRel_1:
  64     return 1;
  65   case FK_Data_2:
  66   case FK_PCRel_2:
  67     return 2;
  68     return 4;
  69   case FK_Data_4:
  70   case FK_PCRel_4:
  71   case VE::fixup_ve_reflong:
  72   case VE::fixup_ve_srel32:
  73   case VE::fixup_ve_hi32:
  74   case VE::fixup_ve_lo32:
  75   case VE::fixup_ve_pc_hi32:
  76   case VE::fixup_ve_pc_lo32:
  77   case VE::fixup_ve_got_hi32:
  78   case VE::fixup_ve_got_lo32:
  79   case VE::fixup_ve_gotoff_hi32:
  80   case VE::fixup_ve_gotoff_lo32:
  81   case VE::fixup_ve_plt_hi32:
  82   case VE::fixup_ve_plt_lo32:
  83   case VE::fixup_ve_tls_gd_hi32:
  84   case VE::fixup_ve_tls_gd_lo32:
  85   case VE::fixup_ve_tpoff_hi32:
  86   case VE::fixup_ve_tpoff_lo32:
  87     return 4;
  88   case FK_Data_8:
  89   case FK_PCRel_8:
  90     return 8;
  91   }
  92 }
  93
  94 namespace {
  95 class VEAsmBackend : public MCAsmBackend {
  96 protected:
  97   const Target &TheTarget;
  98
  99 public:
 100   VEAsmBackend(const Target &T)
 101       : MCAsmBackend(llvm::endianness::little), TheTarget(T) {}
 102
 103   unsigned getNumFixupKinds() const override { return VE::NumTargetFixupKinds; }
 104
 105   const MCFixupKindInfo &getFixupKindInfo(MCFixupKind Kind) const override {
 106     const static MCFixupKindInfo Infos[VE::NumTargetFixupKinds] = {
 107         // name, offset, bits, flags
 108         {"fixup_ve_reflong", 0, 32, 0},
 109         {"fixup_ve_srel32", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
 110         {"fixup_ve_hi32", 0, 32, 0},
 111         {"fixup_ve_lo32", 0, 32, 0},
 112         {"fixup_ve_pc_hi32", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
 113         {"fixup_ve_pc_lo32", 0, 32, MCFixupKindInfo::FKF_IsPCRel},
 114         {"fixup_ve_got_hi32", 0, 32, 0},
 115         {"fixup_ve_got_lo32", 0, 32, 0},
 116         {"fixup_ve_gotoff_hi32", 0, 32, 0},
 117         {"fixup_ve_gotoff_lo32", 0, 32, 0},
 118         {"fixup_ve_plt_hi32", 0, 32, 0},
 119         {"fixup_ve_plt_lo32", 0, 32, 0},
 120         {"fixup_ve_tls_gd_hi32", 0, 32, 0},
 121         {"fixup_ve_tls_gd_lo32", 0, 32, 0},
 122         {"fixup_ve_tpoff_hi32", 0, 32, 0},
 123         {"fixup_ve_tpoff_lo32", 0, 32, 0},
 124     };
 125
 126     if (Kind < FirstTargetFixupKind)
 127       return MCAsmBackend::getFixupKindInfo(Kind);
 128
 129     assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() &&
 130            "Invalid kind!");
 131     return Infos[Kind - FirstTargetFixupKind];
 132   }
 133
 134   bool shouldForceRelocation(const MCAssembler &Asm, const MCFixup &Fixup,
 135                              const MCValue &Target,
 136                              const MCSubtargetInfo *STI) override {
 137     switch ((VE::Fixups)Fixup.getKind()) {
 138     default:
 139       return false;
 140     case VE::fixup_ve_tls_gd_hi32:
 141     case VE::fixup_ve_tls_gd_lo32:
 142     case VE::fixup_ve_tpoff_hi32:
 143     case VE::fixup_ve_tpoff_lo32:
 144       return true;
 145     }
 146   }
 147
 148   bool mayNeedRelaxation(const MCInst &Inst,
 149                          const MCSubtargetInfo &STI) const override {
 150     // Not implemented yet.  For example, if we have a branch with
 151     // lager than SIMM32 immediate value, we want to relaxation such
 152     // branch instructions.
 153     return false;
 154   }
 155
 156   /// fixupNeedsRelaxation - Target specific predicate for whether a given
 157   /// fixup requires the associated instruction to be relaxed.
 158   bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
 159                             const MCRelaxableFragment *DF,
 160                             const MCAsmLayout &Layout) const override {
 161     // Not implemented yet.  For example, if we have a branch with
 162     // lager than SIMM32 immediate value, we want to relaxation such
 163     // branch instructions.
 164     return false;
 165   }
 166   void relaxInstruction(MCInst &Inst,
 167                         const MCSubtargetInfo &STI) const override {
 168     // Aurora VE doesn't support relaxInstruction yet.
 169     llvm_unreachable("relaxInstruction() should not be called");
 170   }
 171
 172   bool writeNopData(raw_ostream &OS, uint64_t Count,
 173                     const MCSubtargetInfo *STI) const override {
 174     if ((Count % 8) != 0)
 175       return false;
 176
 177     for (uint64_t i = 0; i < Count; i += 8)
 178       support::endian::write<uint64_t>(OS, 0x7900000000000000ULL,
 179                                        llvm::endianness::little);
 180
 181     return true;
 182   }
 183 };
 184
 185 class ELFVEAsmBackend : public VEAsmBackend {
 186   Triple::OSType OSType;
 187
 188 public:
 189   ELFVEAsmBackend(const Target &T, Triple::OSType OSType)
 190       : VEAsmBackend(T), OSType(OSType) {}
 191
 192   void applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
 193                   const MCValue &Target, MutableArrayRef<char> Data,
 194                   uint64_t Value, bool IsResolved,
 195                   const MCSubtargetInfo *STI) const override {
 196     Value = adjustFixupValue(Fixup.getKind(), Value);
 197     if (!Value)
 198       return; // Doesn't change encoding.
 199
 200     MCFixupKindInfo Info = getFixupKindInfo(Fixup.getKind());
 201
 202     // Shift the value into position.
 203     Value <<= Info.TargetOffset;
 204
 205     unsigned NumBytes = getFixupKindNumBytes(Fixup.getKind());
 206     unsigned Offset = Fixup.getOffset();
 207     assert(Offset + NumBytes <= Data.size() && "Invalid fixup offset!");
 208     // For each byte of the fragment that the fixup touches, mask in the bits
 209     // from the fixup value. The Value has been "split up" into the
 210     // appropriate bitfields above.
 211     for (unsigned i = 0; i != NumBytes; ++i) {
 212       unsigned Idx =
 213           Endian == llvm::endianness::little ? i : (NumBytes - 1) - i;
 214       Data[Offset + Idx] |= static_cast<uint8_t>((Value >> (i * 8)) & 0xff);
 215     }
 216   }
 217
 218   std::unique_ptr<MCObjectTargetWriter>
 219   createObjectTargetWriter() const override {
 220     uint8_t OSABI = MCELFObjectTargetWriter::getOSABI(OSType);
 221     return createVEELFObjectWriter(OSABI);
 222   }
 223 };
 224 } // end anonymous namespace
 225
 226 MCAsmBackend *llvm::createVEAsmBackend(const Target &T,
 227                                        const MCSubtargetInfo &STI,
 228                                        const MCRegisterInfo &MRI,
 229                                        const MCTargetOptions &Options) {
 230   return new ELFVEAsmBackend(T, STI.getTargetTriple().getOS());
 231 }