| //===-- Nios2AsmBackend.cpp - Nios2 Asm Backend --------------------------===// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| // This file implements the Nios2AsmBackend class. |
| // |
| //===----------------------------------------------------------------------===// |
| // |
| |
| #include "MCTargetDesc/Nios2AsmBackend.h" |
| #include "MCTargetDesc/Nios2FixupKinds.h" |
| #include "MCTargetDesc/Nios2MCTargetDesc.h" |
| #include "llvm/MC/MCAssembler.h" |
| #include "llvm/MC/MCELFObjectWriter.h" |
| #include "llvm/MC/MCFixupKindInfo.h" |
| #include "llvm/MC/MCObjectWriter.h" |
| #include "llvm/MC/MCSubtargetInfo.h" |
| |
| using namespace llvm; |
| |
| // Prepare value for the target space for it |
| static unsigned adjustFixupValue(const MCFixup &Fixup, uint64_t Value) { |
| |
| unsigned Kind = Fixup.getKind(); |
| |
| // Add/subtract and shift |
| switch (Kind) { |
| default: |
| return 0; |
| case Nios2::fixup_Nios2_LO16: |
| break; |
| case Nios2::fixup_Nios2_HI16: |
| // Get the higher 16-bits. Also add 1 if bit 15 is 1. |
| Value = ((Value + 0x8000) >> 16) & 0xffff; |
| break; |
| } |
| |
| return Value; |
| } |
| |
| // Calculate index for Nios2 specific little endian byte order |
| static unsigned calculateLEIndex(unsigned i) { |
| assert(i <= 3 && "Index out of range!"); |
| |
| return (1 - i / 2) * 2 + i % 2; |
| } |
| |
| /// ApplyFixup - Apply the \p Value for given \p Fixup into the provided |
| /// data fragment, at the offset specified by the fixup and following the |
| /// fixup kind as appropriate. |
| void Nios2AsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup, |
| const MCValue &Target, |
| MutableArrayRef<char> Data, uint64_t Value, |
| bool IsResolved) const { |
| MCFixupKind Kind = Fixup.getKind(); |
| Value = adjustFixupValue(Fixup, Value); |
| |
| if (!Value) |
| return; // Doesn't change encoding. |
| |
| // Where do we start in the object |
| unsigned Offset = Fixup.getOffset(); |
| // Number of bytes we need to fixup |
| unsigned NumBytes = (getFixupKindInfo(Kind).TargetSize + 7) / 8; |
| // Grab current value, if any, from bits. |
| uint64_t CurVal = 0; |
| |
| for (unsigned i = 0; i != NumBytes; ++i) { |
| unsigned Idx = calculateLEIndex(i); |
| CurVal |= (uint64_t)((uint8_t)Data[Offset + Idx]) << (i * 8); |
| } |
| |
| uint64_t Mask = ((uint64_t)(-1) >> (64 - getFixupKindInfo(Kind).TargetSize)); |
| CurVal |= Value & Mask; |
| |
| // Write out the fixed up bytes back to the code/data bits. |
| for (unsigned i = 0; i != NumBytes; ++i) { |
| unsigned Idx = calculateLEIndex(i); |
| Data[Offset + Idx] = (uint8_t)((CurVal >> (i * 8)) & 0xff); |
| } |
| } |
| |
| Optional<MCFixupKind> Nios2AsmBackend::getFixupKind(StringRef Name) const { |
| return StringSwitch<Optional<MCFixupKind>>(Name) |
| .Case("R_NIOS2_NONE", (MCFixupKind)Nios2::fixup_Nios2_32) |
| .Case("R_NIOS2_32", FK_Data_4) |
| .Default(MCAsmBackend::getFixupKind(Name)); |
| } |
| |
| //@getFixupKindInfo { |
| const MCFixupKindInfo & |
| Nios2AsmBackend::getFixupKindInfo(MCFixupKind Kind) const { |
| const static MCFixupKindInfo Infos[Nios2::NumTargetFixupKinds] = { |
| // This table *must* be in same the order of fixup_* kinds in |
| // Nios2FixupKinds.h. |
| // |
| // name offset bits flags |
| {"fixup_Nios2_32", 0, 32, 0}, |
| {"fixup_Nios2_HI16", 0, 16, 0}, |
| {"fixup_Nios2_LO16", 0, 16, 0}}; |
| |
| if (Kind < FirstTargetFixupKind) |
| return MCAsmBackend::getFixupKindInfo(Kind); |
| |
| assert(unsigned(Kind - FirstTargetFixupKind) < getNumFixupKinds() && |
| "Invalid kind!"); |
| return Infos[Kind - FirstTargetFixupKind]; |
| } |
| |
| std::unique_ptr<MCObjectTargetWriter> |
| Nios2AsmBackend::createObjectTargetWriter() const { |
| return createNios2ELFObjectWriter(MCELFObjectTargetWriter::getOSABI(OSType)); |
| } |
| |
| bool Nios2AsmBackend::writeNopData(raw_ostream &OS, uint64_t Count) const { |
| return true; |
| } |
| |
| // MCAsmBackend |
| MCAsmBackend *llvm::createNios2AsmBackend(const Target &T, |
| const MCSubtargetInfo &STI, |
| const MCRegisterInfo &MRI, |
| const MCTargetOptions &Options) { |
| return new Nios2AsmBackend(T, STI.getTargetTriple().getOS()); |
| } |