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