1 //===-- BPFAsmBackend.cpp - BPF Assembler Backend -------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 #include "MCTargetDesc/BPFMCTargetDesc.h"
11 #include "llvm/ADT/StringRef.h"
12 #include "llvm/MC/MCAsmBackend.h"
13 #include "llvm/MC/MCFixup.h"
14 #include "llvm/MC/MCObjectWriter.h"
22 class BPFAsmBackend : public MCAsmBackend {
26 BPFAsmBackend(bool IsLittleEndian)
27 : MCAsmBackend(), IsLittleEndian(IsLittleEndian) {}
28 ~BPFAsmBackend() override = default;
30 void applyFixup(const MCFixup &Fixup, char *Data, unsigned DataSize,
31 uint64_t Value, bool IsPCRel, MCContext &Ctx) const override;
33 MCObjectWriter *createObjectWriter(raw_pwrite_stream &OS) const override;
35 // No instruction requires relaxation
36 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
37 const MCRelaxableFragment *DF,
38 const MCAsmLayout &Layout) const override {
42 unsigned getNumFixupKinds() const override { return 1; }
44 bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
46 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
47 MCInst &Res) const override {}
49 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
52 } // end anonymous namespace
54 bool BPFAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
58 for (uint64_t i = 0; i < Count; i += 8)
59 OW->write64(0x15000000);
64 void BPFAsmBackend::applyFixup(const MCFixup &Fixup, char *Data,
65 unsigned DataSize, uint64_t Value, bool IsPCRel,
66 MCContext &Ctx) const {
67 if (Fixup.getKind() == FK_SecRel_4 || Fixup.getKind() == FK_SecRel_8) {
69 } else if (Fixup.getKind() == FK_Data_4 || Fixup.getKind() == FK_Data_8) {
70 unsigned Size = Fixup.getKind() == FK_Data_4 ? 4 : 8;
72 for (unsigned i = 0; i != Size; ++i) {
73 unsigned Idx = IsLittleEndian ? i : Size - i - 1;
74 Data[Fixup.getOffset() + Idx] = uint8_t(Value >> (i * 8));
77 assert(Fixup.getKind() == FK_PCRel_2);
78 Value = (uint16_t)((Value - 8) / 8);
80 Data[Fixup.getOffset() + 2] = Value & 0xFF;
81 Data[Fixup.getOffset() + 3] = Value >> 8;
83 Data[Fixup.getOffset() + 2] = Value >> 8;
84 Data[Fixup.getOffset() + 3] = Value & 0xFF;
89 MCObjectWriter *BPFAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
90 return createBPFELFObjectWriter(OS, 0, IsLittleEndian);
93 MCAsmBackend *llvm::createBPFAsmBackend(const Target &T,
94 const MCRegisterInfo &MRI,
95 const Triple &TT, StringRef CPU,
96 const MCTargetOptions&) {
97 return new BPFAsmBackend(/*IsLittleEndian=*/true);
100 MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
101 const MCRegisterInfo &MRI,
102 const Triple &TT, StringRef CPU,
103 const MCTargetOptions&) {
104 return new BPFAsmBackend(/*IsLittleEndian=*/false);