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 MCAssembler &Asm, const MCFixup &Fixup,
31 const MCValue &Target, MutableArrayRef<char> Data,
32 uint64_t Value, bool IsResolved) const override;
34 std::unique_ptr<MCObjectWriter>
35 createObjectWriter(raw_pwrite_stream &OS) const override;
37 // No instruction requires relaxation
38 bool fixupNeedsRelaxation(const MCFixup &Fixup, uint64_t Value,
39 const MCRelaxableFragment *DF,
40 const MCAsmLayout &Layout) const override {
44 unsigned getNumFixupKinds() const override { return 1; }
46 bool mayNeedRelaxation(const MCInst &Inst) const override { return false; }
48 void relaxInstruction(const MCInst &Inst, const MCSubtargetInfo &STI,
49 MCInst &Res) const override {}
51 bool writeNopData(uint64_t Count, MCObjectWriter *OW) const override;
54 } // end anonymous namespace
56 bool BPFAsmBackend::writeNopData(uint64_t Count, MCObjectWriter *OW) const {
60 for (uint64_t i = 0; i < Count; i += 8)
61 OW->write64(0x15000000);
66 void BPFAsmBackend::applyFixup(const MCAssembler &Asm, const MCFixup &Fixup,
67 const MCValue &Target,
68 MutableArrayRef<char> Data, uint64_t Value,
69 bool IsResolved) const {
70 if (Fixup.getKind() == FK_SecRel_4 || Fixup.getKind() == FK_SecRel_8) {
72 } else if (Fixup.getKind() == FK_Data_4 || Fixup.getKind() == FK_Data_8) {
73 unsigned Size = Fixup.getKind() == FK_Data_4 ? 4 : 8;
75 for (unsigned i = 0; i != Size; ++i) {
76 unsigned Idx = IsLittleEndian ? i : Size - i - 1;
77 Data[Fixup.getOffset() + Idx] = uint8_t(Value >> (i * 8));
79 } else if (Fixup.getKind() == FK_PCRel_4) {
80 Value = (uint32_t)((Value - 8) / 8);
82 Data[Fixup.getOffset() + 1] = 0x10;
83 support::endian::write32le(&Data[Fixup.getOffset() + 4], Value);
85 Data[Fixup.getOffset() + 1] = 0x1;
86 support::endian::write32be(&Data[Fixup.getOffset() + 4], Value);
89 assert(Fixup.getKind() == FK_PCRel_2);
90 Value = (uint16_t)((Value - 8) / 8);
92 Data[Fixup.getOffset() + 2] = Value & 0xFF;
93 Data[Fixup.getOffset() + 3] = Value >> 8;
95 Data[Fixup.getOffset() + 2] = Value >> 8;
96 Data[Fixup.getOffset() + 3] = Value & 0xFF;
101 std::unique_ptr<MCObjectWriter>
102 BPFAsmBackend::createObjectWriter(raw_pwrite_stream &OS) const {
103 return createBPFELFObjectWriter(OS, 0, IsLittleEndian);
106 MCAsmBackend *llvm::createBPFAsmBackend(const Target &T,
107 const MCSubtargetInfo &STI,
108 const MCRegisterInfo &MRI,
109 const MCTargetOptions &) {
110 return new BPFAsmBackend(/*IsLittleEndian=*/true);
113 MCAsmBackend *llvm::createBPFbeAsmBackend(const Target &T,
114 const MCSubtargetInfo &STI,
115 const MCRegisterInfo &MRI,
116 const MCTargetOptions &) {
117 return new BPFAsmBackend(/*IsLittleEndian=*/false);