xref: /openbsd-src/gnu/llvm/llvm/lib/Target/BPF/MCTargetDesc/BPFMCCodeEmitter.cpp (revision d415bd752c734aee168c4ee86ff32e8cc249eb16)
109467b48Spatrick //===-- BPFMCCodeEmitter.cpp - Convert BPF code to machine code -----------===//
209467b48Spatrick //
309467b48Spatrick // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
409467b48Spatrick // See https://llvm.org/LICENSE.txt for license information.
509467b48Spatrick // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
609467b48Spatrick //
709467b48Spatrick //===----------------------------------------------------------------------===//
809467b48Spatrick //
909467b48Spatrick // This file implements the BPFMCCodeEmitter class.
1009467b48Spatrick //
1109467b48Spatrick //===----------------------------------------------------------------------===//
1209467b48Spatrick 
1309467b48Spatrick #include "MCTargetDesc/BPFMCTargetDesc.h"
1409467b48Spatrick #include "llvm/ADT/SmallVector.h"
1509467b48Spatrick #include "llvm/MC/MCCodeEmitter.h"
1673471bf0Spatrick #include "llvm/MC/MCExpr.h"
1709467b48Spatrick #include "llvm/MC/MCFixup.h"
1809467b48Spatrick #include "llvm/MC/MCInst.h"
1909467b48Spatrick #include "llvm/MC/MCInstrInfo.h"
2009467b48Spatrick #include "llvm/MC/MCRegisterInfo.h"
2109467b48Spatrick #include "llvm/MC/MCSubtargetInfo.h"
2209467b48Spatrick #include "llvm/Support/Endian.h"
2309467b48Spatrick #include "llvm/Support/EndianStream.h"
2409467b48Spatrick #include <cassert>
2509467b48Spatrick #include <cstdint>
2609467b48Spatrick 
2709467b48Spatrick using namespace llvm;
2809467b48Spatrick 
2909467b48Spatrick #define DEBUG_TYPE "mccodeemitter"
3009467b48Spatrick 
3109467b48Spatrick namespace {
3209467b48Spatrick 
3309467b48Spatrick class BPFMCCodeEmitter : public MCCodeEmitter {
3409467b48Spatrick   const MCRegisterInfo &MRI;
3509467b48Spatrick   bool IsLittleEndian;
3609467b48Spatrick 
3709467b48Spatrick public:
BPFMCCodeEmitter(const MCInstrInfo &,const MCRegisterInfo & mri,bool IsLittleEndian)38*d415bd75Srobert   BPFMCCodeEmitter(const MCInstrInfo &, const MCRegisterInfo &mri,
3909467b48Spatrick                    bool IsLittleEndian)
40*d415bd75Srobert       : MRI(mri), IsLittleEndian(IsLittleEndian) { }
4109467b48Spatrick   BPFMCCodeEmitter(const BPFMCCodeEmitter &) = delete;
4209467b48Spatrick   void operator=(const BPFMCCodeEmitter &) = delete;
4309467b48Spatrick   ~BPFMCCodeEmitter() override = default;
4409467b48Spatrick 
4509467b48Spatrick   // getBinaryCodeForInstr - TableGen'erated function for getting the
4609467b48Spatrick   // binary encoding for an instruction.
4709467b48Spatrick   uint64_t getBinaryCodeForInstr(const MCInst &MI,
4809467b48Spatrick                                  SmallVectorImpl<MCFixup> &Fixups,
4909467b48Spatrick                                  const MCSubtargetInfo &STI) const;
5009467b48Spatrick 
5109467b48Spatrick   // getMachineOpValue - Return binary encoding of operand. If the machin
5209467b48Spatrick   // operand requires relocation, record the relocation and return zero.
5309467b48Spatrick   unsigned getMachineOpValue(const MCInst &MI, const MCOperand &MO,
5409467b48Spatrick                              SmallVectorImpl<MCFixup> &Fixups,
5509467b48Spatrick                              const MCSubtargetInfo &STI) const;
5609467b48Spatrick 
5709467b48Spatrick   uint64_t getMemoryOpValue(const MCInst &MI, unsigned Op,
5809467b48Spatrick                             SmallVectorImpl<MCFixup> &Fixups,
5909467b48Spatrick                             const MCSubtargetInfo &STI) const;
6009467b48Spatrick 
6109467b48Spatrick   void encodeInstruction(const MCInst &MI, raw_ostream &OS,
6209467b48Spatrick                          SmallVectorImpl<MCFixup> &Fixups,
6309467b48Spatrick                          const MCSubtargetInfo &STI) const override;
6409467b48Spatrick };
6509467b48Spatrick 
6609467b48Spatrick } // end anonymous namespace
6709467b48Spatrick 
createBPFMCCodeEmitter(const MCInstrInfo & MCII,MCContext & Ctx)6809467b48Spatrick MCCodeEmitter *llvm::createBPFMCCodeEmitter(const MCInstrInfo &MCII,
6909467b48Spatrick                                             MCContext &Ctx) {
70*d415bd75Srobert   return new BPFMCCodeEmitter(MCII, *Ctx.getRegisterInfo(), true);
7109467b48Spatrick }
7209467b48Spatrick 
createBPFbeMCCodeEmitter(const MCInstrInfo & MCII,MCContext & Ctx)7309467b48Spatrick MCCodeEmitter *llvm::createBPFbeMCCodeEmitter(const MCInstrInfo &MCII,
7409467b48Spatrick                                               MCContext &Ctx) {
75*d415bd75Srobert   return new BPFMCCodeEmitter(MCII, *Ctx.getRegisterInfo(), false);
7609467b48Spatrick }
7709467b48Spatrick 
getMachineOpValue(const MCInst & MI,const MCOperand & MO,SmallVectorImpl<MCFixup> & Fixups,const MCSubtargetInfo & STI) const7809467b48Spatrick unsigned BPFMCCodeEmitter::getMachineOpValue(const MCInst &MI,
7909467b48Spatrick                                              const MCOperand &MO,
8009467b48Spatrick                                              SmallVectorImpl<MCFixup> &Fixups,
8109467b48Spatrick                                              const MCSubtargetInfo &STI) const {
8209467b48Spatrick   if (MO.isReg())
8309467b48Spatrick     return MRI.getEncodingValue(MO.getReg());
8409467b48Spatrick   if (MO.isImm())
8509467b48Spatrick     return static_cast<unsigned>(MO.getImm());
8609467b48Spatrick 
8709467b48Spatrick   assert(MO.isExpr());
8809467b48Spatrick 
8909467b48Spatrick   const MCExpr *Expr = MO.getExpr();
9009467b48Spatrick 
9109467b48Spatrick   assert(Expr->getKind() == MCExpr::SymbolRef);
9209467b48Spatrick 
9309467b48Spatrick   if (MI.getOpcode() == BPF::JAL)
9409467b48Spatrick     // func call name
9509467b48Spatrick     Fixups.push_back(MCFixup::create(0, Expr, FK_PCRel_4));
9609467b48Spatrick   else if (MI.getOpcode() == BPF::LD_imm64)
9709467b48Spatrick     Fixups.push_back(MCFixup::create(0, Expr, FK_SecRel_8));
9809467b48Spatrick   else
9909467b48Spatrick     // bb label
10009467b48Spatrick     Fixups.push_back(MCFixup::create(0, Expr, FK_PCRel_2));
10109467b48Spatrick 
10209467b48Spatrick   return 0;
10309467b48Spatrick }
10409467b48Spatrick 
SwapBits(uint8_t Val)10509467b48Spatrick static uint8_t SwapBits(uint8_t Val)
10609467b48Spatrick {
10709467b48Spatrick   return (Val & 0x0F) << 4 | (Val & 0xF0) >> 4;
10809467b48Spatrick }
10909467b48Spatrick 
encodeInstruction(const MCInst & MI,raw_ostream & OS,SmallVectorImpl<MCFixup> & Fixups,const MCSubtargetInfo & STI) const11009467b48Spatrick void BPFMCCodeEmitter::encodeInstruction(const MCInst &MI, raw_ostream &OS,
11109467b48Spatrick                                          SmallVectorImpl<MCFixup> &Fixups,
11209467b48Spatrick                                          const MCSubtargetInfo &STI) const {
11309467b48Spatrick   unsigned Opcode = MI.getOpcode();
11409467b48Spatrick   support::endian::Writer OSE(OS,
11509467b48Spatrick                               IsLittleEndian ? support::little : support::big);
11609467b48Spatrick 
11709467b48Spatrick   if (Opcode == BPF::LD_imm64 || Opcode == BPF::LD_pseudo) {
11809467b48Spatrick     uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
11909467b48Spatrick     OS << char(Value >> 56);
12009467b48Spatrick     if (IsLittleEndian)
12109467b48Spatrick       OS << char((Value >> 48) & 0xff);
12209467b48Spatrick     else
12309467b48Spatrick       OS << char(SwapBits((Value >> 48) & 0xff));
12409467b48Spatrick     OSE.write<uint16_t>(0);
12509467b48Spatrick     OSE.write<uint32_t>(Value & 0xffffFFFF);
12609467b48Spatrick 
12709467b48Spatrick     const MCOperand &MO = MI.getOperand(1);
12809467b48Spatrick     uint64_t Imm = MO.isImm() ? MO.getImm() : 0;
12909467b48Spatrick     OSE.write<uint8_t>(0);
13009467b48Spatrick     OSE.write<uint8_t>(0);
13109467b48Spatrick     OSE.write<uint16_t>(0);
13209467b48Spatrick     OSE.write<uint32_t>(Imm >> 32);
13309467b48Spatrick   } else {
13409467b48Spatrick     // Get instruction encoding and emit it
13509467b48Spatrick     uint64_t Value = getBinaryCodeForInstr(MI, Fixups, STI);
13609467b48Spatrick     OS << char(Value >> 56);
13709467b48Spatrick     if (IsLittleEndian)
13809467b48Spatrick       OS << char((Value >> 48) & 0xff);
13909467b48Spatrick     else
14009467b48Spatrick       OS << char(SwapBits((Value >> 48) & 0xff));
14109467b48Spatrick     OSE.write<uint16_t>((Value >> 32) & 0xffff);
14209467b48Spatrick     OSE.write<uint32_t>(Value & 0xffffFFFF);
14309467b48Spatrick   }
14409467b48Spatrick }
14509467b48Spatrick 
14609467b48Spatrick // Encode BPF Memory Operand
getMemoryOpValue(const MCInst & MI,unsigned Op,SmallVectorImpl<MCFixup> & Fixups,const MCSubtargetInfo & STI) const14709467b48Spatrick uint64_t BPFMCCodeEmitter::getMemoryOpValue(const MCInst &MI, unsigned Op,
14809467b48Spatrick                                             SmallVectorImpl<MCFixup> &Fixups,
14909467b48Spatrick                                             const MCSubtargetInfo &STI) const {
15073471bf0Spatrick   // For CMPXCHG instructions, output is implicitly in R0/W0,
15173471bf0Spatrick   // so memory operand starts from operand 0.
15273471bf0Spatrick   int MemOpStartIndex = 1, Opcode = MI.getOpcode();
15373471bf0Spatrick   if (Opcode == BPF::CMPXCHGW32 || Opcode == BPF::CMPXCHGD)
15473471bf0Spatrick     MemOpStartIndex = 0;
15573471bf0Spatrick 
15609467b48Spatrick   uint64_t Encoding;
15773471bf0Spatrick   const MCOperand Op1 = MI.getOperand(MemOpStartIndex);
15809467b48Spatrick   assert(Op1.isReg() && "First operand is not register.");
15909467b48Spatrick   Encoding = MRI.getEncodingValue(Op1.getReg());
16009467b48Spatrick   Encoding <<= 16;
16173471bf0Spatrick   MCOperand Op2 = MI.getOperand(MemOpStartIndex + 1);
16209467b48Spatrick   assert(Op2.isImm() && "Second operand is not immediate.");
16309467b48Spatrick   Encoding |= Op2.getImm() & 0xffff;
16409467b48Spatrick   return Encoding;
16509467b48Spatrick }
16609467b48Spatrick 
16709467b48Spatrick #include "BPFGenMCCodeEmitter.inc"
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