1 //===- R600MCCodeEmitter.cpp - Code Emitter for R600->Cayman GPU families -===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 /// \file
10 ///
11 /// The R600 code emitter produces machine code that can be executed
12 /// directly on the GPU device.
13 //
14 //===----------------------------------------------------------------------===//
15 
16 #include "MCTargetDesc/R600MCTargetDesc.h"
17 #include "R600Defines.h"
18 #include "llvm/MC/MCCodeEmitter.h"
19 #include "llvm/MC/MCContext.h"
20 #include "llvm/MC/MCInst.h"
21 #include "llvm/MC/MCInstrInfo.h"
22 #include "llvm/MC/MCRegisterInfo.h"
23 #include "llvm/MC/MCSubtargetInfo.h"
24 #include "llvm/Support/EndianStream.h"
25 #include "llvm/TargetParser/SubtargetFeature.h"
26 
27 using namespace llvm;
28 
29 namespace {
30 
31 class R600MCCodeEmitter : public MCCodeEmitter {
32   const MCRegisterInfo &MRI;
33   const MCInstrInfo &MCII;
34 
35 public:
R600MCCodeEmitter(const MCInstrInfo & mcii,const MCRegisterInfo & mri)36   R600MCCodeEmitter(const MCInstrInfo &mcii, const MCRegisterInfo &mri)
37     : MRI(mri), MCII(mcii) {}
38   R600MCCodeEmitter(const R600MCCodeEmitter &) = delete;
39   R600MCCodeEmitter &operator=(const R600MCCodeEmitter &) = delete;
40 
41   /// Encode the instruction and write it to the OS.
42   void encodeInstruction(const MCInst &MI, SmallVectorImpl<char> &CB,
43                          SmallVectorImpl<MCFixup> &Fixups,
44                          const MCSubtargetInfo &STI) const override;
45 
46   /// \returns the encoding for an MCOperand.
47   uint64_t getMachineOpValue(const MCInst &MI, const MCOperand &MO,
48                              SmallVectorImpl<MCFixup> &Fixups,
49                              const MCSubtargetInfo &STI) const;
50 
51 private:
52   void emit(uint32_t value, SmallVectorImpl<char> &CB) const;
53   void emit(uint64_t value, SmallVectorImpl<char> &CB) const;
54 
55   unsigned getHWReg(unsigned regNo) const;
56 
57   uint64_t getBinaryCodeForInstr(const MCInst &MI,
58                                  SmallVectorImpl<MCFixup> &Fixups,
59                                  const MCSubtargetInfo &STI) const;
60 };
61 
62 } // end anonymous namespace
63 
64 enum RegElement {
65   ELEMENT_X = 0,
66   ELEMENT_Y,
67   ELEMENT_Z,
68   ELEMENT_W
69 };
70 
71 enum FCInstr {
72   FC_IF_PREDICATE = 0,
73   FC_ELSE,
74   FC_ENDIF,
75   FC_BGNLOOP,
76   FC_ENDLOOP,
77   FC_BREAK_PREDICATE,
78   FC_CONTINUE
79 };
80 
createR600MCCodeEmitter(const MCInstrInfo & MCII,MCContext & Ctx)81 MCCodeEmitter *llvm::createR600MCCodeEmitter(const MCInstrInfo &MCII,
82                                              MCContext &Ctx) {
83   return new R600MCCodeEmitter(MCII, *Ctx.getRegisterInfo());
84 }
85 
encodeInstruction(const MCInst & MI,SmallVectorImpl<char> & CB,SmallVectorImpl<MCFixup> & Fixups,const MCSubtargetInfo & STI) const86 void R600MCCodeEmitter::encodeInstruction(const MCInst &MI,
87                                           SmallVectorImpl<char> &CB,
88                                           SmallVectorImpl<MCFixup> &Fixups,
89                                           const MCSubtargetInfo &STI) const {
90   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
91   if (MI.getOpcode() == R600::RETURN ||
92     MI.getOpcode() == R600::FETCH_CLAUSE ||
93     MI.getOpcode() == R600::ALU_CLAUSE ||
94     MI.getOpcode() == R600::BUNDLE ||
95     MI.getOpcode() == R600::KILL) {
96     return;
97   } else if (IS_VTX(Desc)) {
98     uint64_t InstWord01 = getBinaryCodeForInstr(MI, Fixups, STI);
99     uint32_t InstWord2 = MI.getOperand(2).getImm(); // Offset
100     if (!(STI.hasFeature(R600::FeatureCaymanISA))) {
101       InstWord2 |= 1 << 19; // Mega-Fetch bit
102     }
103 
104     emit(InstWord01, CB);
105     emit(InstWord2, CB);
106     emit((uint32_t)0, CB);
107   } else if (IS_TEX(Desc)) {
108       int64_t Sampler = MI.getOperand(14).getImm();
109 
110       int64_t SrcSelect[4] = {
111         MI.getOperand(2).getImm(),
112         MI.getOperand(3).getImm(),
113         MI.getOperand(4).getImm(),
114         MI.getOperand(5).getImm()
115       };
116       int64_t Offsets[3] = {
117         MI.getOperand(6).getImm() & 0x1F,
118         MI.getOperand(7).getImm() & 0x1F,
119         MI.getOperand(8).getImm() & 0x1F
120       };
121 
122       uint64_t Word01 = getBinaryCodeForInstr(MI, Fixups, STI);
123       uint32_t Word2 = Sampler << 15 | SrcSelect[ELEMENT_X] << 20 |
124           SrcSelect[ELEMENT_Y] << 23 | SrcSelect[ELEMENT_Z] << 26 |
125           SrcSelect[ELEMENT_W] << 29 | Offsets[0] << 0 | Offsets[1] << 5 |
126           Offsets[2] << 10;
127 
128       emit(Word01, CB);
129       emit(Word2, CB);
130       emit((uint32_t)0, CB);
131   } else {
132     uint64_t Inst = getBinaryCodeForInstr(MI, Fixups, STI);
133     if ((STI.hasFeature(R600::FeatureR600ALUInst)) &&
134        ((Desc.TSFlags & R600_InstFlag::OP1) ||
135          Desc.TSFlags & R600_InstFlag::OP2)) {
136       uint64_t ISAOpCode = Inst & (0x3FFULL << 39);
137       Inst &= ~(0x3FFULL << 39);
138       Inst |= ISAOpCode << 1;
139     }
140     emit(Inst, CB);
141   }
142 }
143 
emit(uint32_t Value,SmallVectorImpl<char> & CB) const144 void R600MCCodeEmitter::emit(uint32_t Value, SmallVectorImpl<char> &CB) const {
145   support::endian::write(CB, Value, llvm::endianness::little);
146 }
147 
emit(uint64_t Value,SmallVectorImpl<char> & CB) const148 void R600MCCodeEmitter::emit(uint64_t Value, SmallVectorImpl<char> &CB) const {
149   support::endian::write(CB, Value, llvm::endianness::little);
150 }
151 
getHWReg(unsigned RegNo) const152 unsigned R600MCCodeEmitter::getHWReg(unsigned RegNo) const {
153   return MRI.getEncodingValue(RegNo) & HW_REG_MASK;
154 }
155 
getMachineOpValue(const MCInst & MI,const MCOperand & MO,SmallVectorImpl<MCFixup> & Fixups,const MCSubtargetInfo & STI) const156 uint64_t R600MCCodeEmitter::getMachineOpValue(const MCInst &MI,
157                                               const MCOperand &MO,
158                                         SmallVectorImpl<MCFixup> &Fixups,
159                                         const MCSubtargetInfo &STI) const {
160   if (MO.isReg()) {
161     if (HAS_NATIVE_OPERANDS(MCII.get(MI.getOpcode()).TSFlags))
162       return MRI.getEncodingValue(MO.getReg());
163     return getHWReg(MO.getReg());
164   }
165 
166   if (MO.isExpr()) {
167     // We put rodata at the end of code section, then map the entire
168     // code secetion as vtx buf. Thus the section relative address is the
169     // correct one.
170     // Each R600 literal instruction has two operands
171     // We can't easily get the order of the current one, so compare against
172     // the first one and adjust offset.
173     const unsigned offset = (&MO == &MI.getOperand(0)) ? 0 : 4;
174     Fixups.push_back(MCFixup::create(offset, MO.getExpr(), FK_SecRel_4, MI.getLoc()));
175     return 0;
176   }
177 
178   assert(MO.isImm());
179   return MO.getImm();
180 }
181 
182 #include "R600GenMCCodeEmitter.inc"
183