1 //=- WebAssemblyMCCodeEmitter.cpp - Convert WebAssembly code to machine code -//
2 //
3 //                     The LLVM Compiler Infrastructure
4 //
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //
8 //===----------------------------------------------------------------------===//
9 ///
10 /// \file
11 /// \brief This file implements the WebAssemblyMCCodeEmitter class.
12 ///
13 //===----------------------------------------------------------------------===//
14 
15 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
16 #include "llvm/ADT/STLExtras.h"
17 #include "llvm/ADT/Statistic.h"
18 #include "llvm/MC/MCCodeEmitter.h"
19 #include "llvm/MC/MCFixup.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/MC/MCSymbol.h"
25 #include "llvm/Support/raw_ostream.h"
26 using namespace llvm;
27 
28 #define DEBUG_TYPE "mccodeemitter"
29 
30 STATISTIC(MCNumEmitted, "Number of MC instructions emitted.");
31 STATISTIC(MCNumFixups, "Number of MC fixups created.");
32 
33 namespace {
34 class WebAssemblyMCCodeEmitter final : public MCCodeEmitter {
35   const MCInstrInfo &MCII;
36 
37   // Implementation generated by tablegen.
38   uint64_t getBinaryCodeForInstr(const MCInst &MI,
39                                  SmallVectorImpl<MCFixup> &Fixups,
40                                  const MCSubtargetInfo &STI) const;
41 
42   void encodeInstruction(const MCInst &MI, raw_ostream &OS,
43                          SmallVectorImpl<MCFixup> &Fixups,
44                          const MCSubtargetInfo &STI) const override;
45 
46 public:
47   WebAssemblyMCCodeEmitter(const MCInstrInfo &mcii) : MCII(mcii) {}
48 };
49 } // end anonymous namespace
50 
51 MCCodeEmitter *llvm::createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII) {
52   return new WebAssemblyMCCodeEmitter(MCII);
53 }
54 
55 void WebAssemblyMCCodeEmitter::encodeInstruction(
56     const MCInst &MI, raw_ostream &OS, SmallVectorImpl<MCFixup> &Fixups,
57     const MCSubtargetInfo &STI) const {
58   // FIXME: This is not the real binary encoding. This is an extremely
59   // over-simplified encoding where we just use uint64_t for everything. This
60   // is a temporary measure.
61   support::endian::Writer<support::little>(OS).write<uint64_t>(MI.getOpcode());
62   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
63   if (Desc.isVariadic())
64     support::endian::Writer<support::little>(OS).write<uint64_t>(
65         MI.getNumOperands() - Desc.NumOperands);
66   for (unsigned i = 0, e = MI.getNumOperands(); i < e; ++i) {
67     const MCOperand &MO = MI.getOperand(i);
68     if (MO.isReg()) {
69       support::endian::Writer<support::little>(OS).write<uint64_t>(MO.getReg());
70     } else if (MO.isImm()) {
71       support::endian::Writer<support::little>(OS).write<uint64_t>(MO.getImm());
72     } else if (MO.isFPImm()) {
73       support::endian::Writer<support::little>(OS).write<double>(MO.getFPImm());
74     } else if (MO.isExpr()) {
75       support::endian::Writer<support::little>(OS).write<uint64_t>(0);
76       Fixups.push_back(MCFixup::create(
77           (1 + MCII.get(MI.getOpcode()).isVariadic() + i) * sizeof(uint64_t),
78           MO.getExpr(),
79           STI.getTargetTriple().isArch64Bit() ? FK_Data_8 : FK_Data_4,
80           MI.getLoc()));
81       ++MCNumFixups;
82     } else {
83       llvm_unreachable("unexpected operand kind");
84     }
85   }
86 
87   ++MCNumEmitted; // Keep track of the # of mi's emitted.
88 }
89 
90 #include "WebAssemblyGenMCCodeEmitter.inc"
91