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      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/EndianStream.h"
     26 #include "llvm/Support/raw_ostream.h"
     27 using namespace llvm;
     28 
     29 #define DEBUG_TYPE "mccodeemitter"
     30 
     31 STATISTIC(MCNumEmitted, "Number of MC instructions emitted.");
     32 STATISTIC(MCNumFixups, "Number of MC fixups created.");
     33 
     34 namespace {
     35 class WebAssemblyMCCodeEmitter final : public MCCodeEmitter {
     36   const MCInstrInfo &MCII;
     37 
     38   // Implementation generated by tablegen.
     39   uint64_t getBinaryCodeForInstr(const MCInst &MI,
     40                                  SmallVectorImpl<MCFixup> &Fixups,
     41                                  const MCSubtargetInfo &STI) const;
     42 
     43   void encodeInstruction(const MCInst &MI, raw_ostream &OS,
     44                          SmallVectorImpl<MCFixup> &Fixups,
     45                          const MCSubtargetInfo &STI) const override;
     46 
     47 public:
     48   WebAssemblyMCCodeEmitter(const MCInstrInfo &mcii) : MCII(mcii) {}
     49 };
     50 } // end anonymous namespace
     51 
     52 MCCodeEmitter *llvm::createWebAssemblyMCCodeEmitter(const MCInstrInfo &MCII) {
     53   return new WebAssemblyMCCodeEmitter(MCII);
     54 }
     55 
     56 void WebAssemblyMCCodeEmitter::encodeInstruction(
     57     const MCInst &MI, raw_ostream &OS, SmallVectorImpl<MCFixup> &Fixups,
     58     const MCSubtargetInfo &STI) const {
     59   // FIXME: This is not the real binary encoding. This is an extremely
     60   // over-simplified encoding where we just use uint64_t for everything. This
     61   // is a temporary measure.
     62   support::endian::Writer<support::little>(OS).write<uint64_t>(MI.getOpcode());
     63   const MCInstrDesc &Desc = MCII.get(MI.getOpcode());
     64   if (Desc.isVariadic())
     65     support::endian::Writer<support::little>(OS).write<uint64_t>(
     66         MI.getNumOperands() - Desc.NumOperands);
     67   for (unsigned i = 0, e = MI.getNumOperands(); i < e; ++i) {
     68     const MCOperand &MO = MI.getOperand(i);
     69     if (MO.isReg()) {
     70       support::endian::Writer<support::little>(OS).write<uint64_t>(MO.getReg());
     71     } else if (MO.isImm()) {
     72       support::endian::Writer<support::little>(OS).write<uint64_t>(MO.getImm());
     73     } else if (MO.isFPImm()) {
     74       support::endian::Writer<support::little>(OS).write<double>(MO.getFPImm());
     75     } else if (MO.isExpr()) {
     76       support::endian::Writer<support::little>(OS).write<uint64_t>(0);
     77       Fixups.push_back(MCFixup::create(
     78           (1 + MCII.get(MI.getOpcode()).isVariadic() + i) * sizeof(uint64_t),
     79           MO.getExpr(),
     80           STI.getTargetTriple().isArch64Bit() ? FK_Data_8 : FK_Data_4,
     81           MI.getLoc()));
     82       ++MCNumFixups;
     83     } else {
     84       llvm_unreachable("unexpected operand kind");
     85     }
     86   }
     87 
     88   ++MCNumEmitted; // Keep track of the # of mi's emitted.
     89 }
     90 
     91 #include "WebAssemblyGenMCCodeEmitter.inc"
     92