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      1 //=- WebAssemblyInstPrinter.cpp - WebAssembly assembly instruction printing -=//
      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 Print MCInst instructions to wasm format.
     12 ///
     13 //===----------------------------------------------------------------------===//
     14 
     15 #include "InstPrinter/WebAssemblyInstPrinter.h"
     16 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
     17 #include "WebAssembly.h"
     18 #include "WebAssemblyMachineFunctionInfo.h"
     19 #include "llvm/MC/MCExpr.h"
     20 #include "llvm/MC/MCInst.h"
     21 #include "llvm/MC/MCInstrInfo.h"
     22 #include "llvm/MC/MCSubtargetInfo.h"
     23 #include "llvm/MC/MCSymbol.h"
     24 #include "llvm/Support/ErrorHandling.h"
     25 #include "llvm/Support/FormattedStream.h"
     26 #include "llvm/Target/TargetRegisterInfo.h"
     27 using namespace llvm;
     28 
     29 #define DEBUG_TYPE "asm-printer"
     30 
     31 #include "WebAssemblyGenAsmWriter.inc"
     32 
     33 WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI,
     34                                                const MCInstrInfo &MII,
     35                                                const MCRegisterInfo &MRI)
     36     : MCInstPrinter(MAI, MII, MRI) {}
     37 
     38 void WebAssemblyInstPrinter::printRegName(raw_ostream &OS,
     39                                           unsigned RegNo) const {
     40   assert(RegNo != WebAssemblyFunctionInfo::UnusedReg);
     41   // Note that there's an implicit get_local/set_local here!
     42   OS << "$" << RegNo;
     43 }
     44 
     45 void WebAssemblyInstPrinter::printInst(const MCInst *MI, raw_ostream &OS,
     46                                        StringRef Annot,
     47                                        const MCSubtargetInfo & /*STI*/) {
     48   // Print the instruction (this uses the AsmStrings from the .td files).
     49   printInstruction(MI, OS);
     50 
     51   // Print any additional variadic operands.
     52   const MCInstrDesc &Desc = MII.get(MI->getOpcode());
     53   if (Desc.isVariadic())
     54     for (auto i = Desc.getNumOperands(), e = MI->getNumOperands(); i < e; ++i) {
     55       if (i != 0)
     56         OS << ", ";
     57       printOperand(MI, i, OS);
     58     }
     59 
     60   // Print any added annotation.
     61   printAnnotation(OS, Annot);
     62 }
     63 
     64 static std::string toString(const APFloat &FP) {
     65   static const size_t BufBytes = 128;
     66   char buf[BufBytes];
     67   if (FP.isNaN())
     68     assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
     69             FP.bitwiseIsEqual(
     70                 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
     71            "convertToHexString handles neither SNaN nor NaN payloads");
     72   // Use C99's hexadecimal floating-point representation.
     73   auto Written = FP.convertToHexString(
     74       buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
     75   (void)Written;
     76   assert(Written != 0);
     77   assert(Written < BufBytes);
     78   return buf;
     79 }
     80 
     81 void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
     82                                           raw_ostream &O) {
     83   const MCOperand &Op = MI->getOperand(OpNo);
     84   if (Op.isReg()) {
     85     unsigned WAReg = Op.getReg();
     86     if (int(WAReg) >= 0)
     87       printRegName(O, WAReg);
     88     else if (OpNo >= MII.get(MI->getOpcode()).getNumDefs())
     89       O << "$pop" << (WAReg & INT32_MAX);
     90     else if (WAReg != WebAssemblyFunctionInfo::UnusedReg)
     91       O << "$push" << (WAReg & INT32_MAX);
     92     else
     93       O << "$discard";
     94     // Add a '=' suffix if this is a def.
     95     if (OpNo < MII.get(MI->getOpcode()).getNumDefs())
     96       O << '=';
     97   } else if (Op.isImm()) {
     98     switch (MI->getOpcode()) {
     99     case WebAssembly::PARAM:
    100     case WebAssembly::RESULT:
    101     case WebAssembly::LOCAL:
    102       O << WebAssembly::TypeToString(MVT::SimpleValueType(Op.getImm()));
    103       break;
    104     default:
    105       O << Op.getImm();
    106       break;
    107     }
    108   } else if (Op.isFPImm())
    109     O << toString(APFloat(Op.getFPImm()));
    110   else {
    111     assert(Op.isExpr() && "unknown operand kind in printOperand");
    112     Op.getExpr()->print(O, &MAI);
    113   }
    114 }
    115 
    116 const char *llvm::WebAssembly::TypeToString(MVT Ty) {
    117   switch (Ty.SimpleTy) {
    118   case MVT::i32:
    119     return "i32";
    120   case MVT::i64:
    121     return "i64";
    122   case MVT::f32:
    123     return "f32";
    124   case MVT::f64:
    125     return "f64";
    126   default:
    127     llvm_unreachable("unsupported type");
    128   }
    129 }
    130