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/ADT/SmallSet.h"
20#include "llvm/ADT/StringExtras.h"
21#include "llvm/MC/MCExpr.h"
22#include "llvm/MC/MCInst.h"
23#include "llvm/MC/MCInstrInfo.h"
24#include "llvm/MC/MCSubtargetInfo.h"
25#include "llvm/MC/MCSymbol.h"
26#include "llvm/Support/ErrorHandling.h"
27#include "llvm/Support/FormattedStream.h"
28#include "llvm/Target/TargetRegisterInfo.h"
29using namespace llvm;
30
31#define DEBUG_TYPE "asm-printer"
32
33#include "WebAssemblyGenAsmWriter.inc"
34
35WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI,
36                                               const MCInstrInfo &MII,
37                                               const MCRegisterInfo &MRI)
38    : MCInstPrinter(MAI, MII, MRI), ControlFlowCounter(0) {}
39
40void WebAssemblyInstPrinter::printRegName(raw_ostream &OS,
41                                          unsigned RegNo) const {
42  assert(RegNo != WebAssemblyFunctionInfo::UnusedReg);
43  // Note that there's an implicit get_local/set_local here!
44  OS << "$" << RegNo;
45}
46
47void WebAssemblyInstPrinter::printInst(const MCInst *MI, raw_ostream &OS,
48                                       StringRef Annot,
49                                       const MCSubtargetInfo & /*STI*/) {
50  // Print the instruction (this uses the AsmStrings from the .td files).
51  printInstruction(MI, OS);
52
53  // Print any additional variadic operands.
54  const MCInstrDesc &Desc = MII.get(MI->getOpcode());
55  if (Desc.isVariadic())
56    for (auto i = Desc.getNumOperands(), e = MI->getNumOperands(); i < e; ++i) {
57      if (i != 0)
58        OS << ", ";
59      printOperand(MI, i, OS);
60    }
61
62  // Print any added annotation.
63  printAnnotation(OS, Annot);
64
65  if (CommentStream) {
66    // Observe any effects on the control flow stack, for use in annotating
67    // control flow label references.
68    switch (MI->getOpcode()) {
69    default:
70      break;
71    case WebAssembly::LOOP: {
72      // Grab the TopLabel value first so that labels print in numeric order.
73      uint64_t TopLabel = ControlFlowCounter++;
74      ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
75      printAnnotation(OS, "label" + utostr(TopLabel) + ':');
76      ControlFlowStack.push_back(std::make_pair(TopLabel, true));
77      break;
78    }
79    case WebAssembly::BLOCK:
80      ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
81      break;
82    case WebAssembly::END_LOOP:
83      ControlFlowStack.pop_back();
84      printAnnotation(
85          OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':');
86      break;
87    case WebAssembly::END_BLOCK:
88      printAnnotation(
89          OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':');
90      break;
91    }
92
93    // Annotate any control flow label references.
94    unsigned NumFixedOperands = Desc.NumOperands;
95    SmallSet<uint64_t, 8> Printed;
96    for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
97      const MCOperandInfo &Info = Desc.OpInfo[i];
98      if (!(i < NumFixedOperands
99                ? (Info.OperandType == WebAssembly::OPERAND_BASIC_BLOCK)
100                : (Desc.TSFlags & WebAssemblyII::VariableOpImmediateIsLabel)))
101        continue;
102      uint64_t Depth = MI->getOperand(i).getImm();
103      if (!Printed.insert(Depth).second)
104        continue;
105      const auto &Pair = ControlFlowStack.rbegin()[Depth];
106      printAnnotation(OS, utostr(Depth) + ": " + (Pair.second ? "up" : "down") +
107                              " to label" + utostr(Pair.first));
108    }
109  }
110}
111
112static std::string toString(const APFloat &FP) {
113  static const size_t BufBytes = 128;
114  char buf[BufBytes];
115  if (FP.isNaN())
116    assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
117            FP.bitwiseIsEqual(
118                APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
119           "convertToHexString handles neither SNaN nor NaN payloads");
120  // Use C99's hexadecimal floating-point representation.
121  auto Written = FP.convertToHexString(
122      buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
123  (void)Written;
124  assert(Written != 0);
125  assert(Written < BufBytes);
126  return buf;
127}
128
129void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
130                                          raw_ostream &O) {
131  const MCOperand &Op = MI->getOperand(OpNo);
132  if (Op.isReg()) {
133    assert((OpNo < MII.get(MI->getOpcode()).getNumOperands() ||
134            MII.get(MI->getOpcode()).TSFlags == 0) &&
135           "WebAssembly variable_ops register ops don't use TSFlags");
136    unsigned WAReg = Op.getReg();
137    if (int(WAReg) >= 0)
138      printRegName(O, WAReg);
139    else if (OpNo >= MII.get(MI->getOpcode()).getNumDefs())
140      O << "$pop" << (WAReg & INT32_MAX);
141    else if (WAReg != WebAssemblyFunctionInfo::UnusedReg)
142      O << "$push" << (WAReg & INT32_MAX);
143    else
144      O << "$discard";
145    // Add a '=' suffix if this is a def.
146    if (OpNo < MII.get(MI->getOpcode()).getNumDefs())
147      O << '=';
148  } else if (Op.isImm()) {
149    assert((OpNo < MII.get(MI->getOpcode()).getNumOperands() ||
150            (MII.get(MI->getOpcode()).TSFlags &
151             WebAssemblyII::VariableOpIsImmediate)) &&
152           "WebAssemblyII::VariableOpIsImmediate should be set for "
153           "variable_ops immediate ops");
154    // TODO: (MII.get(MI->getOpcode()).TSFlags &
155    //        WebAssemblyII::VariableOpImmediateIsLabel)
156    // can tell us whether this is an immediate referencing a label in the
157    // control flow stack, and it may be nice to pretty-print.
158    O << Op.getImm();
159  } else if (Op.isFPImm()) {
160    assert((OpNo < MII.get(MI->getOpcode()).getNumOperands() ||
161            MII.get(MI->getOpcode()).TSFlags == 0) &&
162           "WebAssembly variable_ops floating point ops don't use TSFlags");
163    O << toString(APFloat(Op.getFPImm()));
164  } else {
165    assert((OpNo < MII.get(MI->getOpcode()).getNumOperands() ||
166            (MII.get(MI->getOpcode()).TSFlags &
167             WebAssemblyII::VariableOpIsImmediate)) &&
168           "WebAssemblyII::VariableOpIsImmediate should be set for "
169           "variable_ops expr ops");
170    assert(Op.isExpr() && "unknown operand kind in printOperand");
171    Op.getExpr()->print(O, &MAI);
172  }
173}
174
175const char *llvm::WebAssembly::TypeToString(MVT Ty) {
176  switch (Ty.SimpleTy) {
177  case MVT::i32:
178    return "i32";
179  case MVT::i64:
180    return "i64";
181  case MVT::f32:
182    return "f32";
183  case MVT::f64:
184    return "f64";
185  default:
186    llvm_unreachable("unsupported type");
187  }
188}
189