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 /// 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/CodeGen/TargetRegisterInfo.h"
22 #include "llvm/MC/MCExpr.h"
23 #include "llvm/MC/MCInst.h"
24 #include "llvm/MC/MCInstrInfo.h"
25 #include "llvm/MC/MCSubtargetInfo.h"
26 #include "llvm/MC/MCSymbol.h"
27 #include "llvm/Support/ErrorHandling.h"
28 #include "llvm/Support/FormattedStream.h"
29 using namespace llvm;
30 
31 #define DEBUG_TYPE "asm-printer"
32 
33 #include "WebAssemblyGenAsmWriter.inc"
34 
35 WebAssemblyInstPrinter::WebAssemblyInstPrinter(const MCAsmInfo &MAI,
36                                                const MCInstrInfo &MII,
37                                                const MCRegisterInfo &MRI)
38     : MCInstPrinter(MAI, MII, MRI) {}
39 
40 void WebAssemblyInstPrinter::printRegName(raw_ostream &OS,
41                                           unsigned RegNo) const {
42   assert(RegNo != WebAssemblyFunctionInfo::UnusedReg);
43   // Note that there's an implicit local.get/local.set here!
44   OS << "$" << RegNo;
45 }
46 
47 void 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       // FIXME: For CALL_INDIRECT_VOID, don't print a leading comma, because
58       // we have an extra flags operand which is not currently printed, for
59       // compatiblity reasons.
60       if (i != 0 && ((MI->getOpcode() != WebAssembly::CALL_INDIRECT_VOID &&
61                       MI->getOpcode() != WebAssembly::CALL_INDIRECT_VOID_S) ||
62                      i != Desc.getNumOperands()))
63         OS << ", ";
64       printOperand(MI, i, OS);
65     }
66 
67   // Print any added annotation.
68   printAnnotation(OS, Annot);
69 
70   if (CommentStream) {
71     // Observe any effects on the control flow stack, for use in annotating
72     // control flow label references.
73     unsigned Opc = MI->getOpcode();
74     switch (Opc) {
75     default:
76       break;
77 
78     case WebAssembly::LOOP:
79     case WebAssembly::LOOP_S:
80       printAnnotation(OS, "label" + utostr(ControlFlowCounter) + ':');
81       ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, true));
82       break;
83 
84     case WebAssembly::BLOCK:
85     case WebAssembly::BLOCK_S:
86       ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
87       break;
88 
89     case WebAssembly::TRY:
90     case WebAssembly::TRY_S:
91       ControlFlowStack.push_back(std::make_pair(ControlFlowCounter++, false));
92       EHPadStack.push_back(EHPadStackCounter++);
93       LastSeenEHInst = TRY;
94       break;
95 
96     case WebAssembly::END_LOOP:
97     case WebAssembly::END_LOOP_S:
98       if (ControlFlowStack.empty()) {
99         printAnnotation(OS, "End marker mismatch!");
100       } else {
101         ControlFlowStack.pop_back();
102       }
103       break;
104 
105     case WebAssembly::END_BLOCK:
106     case WebAssembly::END_BLOCK_S:
107       if (ControlFlowStack.empty()) {
108         printAnnotation(OS, "End marker mismatch!");
109       } else {
110         printAnnotation(
111             OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':');
112       }
113       break;
114 
115     case WebAssembly::END_TRY:
116     case WebAssembly::END_TRY_S:
117       if (ControlFlowStack.empty()) {
118         printAnnotation(OS, "End marker mismatch!");
119       } else {
120         printAnnotation(
121             OS, "label" + utostr(ControlFlowStack.pop_back_val().first) + ':');
122         LastSeenEHInst = END_TRY;
123       }
124       break;
125 
126     case WebAssembly::CATCH_I32:
127     case WebAssembly::CATCH_I32_S:
128     case WebAssembly::CATCH_I64:
129     case WebAssembly::CATCH_I64_S:
130     case WebAssembly::CATCH_ALL:
131     case WebAssembly::CATCH_ALL_S:
132       // There can be multiple catch instructions for one try instruction, so we
133       // print a label only for the first 'catch' label.
134       if (LastSeenEHInst != CATCH) {
135         if (EHPadStack.empty()) {
136           printAnnotation(OS, "try-catch mismatch!");
137         } else {
138           printAnnotation(OS,
139                           "catch" + utostr(EHPadStack.pop_back_val()) + ':');
140         }
141       }
142       LastSeenEHInst = CATCH;
143       break;
144     }
145 
146     // Annotate any control flow label references.
147     unsigned NumFixedOperands = Desc.NumOperands;
148     SmallSet<uint64_t, 8> Printed;
149     for (unsigned i = 0, e = MI->getNumOperands(); i < e; ++i) {
150       // See if this operand denotes a basic block target.
151       if (i < NumFixedOperands) {
152         // A non-variable_ops operand, check its type.
153         if (Desc.OpInfo[i].OperandType != WebAssembly::OPERAND_BASIC_BLOCK)
154           continue;
155       } else {
156         // A variable_ops operand, which currently can be immediates (used in
157         // br_table) which are basic block targets, or for call instructions
158         // when using -wasm-keep-registers (in which case they are registers,
159         // and should not be processed).
160         if (!MI->getOperand(i).isImm())
161           continue;
162       }
163       uint64_t Depth = MI->getOperand(i).getImm();
164       if (!Printed.insert(Depth).second)
165         continue;
166 
167       if (Opc == WebAssembly::RETHROW || Opc == WebAssembly::RETHROW_S) {
168         if (Depth > EHPadStack.size()) {
169           printAnnotation(OS, "Invalid depth argument!");
170         } else if (Depth == EHPadStack.size()) {
171           // This can happen when rethrow instruction breaks out of all nests
172           // and throws up to the current function's caller.
173           printAnnotation(OS, utostr(Depth) + ": " + "to caller");
174         } else {
175           uint64_t CatchNo = EHPadStack.rbegin()[Depth];
176           printAnnotation(OS, utostr(Depth) + ": " + "down to catch" +
177                                   utostr(CatchNo));
178         }
179 
180       } else {
181         if (Depth >= ControlFlowStack.size()) {
182           printAnnotation(OS, "Invalid depth argument!");
183         } else {
184           const auto &Pair = ControlFlowStack.rbegin()[Depth];
185           printAnnotation(OS, utostr(Depth) + ": " +
186                                   (Pair.second ? "up" : "down") + " to label" +
187                                   utostr(Pair.first));
188         }
189       }
190     }
191   }
192 }
193 
194 static std::string toString(const APFloat &FP) {
195   // Print NaNs with custom payloads specially.
196   if (FP.isNaN() && !FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) &&
197       !FP.bitwiseIsEqual(
198           APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) {
199     APInt AI = FP.bitcastToAPInt();
200     return std::string(AI.isNegative() ? "-" : "") + "nan:0x" +
201            utohexstr(AI.getZExtValue() &
202                          (AI.getBitWidth() == 32 ? INT64_C(0x007fffff)
203                                                  : INT64_C(0x000fffffffffffff)),
204                      /*LowerCase=*/true);
205   }
206 
207   // Use C99's hexadecimal floating-point representation.
208   static const size_t BufBytes = 128;
209   char buf[BufBytes];
210   auto Written = FP.convertToHexString(
211       buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
212   (void)Written;
213   assert(Written != 0);
214   assert(Written < BufBytes);
215   return buf;
216 }
217 
218 void WebAssemblyInstPrinter::printOperand(const MCInst *MI, unsigned OpNo,
219                                           raw_ostream &O) {
220   const MCOperand &Op = MI->getOperand(OpNo);
221   if (Op.isReg()) {
222     unsigned WAReg = Op.getReg();
223     if (int(WAReg) >= 0)
224       printRegName(O, WAReg);
225     else if (OpNo >= MII.get(MI->getOpcode()).getNumDefs())
226       O << "$pop" << WebAssemblyFunctionInfo::getWARegStackId(WAReg);
227     else if (WAReg != WebAssemblyFunctionInfo::UnusedReg)
228       O << "$push" << WebAssemblyFunctionInfo::getWARegStackId(WAReg);
229     else
230       O << "$drop";
231     // Add a '=' suffix if this is a def.
232     if (OpNo < MII.get(MI->getOpcode()).getNumDefs())
233       O << '=';
234   } else if (Op.isImm()) {
235     O << Op.getImm();
236   } else if (Op.isFPImm()) {
237     const MCInstrDesc &Desc = MII.get(MI->getOpcode());
238     const MCOperandInfo &Info = Desc.OpInfo[OpNo];
239     if (Info.OperandType == WebAssembly::OPERAND_F32IMM) {
240       // TODO: MC converts all floating point immediate operands to double.
241       // This is fine for numeric values, but may cause NaNs to change bits.
242       O << ::toString(APFloat(float(Op.getFPImm())));
243     } else {
244       assert(Info.OperandType == WebAssembly::OPERAND_F64IMM);
245       O << ::toString(APFloat(Op.getFPImm()));
246     }
247   } else {
248     assert(Op.isExpr() && "unknown operand kind in printOperand");
249     Op.getExpr()->print(O, &MAI);
250   }
251 }
252 
253 void WebAssemblyInstPrinter::printBrList(const MCInst *MI, unsigned OpNo,
254                                          raw_ostream &O) {
255   O << "{";
256   for (unsigned I = OpNo, E = MI->getNumOperands(); I != E; ++I) {
257     if (I != OpNo)
258       O << ", ";
259     O << MI->getOperand(I).getImm();
260   }
261   O << "}";
262 }
263 
264 void WebAssemblyInstPrinter::printWebAssemblyP2AlignOperand(const MCInst *MI,
265                                                             unsigned OpNo,
266                                                             raw_ostream &O) {
267   int64_t Imm = MI->getOperand(OpNo).getImm();
268   if (Imm == WebAssembly::GetDefaultP2Align(MI->getOpcode()))
269     return;
270   O << ":p2align=" << Imm;
271 }
272 
273 void WebAssemblyInstPrinter::printWebAssemblySignatureOperand(const MCInst *MI,
274                                                               unsigned OpNo,
275                                                               raw_ostream &O) {
276   auto Imm = static_cast<unsigned>(MI->getOperand(OpNo).getImm());
277   if (Imm != wasm::WASM_TYPE_NORESULT)
278     O << WebAssembly::anyTypeToString(Imm);
279 }
280 
281 // We have various enums representing a subset of these types, use this
282 // function to convert any of them to text.
283 const char *llvm::WebAssembly::anyTypeToString(unsigned Ty) {
284   switch (Ty) {
285   case wasm::WASM_TYPE_I32:
286     return "i32";
287   case wasm::WASM_TYPE_I64:
288     return "i64";
289   case wasm::WASM_TYPE_F32:
290     return "f32";
291   case wasm::WASM_TYPE_F64:
292     return "f64";
293   case wasm::WASM_TYPE_V128:
294     return "v128";
295   case wasm::WASM_TYPE_FUNCREF:
296     return "funcref";
297   case wasm::WASM_TYPE_FUNC:
298     return "func";
299   case wasm::WASM_TYPE_EXCEPT_REF:
300     return "except_ref";
301   case wasm::WASM_TYPE_NORESULT:
302     return "void";
303   default:
304     return "invalid_type";
305   }
306 }
307 
308 const char *llvm::WebAssembly::typeToString(wasm::ValType Ty) {
309   return anyTypeToString(static_cast<unsigned>(Ty));
310 }
311