1 //===- WebAssemblyDisassemblerEmitter.cpp - Disassembler tables -*- C++ -*-===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file is part of the WebAssembly Disassembler Emitter.
10 // It contains the implementation of the disassembler tables.
11 // Documentation for the disassembler emitter in general can be found in
12 // WebAssemblyDisassemblerEmitter.h.
14 //===----------------------------------------------------------------------===//
16 #include "WebAssemblyDisassemblerEmitter.h"
17 #include "llvm/TableGen/Record.h"
21 static constexpr int WebAssemblyInstructionTableSize = 256;
23 void emitWebAssemblyDisassemblerTables(
25 const ArrayRef<const CodeGenInstruction *> &NumberedInstructions) {
26 // First lets organize all opcodes by (prefix) byte. Prefix 0 is the
29 std::map<unsigned, std::pair<unsigned, const CodeGenInstruction *>>>
31 for (unsigned I = 0; I != NumberedInstructions.size(); ++I) {
32 auto &CGI = *NumberedInstructions[I];
33 auto &Def = *CGI.TheDef;
34 if (!Def.getValue("Inst"))
36 auto &Inst = *Def.getValueAsBitsInit("Inst");
37 auto Opc = static_cast<unsigned>(
38 reinterpret_cast<IntInit *>(Inst.convertInitializerTo(IntRecTy::get()))
40 if (Opc == 0xFFFFFFFF)
41 continue; // No opcode defined.
42 assert(Opc <= 0xFFFF);
43 auto Prefix = Opc >> 8;
45 auto &CGIP = OpcodeTable[Prefix][Opc];
46 // All wasm instructions have a StackBased field of type string, we only
47 // want the instructions for which this is "true".
49 Def.getValue("StackBased")->getValue()->getCastTo(StringRecTy::get());
52 reinterpret_cast<const StringInit *>(StackString)->getValue() == "true";
56 // We already have an instruction for this slot, so decide which one
57 // should be the canonical one. This determines which variant gets
58 // printed in a disassembly. We want e.g. "call" not "i32.call", and
59 // "end" when we don't know if its "end_loop" or "end_block" etc.
60 auto IsCanonicalExisting = CGIP.second->TheDef->getValue("IsCanonical")
62 ->getAsString() == "1";
63 // We already have one marked explicitly as canonical, so keep it.
64 if (IsCanonicalExisting)
67 Def.getValue("IsCanonical")->getValue()->getAsString() == "1";
68 // If the new one is explicitly marked as canonical, take it.
69 if (!IsCanonicalNew) {
70 // Neither the existing or new instruction is canonical.
71 // Pick the one with the shortest name as heuristic.
72 // Though ideally IsCanonical is always defined for at least one
73 // variant so this never has to apply.
74 if (CGIP.second->AsmString.size() <= CGI.AsmString.size())
78 // Set this instruction as the one to use.
79 CGIP = std::make_pair(I, &CGI);
81 OS << "#include \"MCTargetDesc/WebAssemblyMCTargetDesc.h\"\n";
83 OS << "namespace llvm {\n\n";
84 OS << "static constexpr int WebAssemblyInstructionTableSize = ";
85 OS << WebAssemblyInstructionTableSize << ";\n\n";
86 OS << "enum EntryType : uint8_t { ";
87 OS << "ET_Unused, ET_Prefix, ET_Instruction };\n\n";
88 OS << "struct WebAssemblyInstruction {\n";
89 OS << " uint16_t Opcode;\n";
90 OS << " EntryType ET;\n";
91 OS << " uint8_t NumOperands;\n";
92 OS << " uint16_t OperandStart;\n";
94 std::vector<std::string> OperandTable, CurOperandList;
95 // Output one table per prefix.
96 for (auto &PrefixPair : OpcodeTable) {
97 if (PrefixPair.second.empty())
99 OS << "WebAssemblyInstruction InstructionTable" << PrefixPair.first;
101 for (unsigned I = 0; I < WebAssemblyInstructionTableSize; I++) {
102 auto InstIt = PrefixPair.second.find(I);
103 if (InstIt != PrefixPair.second.end()) {
104 // Regular instruction.
105 assert(InstIt->second.second);
106 auto &CGI = *InstIt->second.second;
108 OS.write_hex(static_cast<unsigned long long>(I));
109 OS << ": " << CGI.AsmString << "\n";
110 OS << " { " << InstIt->second.first << ", ET_Instruction, ";
111 OS << CGI.Operands.OperandList.size() << ", ";
112 // Collect operand types for storage in a shared list.
113 CurOperandList.clear();
114 for (auto &Op : CGI.Operands.OperandList) {
115 assert(Op.OperandType != "MCOI::OPERAND_UNKNOWN");
116 CurOperandList.push_back(Op.OperandType);
118 // See if we already have stored this sequence before. This is not
119 // strictly necessary but makes the table really small.
120 size_t OperandStart = OperandTable.size();
121 if (CurOperandList.size() <= OperandTable.size()) {
122 for (size_t J = 0; J <= OperandTable.size() - CurOperandList.size();
125 for (; K < CurOperandList.size(); ++K) {
126 if (OperandTable[J + K] != CurOperandList[K]) break;
128 if (K == CurOperandList.size()) {
134 // Store operands if no prior occurrence.
135 if (OperandStart == OperandTable.size()) {
136 OperandTable.insert(OperandTable.end(), CurOperandList.begin(),
137 CurOperandList.end());
141 auto PrefixIt = OpcodeTable.find(I);
142 // If we have a non-empty table for it that's not 0, this is a prefix.
143 if (PrefixIt != OpcodeTable.end() && I && !PrefixPair.first) {
144 OS << " { 0, ET_Prefix, 0, 0";
146 OS << " { 0, ET_Unused, 0, 0";
153 // Create a table of all operands:
154 OS << "const uint8_t OperandTable[] = {\n";
155 for (auto &Op : OperandTable) {
156 OS << " " << Op << ",\n";
159 // Create a table of all extension tables:
160 OS << "struct { uint8_t Prefix; const WebAssemblyInstruction *Table; }\n";
161 OS << "PrefixTable[] = {\n";
162 for (auto &PrefixPair : OpcodeTable) {
163 if (PrefixPair.second.empty() || !PrefixPair.first)
165 OS << " { " << PrefixPair.first << ", InstructionTable"
169 OS << " { 0, nullptr }\n};\n\n";
170 OS << "} // end namespace llvm\n";