1 //===-- WebAssemblyAsmPrinter.cpp - WebAssembly LLVM assembly writer ------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
11 /// \brief This file contains a printer that converts from our internal
12 /// representation of machine-dependent LLVM code to the WebAssembly assembly
15 //===----------------------------------------------------------------------===//
17 #include "WebAssembly.h"
18 #include "WebAssemblyMachineFunctionInfo.h"
19 #include "WebAssemblyRegisterInfo.h"
20 #include "WebAssemblySubtarget.h"
21 #include "InstPrinter/WebAssemblyInstPrinter.h"
22 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
24 #include "llvm/ADT/SmallString.h"
25 #include "llvm/CodeGen/AsmPrinter.h"
26 #include "llvm/CodeGen/MachineConstantPool.h"
27 #include "llvm/CodeGen/MachineInstr.h"
28 #include "llvm/IR/DataLayout.h"
29 #include "llvm/IR/DebugInfo.h"
30 #include "llvm/MC/MCStreamer.h"
31 #include "llvm/MC/MCSymbol.h"
32 #include "llvm/Support/Debug.h"
33 #include "llvm/Support/TargetRegistry.h"
34 #include "llvm/Support/raw_ostream.h"
38 #define DEBUG_TYPE "asm-printer"
42 class WebAssemblyAsmPrinter final : public AsmPrinter {
43 const WebAssemblyInstrInfo *TII;
46 WebAssemblyAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
47 : AsmPrinter(TM, std::move(Streamer)), TII(nullptr) {}
50 const char *getPassName() const override {
51 return "WebAssembly Assembly Printer";
54 //===------------------------------------------------------------------===//
55 // MachineFunctionPass Implementation.
56 //===------------------------------------------------------------------===//
58 void getAnalysisUsage(AnalysisUsage &AU) const override {
59 AsmPrinter::getAnalysisUsage(AU);
62 bool runOnMachineFunction(MachineFunction &MF) override {
63 TII = MF.getSubtarget<WebAssemblySubtarget>().getInstrInfo();
64 return AsmPrinter::runOnMachineFunction(MF);
67 //===------------------------------------------------------------------===//
68 // AsmPrinter Implementation.
69 //===------------------------------------------------------------------===//
71 void EmitGlobalVariable(const GlobalVariable *GV) override;
73 void EmitConstantPool() override;
74 void EmitFunctionEntryLabel() override;
75 void EmitFunctionBodyStart() override;
76 void EmitFunctionBodyEnd() override;
78 void EmitInstruction(const MachineInstr *MI) override;
81 } // end anonymous namespace
83 //===----------------------------------------------------------------------===//
85 //===----------------------------------------------------------------------===//
87 // Untyped, lower-case version of the opcode's name matching the names
88 // WebAssembly opcodes are expected to have. The tablegen names are uppercase
89 // and suffixed with their type (after an underscore).
90 static SmallString<32> OpcodeName(const WebAssemblyInstrInfo *TII,
91 const MachineInstr *MI) {
92 std::string N(StringRef(TII->getName(MI->getOpcode())).lower());
93 std::string::size_type End = N.rfind('_');
94 End = std::string::npos == End ? N.length() : End;
95 return SmallString<32>(&N[0], &N[End]);
98 static std::string toSymbol(StringRef S) { return ("$" + S).str(); }
100 static const char *toString(const Type *Ty) {
101 switch (Ty->getTypeID()) {
103 case Type::FloatTyID: return "f32";
104 case Type::DoubleTyID: return "f64";
105 case Type::IntegerTyID:
106 switch (Ty->getIntegerBitWidth()) {
107 case 32: return "i32";
108 case 64: return "i64";
112 DEBUG(dbgs() << "Invalid type "; Ty->print(dbgs()); dbgs() << '\n');
113 llvm_unreachable("invalid type");
117 static std::string toString(const APFloat &FP) {
118 static const size_t BufBytes = 128;
121 assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
123 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
124 "convertToHexString handles neither SNaN nor NaN payloads");
125 // Use C99's hexadecimal floating-point representation.
126 auto Written = FP.convertToHexString(
127 buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
129 assert(Written != 0);
130 assert(Written < BufBytes);
134 //===----------------------------------------------------------------------===//
135 // WebAssemblyAsmPrinter Implementation.
136 //===----------------------------------------------------------------------===//
138 void WebAssemblyAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
139 SmallString<128> Str;
140 raw_svector_ostream OS(Str);
141 StringRef Name = GV->getName();
142 DEBUG(dbgs() << "Global " << Name << '\n');
144 if (!GV->hasInitializer()) {
145 DEBUG(dbgs() << " Skipping declaration.\n");
149 // Check to see if this is a special global used by LLVM.
150 static const char *Ignored[] = {"llvm.used", "llvm.metadata"};
151 for (const char *I : Ignored)
154 // FIXME: Handle the following globals.
155 static const char *Unhandled[] = {"llvm.global_ctors", "llvm.global_dtors"};
156 for (const char *U : Unhandled)
158 report_fatal_error("Unhandled global");
159 if (Name.startswith("llvm."))
160 report_fatal_error("Unknown LLVM-internal global");
162 if (GV->isThreadLocal())
163 report_fatal_error("TLS isn't yet supported by WebAssembly");
165 const DataLayout &DL = getDataLayout();
166 const Constant *Init = GV->getInitializer();
167 if (isa<UndefValue>(Init))
168 Init = Constant::getNullValue(Init->getType());
169 unsigned Align = DL.getPrefTypeAlignment(Init->getType());
171 switch (GV->getLinkage()) {
172 case GlobalValue::InternalLinkage:
173 case GlobalValue::PrivateLinkage:
175 case GlobalValue::AppendingLinkage:
176 case GlobalValue::LinkOnceAnyLinkage:
177 case GlobalValue::LinkOnceODRLinkage:
178 case GlobalValue::WeakAnyLinkage:
179 case GlobalValue::WeakODRLinkage:
180 case GlobalValue::ExternalLinkage:
181 case GlobalValue::CommonLinkage:
182 report_fatal_error("Linkage types other than internal and private aren't "
183 "supported by WebAssembly yet");
185 llvm_unreachable("Unknown linkage type");
189 OS << "(global " << toSymbol(Name) << ' ' << toString(Init->getType()) << ' ';
190 if (const auto *C = dyn_cast<ConstantInt>(Init)) {
191 assert(C->getBitWidth() <= 64 && "Printing wider types unimplemented");
192 OS << C->getZExtValue();
193 } else if (const auto *C = dyn_cast<ConstantFP>(Init)) {
194 OS << toString(C->getValueAPF());
196 assert(false && "Only integer and floating-point constants are supported");
198 OS << ") ;; align " << Align << "\n";
199 OutStreamer->EmitRawText(OS.str());
202 void WebAssemblyAsmPrinter::EmitConstantPool() {
203 assert(MF->getConstantPool()->getConstants().empty() &&
204 "WebAssembly disables constant pools");
207 void WebAssemblyAsmPrinter::EmitFunctionEntryLabel() {
208 SmallString<128> Str;
209 raw_svector_ostream OS(Str);
211 CurrentFnSym->redefineIfPossible();
213 // The function label could have already been emitted if two symbols end up
214 // conflicting due to asm renaming. Detect this and emit an error.
215 if (CurrentFnSym->isVariable())
216 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
217 "' is a protected alias");
218 if (CurrentFnSym->isDefined())
219 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
220 "' label emitted multiple times to assembly file");
222 OS << "(func " << toSymbol(CurrentFnSym->getName());
223 OutStreamer->EmitRawText(OS.str());
226 void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
227 SmallString<128> Str;
228 raw_svector_ostream OS(Str);
229 const Function *F = MF->getFunction();
230 for (const Argument &A : F->args())
231 OS << " (param " << toString(A.getType()) << ')';
232 const Type *Rt = F->getReturnType();
234 OS << " (result " << toString(Rt) << ')';
236 OutStreamer->EmitRawText(OS.str());
239 void WebAssemblyAsmPrinter::EmitFunctionBodyEnd() {
240 SmallString<128> Str;
241 raw_svector_ostream OS(Str);
242 OS << ") ;; end func " << toSymbol(CurrentFnSym->getName()) << '\n';
243 OutStreamer->EmitRawText(OS.str());
246 void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
247 DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
248 SmallString<128> Str;
249 raw_svector_ostream OS(Str);
251 unsigned NumDefs = MI->getDesc().getNumDefs();
252 assert(NumDefs <= 1 &&
253 "Instructions with multiple result values not implemented");
258 const MachineOperand &MO = MI->getOperand(0);
259 unsigned Reg = MO.getReg();
260 OS << "(setlocal @" << TargetRegisterInfo::virtReg2Index(Reg) << ' ';
263 OS << '(' << OpcodeName(TII, MI);
264 for (const MachineOperand &MO : MI->uses())
265 switch (MO.getType()) {
267 llvm_unreachable("unexpected machine operand type");
268 case MachineOperand::MO_Register: {
271 unsigned Reg = MO.getReg();
272 OS << " @" << TargetRegisterInfo::virtReg2Index(Reg);
274 case MachineOperand::MO_Immediate: {
275 OS << ' ' << MO.getImm();
277 case MachineOperand::MO_FPImmediate: {
278 OS << ' ' << toString(MO.getFPImm()->getValueAPF());
280 case MachineOperand::MO_GlobalAddress: {
281 OS << ' ' << toSymbol(MO.getGlobal()->getName());
291 OutStreamer->EmitRawText(OS.str());
294 // Force static initialization.
295 extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
296 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(TheWebAssemblyTarget32);
297 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(TheWebAssemblyTarget64);