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 const auto &Subtarget = MF.getSubtarget<WebAssemblySubtarget>();
64 TII = Subtarget.getInstrInfo();
65 return AsmPrinter::runOnMachineFunction(MF);
68 //===------------------------------------------------------------------===//
69 // AsmPrinter Implementation.
70 //===------------------------------------------------------------------===//
72 void EmitGlobalVariable(const GlobalVariable *GV) override;
74 void EmitJumpTableInfo() override;
75 void EmitConstantPool() override;
76 void EmitFunctionEntryLabel() override;
77 void EmitFunctionBodyStart() override;
78 void EmitFunctionBodyEnd() override;
80 void EmitInstruction(const MachineInstr *MI) override;
82 static std::string toString(const APFloat &APF);
83 const char *toString(Type *Ty) const;
86 } // end anonymous namespace
88 //===----------------------------------------------------------------------===//
90 //===----------------------------------------------------------------------===//
92 // Untyped, lower-case version of the opcode's name matching the names
93 // WebAssembly opcodes are expected to have. The tablegen names are uppercase
94 // and suffixed with their type (after an underscore).
95 static SmallString<32> OpcodeName(const WebAssemblyInstrInfo *TII,
96 const MachineInstr *MI) {
97 std::string N(StringRef(TII->getName(MI->getOpcode())).lower());
98 std::string::size_type End = N.rfind('_');
99 End = std::string::npos == End ? N.length() : End;
100 return SmallString<32>(&N[0], &N[End]);
103 static std::string toSymbol(StringRef S) { return ("$" + S).str(); }
105 std::string WebAssemblyAsmPrinter::toString(const APFloat &FP) {
106 static const size_t BufBytes = 128;
109 assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
111 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
112 "convertToHexString handles neither SNaN nor NaN payloads");
113 // Use C99's hexadecimal floating-point representation.
114 auto Written = FP.convertToHexString(
115 buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
117 assert(Written != 0);
118 assert(Written < BufBytes);
122 const char *WebAssemblyAsmPrinter::toString(Type *Ty) const {
123 switch (Ty->getTypeID()) {
126 // Treat all pointers as the underlying integer into linear memory.
127 case Type::PointerTyID:
128 switch (getPointerSize()) {
134 llvm_unreachable("unsupported pointer size");
137 case Type::FloatTyID:
139 case Type::DoubleTyID:
141 case Type::IntegerTyID:
142 switch (Ty->getIntegerBitWidth()) {
155 DEBUG(dbgs() << "Invalid type "; Ty->print(dbgs()); dbgs() << '\n');
156 llvm_unreachable("invalid type");
160 //===----------------------------------------------------------------------===//
161 // WebAssemblyAsmPrinter Implementation.
162 //===----------------------------------------------------------------------===//
164 void WebAssemblyAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
165 SmallString<128> Str;
166 raw_svector_ostream OS(Str);
167 StringRef Name = GV->getName();
168 DEBUG(dbgs() << "Global " << Name << '\n');
170 if (!GV->hasInitializer()) {
171 DEBUG(dbgs() << " Skipping declaration.\n");
175 // Check to see if this is a special global used by LLVM.
176 static const char *Ignored[] = {"llvm.used", "llvm.metadata"};
177 for (const char *I : Ignored)
180 // FIXME: Handle the following globals.
181 static const char *Unhandled[] = {"llvm.global_ctors", "llvm.global_dtors"};
182 for (const char *U : Unhandled)
184 report_fatal_error("Unhandled global");
185 if (Name.startswith("llvm."))
186 report_fatal_error("Unknown LLVM-internal global");
188 if (GV->isThreadLocal())
189 report_fatal_error("TLS isn't yet supported by WebAssembly");
191 const DataLayout &DL = getDataLayout();
192 const Constant *Init = GV->getInitializer();
193 if (isa<UndefValue>(Init))
194 Init = Constant::getNullValue(Init->getType());
195 unsigned Align = DL.getPrefTypeAlignment(Init->getType());
197 switch (GV->getLinkage()) {
198 case GlobalValue::InternalLinkage:
199 case GlobalValue::PrivateLinkage:
201 case GlobalValue::AppendingLinkage:
202 case GlobalValue::LinkOnceAnyLinkage:
203 case GlobalValue::LinkOnceODRLinkage:
204 case GlobalValue::WeakAnyLinkage:
205 case GlobalValue::WeakODRLinkage:
206 case GlobalValue::ExternalLinkage:
207 case GlobalValue::CommonLinkage:
208 report_fatal_error("Linkage types other than internal and private aren't "
209 "supported by WebAssembly yet");
211 llvm_unreachable("Unknown linkage type");
215 OS << "(global " << toSymbol(Name) << ' ' << toString(Init->getType()) << ' ';
216 if (const auto *C = dyn_cast<ConstantInt>(Init)) {
217 assert(C->getBitWidth() <= 64 && "Printing wider types unimplemented");
218 OS << C->getZExtValue();
219 } else if (const auto *C = dyn_cast<ConstantFP>(Init)) {
220 OS << toString(C->getValueAPF());
222 assert(false && "Only integer and floating-point constants are supported");
224 OS << ") ;; align " << Align;
225 OutStreamer->EmitRawText(OS.str());
228 void WebAssemblyAsmPrinter::EmitConstantPool() {
229 assert(MF->getConstantPool()->getConstants().empty() &&
230 "WebAssembly disables constant pools");
233 void WebAssemblyAsmPrinter::EmitJumpTableInfo() {
234 // Nothing to do; jump tables are incorporated into the instruction stream.
237 void WebAssemblyAsmPrinter::EmitFunctionEntryLabel() {
238 SmallString<128> Str;
239 raw_svector_ostream OS(Str);
241 CurrentFnSym->redefineIfPossible();
243 // The function label could have already been emitted if two symbols end up
244 // conflicting due to asm renaming. Detect this and emit an error.
245 if (CurrentFnSym->isVariable())
246 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
247 "' is a protected alias");
248 if (CurrentFnSym->isDefined())
249 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
250 "' label emitted multiple times to assembly file");
252 OS << "(func " << toSymbol(CurrentFnSym->getName());
253 OutStreamer->EmitRawText(OS.str());
256 void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
257 SmallString<128> Str;
258 raw_svector_ostream OS(Str);
259 const Function *F = MF->getFunction();
260 Type *Rt = F->getReturnType();
261 if (!Rt->isVoidTy() || !F->arg_empty()) {
262 for (const Argument &A : F->args())
263 OS << " (param " << toString(A.getType()) << ')';
265 OS << " (result " << toString(Rt) << ')';
266 OutStreamer->EmitRawText(OS.str());
270 void WebAssemblyAsmPrinter::EmitFunctionBodyEnd() {
271 SmallString<128> Str;
272 raw_svector_ostream OS(Str);
273 OS << ") ;; end func " << toSymbol(CurrentFnSym->getName());
274 OutStreamer->EmitRawText(OS.str());
277 void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
278 DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
279 SmallString<128> Str;
280 raw_svector_ostream OS(Str);
282 unsigned NumDefs = MI->getDesc().getNumDefs();
283 assert(NumDefs <= 1 &&
284 "Instructions with multiple result values not implemented");
289 const MachineOperand &MO = MI->getOperand(0);
290 unsigned Reg = MO.getReg();
291 OS << "(set_local @" << TargetRegisterInfo::virtReg2Index(Reg) << ' ';
294 if (MI->getOpcode() == WebAssembly::COPY) {
295 OS << '@' << TargetRegisterInfo::virtReg2Index(MI->getOperand(1).getReg());
297 OS << '(' << OpcodeName(TII, MI);
298 for (const MachineOperand &MO : MI->uses())
299 switch (MO.getType()) {
301 llvm_unreachable("unexpected machine operand type");
302 case MachineOperand::MO_Register: {
305 unsigned Reg = MO.getReg();
306 OS << " @" << TargetRegisterInfo::virtReg2Index(Reg);
308 case MachineOperand::MO_Immediate: {
309 OS << ' ' << MO.getImm();
311 case MachineOperand::MO_FPImmediate: {
312 OS << ' ' << toString(MO.getFPImm()->getValueAPF());
314 case MachineOperand::MO_GlobalAddress: {
315 OS << ' ' << toSymbol(MO.getGlobal()->getName());
317 case MachineOperand::MO_MachineBasicBlock: {
318 OS << ' ' << toSymbol(MO.getMBB()->getSymbol()->getName());
327 OutStreamer->EmitRawText(OS.str());
330 // Force static initialization.
331 extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
332 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(TheWebAssemblyTarget32);
333 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(TheWebAssemblyTarget64);