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 {
44 const WebAssemblyInstrInfo *TII;
47 WebAssemblyAsmPrinter(TargetMachine &TM, std::unique_ptr<MCStreamer> Streamer)
48 : AsmPrinter(TM, std::move(Streamer)), TII(nullptr) {}
51 const char *getPassName() const override {
52 return "WebAssembly Assembly Printer";
55 //===------------------------------------------------------------------===//
56 // MachineFunctionPass Implementation.
57 //===------------------------------------------------------------------===//
59 void getAnalysisUsage(AnalysisUsage &AU) const override {
60 AsmPrinter::getAnalysisUsage(AU);
63 bool runOnMachineFunction(MachineFunction &MF) override {
64 const auto &Subtarget = MF.getSubtarget<WebAssemblySubtarget>();
65 hasAddr64 = Subtarget.hasAddr64();
66 TII = Subtarget.getInstrInfo();
67 return AsmPrinter::runOnMachineFunction(MF);
70 //===------------------------------------------------------------------===//
71 // AsmPrinter Implementation.
72 //===------------------------------------------------------------------===//
74 void EmitGlobalVariable(const GlobalVariable *GV) override;
76 void EmitJumpTableInfo() override;
77 void EmitConstantPool() override;
78 void EmitFunctionEntryLabel() override;
79 void EmitFunctionBodyStart() override;
80 void EmitFunctionBodyEnd() override;
82 void EmitInstruction(const MachineInstr *MI) override;
85 } // end anonymous namespace
87 //===----------------------------------------------------------------------===//
89 //===----------------------------------------------------------------------===//
91 // Untyped, lower-case version of the opcode's name matching the names
92 // WebAssembly opcodes are expected to have. The tablegen names are uppercase
93 // and suffixed with their type (after an underscore).
94 static SmallString<32> OpcodeName(const WebAssemblyInstrInfo *TII,
95 const MachineInstr *MI) {
96 std::string N(StringRef(TII->getName(MI->getOpcode())).lower());
97 std::string::size_type End = N.rfind('_');
98 End = std::string::npos == End ? N.length() : End;
99 return SmallString<32>(&N[0], &N[End]);
102 static std::string toSymbol(StringRef S) { return ("$" + S).str(); }
104 static std::string toString(const APFloat &FP) {
105 static const size_t BufBytes = 128;
108 assert((FP.bitwiseIsEqual(APFloat::getQNaN(FP.getSemantics())) ||
110 APFloat::getQNaN(FP.getSemantics(), /*Negative=*/true))) &&
111 "convertToHexString handles neither SNaN nor NaN payloads");
112 // Use C99's hexadecimal floating-point representation.
113 auto Written = FP.convertToHexString(
114 buf, /*hexDigits=*/0, /*upperCase=*/false, APFloat::rmNearestTiesToEven);
116 assert(Written != 0);
117 assert(Written < BufBytes);
121 static const char *toString(const Type *Ty, bool hasAddr64) {
122 switch (Ty->getTypeID()) {
124 // Treat all pointers as the underlying integer into linear memory.
125 case Type::PointerTyID: return hasAddr64 ? "i64" : "i32";
126 case Type::FloatTyID: return "f32";
127 case Type::DoubleTyID: return "f64";
128 case Type::IntegerTyID:
129 switch (Ty->getIntegerBitWidth()) {
131 case 16: return "i16";
132 case 32: return "i32";
133 case 64: return "i64";
137 DEBUG(dbgs() << "Invalid type "; Ty->print(dbgs()); dbgs() << '\n');
138 llvm_unreachable("invalid type");
143 //===----------------------------------------------------------------------===//
144 // WebAssemblyAsmPrinter Implementation.
145 //===----------------------------------------------------------------------===//
147 void WebAssemblyAsmPrinter::EmitGlobalVariable(const GlobalVariable *GV) {
148 SmallString<128> Str;
149 raw_svector_ostream OS(Str);
150 StringRef Name = GV->getName();
151 DEBUG(dbgs() << "Global " << Name << '\n');
153 if (!GV->hasInitializer()) {
154 DEBUG(dbgs() << " Skipping declaration.\n");
158 // Check to see if this is a special global used by LLVM.
159 static const char *Ignored[] = {"llvm.used", "llvm.metadata"};
160 for (const char *I : Ignored)
163 // FIXME: Handle the following globals.
164 static const char *Unhandled[] = {"llvm.global_ctors", "llvm.global_dtors"};
165 for (const char *U : Unhandled)
167 report_fatal_error("Unhandled global");
168 if (Name.startswith("llvm."))
169 report_fatal_error("Unknown LLVM-internal global");
171 if (GV->isThreadLocal())
172 report_fatal_error("TLS isn't yet supported by WebAssembly");
174 const DataLayout &DL = getDataLayout();
175 const Constant *Init = GV->getInitializer();
176 if (isa<UndefValue>(Init))
177 Init = Constant::getNullValue(Init->getType());
178 unsigned Align = DL.getPrefTypeAlignment(Init->getType());
180 switch (GV->getLinkage()) {
181 case GlobalValue::InternalLinkage:
182 case GlobalValue::PrivateLinkage:
184 case GlobalValue::AppendingLinkage:
185 case GlobalValue::LinkOnceAnyLinkage:
186 case GlobalValue::LinkOnceODRLinkage:
187 case GlobalValue::WeakAnyLinkage:
188 case GlobalValue::WeakODRLinkage:
189 case GlobalValue::ExternalLinkage:
190 case GlobalValue::CommonLinkage:
191 report_fatal_error("Linkage types other than internal and private aren't "
192 "supported by WebAssembly yet");
194 llvm_unreachable("Unknown linkage type");
198 OS << "(global " << toSymbol(Name) << ' '
199 << toString(Init->getType(), hasAddr64) << ' ';
200 if (const auto *C = dyn_cast<ConstantInt>(Init)) {
201 assert(C->getBitWidth() <= 64 && "Printing wider types unimplemented");
202 OS << C->getZExtValue();
203 } else if (const auto *C = dyn_cast<ConstantFP>(Init)) {
204 OS << toString(C->getValueAPF());
206 assert(false && "Only integer and floating-point constants are supported");
208 OS << ") ;; align " << Align;
209 OutStreamer->EmitRawText(OS.str());
212 void WebAssemblyAsmPrinter::EmitConstantPool() {
213 assert(MF->getConstantPool()->getConstants().empty() &&
214 "WebAssembly disables constant pools");
217 void WebAssemblyAsmPrinter::EmitJumpTableInfo() {
218 // Nothing to do; jump tables are incorporated into the instruction stream.
221 void WebAssemblyAsmPrinter::EmitFunctionEntryLabel() {
222 SmallString<128> Str;
223 raw_svector_ostream OS(Str);
225 CurrentFnSym->redefineIfPossible();
227 // The function label could have already been emitted if two symbols end up
228 // conflicting due to asm renaming. Detect this and emit an error.
229 if (CurrentFnSym->isVariable())
230 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
231 "' is a protected alias");
232 if (CurrentFnSym->isDefined())
233 report_fatal_error("'" + Twine(CurrentFnSym->getName()) +
234 "' label emitted multiple times to assembly file");
236 OS << "(func " << toSymbol(CurrentFnSym->getName());
237 OutStreamer->EmitRawText(OS.str());
240 void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
241 SmallString<128> Str;
242 raw_svector_ostream OS(Str);
243 const Function *F = MF->getFunction();
244 const Type *Rt = F->getReturnType();
245 if (!Rt->isVoidTy() || !F->arg_empty()) {
246 for (const Argument &A : F->args())
247 OS << " (param " << toString(A.getType(), hasAddr64) << ')';
249 OS << " (result " << toString(Rt, hasAddr64) << ')';
250 OutStreamer->EmitRawText(OS.str());
254 void WebAssemblyAsmPrinter::EmitFunctionBodyEnd() {
255 SmallString<128> Str;
256 raw_svector_ostream OS(Str);
257 OS << ") ;; end func " << toSymbol(CurrentFnSym->getName());
258 OutStreamer->EmitRawText(OS.str());
261 void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
262 DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
263 SmallString<128> Str;
264 raw_svector_ostream OS(Str);
266 unsigned NumDefs = MI->getDesc().getNumDefs();
267 assert(NumDefs <= 1 &&
268 "Instructions with multiple result values not implemented");
273 const MachineOperand &MO = MI->getOperand(0);
274 unsigned Reg = MO.getReg();
275 OS << "(setlocal @" << TargetRegisterInfo::virtReg2Index(Reg) << ' ';
278 if (MI->getOpcode() == WebAssembly::COPY) {
279 OS << '@' << TargetRegisterInfo::virtReg2Index(MI->getOperand(1).getReg());
281 OS << '(' << OpcodeName(TII, MI);
282 for (const MachineOperand &MO : MI->uses())
283 switch (MO.getType()) {
285 llvm_unreachable("unexpected machine operand type");
286 case MachineOperand::MO_Register: {
289 unsigned Reg = MO.getReg();
290 OS << " @" << TargetRegisterInfo::virtReg2Index(Reg);
292 case MachineOperand::MO_Immediate: {
293 OS << ' ' << MO.getImm();
295 case MachineOperand::MO_FPImmediate: {
296 OS << ' ' << toString(MO.getFPImm()->getValueAPF());
298 case MachineOperand::MO_GlobalAddress: {
299 OS << ' ' << toSymbol(MO.getGlobal()->getName());
301 case MachineOperand::MO_MachineBasicBlock: {
302 OS << ' ' << toSymbol(MO.getMBB()->getSymbol()->getName());
311 OutStreamer->EmitRawText(OS.str());
314 // Force static initialization.
315 extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
316 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(TheWebAssemblyTarget32);
317 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(TheWebAssemblyTarget64);