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 /// This file contains a printer that converts from our internal
12 /// representation of machine-dependent LLVM code to the WebAssembly assembly
15 //===----------------------------------------------------------------------===//
17 #include "WebAssemblyAsmPrinter.h"
18 #include "InstPrinter/WebAssemblyInstPrinter.h"
19 #include "MCTargetDesc/WebAssemblyMCTargetDesc.h"
20 #include "MCTargetDesc/WebAssemblyTargetStreamer.h"
21 #include "WebAssembly.h"
22 #include "WebAssemblyMCInstLower.h"
23 #include "WebAssemblyMachineFunctionInfo.h"
24 #include "WebAssemblyRegisterInfo.h"
25 #include "llvm/ADT/StringExtras.h"
26 #include "llvm/CodeGen/Analysis.h"
27 #include "llvm/CodeGen/AsmPrinter.h"
28 #include "llvm/CodeGen/MachineConstantPool.h"
29 #include "llvm/CodeGen/MachineInstr.h"
30 #include "llvm/CodeGen/MachineModuleInfoImpls.h"
31 #include "llvm/IR/DataLayout.h"
32 #include "llvm/IR/GlobalVariable.h"
33 #include "llvm/MC/MCContext.h"
34 #include "llvm/MC/MCSectionWasm.h"
35 #include "llvm/MC/MCStreamer.h"
36 #include "llvm/MC/MCSymbol.h"
37 #include "llvm/MC/MCSymbolWasm.h"
38 #include "llvm/Support/Debug.h"
39 #include "llvm/Support/TargetRegistry.h"
40 #include "llvm/Support/raw_ostream.h"
43 #define DEBUG_TYPE "asm-printer"
45 //===----------------------------------------------------------------------===//
47 //===----------------------------------------------------------------------===//
49 MVT WebAssemblyAsmPrinter::getRegType(unsigned RegNo) const {
50 const TargetRegisterInfo *TRI = Subtarget->getRegisterInfo();
51 const TargetRegisterClass *TRC = MRI->getRegClass(RegNo);
52 for (MVT T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64, MVT::v16i8, MVT::v8i16,
53 MVT::v4i32, MVT::v4f32})
54 if (TRI->isTypeLegalForClass(*TRC, T))
56 LLVM_DEBUG(errs() << "Unknown type for register number: " << RegNo);
57 llvm_unreachable("Unknown register type");
61 std::string WebAssemblyAsmPrinter::regToString(const MachineOperand &MO) {
62 unsigned RegNo = MO.getReg();
63 assert(TargetRegisterInfo::isVirtualRegister(RegNo) &&
64 "Unlowered physical register encountered during assembly printing");
65 assert(!MFI->isVRegStackified(RegNo));
66 unsigned WAReg = MFI->getWAReg(RegNo);
67 assert(WAReg != WebAssemblyFunctionInfo::UnusedReg);
68 return '$' + utostr(WAReg);
71 WebAssemblyTargetStreamer *WebAssemblyAsmPrinter::getTargetStreamer() {
72 MCTargetStreamer *TS = OutStreamer->getTargetStreamer();
73 return static_cast<WebAssemblyTargetStreamer *>(TS);
76 //===----------------------------------------------------------------------===//
77 // WebAssemblyAsmPrinter Implementation.
78 //===----------------------------------------------------------------------===//
80 void WebAssemblyAsmPrinter::EmitEndOfAsmFile(Module &M) {
81 for (const auto &F : M) {
82 // Emit function type info for all undefined functions
83 if (F.isDeclarationForLinker() && !F.isIntrinsic()) {
84 SmallVector<MVT, 4> Results;
85 SmallVector<MVT, 4> Params;
86 ComputeSignatureVTs(F, TM, Params, Results);
87 MCSymbol *Sym = getSymbol(&F);
88 getTargetStreamer()->emitIndirectFunctionType(Sym, Params, Results);
90 if (TM.getTargetTriple().isOSBinFormatWasm() &&
91 F.hasFnAttribute("wasm-import-module")) {
92 MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
93 StringRef Name = F.getFnAttribute("wasm-import-module")
95 getTargetStreamer()->emitImportModule(WasmSym, Name);
99 for (const auto &G : M.globals()) {
100 if (!G.hasInitializer() && G.hasExternalLinkage()) {
101 if (G.getValueType()->isSized()) {
102 uint16_t Size = M.getDataLayout().getTypeAllocSize(G.getValueType());
103 OutStreamer->emitELFSize(getSymbol(&G),
104 MCConstantExpr::create(Size, OutContext));
109 if (const NamedMDNode *Named = M.getNamedMetadata("wasm.custom_sections")) {
110 for (const Metadata *MD : Named->operands()) {
111 const MDTuple *Tuple = dyn_cast<MDTuple>(MD);
112 if (!Tuple || Tuple->getNumOperands() != 2)
114 const MDString *Name = dyn_cast<MDString>(Tuple->getOperand(0));
115 const MDString *Contents = dyn_cast<MDString>(Tuple->getOperand(1));
116 if (!Name || !Contents)
119 OutStreamer->PushSection();
120 std::string SectionName = (".custom_section." + Name->getString()).str();
121 MCSectionWasm *mySection =
122 OutContext.getWasmSection(SectionName, SectionKind::getMetadata());
123 OutStreamer->SwitchSection(mySection);
124 OutStreamer->EmitBytes(Contents->getString());
125 OutStreamer->PopSection();
130 void WebAssemblyAsmPrinter::EmitConstantPool() {
131 assert(MF->getConstantPool()->getConstants().empty() &&
132 "WebAssembly disables constant pools");
135 void WebAssemblyAsmPrinter::EmitJumpTableInfo() {
136 // Nothing to do; jump tables are incorporated into the instruction stream.
139 void WebAssemblyAsmPrinter::EmitFunctionBodyStart() {
140 getTargetStreamer()->emitParam(CurrentFnSym, MFI->getParams());
142 SmallVector<MVT, 4> ResultVTs;
143 const Function &F = MF->getFunction();
145 // Emit the function index.
146 if (MDNode *Idx = F.getMetadata("wasm.index")) {
147 assert(Idx->getNumOperands() == 1);
149 getTargetStreamer()->emitIndIdx(AsmPrinter::lowerConstant(
150 cast<ConstantAsMetadata>(Idx->getOperand(0))->getValue()));
153 ComputeLegalValueVTs(F, TM, F.getReturnType(), ResultVTs);
155 // If the return type needs to be legalized it will get converted into
156 // passing a pointer.
157 if (ResultVTs.size() == 1)
158 getTargetStreamer()->emitResult(CurrentFnSym, ResultVTs);
160 getTargetStreamer()->emitResult(CurrentFnSym, ArrayRef<MVT>());
162 getTargetStreamer()->emitLocal(MFI->getLocals());
164 AsmPrinter::EmitFunctionBodyStart();
167 void WebAssemblyAsmPrinter::EmitInstruction(const MachineInstr *MI) {
168 LLVM_DEBUG(dbgs() << "EmitInstruction: " << *MI << '\n');
170 switch (MI->getOpcode()) {
171 case WebAssembly::ARGUMENT_I32:
172 case WebAssembly::ARGUMENT_I64:
173 case WebAssembly::ARGUMENT_F32:
174 case WebAssembly::ARGUMENT_F64:
175 case WebAssembly::ARGUMENT_v16i8:
176 case WebAssembly::ARGUMENT_v8i16:
177 case WebAssembly::ARGUMENT_v4i32:
178 case WebAssembly::ARGUMENT_v4f32:
179 // These represent values which are live into the function entry, so there's
180 // no instruction to emit.
182 case WebAssembly::FALLTHROUGH_RETURN_I32:
183 case WebAssembly::FALLTHROUGH_RETURN_I64:
184 case WebAssembly::FALLTHROUGH_RETURN_F32:
185 case WebAssembly::FALLTHROUGH_RETURN_F64:
186 case WebAssembly::FALLTHROUGH_RETURN_v16i8:
187 case WebAssembly::FALLTHROUGH_RETURN_v8i16:
188 case WebAssembly::FALLTHROUGH_RETURN_v4i32:
189 case WebAssembly::FALLTHROUGH_RETURN_v4f32: {
190 // These instructions represent the implicit return at the end of a
191 // function body. The operand is always a pop.
192 assert(MFI->isVRegStackified(MI->getOperand(0).getReg()));
195 OutStreamer->AddComment("fallthrough-return: $pop" +
196 Twine(MFI->getWARegStackId(
197 MFI->getWAReg(MI->getOperand(0).getReg()))));
198 OutStreamer->AddBlankLine();
202 case WebAssembly::FALLTHROUGH_RETURN_VOID:
203 // This instruction represents the implicit return at the end of a
204 // function body with no return value.
206 OutStreamer->AddComment("fallthrough-return");
207 OutStreamer->AddBlankLine();
211 WebAssemblyMCInstLower MCInstLowering(OutContext, *this);
213 MCInstLowering.Lower(MI, TmpInst);
214 EmitToStreamer(*OutStreamer, TmpInst);
220 const MCExpr *WebAssemblyAsmPrinter::lowerConstant(const Constant *CV) {
221 if (const GlobalValue *GV = dyn_cast<GlobalValue>(CV))
222 if (GV->getValueType()->isFunctionTy()) {
223 return MCSymbolRefExpr::create(
224 getSymbol(GV), MCSymbolRefExpr::VK_WebAssembly_FUNCTION, OutContext);
226 return AsmPrinter::lowerConstant(CV);
229 bool WebAssemblyAsmPrinter::PrintAsmOperand(const MachineInstr *MI,
230 unsigned OpNo, unsigned AsmVariant,
231 const char *ExtraCode,
234 report_fatal_error("There are no defined alternate asm variants");
236 // First try the generic code, which knows about modifiers like 'c' and 'n'.
237 if (!AsmPrinter::PrintAsmOperand(MI, OpNo, AsmVariant, ExtraCode, OS))
241 const MachineOperand &MO = MI->getOperand(OpNo);
242 switch (MO.getType()) {
243 case MachineOperand::MO_Immediate:
246 case MachineOperand::MO_Register:
247 OS << regToString(MO);
249 case MachineOperand::MO_GlobalAddress:
250 getSymbol(MO.getGlobal())->print(OS, MAI);
251 printOffset(MO.getOffset(), OS);
253 case MachineOperand::MO_ExternalSymbol:
254 GetExternalSymbolSymbol(MO.getSymbolName())->print(OS, MAI);
255 printOffset(MO.getOffset(), OS);
257 case MachineOperand::MO_MachineBasicBlock:
258 MO.getMBB()->getSymbol()->print(OS, MAI);
268 bool WebAssemblyAsmPrinter::PrintAsmMemoryOperand(const MachineInstr *MI,
271 const char *ExtraCode,
274 report_fatal_error("There are no defined alternate asm variants");
276 // The current approach to inline asm is that "r" constraints are expressed
277 // as local indices, rather than values on the operand stack. This simplifies
278 // using "r" as it eliminates the need to push and pop the values in a
279 // particular order, however it also makes it impossible to have an "m"
280 // constraint. So we don't support it.
282 return AsmPrinter::PrintAsmMemoryOperand(MI, OpNo, AsmVariant, ExtraCode, OS);
285 // Force static initialization.
286 extern "C" void LLVMInitializeWebAssemblyAsmPrinter() {
287 RegisterAsmPrinter<WebAssemblyAsmPrinter> X(getTheWebAssemblyTarget32());
288 RegisterAsmPrinter<WebAssemblyAsmPrinter> Y(getTheWebAssemblyTarget64());