MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol(
const MachineOperand &MO) const {
const char *Name = MO.getSymbolName();
MCSymbol *Sym = Printer.GetExternalSymbolSymbol(Name);
if (isa<MCSymbolELF>(Sym))
return Sym;
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
const WebAssemblySubtarget &Subtarget = Printer.getSubtarget();
// __stack_pointer is a global variable; all other external symbols used by
// CodeGen are functions.
if (strcmp(Name, "__stack_pointer") == 0)
return WasmSym;
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
GetSignature(Subtarget, Name, Returns, Params);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
return WasmSym;
}
MCSymbol *
WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
const GlobalValue *Global = MO.getGlobal();
MCSymbol *Sym = Printer.getSymbol(Global);
if (isa<MCSymbolELF>(Sym))
return Sym;
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
if (const auto *FuncTy = dyn_cast<FunctionType>(Global->getValueType())) {
const MachineFunction &MF = *MO.getParent()->getParent()->getParent();
const TargetMachine &TM = MF.getTarget();
const Function &CurrentFunc = *MF.getFunction();
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
wasm::ValType iPTR =
MF.getSubtarget<WebAssemblySubtarget>().hasAddr64() ?
wasm::ValType::I64 :
wasm::ValType::I32;
SmallVector<MVT, 4> ResultMVTs;
ComputeLegalValueVTs(CurrentFunc, TM, FuncTy->getReturnType(), ResultMVTs);
// WebAssembly can't currently handle returning tuples.
if (ResultMVTs.size() <= 1)
for (MVT ResultMVT : ResultMVTs)
Returns.push_back(WebAssembly::toValType(ResultMVT));
else
Params.push_back(iPTR);
for (Type *Ty : FuncTy->params()) {
SmallVector<MVT, 4> ParamMVTs;
ComputeLegalValueVTs(CurrentFunc, TM, Ty, ParamMVTs);
for (MVT ParamMVT : ParamMVTs)
Params.push_back(WebAssembly::toValType(ParamMVT));
}
if (FuncTy->isVarArg())
Params.push_back(iPTR);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
}
return WasmSym;
}
MCSymbol *WebAssemblyMCInstLower::GetExternalSymbolSymbol(
const MachineOperand &MO) const {
const char *Name = MO.getSymbolName();
MCSymbolWasm *WasmSym =
cast<MCSymbolWasm>(Printer.GetExternalSymbolSymbol(Name));
const WebAssemblySubtarget &Subtarget = Printer.getSubtarget();
// Except for the two exceptions (__stack_pointer and __cpp_exception), all
// other external symbols used by CodeGen are functions. It's OK to hardcode
// knowledge of specific symbols here; this method is precisely there for
// fetching the signatures of known Clang-provided symbols.
if (strcmp(Name, "__stack_pointer") == 0) {
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_GLOBAL);
WasmSym->setGlobalType(wasm::WasmGlobalType{
uint8_t(Subtarget.hasAddr64() ? wasm::WASM_TYPE_I64
: wasm::WASM_TYPE_I32),
true});
return WasmSym;
}
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
if (strcmp(Name, "__cpp_exception") == 0) {
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_EVENT);
// We can't confirm its signature index for now because there can be
// imported exceptions. Set it to be 0 for now.
WasmSym->setEventType(
{wasm::WASM_EVENT_ATTRIBUTE_EXCEPTION, /* SigIndex */ 0});
// We may have multiple C++ compilation units to be linked together, each of
// which defines the exception symbol. To resolve them, we declare them as
// weak.
WasmSym->setWeak(true);
WasmSym->setExternal(true);
// All C++ exceptions are assumed to have a single i32 (for wasm32) or i64
// (for wasm64) param type and void return type. The reaon is, all C++
// exception values are pointers, and to share the type section with
// functions, exceptions are assumed to have void return type.
Params.push_back(Subtarget.hasAddr64() ? wasm::ValType::I64
: wasm::ValType::I32);
} else { // Function symbols
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
GetLibcallSignature(Subtarget, Name, Returns, Params);
}
auto Signature =
make_unique<wasm::WasmSignature>(std::move(Returns), std::move(Params));
WasmSym->setSignature(Signature.get());
Printer.addSignature(std::move(Signature));
return WasmSym;
}
void WebAssemblyTargetWasmStreamer::emitIndirectFunctionType(
MCSymbol *Symbol, SmallVectorImpl<MVT> &Params,
SmallVectorImpl<MVT> &Results) {
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Symbol);
if (WasmSym->isFunction()) {
// Symbol already has its arguments and result set.
return;
}
SmallVector<wasm::ValType, 4> ValParams;
for (MVT Ty : Params)
ValParams.push_back(WebAssembly::toValType(Ty));
SmallVector<wasm::ValType, 1> ValResults;
for (MVT Ty : Results)
ValResults.push_back(WebAssembly::toValType(Ty));
WasmSym->setParams(std::move(ValParams));
WasmSym->setReturns(std::move(ValResults));
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
}
MCSymbol *
WebAssemblyMCInstLower::GetGlobalAddressSymbol(const MachineOperand &MO) const {
const GlobalValue *Global = MO.getGlobal();
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Printer.getSymbol(Global));
if (const auto *FuncTy = dyn_cast<FunctionType>(Global->getValueType())) {
const MachineFunction &MF = *MO.getParent()->getParent()->getParent();
const TargetMachine &TM = MF.getTarget();
const Function &CurrentFunc = MF.getFunction();
SmallVector<MVT, 1> ResultMVTs;
SmallVector<MVT, 4> ParamMVTs;
ComputeSignatureVTs(FuncTy, CurrentFunc, TM, ParamMVTs, ResultMVTs);
auto Signature = SignatureFromMVTs(ResultMVTs, ParamMVTs);
WasmSym->setSignature(Signature.get());
Printer.addSignature(std::move(Signature));
WasmSym->setType(wasm::WASM_SYMBOL_TYPE_FUNCTION);
}
return WasmSym;
}
void WebAssemblyMCInstLower::Lower(const MachineInstr *MI,
MCInst &OutMI) const {
OutMI.setOpcode(MI->getOpcode());
const MCInstrDesc &Desc = MI->getDesc();
for (unsigned i = 0, e = MI->getNumOperands(); i != e; ++i) {
const MachineOperand &MO = MI->getOperand(i);
MCOperand MCOp;
switch (MO.getType()) {
default:
MI->print(errs());
llvm_unreachable("unknown operand type");
case MachineOperand::MO_MachineBasicBlock:
MI->print(errs());
llvm_unreachable("MachineBasicBlock operand should have been rewritten");
case MachineOperand::MO_Register: {
// Ignore all implicit register operands.
if (MO.isImplicit())
continue;
const WebAssemblyFunctionInfo &MFI =
*MI->getParent()->getParent()->getInfo<WebAssemblyFunctionInfo>();
unsigned WAReg = MFI.getWAReg(MO.getReg());
MCOp = MCOperand::createReg(WAReg);
break;
}
case MachineOperand::MO_Immediate:
if (i < Desc.NumOperands) {
const MCOperandInfo &Info = Desc.OpInfo[i];
if (Info.OperandType == WebAssembly::OPERAND_TYPEINDEX) {
MCSymbol *Sym = Printer.createTempSymbol("typeindex");
if (!isa<MCSymbolELF>(Sym)) {
SmallVector<wasm::ValType, 4> Returns;
SmallVector<wasm::ValType, 4> Params;
const MachineRegisterInfo &MRI =
MI->getParent()->getParent()->getRegInfo();
for (const MachineOperand &MO : MI->defs())
Returns.push_back(getType(MRI.getRegClass(MO.getReg())));
for (const MachineOperand &MO : MI->explicit_uses())
if (MO.isReg())
Params.push_back(getType(MRI.getRegClass(MO.getReg())));
// call_indirect instructions have a callee operand at the end which
// doesn't count as a param.
if (WebAssembly::isCallIndirect(*MI))
Params.pop_back();
MCSymbolWasm *WasmSym = cast<MCSymbolWasm>(Sym);
WasmSym->setReturns(std::move(Returns));
WasmSym->setParams(std::move(Params));
WasmSym->setIsFunction(true);
const MCExpr *Expr =
MCSymbolRefExpr::create(WasmSym,
MCSymbolRefExpr::VK_WebAssembly_TYPEINDEX,
Ctx);
MCOp = MCOperand::createExpr(Expr);
break;
}
}
}
MCOp = MCOperand::createImm(MO.getImm());
break;
case MachineOperand::MO_FPImmediate: {
// TODO: MC converts all floating point immediate operands to double.
// This is fine for numeric values, but may cause NaNs to change bits.
const ConstantFP *Imm = MO.getFPImm();
if (Imm->getType()->isFloatTy())
MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToFloat());
else if (Imm->getType()->isDoubleTy())
MCOp = MCOperand::createFPImm(Imm->getValueAPF().convertToDouble());
else
llvm_unreachable("unknown floating point immediate type");
break;
}
case MachineOperand::MO_GlobalAddress:
assert(MO.getTargetFlags() == 0 &&
"WebAssembly does not use target flags on GlobalAddresses");
MCOp = LowerSymbolOperand(GetGlobalAddressSymbol(MO), MO.getOffset(),
MO.getGlobal()->getValueType()->isFunctionTy());
break;
case MachineOperand::MO_ExternalSymbol:
// The target flag indicates whether this is a symbol for a
// variable or a function.
assert((MO.getTargetFlags() & -2) == 0 &&
"WebAssembly uses only one target flag bit on ExternalSymbols");
MCOp = LowerSymbolOperand(GetExternalSymbolSymbol(MO), /*Offset=*/0,
MO.getTargetFlags() & 1);
break;
}
OutMI.addOperand(MCOp);
}
}
