| //=- WebAssemblyISelLowering.cpp - WebAssembly DAG Lowering Implementation -==// |
| // |
| // The LLVM Compiler Infrastructure |
| // |
| // This file is distributed under the University of Illinois Open Source |
| // License. See LICENSE.TXT for details. |
| // |
| //===----------------------------------------------------------------------===// |
| /// |
| /// \file |
| /// \brief This file implements the WebAssemblyTargetLowering class. |
| /// |
| //===----------------------------------------------------------------------===// |
| |
| #include "WebAssemblyISelLowering.h" |
| #include "MCTargetDesc/WebAssemblyMCTargetDesc.h" |
| #include "WebAssemblyMachineFunctionInfo.h" |
| #include "WebAssemblySubtarget.h" |
| #include "WebAssemblyTargetMachine.h" |
| #include "llvm/CodeGen/Analysis.h" |
| #include "llvm/CodeGen/CallingConvLower.h" |
| #include "llvm/CodeGen/MachineJumpTableInfo.h" |
| #include "llvm/CodeGen/MachineRegisterInfo.h" |
| #include "llvm/CodeGen/SelectionDAG.h" |
| #include "llvm/IR/DiagnosticInfo.h" |
| #include "llvm/IR/DiagnosticPrinter.h" |
| #include "llvm/IR/Function.h" |
| #include "llvm/IR/Intrinsics.h" |
| #include "llvm/Support/Debug.h" |
| #include "llvm/Support/ErrorHandling.h" |
| #include "llvm/Support/raw_ostream.h" |
| #include "llvm/Target/TargetOptions.h" |
| using namespace llvm; |
| |
| #define DEBUG_TYPE "wasm-lower" |
| |
| WebAssemblyTargetLowering::WebAssemblyTargetLowering( |
| const TargetMachine &TM, const WebAssemblySubtarget &STI) |
| : TargetLowering(TM), Subtarget(&STI) { |
| auto MVTPtr = Subtarget->hasAddr64() ? MVT::i64 : MVT::i32; |
| |
| // Booleans always contain 0 or 1. |
| setBooleanContents(ZeroOrOneBooleanContent); |
| // WebAssembly does not produce floating-point exceptions on normal floating |
| // point operations. |
| setHasFloatingPointExceptions(false); |
| // We don't know the microarchitecture here, so just reduce register pressure. |
| setSchedulingPreference(Sched::RegPressure); |
| // Tell ISel that we have a stack pointer. |
| setStackPointerRegisterToSaveRestore( |
| Subtarget->hasAddr64() ? WebAssembly::SP64 : WebAssembly::SP32); |
| // Set up the register classes. |
| addRegisterClass(MVT::i32, &WebAssembly::I32RegClass); |
| addRegisterClass(MVT::i64, &WebAssembly::I64RegClass); |
| addRegisterClass(MVT::f32, &WebAssembly::F32RegClass); |
| addRegisterClass(MVT::f64, &WebAssembly::F64RegClass); |
| if (Subtarget->hasSIMD128()) { |
| addRegisterClass(MVT::v16i8, &WebAssembly::V128RegClass); |
| addRegisterClass(MVT::v8i16, &WebAssembly::V128RegClass); |
| addRegisterClass(MVT::v4i32, &WebAssembly::V128RegClass); |
| addRegisterClass(MVT::v4f32, &WebAssembly::V128RegClass); |
| } |
| // Compute derived properties from the register classes. |
| computeRegisterProperties(Subtarget->getRegisterInfo()); |
| |
| setOperationAction(ISD::GlobalAddress, MVTPtr, Custom); |
| setOperationAction(ISD::ExternalSymbol, MVTPtr, Custom); |
| setOperationAction(ISD::JumpTable, MVTPtr, Custom); |
| setOperationAction(ISD::BlockAddress, MVTPtr, Custom); |
| setOperationAction(ISD::BRIND, MVT::Other, Custom); |
| |
| // Take the default expansion for va_arg, va_copy, and va_end. There is no |
| // default action for va_start, so we do that custom. |
| setOperationAction(ISD::VASTART, MVT::Other, Custom); |
| setOperationAction(ISD::VAARG, MVT::Other, Expand); |
| setOperationAction(ISD::VACOPY, MVT::Other, Expand); |
| setOperationAction(ISD::VAEND, MVT::Other, Expand); |
| |
| for (auto T : {MVT::f32, MVT::f64}) { |
| // Don't expand the floating-point types to constant pools. |
| setOperationAction(ISD::ConstantFP, T, Legal); |
| // Expand floating-point comparisons. |
| for (auto CC : {ISD::SETO, ISD::SETUO, ISD::SETUEQ, ISD::SETONE, |
| ISD::SETULT, ISD::SETULE, ISD::SETUGT, ISD::SETUGE}) |
| setCondCodeAction(CC, T, Expand); |
| // Expand floating-point library function operators. |
| for (auto Op : {ISD::FSIN, ISD::FCOS, ISD::FSINCOS, ISD::FPOW, ISD::FREM, |
| ISD::FMA}) |
| setOperationAction(Op, T, Expand); |
| // Note supported floating-point library function operators that otherwise |
| // default to expand. |
| for (auto Op : |
| {ISD::FCEIL, ISD::FFLOOR, ISD::FTRUNC, ISD::FNEARBYINT, ISD::FRINT}) |
| setOperationAction(Op, T, Legal); |
| // Support minnan and maxnan, which otherwise default to expand. |
| setOperationAction(ISD::FMINNAN, T, Legal); |
| setOperationAction(ISD::FMAXNAN, T, Legal); |
| // WebAssembly currently has no builtin f16 support. |
| setOperationAction(ISD::FP16_TO_FP, T, Expand); |
| setOperationAction(ISD::FP_TO_FP16, T, Expand); |
| setLoadExtAction(ISD::EXTLOAD, T, MVT::f16, Expand); |
| setTruncStoreAction(T, MVT::f16, Expand); |
| } |
| |
| for (auto T : {MVT::i32, MVT::i64}) { |
| // Expand unavailable integer operations. |
| for (auto Op : |
| {ISD::BSWAP, ISD::SMUL_LOHI, ISD::UMUL_LOHI, |
| ISD::MULHS, ISD::MULHU, ISD::SDIVREM, ISD::UDIVREM, ISD::SHL_PARTS, |
| ISD::SRA_PARTS, ISD::SRL_PARTS, ISD::ADDC, ISD::ADDE, ISD::SUBC, |
| ISD::SUBE}) { |
| setOperationAction(Op, T, Expand); |
| } |
| } |
| |
| // As a special case, these operators use the type to mean the type to |
| // sign-extend from. |
| setOperationAction(ISD::SIGN_EXTEND_INREG, MVT::i1, Expand); |
| if (!Subtarget->hasAtomics()) { |
| // The Atomics feature includes signext intructions. |
| for (auto T : {MVT::i8, MVT::i16, MVT::i32}) |
| setOperationAction(ISD::SIGN_EXTEND_INREG, T, Expand); |
| } |
| |
| // Dynamic stack allocation: use the default expansion. |
| setOperationAction(ISD::STACKSAVE, MVT::Other, Expand); |
| setOperationAction(ISD::STACKRESTORE, MVT::Other, Expand); |
| setOperationAction(ISD::DYNAMIC_STACKALLOC, MVTPtr, Expand); |
| |
| setOperationAction(ISD::FrameIndex, MVT::i32, Custom); |
| setOperationAction(ISD::CopyToReg, MVT::Other, Custom); |
| |
| // Expand these forms; we pattern-match the forms that we can handle in isel. |
| for (auto T : {MVT::i32, MVT::i64, MVT::f32, MVT::f64}) |
| for (auto Op : {ISD::BR_CC, ISD::SELECT_CC}) |
| setOperationAction(Op, T, Expand); |
| |
| // We have custom switch handling. |
| setOperationAction(ISD::BR_JT, MVT::Other, Custom); |
| |
| // WebAssembly doesn't have: |
| // - Floating-point extending loads. |
| // - Floating-point truncating stores. |
| // - i1 extending loads. |
| setLoadExtAction(ISD::EXTLOAD, MVT::f64, MVT::f32, Expand); |
| setTruncStoreAction(MVT::f64, MVT::f32, Expand); |
| for (auto T : MVT::integer_valuetypes()) |
| for (auto Ext : {ISD::EXTLOAD, ISD::ZEXTLOAD, ISD::SEXTLOAD}) |
| setLoadExtAction(Ext, T, MVT::i1, Promote); |
| |
| // Trap lowers to wasm unreachable |
| setOperationAction(ISD::TRAP, MVT::Other, Legal); |
| |
| setMaxAtomicSizeInBitsSupported(64); |
| } |
| |
| FastISel *WebAssemblyTargetLowering::createFastISel( |
| FunctionLoweringInfo &FuncInfo, const TargetLibraryInfo *LibInfo) const { |
| return WebAssembly::createFastISel(FuncInfo, LibInfo); |
| } |
| |
| bool WebAssemblyTargetLowering::isOffsetFoldingLegal( |
| const GlobalAddressSDNode * /*GA*/) const { |
| // All offsets can be folded. |
| return true; |
| } |
| |
| MVT WebAssemblyTargetLowering::getScalarShiftAmountTy(const DataLayout & /*DL*/, |
| EVT VT) const { |
| unsigned BitWidth = NextPowerOf2(VT.getSizeInBits() - 1); |
| if (BitWidth > 1 && BitWidth < 8) BitWidth = 8; |
| |
| if (BitWidth > 64) { |
| // The shift will be lowered to a libcall, and compiler-rt libcalls expect |
| // the count to be an i32. |
| BitWidth = 32; |
| assert(BitWidth >= Log2_32_Ceil(VT.getSizeInBits()) && |
| "32-bit shift counts ought to be enough for anyone"); |
| } |
| |
| MVT Result = MVT::getIntegerVT(BitWidth); |
| assert(Result != MVT::INVALID_SIMPLE_VALUE_TYPE && |
| "Unable to represent scalar shift amount type"); |
| return Result; |
| } |
| |
| const char *WebAssemblyTargetLowering::getTargetNodeName( |
| unsigned Opcode) const { |
| switch (static_cast<WebAssemblyISD::NodeType>(Opcode)) { |
| case WebAssemblyISD::FIRST_NUMBER: |
| break; |
| #define HANDLE_NODETYPE(NODE) \ |
| case WebAssemblyISD::NODE: \ |
| return "WebAssemblyISD::" #NODE; |
| #include "WebAssemblyISD.def" |
| #undef HANDLE_NODETYPE |
| } |
| return nullptr; |
| } |
| |
| std::pair<unsigned, const TargetRegisterClass *> |
| WebAssemblyTargetLowering::getRegForInlineAsmConstraint( |
| const TargetRegisterInfo *TRI, StringRef Constraint, MVT VT) const { |
| // First, see if this is a constraint that directly corresponds to a |
| // WebAssembly register class. |
| if (Constraint.size() == 1) { |
| switch (Constraint[0]) { |
| case 'r': |
| assert(VT != MVT::iPTR && "Pointer MVT not expected here"); |
| if (Subtarget->hasSIMD128() && VT.isVector()) { |
| if (VT.getSizeInBits() == 128) |
| return std::make_pair(0U, &WebAssembly::V128RegClass); |
| } |
| if (VT.isInteger() && !VT.isVector()) { |
| if (VT.getSizeInBits() <= 32) |
| return std::make_pair(0U, &WebAssembly::I32RegClass); |
| if (VT.getSizeInBits() <= 64) |
| return std::make_pair(0U, &WebAssembly::I64RegClass); |
| } |
| break; |
| default: |
| break; |
| } |
| } |
| |
| return TargetLowering::getRegForInlineAsmConstraint(TRI, Constraint, VT); |
| } |
| |
| bool WebAssemblyTargetLowering::isCheapToSpeculateCttz() const { |
| // Assume ctz is a relatively cheap operation. |
| return true; |
| } |
| |
| bool WebAssemblyTargetLowering::isCheapToSpeculateCtlz() const { |
| // Assume clz is a relatively cheap operation. |
| return true; |
| } |
| |
| bool WebAssemblyTargetLowering::isLegalAddressingMode(const DataLayout &DL, |
| const AddrMode &AM, |
| Type *Ty, |
| unsigned AS, |
| Instruction *I) const { |
| // WebAssembly offsets are added as unsigned without wrapping. The |
| // isLegalAddressingMode gives us no way to determine if wrapping could be |
| // happening, so we approximate this by accepting only non-negative offsets. |
| if (AM.BaseOffs < 0) return false; |
| |
| // WebAssembly has no scale register operands. |
| if (AM.Scale != 0) return false; |
| |
| // Everything else is legal. |
| return true; |
| } |
| |
| bool WebAssemblyTargetLowering::allowsMisalignedMemoryAccesses( |
| EVT /*VT*/, unsigned /*AddrSpace*/, unsigned /*Align*/, bool *Fast) const { |
| // WebAssembly supports unaligned accesses, though it should be declared |
| // with the p2align attribute on loads and stores which do so, and there |
| // may be a performance impact. We tell LLVM they're "fast" because |
| // for the kinds of things that LLVM uses this for (merging adjacent stores |
| // of constants, etc.), WebAssembly implementations will either want the |
| // unaligned access or they'll split anyway. |
| if (Fast) *Fast = true; |
| return true; |
| } |
| |
| bool WebAssemblyTargetLowering::isIntDivCheap(EVT VT, |
| AttributeList Attr) const { |
| // The current thinking is that wasm engines will perform this optimization, |
| // so we can save on code size. |
| return true; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // WebAssembly Lowering private implementation. |
| //===----------------------------------------------------------------------===// |
| |
| //===----------------------------------------------------------------------===// |
| // Lowering Code |
| //===----------------------------------------------------------------------===// |
| |
| static void fail(const SDLoc &DL, SelectionDAG &DAG, const char *msg) { |
| MachineFunction &MF = DAG.getMachineFunction(); |
| DAG.getContext()->diagnose( |
| DiagnosticInfoUnsupported(*MF.getFunction(), msg, DL.getDebugLoc())); |
| } |
| |
| // Test whether the given calling convention is supported. |
| static bool CallingConvSupported(CallingConv::ID CallConv) { |
| // We currently support the language-independent target-independent |
| // conventions. We don't yet have a way to annotate calls with properties like |
| // "cold", and we don't have any call-clobbered registers, so these are mostly |
| // all handled the same. |
| return CallConv == CallingConv::C || CallConv == CallingConv::Fast || |
| CallConv == CallingConv::Cold || |
| CallConv == CallingConv::PreserveMost || |
| CallConv == CallingConv::PreserveAll || |
| CallConv == CallingConv::CXX_FAST_TLS; |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerCall( |
| CallLoweringInfo &CLI, SmallVectorImpl<SDValue> &InVals) const { |
| SelectionDAG &DAG = CLI.DAG; |
| SDLoc DL = CLI.DL; |
| SDValue Chain = CLI.Chain; |
| SDValue Callee = CLI.Callee; |
| MachineFunction &MF = DAG.getMachineFunction(); |
| auto Layout = MF.getDataLayout(); |
| |
| CallingConv::ID CallConv = CLI.CallConv; |
| if (!CallingConvSupported(CallConv)) |
| fail(DL, DAG, |
| "WebAssembly doesn't support language-specific or target-specific " |
| "calling conventions yet"); |
| if (CLI.IsPatchPoint) |
| fail(DL, DAG, "WebAssembly doesn't support patch point yet"); |
| |
| // WebAssembly doesn't currently support explicit tail calls. If they are |
| // required, fail. Otherwise, just disable them. |
| if ((CallConv == CallingConv::Fast && CLI.IsTailCall && |
| MF.getTarget().Options.GuaranteedTailCallOpt) || |
| (CLI.CS && CLI.CS.isMustTailCall())) |
| fail(DL, DAG, "WebAssembly doesn't support tail call yet"); |
| CLI.IsTailCall = false; |
| |
| SmallVectorImpl<ISD::InputArg> &Ins = CLI.Ins; |
| if (Ins.size() > 1) |
| fail(DL, DAG, "WebAssembly doesn't support more than 1 returned value yet"); |
| |
| SmallVectorImpl<ISD::OutputArg> &Outs = CLI.Outs; |
| SmallVectorImpl<SDValue> &OutVals = CLI.OutVals; |
| for (unsigned i = 0; i < Outs.size(); ++i) { |
| const ISD::OutputArg &Out = Outs[i]; |
| SDValue &OutVal = OutVals[i]; |
| if (Out.Flags.isNest()) |
| fail(DL, DAG, "WebAssembly hasn't implemented nest arguments"); |
| if (Out.Flags.isInAlloca()) |
| fail(DL, DAG, "WebAssembly hasn't implemented inalloca arguments"); |
| if (Out.Flags.isInConsecutiveRegs()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs arguments"); |
| if (Out.Flags.isInConsecutiveRegsLast()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs last arguments"); |
| if (Out.Flags.isByVal() && Out.Flags.getByValSize() != 0) { |
| auto &MFI = MF.getFrameInfo(); |
| int FI = MFI.CreateStackObject(Out.Flags.getByValSize(), |
| Out.Flags.getByValAlign(), |
| /*isSS=*/false); |
| SDValue SizeNode = |
| DAG.getConstant(Out.Flags.getByValSize(), DL, MVT::i32); |
| SDValue FINode = DAG.getFrameIndex(FI, getPointerTy(Layout)); |
| Chain = DAG.getMemcpy( |
| Chain, DL, FINode, OutVal, SizeNode, Out.Flags.getByValAlign(), |
| /*isVolatile*/ false, /*AlwaysInline=*/false, |
| /*isTailCall*/ false, MachinePointerInfo(), MachinePointerInfo()); |
| OutVal = FINode; |
| } |
| } |
| |
| bool IsVarArg = CLI.IsVarArg; |
| unsigned NumFixedArgs = CLI.NumFixedArgs; |
| |
| auto PtrVT = getPointerTy(Layout); |
| |
| // Analyze operands of the call, assigning locations to each operand. |
| SmallVector<CCValAssign, 16> ArgLocs; |
| CCState CCInfo(CallConv, IsVarArg, MF, ArgLocs, *DAG.getContext()); |
| |
| if (IsVarArg) { |
| // Outgoing non-fixed arguments are placed in a buffer. First |
| // compute their offsets and the total amount of buffer space needed. |
| for (SDValue Arg : |
| make_range(OutVals.begin() + NumFixedArgs, OutVals.end())) { |
| EVT VT = Arg.getValueType(); |
| assert(VT != MVT::iPTR && "Legalized args should be concrete"); |
| Type *Ty = VT.getTypeForEVT(*DAG.getContext()); |
| unsigned Offset = CCInfo.AllocateStack(Layout.getTypeAllocSize(Ty), |
| Layout.getABITypeAlignment(Ty)); |
| CCInfo.addLoc(CCValAssign::getMem(ArgLocs.size(), VT.getSimpleVT(), |
| Offset, VT.getSimpleVT(), |
| CCValAssign::Full)); |
| } |
| } |
| |
| unsigned NumBytes = CCInfo.getAlignedCallFrameSize(); |
| |
| SDValue FINode; |
| if (IsVarArg && NumBytes) { |
| // For non-fixed arguments, next emit stores to store the argument values |
| // to the stack buffer at the offsets computed above. |
| int FI = MF.getFrameInfo().CreateStackObject(NumBytes, |
| Layout.getStackAlignment(), |
| /*isSS=*/false); |
| unsigned ValNo = 0; |
| SmallVector<SDValue, 8> Chains; |
| for (SDValue Arg : |
| make_range(OutVals.begin() + NumFixedArgs, OutVals.end())) { |
| assert(ArgLocs[ValNo].getValNo() == ValNo && |
| "ArgLocs should remain in order and only hold varargs args"); |
| unsigned Offset = ArgLocs[ValNo++].getLocMemOffset(); |
| FINode = DAG.getFrameIndex(FI, getPointerTy(Layout)); |
| SDValue Add = DAG.getNode(ISD::ADD, DL, PtrVT, FINode, |
| DAG.getConstant(Offset, DL, PtrVT)); |
| Chains.push_back(DAG.getStore( |
| Chain, DL, Arg, Add, |
| MachinePointerInfo::getFixedStack(MF, FI, Offset), 0)); |
| } |
| if (!Chains.empty()) |
| Chain = DAG.getNode(ISD::TokenFactor, DL, MVT::Other, Chains); |
| } else if (IsVarArg) { |
| FINode = DAG.getIntPtrConstant(0, DL); |
| } |
| |
| // Compute the operands for the CALLn node. |
| SmallVector<SDValue, 16> Ops; |
| Ops.push_back(Chain); |
| Ops.push_back(Callee); |
| |
| // Add all fixed arguments. Note that for non-varargs calls, NumFixedArgs |
| // isn't reliable. |
| Ops.append(OutVals.begin(), |
| IsVarArg ? OutVals.begin() + NumFixedArgs : OutVals.end()); |
| // Add a pointer to the vararg buffer. |
| if (IsVarArg) Ops.push_back(FINode); |
| |
| SmallVector<EVT, 8> InTys; |
| for (const auto &In : Ins) { |
| assert(!In.Flags.isByVal() && "byval is not valid for return values"); |
| assert(!In.Flags.isNest() && "nest is not valid for return values"); |
| if (In.Flags.isInAlloca()) |
| fail(DL, DAG, "WebAssembly hasn't implemented inalloca return values"); |
| if (In.Flags.isInConsecutiveRegs()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs return values"); |
| if (In.Flags.isInConsecutiveRegsLast()) |
| fail(DL, DAG, |
| "WebAssembly hasn't implemented cons regs last return values"); |
| // Ignore In.getOrigAlign() because all our arguments are passed in |
| // registers. |
| InTys.push_back(In.VT); |
| } |
| InTys.push_back(MVT::Other); |
| SDVTList InTyList = DAG.getVTList(InTys); |
| SDValue Res = |
| DAG.getNode(Ins.empty() ? WebAssemblyISD::CALL0 : WebAssemblyISD::CALL1, |
| DL, InTyList, Ops); |
| if (Ins.empty()) { |
| Chain = Res; |
| } else { |
| InVals.push_back(Res); |
| Chain = Res.getValue(1); |
| } |
| |
| return Chain; |
| } |
| |
| bool WebAssemblyTargetLowering::CanLowerReturn( |
| CallingConv::ID /*CallConv*/, MachineFunction & /*MF*/, bool /*IsVarArg*/, |
| const SmallVectorImpl<ISD::OutputArg> &Outs, |
| LLVMContext & /*Context*/) const { |
| // WebAssembly can't currently handle returning tuples. |
| return Outs.size() <= 1; |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerReturn( |
| SDValue Chain, CallingConv::ID CallConv, bool /*IsVarArg*/, |
| const SmallVectorImpl<ISD::OutputArg> &Outs, |
| const SmallVectorImpl<SDValue> &OutVals, const SDLoc &DL, |
| SelectionDAG &DAG) const { |
| assert(Outs.size() <= 1 && "WebAssembly can only return up to one value"); |
| if (!CallingConvSupported(CallConv)) |
| fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions"); |
| |
| SmallVector<SDValue, 4> RetOps(1, Chain); |
| RetOps.append(OutVals.begin(), OutVals.end()); |
| Chain = DAG.getNode(WebAssemblyISD::RETURN, DL, MVT::Other, RetOps); |
| |
| // Record the number and types of the return values. |
| for (const ISD::OutputArg &Out : Outs) { |
| assert(!Out.Flags.isByVal() && "byval is not valid for return values"); |
| assert(!Out.Flags.isNest() && "nest is not valid for return values"); |
| assert(Out.IsFixed && "non-fixed return value is not valid"); |
| if (Out.Flags.isInAlloca()) |
| fail(DL, DAG, "WebAssembly hasn't implemented inalloca results"); |
| if (Out.Flags.isInConsecutiveRegs()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs results"); |
| if (Out.Flags.isInConsecutiveRegsLast()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs last results"); |
| } |
| |
| return Chain; |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerFormalArguments( |
| SDValue Chain, CallingConv::ID CallConv, bool IsVarArg, |
| const SmallVectorImpl<ISD::InputArg> &Ins, const SDLoc &DL, |
| SelectionDAG &DAG, SmallVectorImpl<SDValue> &InVals) const { |
| if (!CallingConvSupported(CallConv)) |
| fail(DL, DAG, "WebAssembly doesn't support non-C calling conventions"); |
| |
| MachineFunction &MF = DAG.getMachineFunction(); |
| auto *MFI = MF.getInfo<WebAssemblyFunctionInfo>(); |
| |
| // Set up the incoming ARGUMENTS value, which serves to represent the liveness |
| // of the incoming values before they're represented by virtual registers. |
| MF.getRegInfo().addLiveIn(WebAssembly::ARGUMENTS); |
| |
| for (const ISD::InputArg &In : Ins) { |
| if (In.Flags.isInAlloca()) |
| fail(DL, DAG, "WebAssembly hasn't implemented inalloca arguments"); |
| if (In.Flags.isNest()) |
| fail(DL, DAG, "WebAssembly hasn't implemented nest arguments"); |
| if (In.Flags.isInConsecutiveRegs()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs arguments"); |
| if (In.Flags.isInConsecutiveRegsLast()) |
| fail(DL, DAG, "WebAssembly hasn't implemented cons regs last arguments"); |
| // Ignore In.getOrigAlign() because all our arguments are passed in |
| // registers. |
| InVals.push_back( |
| In.Used |
| ? DAG.getNode(WebAssemblyISD::ARGUMENT, DL, In.VT, |
| DAG.getTargetConstant(InVals.size(), DL, MVT::i32)) |
| : DAG.getUNDEF(In.VT)); |
| |
| // Record the number and types of arguments. |
| MFI->addParam(In.VT); |
| } |
| |
| // Varargs are copied into a buffer allocated by the caller, and a pointer to |
| // the buffer is passed as an argument. |
| if (IsVarArg) { |
| MVT PtrVT = getPointerTy(MF.getDataLayout()); |
| unsigned VarargVreg = |
| MF.getRegInfo().createVirtualRegister(getRegClassFor(PtrVT)); |
| MFI->setVarargBufferVreg(VarargVreg); |
| Chain = DAG.getCopyToReg( |
| Chain, DL, VarargVreg, |
| DAG.getNode(WebAssemblyISD::ARGUMENT, DL, PtrVT, |
| DAG.getTargetConstant(Ins.size(), DL, MVT::i32))); |
| MFI->addParam(PtrVT); |
| } |
| |
| // Record the number and types of results. |
| SmallVector<MVT, 4> Params; |
| SmallVector<MVT, 4> Results; |
| ComputeSignatureVTs(*MF.getFunction(), DAG.getTarget(), Params, Results); |
| for (MVT VT : Results) |
| MFI->addResult(VT); |
| |
| return Chain; |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // Custom lowering hooks. |
| //===----------------------------------------------------------------------===// |
| |
| SDValue WebAssemblyTargetLowering::LowerOperation(SDValue Op, |
| SelectionDAG &DAG) const { |
| SDLoc DL(Op); |
| switch (Op.getOpcode()) { |
| default: |
| llvm_unreachable("unimplemented operation lowering"); |
| return SDValue(); |
| case ISD::FrameIndex: |
| return LowerFrameIndex(Op, DAG); |
| case ISD::GlobalAddress: |
| return LowerGlobalAddress(Op, DAG); |
| case ISD::ExternalSymbol: |
| return LowerExternalSymbol(Op, DAG); |
| case ISD::JumpTable: |
| return LowerJumpTable(Op, DAG); |
| case ISD::BR_JT: |
| return LowerBR_JT(Op, DAG); |
| case ISD::VASTART: |
| return LowerVASTART(Op, DAG); |
| case ISD::BlockAddress: |
| case ISD::BRIND: |
| fail(DL, DAG, "WebAssembly hasn't implemented computed gotos"); |
| return SDValue(); |
| case ISD::RETURNADDR: // Probably nothing meaningful can be returned here. |
| fail(DL, DAG, "WebAssembly hasn't implemented __builtin_return_address"); |
| return SDValue(); |
| case ISD::FRAMEADDR: |
| return LowerFRAMEADDR(Op, DAG); |
| case ISD::CopyToReg: |
| return LowerCopyToReg(Op, DAG); |
| } |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerCopyToReg(SDValue Op, |
| SelectionDAG &DAG) const { |
| SDValue Src = Op.getOperand(2); |
| if (isa<FrameIndexSDNode>(Src.getNode())) { |
| // CopyToReg nodes don't support FrameIndex operands. Other targets select |
| // the FI to some LEA-like instruction, but since we don't have that, we |
| // need to insert some kind of instruction that can take an FI operand and |
| // produces a value usable by CopyToReg (i.e. in a vreg). So insert a dummy |
| // copy_local between Op and its FI operand. |
| SDValue Chain = Op.getOperand(0); |
| SDLoc DL(Op); |
| unsigned Reg = cast<RegisterSDNode>(Op.getOperand(1))->getReg(); |
| EVT VT = Src.getValueType(); |
| SDValue Copy( |
| DAG.getMachineNode(VT == MVT::i32 ? WebAssembly::COPY_I32 |
| : WebAssembly::COPY_I64, |
| DL, VT, Src), |
| 0); |
| return Op.getNode()->getNumValues() == 1 |
| ? DAG.getCopyToReg(Chain, DL, Reg, Copy) |
| : DAG.getCopyToReg(Chain, DL, Reg, Copy, Op.getNumOperands() == 4 |
| ? Op.getOperand(3) |
| : SDValue()); |
| } |
| return SDValue(); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerFrameIndex(SDValue Op, |
| SelectionDAG &DAG) const { |
| int FI = cast<FrameIndexSDNode>(Op)->getIndex(); |
| return DAG.getTargetFrameIndex(FI, Op.getValueType()); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerFRAMEADDR(SDValue Op, |
| SelectionDAG &DAG) const { |
| // Non-zero depths are not supported by WebAssembly currently. Use the |
| // legalizer's default expansion, which is to return 0 (what this function is |
| // documented to do). |
| if (Op.getConstantOperandVal(0) > 0) |
| return SDValue(); |
| |
| DAG.getMachineFunction().getFrameInfo().setFrameAddressIsTaken(true); |
| EVT VT = Op.getValueType(); |
| unsigned FP = |
| Subtarget->getRegisterInfo()->getFrameRegister(DAG.getMachineFunction()); |
| return DAG.getCopyFromReg(DAG.getEntryNode(), SDLoc(Op), FP, VT); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerGlobalAddress(SDValue Op, |
| SelectionDAG &DAG) const { |
| SDLoc DL(Op); |
| const auto *GA = cast<GlobalAddressSDNode>(Op); |
| EVT VT = Op.getValueType(); |
| assert(GA->getTargetFlags() == 0 && |
| "Unexpected target flags on generic GlobalAddressSDNode"); |
| if (GA->getAddressSpace() != 0) |
| fail(DL, DAG, "WebAssembly only expects the 0 address space"); |
| return DAG.getNode( |
| WebAssemblyISD::Wrapper, DL, VT, |
| DAG.getTargetGlobalAddress(GA->getGlobal(), DL, VT, GA->getOffset())); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerExternalSymbol( |
| SDValue Op, SelectionDAG &DAG) const { |
| SDLoc DL(Op); |
| const auto *ES = cast<ExternalSymbolSDNode>(Op); |
| EVT VT = Op.getValueType(); |
| assert(ES->getTargetFlags() == 0 && |
| "Unexpected target flags on generic ExternalSymbolSDNode"); |
| // Set the TargetFlags to 0x1 which indicates that this is a "function" |
| // symbol rather than a data symbol. We do this unconditionally even though |
| // we don't know anything about the symbol other than its name, because all |
| // external symbols used in target-independent SelectionDAG code are for |
| // functions. |
| return DAG.getNode(WebAssemblyISD::Wrapper, DL, VT, |
| DAG.getTargetExternalSymbol(ES->getSymbol(), VT, |
| /*TargetFlags=*/0x1)); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerJumpTable(SDValue Op, |
| SelectionDAG &DAG) const { |
| // There's no need for a Wrapper node because we always incorporate a jump |
| // table operand into a BR_TABLE instruction, rather than ever |
| // materializing it in a register. |
| const JumpTableSDNode *JT = cast<JumpTableSDNode>(Op); |
| return DAG.getTargetJumpTable(JT->getIndex(), Op.getValueType(), |
| JT->getTargetFlags()); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerBR_JT(SDValue Op, |
| SelectionDAG &DAG) const { |
| SDLoc DL(Op); |
| SDValue Chain = Op.getOperand(0); |
| const auto *JT = cast<JumpTableSDNode>(Op.getOperand(1)); |
| SDValue Index = Op.getOperand(2); |
| assert(JT->getTargetFlags() == 0 && "WebAssembly doesn't set target flags"); |
| |
| SmallVector<SDValue, 8> Ops; |
| Ops.push_back(Chain); |
| Ops.push_back(Index); |
| |
| MachineJumpTableInfo *MJTI = DAG.getMachineFunction().getJumpTableInfo(); |
| const auto &MBBs = MJTI->getJumpTables()[JT->getIndex()].MBBs; |
| |
| // Add an operand for each case. |
| for (auto MBB : MBBs) Ops.push_back(DAG.getBasicBlock(MBB)); |
| |
| // TODO: For now, we just pick something arbitrary for a default case for now. |
| // We really want to sniff out the guard and put in the real default case (and |
| // delete the guard). |
| Ops.push_back(DAG.getBasicBlock(MBBs[0])); |
| |
| return DAG.getNode(WebAssemblyISD::BR_TABLE, DL, MVT::Other, Ops); |
| } |
| |
| SDValue WebAssemblyTargetLowering::LowerVASTART(SDValue Op, |
| SelectionDAG &DAG) const { |
| SDLoc DL(Op); |
| EVT PtrVT = getPointerTy(DAG.getMachineFunction().getDataLayout()); |
| |
| auto *MFI = DAG.getMachineFunction().getInfo<WebAssemblyFunctionInfo>(); |
| const Value *SV = cast<SrcValueSDNode>(Op.getOperand(2))->getValue(); |
| |
| SDValue ArgN = DAG.getCopyFromReg(DAG.getEntryNode(), DL, |
| MFI->getVarargBufferVreg(), PtrVT); |
| return DAG.getStore(Op.getOperand(0), DL, ArgN, Op.getOperand(1), |
| MachinePointerInfo(SV), 0); |
| } |
| |
| //===----------------------------------------------------------------------===// |
| // WebAssembly Optimization Hooks |
| //===----------------------------------------------------------------------===// |
