Initial Subzero WASM prototype.

src/WasmTranslator.cpp

Index: src/WasmTranslator.cpp
diff --git a/src/WasmTranslator.cpp b/src/WasmTranslator.cpp
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+++ b/src/WasmTranslator.cpp
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+//===- subzero/src/WasmTranslator.cpp - WASM to Subzero Translation -------===//
+//
+//                        The Subzero Code Generator
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+///
+/// \file
+/// \brief Defines a driver for translating Wasm bitcode into PNaCl bitcode.
+///
+/// The translator uses V8's WebAssembly decoder to handle the binary Wasm
+/// format but replaces the usual TurboFan builder with a new PNaCl builder.
+///
+//===----------------------------------------------------------------------===//
+
+#include "llvm/Support/StreamingMemoryObject.h"
+
+#include "WasmTranslator.h"
+
+#include "src/wasm/module-decoder.h"
+#include "src/wasm/wasm-opcodes.h"
+#include "src/zone.h"
+
+#include "IceCfgNode.h"
+#include "IceGlobalInits.h"
+
+using namespace std;
+using namespace Ice;
+using namespace v8;
+using namespace v8::internal;
+using namespace v8::internal::wasm;
+using v8::internal::wasm::DecodeWasmModule;
+
+#include "src/wasm/ast-decoder-impl.h"
+
+#define LOG(Expr) log([&](Ostream & out) { Expr; })
+
+namespace {
+
+Ice::Type toIceType(v8::internal::MachineType) {
+  // TODO(eholk): actually convert this.
+  return IceType_i32;
+}
+
+Ice::Type toIceType(wasm::LocalType Type) {
+  switch (Type) {
+  default:
+    llvm::report_fatal_error("unexpected enum value");
+  case MachineRepresentation::kNone:
+    llvm::report_fatal_error("kNone type not supported");
+  case MachineRepresentation::kBit:
+    return IceType_i1;
+  case MachineRepresentation::kWord8:
+    return IceType_i8;
+  case MachineRepresentation::kWord16:
+    return IceType_i16;
+  case MachineRepresentation::kWord32:
+    return IceType_i32;
+  case MachineRepresentation::kWord64:
+    return IceType_i64;
+  case MachineRepresentation::kFloat32:
+    return IceType_f32;
+  case MachineRepresentation::kFloat64:
+    return IceType_f64;
+  case MachineRepresentation::kSimd128:
+    llvm::report_fatal_error("ambiguous SIMD type");
+  case MachineRepresentation::kTagged:
+    llvm::report_fatal_error("kTagged type not supported");
+  }
+}
+
+} // end of anonymous namespace
+
+/// This class wraps either an Operand or a CfgNode.
+///
+/// Turbofan's sea of nodes representation only has nodes for values, control
+/// flow, etc. In Subzero these concepts are all separate. This class lets V8's
+/// Wasm decoder treat Subzero objects as though they are all the same.
+class OperandNode {
+  static constexpr uintptr_t NODE_FLAG = 1;
+  static constexpr uintptr_t UNDEF_PTR = (uintptr_t)-1;
+
+  uintptr_t Data = UNDEF_PTR;
+
+public:
+  OperandNode() = default;
+  explicit OperandNode(Operand *Operand)
+      : Data(reinterpret_cast<uintptr_t>(Operand)) {}
+  explicit OperandNode(CfgNode *Node)
+      : Data(reinterpret_cast<uintptr_t>(Node) | NODE_FLAG) {}
+  explicit OperandNode(nullptr_t) : Data(UNDEF_PTR) {}
+
+  operator Operand *() const {
+    if (UNDEF_PTR == Data) {
+      return nullptr;
+    }
+    if (!isOperand()) {
+      llvm::report_fatal_error("This OperandNode is not an Operand");
+    }
+    return reinterpret_cast<Operand *>(Data);
+  }
+
+  operator CfgNode *() const {
+    if (UNDEF_PTR == Data) {
+      return nullptr;
+    }
+    if (!isCfgNode()) {
+      llvm::report_fatal_error("This OperandNode is not a CfgNode");
+    }
+    return reinterpret_cast<CfgNode *>(Data & ~NODE_FLAG);
+  }
+
+  explicit operator bool() const { return (Data != UNDEF_PTR) && Data; }
+  bool operator==(const OperandNode &Rhs) const {
+    return (Data == Rhs.Data) ||
+           (UNDEF_PTR == Data && (Rhs.Data == 0 || Rhs.Data == NODE_FLAG)) ||
+           (UNDEF_PTR == Rhs.Data && (Data == 0 || Data == NODE_FLAG));
+  }
+  bool operator!=(const OperandNode &Rhs) const { return !(*this == Rhs); }
+
+  bool isOperand() const { return (Data != UNDEF_PTR) && !(Data & NODE_FLAG); }
+  bool isCfgNode() const { return (Data != UNDEF_PTR) && (Data & NODE_FLAG); }
+
+  Operand *toOperand() const { return static_cast<Operand *>(*this); }
+
+  CfgNode *toCfgNode() const { return static_cast<CfgNode *>(*this); }
+};
+
+Ostream &operator<<(Ostream &Out, const OperandNode &Op) {
+  if (Op.isOperand()) {
+    Out << "(Operand*)" << Op.toOperand();
+  } else if (Op.isCfgNode()) {
+    Out << "(CfgNode*)" << Op.toCfgNode();
+  } else {
+    Out << "nullptr";
+  }
+  return Out;
+}
+
+constexpr bool isComparison(wasm::WasmOpcode Opcode) {
+  switch (Opcode) {
+  case kExprI32Ne:
+  case kExprI64Ne:
+  case kExprI32Eq:
+  case kExprI64Eq:
+  case kExprI32LtS:
+  case kExprI64LtS:
+  case kExprI32LtU:
+  case kExprI64LtU:
+  case kExprI32GeS:
+  case kExprI64GeS:
+  case kExprI32GtS:
+  case kExprI64GtS:
+  case kExprI32GtU:
+  case kExprI64GtU:
+    return true;
+  default:
+    return false;
+  }
+}
+
+class IceBuilder {
+  using Node = OperandNode;
+
+  IceBuilder() = delete;
+  IceBuilder(const IceBuilder &) = delete;
+  IceBuilder &operator=(const IceBuilder &) = delete;
+
+public:
+  explicit IceBuilder(class Cfg *Func)
+      : Func(Func), Ctx(Func->getContext()), ControlPtr(nullptr) {}
+
+  /// Allocates a buffer of Nodes for use by V8.
+  Node *Buffer(size_t Count) {
+    LOG(out << "Buffer(" << Count << ")\n");
+    return Func->allocateArrayOf<Node>(Count);
+  }
+
+  Node Error() { llvm::report_fatal_error("Error"); }
+  Node Start(unsigned Params) {
+    LOG(out << "Start(" << Params << ") = ");
+    auto *Entry = Func->makeNode();
+    Func->setEntryNode(Entry);
+    LOG(out << Node(Entry) << "\n");
+    return OperandNode(Entry);
+  }
+  Node Param(unsigned Index, wasm::LocalType Type) {
+    LOG(out << "Param(" << Index << ") = ");
+    auto *Arg = makeVariable(toIceType(Type));
+    assert(Index == NextArg);
+    Func->addArg(Arg);
+    ++NextArg;
+    LOG(out << Node(Arg) << "\n");
+    return OperandNode(Arg);
+  }
+  Node Loop(CfgNode *Entry) {
+    auto *Loop = Func->makeNode();
+    LOG(out << "Loop(" << Entry << ") = " << Loop << "\n");
+    Entry->appendInst(InstBr::create(Func, Loop));
+    return OperandNode(Loop);
+  }
+  void Terminate(Node Effect, Node Control) {
+    // TODO(eholk): this is almost certainly wrong
+    LOG(out << "Terminate(" << Effect << ", " << Control << ")"
+            << "\n");
+  }
+  Node Merge(unsigned Count, Node *Controls) {
+    LOG(out << "Merge(" << Count);
+    for (unsigned i = 0; i < Count; ++i) {
+      LOG(out << ", " << Controls[i]);
+    }
+    LOG(out << ") = ");
+
+    auto *MergedNode = Func->makeNode();
+
+    for (unsigned i = 0; i < Count; ++i) {
+      CfgNode *Control = Controls[i];
+      Control->appendInst(InstBr::create(Func, MergedNode));
+    }
+    LOG(out << (OperandNode)MergedNode << "\n");
+    return OperandNode(MergedNode);
+  }
+  Node Phi(wasm::LocalType Type, unsigned Count, Node *Vals, Node Control) {
+    LOG(out << "Phi(" << Count << ", " << Control);
+    for (int i = 0; i < Count; ++i) {
+      LOG(out << ", " << Vals[i]);
+    }
+    LOG(out << ") = ");
+
+    const auto &InEdges = Control.toCfgNode()->getInEdges();
+    assert(Count == InEdges.size());
+
+    assert(Count > 0);
+
+    auto *Dest = makeVariable(Vals[0].toOperand()->getType(), Control);
+
+    // Multiply by 10 in case more things get added later.
+
+    // TODO(eholk): find a better way besides multiplying by some arbitrary
+    // constant.
+    auto *Phi = InstPhi::create(Func, Count * 10, Dest);
+    for (int i = 0; i < Count; ++i) {
+      auto *Op = Vals[i].toOperand();
+      assert(Op);
+      Phi->addArgument(Op, InEdges[i]);
+    }
+    setDefiningInst(Dest, Phi);
+    Control.toCfgNode()->appendInst(Phi);
+    LOG(out << Node(Dest) << "\n");
+    return OperandNode(Dest);
+  }
+  Node EffectPhi(unsigned Count, Node *Effects, Node Control) {
+    // TODO(eholk): this function is almost certainly wrong.
+    LOG(out << "EffectPhi(" << Count << ", " << Control << "):\n");
+    for (unsigned i = 0; i < Count; ++i) {
+      LOG(out << "  " << Effects[i] << "\n");
+    }
+    return OperandNode(nullptr);
+  }
+  Node Int32Constant(int32_t Value) {
+    LOG(out << "Int32Constant(" << Value << ") = ");
+    auto *Const = Ctx->getConstantInt32(Value);
+    assert(Const);
+    assert(Control());
+    LOG(out << Node(Const) << "\n");
+    return OperandNode(Const);
+  }
+  Node Int64Constant(int64_t Value) {
+    LOG(out << "Int64Constant(" << Value << ") = ");
+    auto *Const = Ctx->getConstantInt64(Value);
+    assert(Const);
+    LOG(out << Node(Const) << "\n");
+    return OperandNode(Const);
+  }
+  Node Float32Constant(float Value) {
+    LOG(out << "Float32Constant(" << Value << ") = ");
+    auto *Const = Ctx->getConstantFloat(Value);
+    assert(Const);
+    LOG(out << Node(Const) << "\n");
+    return OperandNode(Const);
+  }
+  Node Float64Constant(double Value) {
+    LOG(out << "Float64Constant(" << Value << ") = ");
+    auto *Const = Ctx->getConstantDouble(Value);
+    assert(Const);
+    LOG(out << Node(Const) << "\n");
+    return OperandNode(Const);
+  }
+  Node Binop(wasm::WasmOpcode Opcode, Node Left, Node Right) {
+    LOG(out << "Binop(" << WasmOpcodes::OpcodeName(Opcode) << ", " << Left
+            << ", " << Right << ") = ");
+    auto *Dest = makeVariable(
+        isComparison(Opcode) ? IceType_i1 : Left.toOperand()->getType());
+    switch (Opcode) {
+    case kExprI32Add:
+    case kExprI64Add:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Add, Dest, Left, Right));
+      break;
+    case kExprI32Sub:
+    case kExprI64Sub:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Sub, Dest, Left, Right));
+      break;
+    case kExprI32Mul:
+    case kExprI64Mul:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Mul, Dest, Left, Right));
+      break;
+    case kExprI32DivU:
+    case kExprI64DivU:
+      Control()->appendInst(InstArithmetic::create(Func, InstArithmetic::Udiv,
+                                                   Dest, Left, Right));
+      break;
+    case kExprI32RemU:
+    case kExprI64RemU:
+      Control()->appendInst(InstArithmetic::create(Func, InstArithmetic::Urem,
+                                                   Dest, Left, Right));
+      break;
+    case kExprI32Ior:
+    case kExprI64Ior:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Or, Dest, Left, Right));
+      break;
+    case kExprI32Xor:
+    case kExprI64Xor:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Xor, Dest, Left, Right));
+      break;
+    case kExprI32Shl:
+    case kExprI64Shl:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::Shl, Dest, Left, Right));
+      break;
+    case kExprI32ShrU:
+    case kExprI64ShrU:
+    case kExprI32ShrS:
+    case kExprI64ShrS:
+      Control()->appendInst(InstArithmetic::create(Func, InstArithmetic::Ashr,
+                                                   Dest, Left, Right));
+      break;
+    case kExprI32And:
+    case kExprI64And:
+      Control()->appendInst(
+          InstArithmetic::create(Func, InstArithmetic::And, Dest, Left, Right));
+      break;
+    case kExprI32Ne:
+    case kExprI64Ne:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Ne, Dest, Left, Right));
+      break;
+    case kExprI32Eq:
+    case kExprI64Eq:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Eq, Dest, Left, Right));
+      break;
+    case kExprI32LtS:
+    case kExprI64LtS:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Slt, Dest, Left, Right));
+      break;
+    case kExprI32LtU:
+    case kExprI64LtU:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Ult, Dest, Left, Right));
+      break;
+    case kExprI32GeS:
+    case kExprI64GeS:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Sge, Dest, Left, Right));
+    case kExprI32GtS:
+    case kExprI64GtS:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Sgt, Dest, Left, Right));
+      break;
+    case kExprI32GtU:
+    case kExprI64GtU:
+      Control()->appendInst(
+          InstIcmp::create(Func, InstIcmp::Ugt, Dest, Left, Right));
+      break;
+    default:
+      LOG(out << "Unknown binop: " << WasmOpcodes::OpcodeName(Opcode) << "\n");
+      llvm::report_fatal_error("Uncovered or invalid binop.");
+      return OperandNode(nullptr);
+    }
+    LOG(out << Dest << "\n");
+    return OperandNode(Dest);
+  }
+  Node Unop(wasm::WasmOpcode Opcode, Node Input) {
+    LOG(out << "Unop(" << WasmOpcodes::OpcodeName(Opcode) << ", " << Input
+            << ") = ");
+    Ice::Variable *Dest = nullptr;
+    switch (Opcode) {
+    case kExprF32Neg: {
+      Dest = makeVariable(IceType_f32);
+      Control()->appendInst(InstArithmetic::create(
+          Func, InstArithmetic::Fsub, Dest, Ctx->getConstantFloat(0), Input));
+      break;
+    }
+    case kExprF64Neg: {
+      Dest = makeVariable(IceType_f64);
+      Control()->appendInst(InstArithmetic::create(
+          Func, InstArithmetic::Fsub, Dest, Ctx->getConstantDouble(0), Input));
+      break;
+    }
+    case kExprI64UConvertI32:
+      Dest = makeVariable(IceType_i64);
+      Control()->appendInst(
+          InstCast::create(Func, InstCast::Zext, Dest, Input));
+      break;
+    default:
+      LOG(out << "Unknown unop: " << WasmOpcodes::OpcodeName(Opcode) << "\n");
+      llvm::report_fatal_error("Uncovered or invalid unop.");
+      return OperandNode(nullptr);
+    }
+    LOG(out << Dest << "\n");
+    return OperandNode(Dest);
+  }
+  unsigned InputCount(CfgNode *Node) const { return Node->getInEdges().size(); }
+  bool IsPhiWithMerge(Node Phi, Node Merge) const {
+    LOG(out << "IsPhiWithMerge(" << Phi << ", " << Merge << ")"
+            << "\n");
+    if (Phi && Phi.isOperand()) {
+      LOG(out << "  ...is operand"
+              << "\n");
+      if (auto *Inst = getDefiningInst(Phi)) {
+        LOG(out << "  ...has defining instruction"
+                << "\n");
+        LOG(out << getDefNode(Phi) << "\n");
+        LOG(out << "  ..." << (getDefNode(Phi) == Merge) << "\n");
+        return getDefNode(Phi) == Merge;
+      }
+    }
+    return false;
+  }
+  void AppendToMerge(CfgNode *Merge, CfgNode *From) const {
+    From->appendInst(InstBr::create(Func, Merge));
+  }
+  void AppendToPhi(Node Merge, Node Phi, Node From) {
+    LOG(out << "AppendToPhi(" << Merge << ", " << Phi << ", " << From << ")"
+            << "\n");
+    auto *Inst = getDefiningInst(Phi);
+    Inst->addArgument(From, getDefNode(From));
+  }
+
+  //-----------------------------------------------------------------------
+  // Operations that read and/or write {control} and {effect}.
+  //-----------------------------------------------------------------------
+  Node Branch(Node Cond, Node *TrueNode, Node *FalseNode) {
+    // true_node and false_node appear to be out parameters.
+    LOG(out << "Branch(" << Cond << ", ");
+
+    // save control here because true_node appears to alias control.
+    auto *Ctrl = Control();
+
+    *TrueNode = OperandNode(Func->makeNode());
+    *FalseNode = OperandNode(Func->makeNode());
+
+    LOG(out << *TrueNode << ", " << *FalseNode << ")"
+            << "\n");
+
+    Ctrl->appendInst(InstBr::create(Func, Cond, *TrueNode, *FalseNode));
+    return OperandNode(nullptr);
+  }
+  Node Switch(unsigned Count, Node Key) { llvm::report_fatal_error("Switch"); }
+  Node IfValue(int32_t Value, Node Sw) { llvm::report_fatal_error("IfValue"); }
+  Node IfDefault(Node Sw) { llvm::report_fatal_error("IfDefault"); }
+  Node Return(unsigned Count, Node *Vals) {
+    assert(1 >= Count);
+    LOG(out << "Return(");
+    if (Count > 0)
+      LOG(out << Vals[0]);
+    LOG(out << ")"
+            << "\n");
+    auto *Instr =
+        1 == Count ? InstRet::create(Func, Vals[0]) : InstRet::create(Func);
+    Control()->appendInst(Instr);
+    Control()->setHasReturn();
+    LOG(out << Node(nullptr) << "\n");
+    return OperandNode(nullptr);
+  }
+  Node ReturnVoid() {
+    LOG(out << "ReturnVoid() = ");
+    auto *Instr = InstRet::create(Func);
+    Control()->appendInst(Instr);
+    Control()->setHasReturn();
+    LOG(out << Node(nullptr) << "\n");
+    return OperandNode(nullptr);
+  }
+  Node Unreachable() {
+    LOG(out << "Unreachable() = ");
+    auto *Instr = InstUnreachable::create(Func);
+    Control()->appendInst(Instr);
+    LOG(out << Node(nullptr) << "\n");
+    return OperandNode(nullptr);
+  }
+
+  Node CallDirect(uint32_t Index, Node *Args) {
+    LOG(out << "CallDirect(" << Index << ")"
+            << "\n");
+    assert(Module->IsValidFunction(Index));
+    const auto *Module = this->Module->module;
+    assert(Module);
+    const auto &Target = Module->functions[Index];
+    const auto *Sig = Target.sig;
+    assert(Sig);
+    const auto NumArgs = Sig->parameter_count();
+    LOG(out << "  number of args: " << NumArgs << "\n");
+
+    const auto TargetName =
+        Ctx->getGlobalString(Module->GetName(Target.name_offset));
+    LOG(out << "  target name: " << TargetName << "\n");
+
+    assert(Sig->return_count() <= 1);
+
+    auto *TargetOperand = Ctx->getConstantSym(0, TargetName);
+
+    auto *Dest = Sig->return_count() > 0
+                     ? makeVariable(toIceType(Sig->GetReturn()))
+                     : nullptr;
+    auto *Call = InstCall::create(Func, NumArgs, Dest, TargetOperand,
+                                  false /* HasTailCall */);
+    for (int i = 0; i < NumArgs; ++i) {
+      // The builder reserves the first argument for the code object.
+      LOG(out << "  args[" << i << "] = " << Args[i + 1] << "\n");
+      Call->addArg(Args[i + 1]);
+    }
+
+    Control()->appendInst(Call);
+    LOG(out << "Call Result = " << Node(Dest) << "\n");
+    return OperandNode(Dest);
+  }
+  Node CallImport(uint32_t Index, Node *Args) {
+    LOG(out << "CallImport(" << Index << ")"
+            << "\n");
+    const auto *Module = this->Module->module;
+    assert(Module);
+    const auto *Sig = this->Module->GetImportSignature(Index);
+    assert(Sig);
+    const auto NumArgs = Sig->parameter_count();
+    LOG(out << "  number of args: " << NumArgs << "\n");
+
+    const auto &Target = Module->import_table[Index];
+    const auto TargetName =
+        Ctx->getGlobalString(Module->GetName(Target.function_name_offset));
+    LOG(out << "  target name: " << TargetName << "\n");
+
+    assert(Sig->return_count() <= 1);
+
+    auto *TargetOperand = Ctx->getConstantSym(0, TargetName);
+
+    auto *Dest = Sig->return_count() > 0
+                     ? makeVariable(toIceType(Sig->GetReturn()))
+                     : nullptr;
+    constexpr bool NoTailCall = false;
+    auto *Call =
+        InstCall::create(Func, NumArgs, Dest, TargetOperand, NoTailCall);
+    for (int i = 0; i < NumArgs; ++i) {
+      // The builder reserves the first argument for the code object.
+      LOG(out << "  args[" << i << "] = " << Args[i + 1] << "\n");
+      Call->addArg(Args[i + 1]);
+    }
+
+    Control()->appendInst(Call);
+    LOG(out << "Call Result = " << Node(Dest) << "\n");
+    return OperandNode(Dest);
+  }
+  Node CallIndirect(uint32_t Index, Node *Args) {
+    llvm::report_fatal_error("CallIndirect");
+  }
+  Node Invert(Node Node) { llvm::report_fatal_error("Invert"); }
+  Node FunctionTable() { llvm::report_fatal_error("FunctionTable"); }
+
+  //-----------------------------------------------------------------------
+  // Operations that concern the linear memory.
+  //-----------------------------------------------------------------------
+  Node MemSize(uint32_t Offset) { llvm::report_fatal_error("MemSize"); }
+  Node LoadGlobal(uint32_t Index) { llvm::report_fatal_error("LoadGlobal"); }
+  Node StoreGlobal(uint32_t Index, Node Val) {
+    llvm::report_fatal_error("StoreGlobal");
+  }
+  Node LoadMem(wasm::LocalType Type, MachineType MemType, Node Index,
+               uint32_t Offset) {
+    LOG(out << "LoadMem(" << Index << "[" << Offset << "]) = ");
+
+    // first, add the index and the offset together.
+    auto *OffsetConstant = Ctx->getConstantInt32(Offset);
+    auto *Addr = makeVariable(IceType_i32);
+    Control()->appendInst(InstArithmetic::create(Func, InstArithmetic::Add,
+                                                 Addr, Index, OffsetConstant));
+
+    // then load the memory
+    auto *LoadResult = makeVariable(toIceType(MemType));
+    Control()->appendInst(InstLoad::create(Func, LoadResult, Addr));
+
+    // and cast, if needed
+    Ice::Variable *Result = nullptr;
+    if (toIceType(Type) != toIceType(MemType)) {
+      Result = makeVariable(toIceType(Type));
+      // TODO(eholk): handle signs correctly.
+      Control()->appendInst(
+          InstCast::create(Func, InstCast::Sext, Result, LoadResult));
+    } else {
+      Result = LoadResult;
+    }
+
+    LOG(out << Result << "\n");
+    return OperandNode(Result);
+  }
+  void StoreMem(MachineType Type, Node Index, uint32_t Offset, Node Val) {
+    LOG(out << "StoreMem(" << Index << "[" << Offset << "] = " << Val << ")"
+            << "\n");
+
+    // TODO(eholk): surely there is a better way to do this.
+
+    // first, add the index and the offset together.
+    auto *OffsetConstant = Ctx->getConstantInt32(Offset);
+    auto *Addr = makeVariable(IceType_i32);
+    Control()->appendInst(InstArithmetic::create(Func, InstArithmetic::Add,
+                                                 Addr, Index, OffsetConstant));
+
+    // cast the value to the right type, if needed
+    Operand *StoreVal = nullptr;
+    if (toIceType(Type) != Val.toOperand()->getType()) {
+      auto *LocalStoreVal = makeVariable(toIceType(Type));
+      Control()->appendInst(
+          InstCast::create(Func, InstCast::Trunc, LocalStoreVal, Val));
+      StoreVal = LocalStoreVal;
+    } else {
+      StoreVal = Val;
+    }
+
+    // then store the memory
+    Control()->appendInst(InstStore::create(Func, StoreVal, Addr));
+  }
+
+  static void PrintDebugName(Node node) {
+    llvm::report_fatal_error("PrintDebugName");
+  }
+
+  CfgNode *Control() {
+    return ControlPtr ? ControlPtr->toCfgNode() : Func->getEntryNode();
+  }
+  Node Effect() { return *EffectPtr; }
+
+  void set_module(wasm::ModuleEnv *Module) { this->Module = Module; }
+
+  void set_control_ptr(Node *Control) { this->ControlPtr = Control; }
+
+  void set_effect_ptr(Node *Effect) { this->EffectPtr = Effect; }
+
+private:
+  wasm::ModuleEnv *Module;
+  Node *ControlPtr;
+  Node *EffectPtr;
+
+  class Cfg *Func;
+  GlobalContext *Ctx;
+
+  SizeT NextArg = 0;
+
+  CfgUnorderedMap<Operand *, InstPhi *> PhiMap;
+  CfgUnorderedMap<Operand *, CfgNode *> DefNodeMap;
+
+  InstPhi *getDefiningInst(Operand *Op) const {
+    const auto &Iter = PhiMap.find(Op);
+    if (Iter == PhiMap.end()) {
+      return nullptr;
+    }
+    return Iter->second;
+  }
+
+  void setDefiningInst(Operand *Op, InstPhi *Phi) {
+    LOG(out << "\n== setDefiningInst(" << Op << ", " << Phi << ") ==\n");
+    PhiMap.emplace(Op, Phi);
+  }
+
+  Ice::Variable *makeVariable(Ice::Type Type) {
+    return makeVariable(Type, Control());
+  }
+
+  Ice::Variable *makeVariable(Ice::Type Type, CfgNode *DefNode) {
+    auto *Var = Func->makeVariable(Type);
+    DefNodeMap.emplace(Var, DefNode);
+    return Var;
+  }
+
+  CfgNode *getDefNode(Operand *Op) const {
+    const auto &Iter = DefNodeMap.find(Op);
+    if (Iter == DefNodeMap.end()) {
+      return nullptr;
+    }
+    return Iter->second;
+  }
+
+  template <typename F = std::function<void(Ostream &)>> void log(F Fn) const {
+    if (BuildDefs::dump() && (getFlags().getVerbose() & IceV_Wasm)) {
+      Fn(Ctx->getStrDump());
+      Ctx->getStrDump().flush();
+    }
+  }
+};
+
+std::string fnNameFromId(uint32_t Id) {
+  return std::string("fn") + to_string(Id);
+}
+
+std::unique_ptr<Cfg> WasmTranslator::translateFunction(Zone *Zone,
+                                                       FunctionEnv *Env,
+                                                       const byte *Base,
+                                                       const byte *Start,
+                                                       const byte *End) {
+  OstreamLocker L1(Ctx);
+  auto Func = Cfg::create(Ctx, getNextSequenceNumber());
+  Ice::CfgLocalAllocatorScope L2(Func.get());
+
+  // TODO: parse the function signature...
+
+  IceBuilder Builder(Func.get());
+  LR_WasmDecoder<OperandNode, IceBuilder> Decoder(Zone, &Builder);
+
+  LOG(out << getFlags().getDefaultGlobalPrefix() << "\n");
+  Decoder.Decode(Env, Base, Start, End);
+
+  // We don't always know where the incoming branches are in phi nodes, so this
+  // function finds them.
+  Func->fixPhiNodes();
+
+  return Func;
+}
+
+WasmTranslator::WasmTranslator(GlobalContext *Ctx)
+    : Translator(Ctx), BufferSize(24 << 10), Buffer(new uint8_t[24 << 10]) {
+  // TODO(eholk): compute the correct buffer size. This uses 24k by default,
+  // which has been big enough for testing but is not a general solution.
+}
+
+void WasmTranslator::translate(
+    const std::string &IRFilename,
+    std::unique_ptr<llvm::DataStreamer> InputStream) {
+  LOG(out << "Initializing v8/wasm stuff..."
+          << "\n");
+  Zone Zone;
+  ZoneScope _(&Zone);
+
+  SizeT BytesRead = InputStream->GetBytes(Buffer.get(), BufferSize);
+  LOG(out << "Read " << BytesRead << " bytes"
+          << "\n");
+
+  LOG(out << "Decoding module " << IRFilename << "\n");
+
+  constexpr v8::internal::Isolate *NoIsolate = nullptr;
+  auto Result = DecodeWasmModule(NoIsolate, &Zone, Buffer.get(),
+                                 Buffer.get() + BytesRead, false, kWasmOrigin);
+
+  auto Module = Result.val;
+
+  LOG(out << "Module info:"
+          << "\n");
+  LOG(out << "  number of globals:       " << Module->globals.size() << "\n");
+  LOG(out << "  number of signatures:    " << Module->signatures.size()
+          << "\n");
+  LOG(out << "  number of functions:     " << Module->functions.size() << "\n");
+  LOG(out << "  number of data_segments: " << Module->data_segments.size()
+          << "\n");
+  LOG(out << "  function table size:     " << Module->function_table.size()
+          << "\n");
+
+  ModuleEnv ModuleEnv;
+  ModuleEnv.module = Module;
+
+  LOG(out << "\n"
+          << "Function information:"
+          << "\n");
+  for (const auto F : Module->functions) {
+    LOG(out << "  " << F.name_offset << ": " << Module->GetName(F.name_offset));
+    if (F.exported)
+      LOG(out << " export");
+    if (F.external)
+      LOG(out << " extern");
+    LOG(out << "\n");
+  }
+
+  FunctionEnv Fenv;
+  Fenv.module = &ModuleEnv;
+
+  LOG(out << "Translating " << IRFilename << "\n");
+
+  // Translate each function.
+  uint32_t Id = 0;
+  for (const auto Fn : Module->functions) {
+    std::string NewName = fnNameFromId(Id++);
+    LOG(out << "  " << Fn.name_offset << ": " << Module->GetName(Fn.name_offset)
+            << " -> " << NewName << "...");
+
+    Fenv.sig = Fn.sig;
+    Fenv.local_i32_count = Fn.local_i32_count;
+    Fenv.local_i64_count = Fn.local_i64_count;
+    Fenv.local_f32_count = Fn.local_f32_count;
+    Fenv.local_f64_count = Fn.local_f64_count;
+    Fenv.SumLocals();
+
+    auto Func = translateFunction(&Zone, &Fenv, Buffer.get(),
+                                  Buffer.get() + Fn.code_start_offset,
+                                  Buffer.get() + Fn.code_end_offset);
+    Func->setFunctionName(Ctx->getGlobalString(NewName));
+
+    Ctx->optQueueBlockingPush(makeUnique<CfgOptWorkItem>(std::move(Func)));
+    LOG(out << "done.\n");
+  }
+
+  return;
+}