Add m-esr52 at 52.6.0

1 files changed, 3811 insertions, 0 deletions

diff --git a/js/src/wasm/WasmIonCompile.cpp b/js/src/wasm/WasmIonCompile.cpp
new file mode 100644
index 000000000..dd7e84ca1
--- /dev/null
+++ b/js/src/wasm/WasmIonCompile.cpp
@@ -0,0 +1,3811 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ *
+ * Copyright 2015 Mozilla Foundation
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include "wasm/WasmIonCompile.h"
+
+#include "mozilla/MathAlgorithms.h"
+
+#include "jit/CodeGenerator.h"
+
+#include "wasm/WasmBaselineCompile.h"
+#include "wasm/WasmBinaryFormat.h"
+#include "wasm/WasmBinaryIterator.h"
+#include "wasm/WasmGenerator.h"
+#include "wasm/WasmSignalHandlers.h"
+
+using namespace js;
+using namespace js::jit;
+using namespace js::wasm;
+
+using mozilla::DebugOnly;
+using mozilla::IsPowerOfTwo;
+using mozilla::Maybe;
+using mozilla::Nothing;
+using mozilla::Some;
+
+namespace {
+
+typedef Vector<MBasicBlock*, 8, SystemAllocPolicy> BlockVector;
+
+struct IonCompilePolicy : OpIterPolicy
+{
+    // Producing output is what we're all about here.
+    static const bool Output = true;
+
+    // We store SSA definitions in the value stack.
+    typedef MDefinition* Value;
+
+    // We store loop headers and then/else blocks in the control flow stack.
+    typedef MBasicBlock* ControlItem;
+};
+
+typedef OpIter<IonCompilePolicy> IonOpIter;
+
+class FunctionCompiler;
+
+// TlsUsage describes how the TLS register is used during a function call.
+
+enum class TlsUsage {
+    Unused,     // No particular action is taken with respect to the TLS register.
+    Need,       // The TLS register must be reloaded just before the call.
+    CallerSaved // Same, plus space must be allocated to save/restore the TLS
+                // register.
+};
+
+static bool
+NeedsTls(TlsUsage usage) {
+    return usage == TlsUsage::Need || usage == TlsUsage::CallerSaved;
+}
+
+// CallCompileState describes a call that is being compiled. Due to expression
+// nesting, multiple calls can be in the middle of compilation at the same time
+// and these are tracked in a stack by FunctionCompiler.
+
+class CallCompileState
+{
+    // The line or bytecode of the call.
+    uint32_t lineOrBytecode_;
+
+    // A generator object that is passed each argument as it is compiled.
+    ABIArgGenerator abi_;
+
+    // The maximum number of bytes used by "child" calls, i.e., calls that occur
+    // while evaluating the arguments of the call represented by this
+    // CallCompileState.
+    uint32_t maxChildStackBytes_;
+
+    // Set by FunctionCompiler::finishCall(), tells the MWasmCall by how
+    // much to bump the stack pointer before making the call. See
+    // FunctionCompiler::startCall() comment below.
+    uint32_t spIncrement_;
+
+    // Set by FunctionCompiler::finishCall(), tells a potentially-inter-module
+    // call the offset of the reserved space in which it can save the caller's
+    // WasmTlsReg.
+    uint32_t tlsStackOffset_;
+
+    // Accumulates the register arguments while compiling arguments.
+    MWasmCall::Args regArgs_;
+
+    // Reserved argument for passing Instance* to builtin instance method calls.
+    ABIArg instanceArg_;
+
+    // Accumulates the stack arguments while compiling arguments. This is only
+    // necessary to track when childClobbers_ is true so that the stack offsets
+    // can be updated.
+    Vector<MWasmStackArg*, 0, SystemAllocPolicy> stackArgs_;
+
+    // Set by child calls (i.e., calls that execute while evaluating a parent's
+    // operands) to indicate that the child and parent call cannot reuse the
+    // same stack space -- the parent must store its stack arguments below the
+    // child's and increment sp when performing its call.
+    bool childClobbers_;
+
+    // Only FunctionCompiler should be directly manipulating CallCompileState.
+    friend class FunctionCompiler;
+
+  public:
+    CallCompileState(FunctionCompiler& f, uint32_t lineOrBytecode)
+      : lineOrBytecode_(lineOrBytecode),
+        maxChildStackBytes_(0),
+        spIncrement_(0),
+        tlsStackOffset_(MWasmCall::DontSaveTls),
+        childClobbers_(false)
+    { }
+};
+
+// Encapsulates the compilation of a single function in an asm.js module. The
+// function compiler handles the creation and final backend compilation of the
+// MIR graph.
+class FunctionCompiler
+{
+    struct ControlFlowPatch {
+        MControlInstruction* ins;
+        uint32_t index;
+        ControlFlowPatch(MControlInstruction* ins, uint32_t index)
+          : ins(ins),
+            index(index)
+        {}
+    };
+
+    typedef Vector<ControlFlowPatch, 0, SystemAllocPolicy> ControlFlowPatchVector;
+    typedef Vector<ControlFlowPatchVector, 0, SystemAllocPolicy> ControlFlowPatchsVector;
+    typedef Vector<CallCompileState*, 0, SystemAllocPolicy> CallCompileStateVector;
+
+    const ModuleGeneratorData& mg_;
+    IonOpIter                  iter_;
+    const FuncBytes&           func_;
+    const ValTypeVector&       locals_;
+    size_t                     lastReadCallSite_;
+
+    TempAllocator&             alloc_;
+    MIRGraph&                  graph_;
+    const CompileInfo&         info_;
+    MIRGenerator&              mirGen_;
+
+    MInstruction*              dummyIns_;
+
+    MBasicBlock*               curBlock_;
+    CallCompileStateVector     callStack_;
+    uint32_t                   maxStackArgBytes_;
+
+    uint32_t                   loopDepth_;
+    uint32_t                   blockDepth_;
+    ControlFlowPatchsVector    blockPatches_;
+
+    FuncCompileResults&        compileResults_;
+
+    // TLS pointer argument to the current function.
+    MWasmParameter*            tlsPointer_;
+
+  public:
+    FunctionCompiler(const ModuleGeneratorData& mg,
+                     Decoder& decoder,
+                     const FuncBytes& func,
+                     const ValTypeVector& locals,
+                     MIRGenerator& mirGen,
+                     FuncCompileResults& compileResults)
+      : mg_(mg),
+        iter_(decoder, func.lineOrBytecode()),
+        func_(func),
+        locals_(locals),
+        lastReadCallSite_(0),
+        alloc_(mirGen.alloc()),
+        graph_(mirGen.graph()),
+        info_(mirGen.info()),
+        mirGen_(mirGen),
+        dummyIns_(nullptr),
+        curBlock_(nullptr),
+        maxStackArgBytes_(0),
+        loopDepth_(0),
+        blockDepth_(0),
+        compileResults_(compileResults),
+        tlsPointer_(nullptr)
+    {}
+
+    const ModuleGeneratorData& mg() const    { return mg_; }
+    IonOpIter&                 iter()        { return iter_; }
+    TempAllocator&             alloc() const { return alloc_; }
+    MacroAssembler&            masm() const  { return compileResults_.masm(); }
+    const Sig&                 sig() const   { return func_.sig(); }
+
+    TrapOffset trapOffset() const {
+        return iter_.trapOffset();
+    }
+    Maybe<TrapOffset> trapIfNotAsmJS() const {
+        return mg_.isAsmJS() ? Nothing() : Some(iter_.trapOffset());
+    }
+
+    bool init()
+    {
+        // Prepare the entry block for MIR generation:
+
+        const ValTypeVector& args = func_.sig().args();
+
+        if (!mirGen_.ensureBallast())
+            return false;
+        if (!newBlock(/* prev */ nullptr, &curBlock_))
+            return false;
+
+        for (ABIArgValTypeIter i(args); !i.done(); i++) {
+            MWasmParameter* ins = MWasmParameter::New(alloc(), *i, i.mirType());
+            curBlock_->add(ins);
+            curBlock_->initSlot(info().localSlot(i.index()), ins);
+            if (!mirGen_.ensureBallast())
+                return false;
+        }
+
+        // Set up a parameter that receives the hidden TLS pointer argument.
+        tlsPointer_ = MWasmParameter::New(alloc(), ABIArg(WasmTlsReg), MIRType::Pointer);
+        curBlock_->add(tlsPointer_);
+        if (!mirGen_.ensureBallast())
+            return false;
+
+        for (size_t i = args.length(); i < locals_.length(); i++) {
+            MInstruction* ins = nullptr;
+            switch (locals_[i]) {
+              case ValType::I32:
+                ins = MConstant::New(alloc(), Int32Value(0), MIRType::Int32);
+                break;
+              case ValType::I64:
+                ins = MConstant::NewInt64(alloc(), 0);
+                break;
+              case ValType::F32:
+                ins = MConstant::New(alloc(), Float32Value(0.f), MIRType::Float32);
+                break;
+              case ValType::F64:
+                ins = MConstant::New(alloc(), DoubleValue(0.0), MIRType::Double);
+                break;
+              case ValType::I8x16:
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX16(0), MIRType::Int8x16);
+                break;
+              case ValType::I16x8:
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX8(0), MIRType::Int16x8);
+                break;
+              case ValType::I32x4:
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX4(0), MIRType::Int32x4);
+                break;
+              case ValType::F32x4:
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX4(0.f), MIRType::Float32x4);
+                break;
+              case ValType::B8x16:
+                // Bool8x16 uses the same data layout as Int8x16.
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX16(0), MIRType::Bool8x16);
+                break;
+              case ValType::B16x8:
+                // Bool16x8 uses the same data layout as Int16x8.
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX8(0), MIRType::Bool16x8);
+                break;
+              case ValType::B32x4:
+                // Bool32x4 uses the same data layout as Int32x4.
+                ins = MSimdConstant::New(alloc(), SimdConstant::SplatX4(0), MIRType::Bool32x4);
+                break;
+            }
+
+            curBlock_->add(ins);
+            curBlock_->initSlot(info().localSlot(i), ins);
+            if (!mirGen_.ensureBallast())
+                return false;
+        }
+
+        dummyIns_ = MConstant::New(alloc(), Int32Value(0), MIRType::Int32);
+        curBlock_->add(dummyIns_);
+
+        addInterruptCheck();
+
+        return true;
+    }
+
+    void finish()
+    {
+        mirGen().initWasmMaxStackArgBytes(maxStackArgBytes_);
+
+        MOZ_ASSERT(callStack_.empty());
+        MOZ_ASSERT(loopDepth_ == 0);
+        MOZ_ASSERT(blockDepth_ == 0);
+#ifdef DEBUG
+        for (ControlFlowPatchVector& patches : blockPatches_)
+            MOZ_ASSERT(patches.empty());
+#endif
+        MOZ_ASSERT(inDeadCode());
+        MOZ_ASSERT(done(), "all bytes must be consumed");
+        MOZ_ASSERT(func_.callSiteLineNums().length() == lastReadCallSite_);
+    }
+
+    /************************* Read-only interface (after local scope setup) */
+
+    MIRGenerator&       mirGen() const     { return mirGen_; }
+    MIRGraph&           mirGraph() const   { return graph_; }
+    const CompileInfo&  info() const       { return info_; }
+
+    MDefinition* getLocalDef(unsigned slot)
+    {
+        if (inDeadCode())
+            return nullptr;
+        return curBlock_->getSlot(info().localSlot(slot));
+    }
+
+    const ValTypeVector& locals() const { return locals_; }
+
+    /***************************** Code generation (after local scope setup) */
+
+    MDefinition* constant(const SimdConstant& v, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+        MInstruction* constant;
+        constant = MSimdConstant::New(alloc(), v, type);
+        curBlock_->add(constant);
+        return constant;
+    }
+
+    MDefinition* constant(const Value& v, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+        MConstant* constant = MConstant::New(alloc(), v, type);
+        curBlock_->add(constant);
+        return constant;
+    }
+
+    MDefinition* constant(int64_t i)
+    {
+        if (inDeadCode())
+            return nullptr;
+        MConstant* constant = MConstant::NewInt64(alloc(), i);
+        curBlock_->add(constant);
+        return constant;
+    }
+
+    MDefinition* constant(RawF32 f)
+    {
+        if (inDeadCode())
+            return nullptr;
+        MConstant* constant = MConstant::New(alloc(), f);
+        curBlock_->add(constant);
+        return constant;
+    }
+
+    MDefinition* constant(RawF64 d)
+    {
+        if (inDeadCode())
+            return nullptr;
+        MConstant* constant = MConstant::New(alloc(), d);
+        curBlock_->add(constant);
+        return constant;
+    }
+
+    template <class T>
+    MDefinition* unary(MDefinition* op)
+    {
+        if (inDeadCode())
+            return nullptr;
+        T* ins = T::New(alloc(), op);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    template <class T>
+    MDefinition* unary(MDefinition* op, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+        T* ins = T::New(alloc(), op, type);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    template <class T>
+    MDefinition* binary(MDefinition* lhs, MDefinition* rhs)
+    {
+        if (inDeadCode())
+            return nullptr;
+        T* ins = T::New(alloc(), lhs, rhs);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    template <class T>
+    MDefinition* binary(MDefinition* lhs, MDefinition* rhs, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+        T* ins = T::New(alloc(), lhs, rhs, type);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    bool mustPreserveNaN(MIRType type)
+    {
+        return IsFloatingPointType(type) && mg().kind == ModuleKind::Wasm;
+    }
+
+    MDefinition* sub(MDefinition* lhs, MDefinition* rhs, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        // wasm can't fold x - 0.0 because of NaN with custom payloads.
+        MSub* ins = MSub::New(alloc(), lhs, rhs, type, mustPreserveNaN(type));
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* unarySimd(MDefinition* input, MSimdUnaryArith::Operation op, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(input->type()) && input->type() == type);
+        MInstruction* ins = MSimdUnaryArith::New(alloc(), input, op);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* binarySimd(MDefinition* lhs, MDefinition* rhs, MSimdBinaryArith::Operation op,
+                            MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(lhs->type()) && rhs->type() == lhs->type());
+        MOZ_ASSERT(lhs->type() == type);
+        return MSimdBinaryArith::AddLegalized(alloc(), curBlock_, lhs, rhs, op);
+    }
+
+    MDefinition* binarySimd(MDefinition* lhs, MDefinition* rhs, MSimdBinaryBitwise::Operation op,
+                            MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(lhs->type()) && rhs->type() == lhs->type());
+        MOZ_ASSERT(lhs->type() == type);
+        auto* ins = MSimdBinaryBitwise::New(alloc(), lhs, rhs, op);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* binarySimdComp(MDefinition* lhs, MDefinition* rhs, MSimdBinaryComp::Operation op,
+                                SimdSign sign)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        return MSimdBinaryComp::AddLegalized(alloc(), curBlock_, lhs, rhs, op, sign);
+    }
+
+    MDefinition* binarySimdSaturating(MDefinition* lhs, MDefinition* rhs,
+                                      MSimdBinarySaturating::Operation op, SimdSign sign)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        auto* ins = MSimdBinarySaturating::New(alloc(), lhs, rhs, op, sign);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* binarySimdShift(MDefinition* lhs, MDefinition* rhs, MSimdShift::Operation op)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        return MSimdShift::AddLegalized(alloc(), curBlock_, lhs, rhs, op);
+    }
+
+    MDefinition* swizzleSimd(MDefinition* vector, const uint8_t lanes[], MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(vector->type() == type);
+        MSimdSwizzle* ins = MSimdSwizzle::New(alloc(), vector, lanes);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* shuffleSimd(MDefinition* lhs, MDefinition* rhs, const uint8_t lanes[],
+                             MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(lhs->type() == type);
+        MInstruction* ins = MSimdShuffle::New(alloc(), lhs, rhs, lanes);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* insertElementSimd(MDefinition* vec, MDefinition* val, unsigned lane, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(vec->type()) && vec->type() == type);
+        MOZ_ASSERT(SimdTypeToLaneArgumentType(vec->type()) == val->type());
+        MSimdInsertElement* ins = MSimdInsertElement::New(alloc(), vec, val, lane);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* selectSimd(MDefinition* mask, MDefinition* lhs, MDefinition* rhs, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(mask->type()));
+        MOZ_ASSERT(IsSimdType(lhs->type()) && rhs->type() == lhs->type());
+        MOZ_ASSERT(lhs->type() == type);
+        MSimdSelect* ins = MSimdSelect::New(alloc(), mask, lhs, rhs);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* simdAllTrue(MDefinition* boolVector)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MSimdAllTrue* ins = MSimdAllTrue::New(alloc(), boolVector, MIRType::Int32);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* simdAnyTrue(MDefinition* boolVector)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MSimdAnyTrue* ins = MSimdAnyTrue::New(alloc(), boolVector, MIRType::Int32);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    // fromXXXBits()
+    MDefinition* bitcastSimd(MDefinition* vec, MIRType from, MIRType to)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(vec->type() == from);
+        MOZ_ASSERT(IsSimdType(from) && IsSimdType(to) && from != to);
+        auto* ins = MSimdReinterpretCast::New(alloc(), vec, to);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    // Int <--> Float conversions.
+    MDefinition* convertSimd(MDefinition* vec, MIRType from, MIRType to, SimdSign sign)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(from) && IsSimdType(to) && from != to);
+        return MSimdConvert::AddLegalized(alloc(), curBlock_, vec, to, sign, trapOffset());
+    }
+
+    MDefinition* splatSimd(MDefinition* v, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(type));
+        MOZ_ASSERT(SimdTypeToLaneArgumentType(type) == v->type());
+        MSimdSplat* ins = MSimdSplat::New(alloc(), v, type);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* minMax(MDefinition* lhs, MDefinition* rhs, MIRType type, bool isMax) {
+        if (inDeadCode())
+            return nullptr;
+
+        if (mustPreserveNaN(type)) {
+            // Convert signaling NaN to quiet NaNs.
+            MDefinition* zero = constant(DoubleValue(0.0), type);
+            lhs = sub(lhs, zero, type);
+            rhs = sub(rhs, zero, type);
+        }
+
+        MMinMax* ins = MMinMax::NewWasm(alloc(), lhs, rhs, type, isMax);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* mul(MDefinition* lhs, MDefinition* rhs, MIRType type, MMul::Mode mode)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        // wasm can't fold x * 1.0 because of NaN with custom payloads.
+        auto* ins = MMul::NewWasm(alloc(), lhs, rhs, type, mode, mustPreserveNaN(type));
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* div(MDefinition* lhs, MDefinition* rhs, MIRType type, bool unsignd)
+    {
+        if (inDeadCode())
+            return nullptr;
+        bool trapOnError = !mg().isAsmJS();
+        auto* ins = MDiv::New(alloc(), lhs, rhs, type, unsignd, trapOnError, trapOffset(),
+                              mustPreserveNaN(type));
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* mod(MDefinition* lhs, MDefinition* rhs, MIRType type, bool unsignd)
+    {
+        if (inDeadCode())
+            return nullptr;
+        bool trapOnError = !mg().isAsmJS();
+        auto* ins = MMod::New(alloc(), lhs, rhs, type, unsignd, trapOnError, trapOffset());
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* bitnot(MDefinition* op)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MBitNot::NewInt32(alloc(), op);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* select(MDefinition* trueExpr, MDefinition* falseExpr, MDefinition* condExpr)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MWasmSelect::New(alloc(), trueExpr, falseExpr, condExpr);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* extendI32(MDefinition* op, bool isUnsigned)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MExtendInt32ToInt64::New(alloc(), op, isUnsigned);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* convertI64ToFloatingPoint(MDefinition* op, MIRType type, bool isUnsigned)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MInt64ToFloatingPoint::New(alloc(), op, type, isUnsigned);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* rotate(MDefinition* input, MDefinition* count, MIRType type, bool left)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MRotate::New(alloc(), input, count, type, left);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    template <class T>
+    MDefinition* truncate(MDefinition* op, bool isUnsigned)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = T::New(alloc(), op, isUnsigned, trapOffset());
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    MDefinition* compare(MDefinition* lhs, MDefinition* rhs, JSOp op, MCompare::CompareType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+        auto* ins = MCompare::New(alloc(), lhs, rhs, op, type);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    void assign(unsigned slot, MDefinition* def)
+    {
+        if (inDeadCode())
+            return;
+        curBlock_->setSlot(info().localSlot(slot), def);
+    }
+
+  private:
+    void checkOffsetAndBounds(MemoryAccessDesc* access, MDefinition** base)
+    {
+        // If the offset is bigger than the guard region, a separate instruction
+        // is necessary to add the offset to the base and check for overflow.
+        if (access->offset() >= OffsetGuardLimit || !JitOptions.wasmFoldOffsets) {
+            auto* ins = MWasmAddOffset::New(alloc(), *base, access->offset(), trapOffset());
+            curBlock_->add(ins);
+
+            *base = ins;
+            access->clearOffset();
+        }
+
+#ifndef WASM_HUGE_MEMORY
+        curBlock_->add(MWasmBoundsCheck::New(alloc(), *base, trapOffset()));
+#endif
+    }
+
+  public:
+    MDefinition* load(MDefinition* base, MemoryAccessDesc access, ValType result)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MInstruction* load = nullptr;
+        if (access.isPlainAsmJS()) {
+            MOZ_ASSERT(access.offset() == 0);
+            load = MAsmJSLoadHeap::New(alloc(), base, access.type());
+        } else {
+            checkOffsetAndBounds(&access, &base);
+            load = MWasmLoad::New(alloc(), base, access, ToMIRType(result));
+        }
+
+        curBlock_->add(load);
+        return load;
+    }
+
+    void store(MDefinition* base, MemoryAccessDesc access, MDefinition* v)
+    {
+        if (inDeadCode())
+            return;
+
+        MInstruction* store = nullptr;
+        if (access.isPlainAsmJS()) {
+            MOZ_ASSERT(access.offset() == 0);
+            store = MAsmJSStoreHeap::New(alloc(), base, access.type(), v);
+        } else {
+            checkOffsetAndBounds(&access, &base);
+            store = MWasmStore::New(alloc(), base, access, v);
+        }
+
+        curBlock_->add(store);
+    }
+
+    MDefinition* atomicCompareExchangeHeap(MDefinition* base, MemoryAccessDesc access,
+                                           MDefinition* oldv, MDefinition* newv)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        checkOffsetAndBounds(&access, &base);
+        auto* cas = MAsmJSCompareExchangeHeap::New(alloc(), base, access, oldv, newv, tlsPointer_);
+        curBlock_->add(cas);
+        return cas;
+    }
+
+    MDefinition* atomicExchangeHeap(MDefinition* base, MemoryAccessDesc access,
+                                    MDefinition* value)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        checkOffsetAndBounds(&access, &base);
+        auto* cas = MAsmJSAtomicExchangeHeap::New(alloc(), base, access, value, tlsPointer_);
+        curBlock_->add(cas);
+        return cas;
+    }
+
+    MDefinition* atomicBinopHeap(js::jit::AtomicOp op,
+                                 MDefinition* base, MemoryAccessDesc access,
+                                 MDefinition* v)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        checkOffsetAndBounds(&access, &base);
+        auto* binop = MAsmJSAtomicBinopHeap::New(alloc(), op, base, access, v, tlsPointer_);
+        curBlock_->add(binop);
+        return binop;
+    }
+
+    MDefinition* loadGlobalVar(unsigned globalDataOffset, bool isConst, MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        auto* load = MWasmLoadGlobalVar::New(alloc(), type, globalDataOffset, isConst);
+        curBlock_->add(load);
+        return load;
+    }
+
+    void storeGlobalVar(uint32_t globalDataOffset, MDefinition* v)
+    {
+        if (inDeadCode())
+            return;
+        curBlock_->add(MWasmStoreGlobalVar::New(alloc(), globalDataOffset, v));
+    }
+
+    void addInterruptCheck()
+    {
+        // We rely on signal handlers for interrupts on Asm.JS/Wasm
+        MOZ_RELEASE_ASSERT(wasm::HaveSignalHandlers());
+    }
+
+    MDefinition* extractSimdElement(unsigned lane, MDefinition* base, MIRType type, SimdSign sign)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(base->type()));
+        MOZ_ASSERT(!IsSimdType(type));
+        auto* ins = MSimdExtractElement::New(alloc(), base, type, lane, sign);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    template<typename T>
+    MDefinition* constructSimd(MDefinition* x, MDefinition* y, MDefinition* z, MDefinition* w,
+                               MIRType type)
+    {
+        if (inDeadCode())
+            return nullptr;
+
+        MOZ_ASSERT(IsSimdType(type));
+        T* ins = T::New(alloc(), type, x, y, z, w);
+        curBlock_->add(ins);
+        return ins;
+    }
+
+    /***************************************************************** Calls */
+
+    // The IonMonkey backend maintains a single stack offset (from the stack
+    // pointer to the base of the frame) by adding the total amount of spill
+    // space required plus the maximum stack required for argument passing.
+    // Since we do not use IonMonkey's MPrepareCall/MPassArg/MCall, we must
+    // manually accumulate, for the entire function, the maximum required stack
+    // space for argument passing. (This is passed to the CodeGenerator via
+    // MIRGenerator::maxWasmStackArgBytes.) Naively, this would just be the
+    // maximum of the stack space required for each individual call (as
+    // determined by the call ABI). However, as an optimization, arguments are
+    // stored to the stack immediately after evaluation (to decrease live
+    // ranges and reduce spilling). This introduces the complexity that,
+    // between evaluating an argument and making the call, another argument
+    // evaluation could perform a call that also needs to store to the stack.
+    // When this occurs childClobbers_ = true and the parent expression's
+    // arguments are stored above the maximum depth clobbered by a child
+    // expression.
+
+    bool startCall(CallCompileState* call)
+    {
+        // Always push calls to maintain the invariant that if we're inDeadCode
+        // in finishCall, we have something to pop.
+        return callStack_.append(call);
+    }
+
+    bool passInstance(CallCompileState* args)
+    {
+        if (inDeadCode())
+            return true;
+
+        // Should only pass an instance once.
+        MOZ_ASSERT(args->instanceArg_ == ABIArg());
+        args->instanceArg_ = args->abi_.next(MIRType::Pointer);
+        return true;
+    }
+
+    bool passArg(MDefinition* argDef, ValType type, CallCompileState* call)
+    {
+        if (inDeadCode())
+            return true;
+
+        ABIArg arg = call->abi_.next(ToMIRType(type));
+        switch (arg.kind()) {
+#ifdef JS_CODEGEN_REGISTER_PAIR
+          case ABIArg::GPR_PAIR: {
+            auto mirLow = MWrapInt64ToInt32::New(alloc(), argDef, /* bottomHalf = */ true);
+            curBlock_->add(mirLow);
+            auto mirHigh = MWrapInt64ToInt32::New(alloc(), argDef, /* bottomHalf = */ false);
+            curBlock_->add(mirHigh);
+            return call->regArgs_.append(MWasmCall::Arg(AnyRegister(arg.gpr64().low), mirLow)) &&
+                   call->regArgs_.append(MWasmCall::Arg(AnyRegister(arg.gpr64().high), mirHigh));
+          }
+#endif
+          case ABIArg::GPR:
+          case ABIArg::FPU:
+            return call->regArgs_.append(MWasmCall::Arg(arg.reg(), argDef));
+          case ABIArg::Stack: {
+            auto* mir = MWasmStackArg::New(alloc(), arg.offsetFromArgBase(), argDef);
+            curBlock_->add(mir);
+            return call->stackArgs_.append(mir);
+          }
+          default:
+            MOZ_CRASH("Unknown ABIArg kind.");
+        }
+    }
+
+    void propagateMaxStackArgBytes(uint32_t stackBytes)
+    {
+        if (callStack_.empty()) {
+            // Outermost call
+            maxStackArgBytes_ = Max(maxStackArgBytes_, stackBytes);
+            return;
+        }
+
+        // Non-outermost call
+        CallCompileState* outer = callStack_.back();
+        outer->maxChildStackBytes_ = Max(outer->maxChildStackBytes_, stackBytes);
+        if (stackBytes && !outer->stackArgs_.empty())
+            outer->childClobbers_ = true;
+    }
+
+    bool finishCall(CallCompileState* call, TlsUsage tls)
+    {
+        MOZ_ALWAYS_TRUE(callStack_.popCopy() == call);
+
+        if (inDeadCode()) {
+            propagateMaxStackArgBytes(call->maxChildStackBytes_);
+            return true;
+        }
+
+        if (NeedsTls(tls)) {
+            if (!call->regArgs_.append(MWasmCall::Arg(AnyRegister(WasmTlsReg), tlsPointer_)))
+                return false;
+        }
+
+        uint32_t stackBytes = call->abi_.stackBytesConsumedSoFar();
+
+        // If this is a potentially-inter-module call, allocate an extra word of
+        // stack space to save/restore the caller's WasmTlsReg during the call.
+        // Record the stack offset before including spIncrement since MWasmCall
+        // will use this offset after having bumped the stack pointer.
+        if (tls == TlsUsage::CallerSaved) {
+            call->tlsStackOffset_ = stackBytes;
+            stackBytes += sizeof(void*);
+        }
+
+        if (call->childClobbers_) {
+            call->spIncrement_ = AlignBytes(call->maxChildStackBytes_, WasmStackAlignment);
+            for (MWasmStackArg* stackArg : call->stackArgs_)
+                stackArg->incrementOffset(call->spIncrement_);
+
+            // If instanceArg_ is not initialized then instanceArg_.kind() != ABIArg::Stack
+            if (call->instanceArg_.kind() == ABIArg::Stack) {
+                call->instanceArg_ = ABIArg(call->instanceArg_.offsetFromArgBase() +
+                                            call->spIncrement_);
+            }
+
+            stackBytes += call->spIncrement_;
+        } else {
+            call->spIncrement_ = 0;
+            stackBytes = Max(stackBytes, call->maxChildStackBytes_);
+        }
+
+        propagateMaxStackArgBytes(stackBytes);
+        return true;
+    }
+
+    bool callDirect(const Sig& sig, uint32_t funcIndex, const CallCompileState& call,
+                    MDefinition** def)
+    {
+        if (inDeadCode()) {
+            *def = nullptr;
+            return true;
+        }
+
+        CallSiteDesc desc(call.lineOrBytecode_, CallSiteDesc::Func);
+        MIRType ret = ToMIRType(sig.ret());
+        auto callee = CalleeDesc::function(funcIndex);
+        auto* ins = MWasmCall::New(alloc(), desc, callee, call.regArgs_, ret,
+                                   call.spIncrement_, MWasmCall::DontSaveTls);
+        if (!ins)
+            return false;
+
+        curBlock_->add(ins);
+        *def = ins;
+        return true;
+    }
+
+    bool callIndirect(uint32_t sigIndex, MDefinition* index, const CallCompileState& call,
+                      MDefinition** def)
+    {
+        if (inDeadCode()) {
+            *def = nullptr;
+            return true;
+        }
+
+        const SigWithId& sig = mg_.sigs[sigIndex];
+
+        CalleeDesc callee;
+        if (mg_.isAsmJS()) {
+            MOZ_ASSERT(sig.id.kind() == SigIdDesc::Kind::None);
+            const TableDesc& table = mg_.tables[mg_.asmJSSigToTableIndex[sigIndex]];
+            MOZ_ASSERT(IsPowerOfTwo(table.limits.initial));
+            MOZ_ASSERT(!table.external);
+            MOZ_ASSERT(call.tlsStackOffset_ == MWasmCall::DontSaveTls);
+
+            MConstant* mask = MConstant::New(alloc(), Int32Value(table.limits.initial - 1));
+            curBlock_->add(mask);
+            MBitAnd* maskedIndex = MBitAnd::New(alloc(), index, mask, MIRType::Int32);
+            curBlock_->add(maskedIndex);
+
+            index = maskedIndex;
+            callee = CalleeDesc::asmJSTable(table);
+        } else {
+            MOZ_ASSERT(sig.id.kind() != SigIdDesc::Kind::None);
+            MOZ_ASSERT(mg_.tables.length() == 1);
+            const TableDesc& table = mg_.tables[0];
+            MOZ_ASSERT(table.external == (call.tlsStackOffset_ != MWasmCall::DontSaveTls));
+
+            callee = CalleeDesc::wasmTable(table, sig.id);
+        }
+
+        CallSiteDesc desc(call.lineOrBytecode_, CallSiteDesc::Dynamic);
+        auto* ins = MWasmCall::New(alloc(), desc, callee, call.regArgs_, ToMIRType(sig.ret()),
+                                   call.spIncrement_, call.tlsStackOffset_, index);
+        if (!ins)
+            return false;
+
+        curBlock_->add(ins);
+        *def = ins;
+        return true;
+    }
+
+    bool callImport(unsigned globalDataOffset, const CallCompileState& call, ExprType ret,
+                    MDefinition** def)
+    {
+        if (inDeadCode()) {
+            *def = nullptr;
+            return true;
+        }
+
+        MOZ_ASSERT(call.tlsStackOffset_ != MWasmCall::DontSaveTls);
+
+        CallSiteDesc desc(call.lineOrBytecode_, CallSiteDesc::Dynamic);
+        auto callee = CalleeDesc::import(globalDataOffset);
+        auto* ins = MWasmCall::New(alloc(), desc, callee, call.regArgs_, ToMIRType(ret),
+                                   call.spIncrement_, call.tlsStackOffset_);
+        if (!ins)
+            return false;
+
+        curBlock_->add(ins);
+        *def = ins;
+        return true;
+    }
+
+    bool builtinCall(SymbolicAddress builtin, const CallCompileState& call, ValType ret,
+                     MDefinition** def)
+    {
+        if (inDeadCode()) {
+            *def = nullptr;
+            return true;
+        }
+
+        CallSiteDesc desc(call.lineOrBytecode_, CallSiteDesc::Symbolic);
+        auto callee = CalleeDesc::builtin(builtin);
+        auto* ins = MWasmCall::New(alloc(), desc, callee, call.regArgs_, ToMIRType(ret),
+                                   call.spIncrement_, MWasmCall::DontSaveTls);
+        if (!ins)
+            return false;
+
+        curBlock_->add(ins);
+        *def = ins;
+        return true;
+    }
+
+    bool builtinInstanceMethodCall(SymbolicAddress builtin, const CallCompileState& call,
+                                   ValType ret, MDefinition** def)
+    {
+        if (inDeadCode()) {
+            *def = nullptr;
+            return true;
+        }
+
+        CallSiteDesc desc(call.lineOrBytecode_, CallSiteDesc::Symbolic);
+        auto* ins = MWasmCall::NewBuiltinInstanceMethodCall(alloc(), desc, builtin,
+                                                            call.instanceArg_, call.regArgs_,
+                                                            ToMIRType(ret), call.spIncrement_,
+                                                            call.tlsStackOffset_);
+        if (!ins)
+            return false;
+
+        curBlock_->add(ins);
+        *def = ins;
+        return true;
+    }
+
+    /*********************************************** Control flow generation */
+
+    inline bool inDeadCode() const {
+        return curBlock_ == nullptr;
+    }
+
+    void returnExpr(MDefinition* operand)
+    {
+        if (inDeadCode())
+            return;
+
+        MWasmReturn* ins = MWasmReturn::New(alloc(), operand, tlsPointer_);
+        curBlock_->end(ins);
+        curBlock_ = nullptr;
+    }
+
+    void returnVoid()
+    {
+        if (inDeadCode())
+            return;
+
+        MWasmReturnVoid* ins = MWasmReturnVoid::New(alloc(), tlsPointer_);
+        curBlock_->end(ins);
+        curBlock_ = nullptr;
+    }
+
+    void unreachableTrap()
+    {
+        if (inDeadCode())
+            return;
+
+        auto* ins = MWasmTrap::New(alloc(), wasm::Trap::Unreachable, trapOffset());
+        curBlock_->end(ins);
+        curBlock_ = nullptr;
+    }
+
+  private:
+    static bool hasPushed(MBasicBlock* block)
+    {
+        uint32_t numPushed = block->stackDepth() - block->info().firstStackSlot();
+        MOZ_ASSERT(numPushed == 0 || numPushed == 1);
+        return numPushed;
+    }
+
+    static MDefinition* peekPushedDef(MBasicBlock* block)
+    {
+        MOZ_ASSERT(hasPushed(block));
+        return block->getSlot(block->stackDepth() - 1);
+    }
+
+  public:
+    void pushDef(MDefinition* def)
+    {
+        if (inDeadCode())
+            return;
+        MOZ_ASSERT(!hasPushed(curBlock_));
+        if (def && def->type() != MIRType::None)
+            curBlock_->push(def);
+    }
+
+    MDefinition* popDefIfPushed(bool shouldReturn = true)
+    {
+        if (!hasPushed(curBlock_))
+            return nullptr;
+        MDefinition* def = curBlock_->pop();
+        MOZ_ASSERT_IF(def->type() == MIRType::Value, !shouldReturn);
+        return shouldReturn ? def : nullptr;
+    }
+
+    template <typename GetBlock>
+    bool ensurePushInvariants(const GetBlock& getBlock, size_t numBlocks)
+    {
+        // Preserve the invariant that, for every iterated MBasicBlock, either:
+        // every MBasicBlock has a pushed expression with the same type (to
+        // prevent creating used phis with type Value) OR no MBasicBlock has any
+        // pushed expression. This is required by MBasicBlock::addPredecessor.
+        if (numBlocks < 2)
+            return true;
+
+        MBasicBlock* block = getBlock(0);
+
+        bool allPushed = hasPushed(block);
+        if (allPushed) {
+            MIRType type = peekPushedDef(block)->type();
+            for (size_t i = 1; allPushed && i < numBlocks; i++) {
+                block = getBlock(i);
+                allPushed = hasPushed(block) && peekPushedDef(block)->type() == type;
+            }
+        }
+
+        if (!allPushed) {
+            for (size_t i = 0; i < numBlocks; i++) {
+                block = getBlock(i);
+                if (!hasPushed(block))
+                    block->push(dummyIns_);
+            }
+        }
+
+        return allPushed;
+    }
+
+  private:
+    void addJoinPredecessor(MDefinition* def, MBasicBlock** joinPred)
+    {
+        *joinPred = curBlock_;
+        if (inDeadCode())
+            return;
+        pushDef(def);
+    }
+
+  public:
+    bool branchAndStartThen(MDefinition* cond, MBasicBlock** elseBlock)
+    {
+        if (inDeadCode()) {
+            *elseBlock = nullptr;
+        } else {
+            MBasicBlock* thenBlock;
+            if (!newBlock(curBlock_, &thenBlock))
+                return false;
+            if (!newBlock(curBlock_, elseBlock))
+                return false;
+
+            curBlock_->end(MTest::New(alloc(), cond, thenBlock, *elseBlock));
+
+            curBlock_ = thenBlock;
+            mirGraph().moveBlockToEnd(curBlock_);
+        }
+
+        return startBlock();
+    }
+
+    bool switchToElse(MBasicBlock* elseBlock, MBasicBlock** thenJoinPred)
+    {
+        MDefinition* ifDef;
+        if (!finishBlock(&ifDef))
+            return false;
+
+        if (!elseBlock) {
+            *thenJoinPred = nullptr;
+        } else {
+            addJoinPredecessor(ifDef, thenJoinPred);
+
+            curBlock_ = elseBlock;
+            mirGraph().moveBlockToEnd(curBlock_);
+        }
+
+        return startBlock();
+    }
+
+    bool joinIfElse(MBasicBlock* thenJoinPred, MDefinition** def)
+    {
+        MDefinition* elseDef;
+        if (!finishBlock(&elseDef))
+            return false;
+
+        if (!thenJoinPred && inDeadCode()) {
+            *def = nullptr;
+        } else {
+            MBasicBlock* elseJoinPred;
+            addJoinPredecessor(elseDef, &elseJoinPred);
+
+            mozilla::Array<MBasicBlock*, 2> blocks;
+            size_t numJoinPreds = 0;
+            if (thenJoinPred)
+                blocks[numJoinPreds++] = thenJoinPred;
+            if (elseJoinPred)
+                blocks[numJoinPreds++] = elseJoinPred;
+
+            auto getBlock = [&](size_t i) -> MBasicBlock* { return blocks[i]; };
+            bool yieldsValue = ensurePushInvariants(getBlock, numJoinPreds);
+
+            if (numJoinPreds == 0) {
+                *def = nullptr;
+                return true;
+            }
+
+            MBasicBlock* join;
+            if (!goToNewBlock(blocks[0], &join))
+                return false;
+            for (size_t i = 1; i < numJoinPreds; ++i) {
+                if (!goToExistingBlock(blocks[i], join))
+                    return false;
+            }
+
+            curBlock_ = join;
+            *def = popDefIfPushed(yieldsValue);
+        }
+
+        return true;
+    }
+
+    bool startBlock()
+    {
+        MOZ_ASSERT_IF(blockDepth_ < blockPatches_.length(), blockPatches_[blockDepth_].empty());
+        blockDepth_++;
+        return true;
+    }
+
+    bool finishBlock(MDefinition** def)
+    {
+        MOZ_ASSERT(blockDepth_);
+        uint32_t topLabel = --blockDepth_;
+        return bindBranches(topLabel, def);
+    }
+
+    bool startLoop(MBasicBlock** loopHeader)
+    {
+        *loopHeader = nullptr;
+
+        blockDepth_++;
+        loopDepth_++;
+
+        if (inDeadCode())
+            return true;
+
+        // Create the loop header.
+        MOZ_ASSERT(curBlock_->loopDepth() == loopDepth_ - 1);
+        *loopHeader = MBasicBlock::New(mirGraph(), info(), curBlock_,
+                                       MBasicBlock::PENDING_LOOP_HEADER);
+        if (!*loopHeader)
+            return false;
+
+        (*loopHeader)->setLoopDepth(loopDepth_);
+        mirGraph().addBlock(*loopHeader);
+        curBlock_->end(MGoto::New(alloc(), *loopHeader));
+
+        MBasicBlock* body;
+        if (!goToNewBlock(*loopHeader, &body))
+            return false;
+        curBlock_ = body;
+        return true;
+    }
+
+  private:
+    void fixupRedundantPhis(MBasicBlock* b)
+    {
+        for (size_t i = 0, depth = b->stackDepth(); i < depth; i++) {
+            MDefinition* def = b->getSlot(i);
+            if (def->isUnused())
+                b->setSlot(i, def->toPhi()->getOperand(0));
+        }
+    }
+
+    bool setLoopBackedge(MBasicBlock* loopEntry, MBasicBlock* loopBody, MBasicBlock* backedge)
+    {
+        if (!loopEntry->setBackedgeWasm(backedge))
+            return false;
+
+        // Flag all redundant phis as unused.
+        for (MPhiIterator phi = loopEntry->phisBegin(); phi != loopEntry->phisEnd(); phi++) {
+            MOZ_ASSERT(phi->numOperands() == 2);
+            if (phi->getOperand(0) == phi->getOperand(1))
+                phi->setUnused();
+        }
+
+        // Fix up phis stored in the slots Vector of pending blocks.
+        for (ControlFlowPatchVector& patches : blockPatches_) {
+            for (ControlFlowPatch& p : patches) {
+                MBasicBlock* block = p.ins->block();
+                if (block->loopDepth() >= loopEntry->loopDepth())
+                    fixupRedundantPhis(block);
+            }
+        }
+
+        // The loop body, if any, might be referencing recycled phis too.
+        if (loopBody)
+            fixupRedundantPhis(loopBody);
+
+        // Discard redundant phis and add to the free list.
+        for (MPhiIterator phi = loopEntry->phisBegin(); phi != loopEntry->phisEnd(); ) {
+            MPhi* entryDef = *phi++;
+            if (!entryDef->isUnused())
+                continue;
+
+            entryDef->justReplaceAllUsesWith(entryDef->getOperand(0));
+            loopEntry->discardPhi(entryDef);
+            mirGraph().addPhiToFreeList(entryDef);
+        }
+
+        return true;
+    }
+
+  public:
+    bool closeLoop(MBasicBlock* loopHeader, MDefinition** loopResult)
+    {
+        MOZ_ASSERT(blockDepth_ >= 1);
+        MOZ_ASSERT(loopDepth_);
+
+        uint32_t headerLabel = blockDepth_ - 1;
+
+        if (!loopHeader) {
+            MOZ_ASSERT(inDeadCode());
+            MOZ_ASSERT(headerLabel >= blockPatches_.length() || blockPatches_[headerLabel].empty());
+            blockDepth_--;
+            loopDepth_--;
+            *loopResult = nullptr;
+            return true;
+        }
+
+        // Op::Loop doesn't have an implicit backedge so temporarily set
+        // aside the end of the loop body to bind backedges.
+        MBasicBlock* loopBody = curBlock_;
+        curBlock_ = nullptr;
+
+        // As explained in bug 1253544, Ion apparently has an invariant that
+        // there is only one backedge to loop headers. To handle wasm's ability
+        // to have multiple backedges to the same loop header, we bind all those
+        // branches as forward jumps to a single backward jump. This is
+        // unfortunate but the optimizer is able to fold these into single jumps
+        // to backedges.
+        MDefinition* _;
+        if (!bindBranches(headerLabel, &_))
+            return false;
+
+        MOZ_ASSERT(loopHeader->loopDepth() == loopDepth_);
+
+        if (curBlock_) {
+            // We're on the loop backedge block, created by bindBranches.
+            if (hasPushed(curBlock_))
+                curBlock_->pop();
+
+            MOZ_ASSERT(curBlock_->loopDepth() == loopDepth_);
+            curBlock_->end(MGoto::New(alloc(), loopHeader));
+            if (!setLoopBackedge(loopHeader, loopBody, curBlock_))
+                return false;
+        }
+
+        curBlock_ = loopBody;
+
+        loopDepth_--;
+
+        // If the loop depth still at the inner loop body, correct it.
+        if (curBlock_ && curBlock_->loopDepth() != loopDepth_) {
+            MBasicBlock* out;
+            if (!goToNewBlock(curBlock_, &out))
+                return false;
+            curBlock_ = out;
+        }
+
+        blockDepth_ -= 1;
+        *loopResult = inDeadCode() ? nullptr : popDefIfPushed();
+        return true;
+    }
+
+    bool addControlFlowPatch(MControlInstruction* ins, uint32_t relative, uint32_t index) {
+        MOZ_ASSERT(relative < blockDepth_);
+        uint32_t absolute = blockDepth_ - 1 - relative;
+
+        if (absolute >= blockPatches_.length() && !blockPatches_.resize(absolute + 1))
+            return false;
+
+        return blockPatches_[absolute].append(ControlFlowPatch(ins, index));
+    }
+
+    bool br(uint32_t relativeDepth, MDefinition* maybeValue)
+    {
+        if (inDeadCode())
+            return true;
+
+        MGoto* jump = MGoto::New(alloc());
+        if (!addControlFlowPatch(jump, relativeDepth, MGoto::TargetIndex))
+            return false;
+
+        pushDef(maybeValue);
+
+        curBlock_->end(jump);
+        curBlock_ = nullptr;
+        return true;
+    }
+
+    bool brIf(uint32_t relativeDepth, MDefinition* maybeValue, MDefinition* condition)
+    {
+        if (inDeadCode())
+            return true;
+
+        MBasicBlock* joinBlock = nullptr;
+        if (!newBlock(curBlock_, &joinBlock))
+            return false;
+
+        MTest* test = MTest::New(alloc(), condition, joinBlock);
+        if (!addControlFlowPatch(test, relativeDepth, MTest::TrueBranchIndex))
+            return false;
+
+        pushDef(maybeValue);
+
+        curBlock_->end(test);
+        curBlock_ = joinBlock;
+        return true;
+    }
+
+    bool brTable(MDefinition* operand, uint32_t defaultDepth, const Uint32Vector& depths,
+                 MDefinition* maybeValue)
+    {
+        if (inDeadCode())
+            return true;
+
+        size_t numCases = depths.length();
+        MOZ_ASSERT(numCases <= INT32_MAX);
+        MOZ_ASSERT(numCases);
+
+        MTableSwitch* table = MTableSwitch::New(alloc(), operand, 0, int32_t(numCases - 1));
+
+        size_t defaultIndex;
+        if (!table->addDefault(nullptr, &defaultIndex))
+            return false;
+        if (!addControlFlowPatch(table, defaultDepth, defaultIndex))
+            return false;
+
+        typedef HashMap<uint32_t, uint32_t, DefaultHasher<uint32_t>, SystemAllocPolicy>
+            IndexToCaseMap;
+
+        IndexToCaseMap indexToCase;
+        if (!indexToCase.init() || !indexToCase.put(defaultDepth, defaultIndex))
+            return false;
+
+        for (size_t i = 0; i < numCases; i++) {
+            uint32_t depth = depths[i];
+
+            size_t caseIndex;
+            IndexToCaseMap::AddPtr p = indexToCase.lookupForAdd(depth);
+            if (!p) {
+                if (!table->addSuccessor(nullptr, &caseIndex))
+                    return false;
+                if (!addControlFlowPatch(table, depth, caseIndex))
+                    return false;
+                if (!indexToCase.add(p, depth, caseIndex))
+                    return false;
+            } else {
+                caseIndex = p->value();
+            }
+
+            if (!table->addCase(caseIndex))
+                return false;
+        }
+
+        pushDef(maybeValue);
+
+        curBlock_->end(table);
+        curBlock_ = nullptr;
+
+        return true;
+    }
+
+    /************************************************************ DECODING ***/
+
+    uint32_t readCallSiteLineOrBytecode() {
+        if (!func_.callSiteLineNums().empty())
+            return func_.callSiteLineNums()[lastReadCallSite_++];
+        return iter_.trapOffset().bytecodeOffset;
+    }
+
+    bool done() const { return iter_.done(); }
+
+    /*************************************************************************/
+  private:
+    bool newBlock(MBasicBlock* pred, MBasicBlock** block)
+    {
+        *block = MBasicBlock::New(mirGraph(), info(), pred, MBasicBlock::NORMAL);
+        if (!*block)
+            return false;
+        mirGraph().addBlock(*block);
+        (*block)->setLoopDepth(loopDepth_);
+        return true;
+    }
+
+    bool goToNewBlock(MBasicBlock* pred, MBasicBlock** block)
+    {
+        if (!newBlock(pred, block))
+            return false;
+        pred->end(MGoto::New(alloc(), *block));
+        return true;
+    }
+
+    bool goToExistingBlock(MBasicBlock* prev, MBasicBlock* next)
+    {
+        MOZ_ASSERT(prev);
+        MOZ_ASSERT(next);
+        prev->end(MGoto::New(alloc(), next));
+        return next->addPredecessor(alloc(), prev);
+    }
+
+    bool bindBranches(uint32_t absolute, MDefinition** def)
+    {
+        if (absolute >= blockPatches_.length() || blockPatches_[absolute].empty()) {
+            *def = inDeadCode() ? nullptr : popDefIfPushed();
+            return true;
+        }
+
+        ControlFlowPatchVector& patches = blockPatches_[absolute];
+
+        auto getBlock = [&](size_t i) -> MBasicBlock* {
+            if (i < patches.length())
+                return patches[i].ins->block();
+            return curBlock_;
+        };
+
+        bool yieldsValue = ensurePushInvariants(getBlock, patches.length() + !!curBlock_);
+
+        MBasicBlock* join = nullptr;
+        MControlInstruction* ins = patches[0].ins;
+        MBasicBlock* pred = ins->block();
+        if (!newBlock(pred, &join))
+            return false;
+
+        pred->mark();
+        ins->replaceSuccessor(patches[0].index, join);
+
+        for (size_t i = 1; i < patches.length(); i++) {
+            ins = patches[i].ins;
+
+            pred = ins->block();
+            if (!pred->isMarked()) {
+                if (!join->addPredecessor(alloc(), pred))
+                    return false;
+                pred->mark();
+            }
+
+            ins->replaceSuccessor(patches[i].index, join);
+        }
+
+        MOZ_ASSERT_IF(curBlock_, !curBlock_->isMarked());
+        for (uint32_t i = 0; i < join->numPredecessors(); i++)
+            join->getPredecessor(i)->unmark();
+
+        if (curBlock_ && !goToExistingBlock(curBlock_, join))
+            return false;
+
+        curBlock_ = join;
+
+        *def = popDefIfPushed(yieldsValue);
+
+        patches.clear();
+        return true;
+    }
+};
+
+template <>
+MDefinition* FunctionCompiler::unary<MToFloat32>(MDefinition* op)
+{
+    if (inDeadCode())
+        return nullptr;
+    auto* ins = MToFloat32::New(alloc(), op, mustPreserveNaN(op->type()));
+    curBlock_->add(ins);
+    return ins;
+}
+
+template <>
+MDefinition* FunctionCompiler::unary<MNot>(MDefinition* op)
+{
+    if (inDeadCode())
+        return nullptr;
+    auto* ins = MNot::NewInt32(alloc(), op);
+    curBlock_->add(ins);
+    return ins;
+}
+
+template <>
+MDefinition* FunctionCompiler::unary<MAbs>(MDefinition* op, MIRType type)
+{
+    if (inDeadCode())
+        return nullptr;
+    auto* ins = MAbs::NewWasm(alloc(), op, type);
+    curBlock_->add(ins);
+    return ins;
+}
+
+} // end anonymous namespace
+
+static bool
+EmitBlock(FunctionCompiler& f)
+{
+    return f.iter().readBlock() &&
+           f.startBlock();
+}
+
+static bool
+EmitLoop(FunctionCompiler& f)
+{
+    if (!f.iter().readLoop())
+        return false;
+
+    MBasicBlock* loopHeader;
+    if (!f.startLoop(&loopHeader))
+        return false;
+
+    f.addInterruptCheck();
+
+    f.iter().controlItem() = loopHeader;
+    return true;
+}
+
+static bool
+EmitIf(FunctionCompiler& f)
+{
+    MDefinition* condition = nullptr;
+    if (!f.iter().readIf(&condition))
+        return false;
+
+    MBasicBlock* elseBlock;
+    if (!f.branchAndStartThen(condition, &elseBlock))
+        return false;
+
+    f.iter().controlItem() = elseBlock;
+    return true;
+}
+
+static bool
+EmitElse(FunctionCompiler& f)
+{
+    MBasicBlock* block = f.iter().controlItem();
+
+    ExprType thenType;
+    MDefinition* thenValue;
+    if (!f.iter().readElse(&thenType, &thenValue))
+        return false;
+
+    if (!IsVoid(thenType))
+        f.pushDef(thenValue);
+
+    if (!f.switchToElse(block, &f.iter().controlItem()))
+        return false;
+
+    return true;
+}
+
+static bool
+EmitEnd(FunctionCompiler& f)
+{
+    MBasicBlock* block = f.iter().controlItem();
+
+    LabelKind kind;
+    ExprType type;
+    MDefinition* value;
+    if (!f.iter().readEnd(&kind, &type, &value))
+        return false;
+
+    if (!IsVoid(type))
+        f.pushDef(value);
+
+    MDefinition* def = nullptr;
+    switch (kind) {
+      case LabelKind::Block:
+        if (!f.finishBlock(&def))
+            return false;
+        break;
+      case LabelKind::Loop:
+        if (!f.closeLoop(block, &def))
+            return false;
+        break;
+      case LabelKind::Then:
+      case LabelKind::UnreachableThen:
+        // If we didn't see an Else, create a trivial else block so that we create
+        // a diamond anyway, to preserve Ion invariants.
+        if (!f.switchToElse(block, &block))
+            return false;
+
+        if (!f.joinIfElse(block, &def))
+            return false;
+        break;
+      case LabelKind::Else:
+        if (!f.joinIfElse(block, &def))
+            return false;
+        break;
+    }
+
+    if (!IsVoid(type)) {
+        MOZ_ASSERT_IF(!f.inDeadCode(), def);
+        f.iter().setResult(def);
+    }
+
+    return true;
+}
+
+static bool
+EmitBr(FunctionCompiler& f)
+{
+    uint32_t relativeDepth;
+    ExprType type;
+    MDefinition* value;
+    if (!f.iter().readBr(&relativeDepth, &type, &value))
+        return false;
+
+    if (IsVoid(type)) {
+        if (!f.br(relativeDepth, nullptr))
+            return false;
+    } else {
+        if (!f.br(relativeDepth, value))
+            return false;
+    }
+
+    return true;
+}
+
+static bool
+EmitBrIf(FunctionCompiler& f)
+{
+    uint32_t relativeDepth;
+    ExprType type;
+    MDefinition* value;
+    MDefinition* condition;
+    if (!f.iter().readBrIf(&relativeDepth, &type, &value, &condition))
+        return false;
+
+    if (IsVoid(type)) {
+        if (!f.brIf(relativeDepth, nullptr, condition))
+            return false;
+    } else {
+        if (!f.brIf(relativeDepth, value, condition))
+            return false;
+    }
+
+    return true;
+}
+
+static bool
+EmitBrTable(FunctionCompiler& f)
+{
+    uint32_t tableLength;
+    ExprType type;
+    MDefinition* value;
+    MDefinition* index;
+    if (!f.iter().readBrTable(&tableLength, &type, &value, &index))
+        return false;
+
+    Uint32Vector depths;
+    if (!depths.reserve(tableLength))
+        return false;
+
+    for (size_t i = 0; i < tableLength; ++i) {
+        uint32_t depth;
+        if (!f.iter().readBrTableEntry(&type, &value, &depth))
+            return false;
+        depths.infallibleAppend(depth);
+    }
+
+    // Read the default label.
+    uint32_t defaultDepth;
+    if (!f.iter().readBrTableDefault(&type, &value, &defaultDepth))
+        return false;
+
+    MDefinition* maybeValue = IsVoid(type) ? nullptr : value;
+
+    // If all the targets are the same, or there are no targets, we can just
+    // use a goto. This is not just an optimization: MaybeFoldConditionBlock
+    // assumes that tables have more than one successor.
+    bool allSameDepth = true;
+    for (uint32_t depth : depths) {
+        if (depth != defaultDepth) {
+            allSameDepth = false;
+            break;
+        }
+    }
+
+    if (allSameDepth)
+        return f.br(defaultDepth, maybeValue);
+
+    return f.brTable(index, defaultDepth, depths, maybeValue);
+}
+
+static bool
+EmitReturn(FunctionCompiler& f)
+{
+    MDefinition* value;
+    if (!f.iter().readReturn(&value))
+        return false;
+
+    if (f.inDeadCode())
+        return true;
+
+    if (IsVoid(f.sig().ret())) {
+        f.returnVoid();
+        return true;
+    }
+
+    f.returnExpr(value);
+    return true;
+}
+
+static bool
+EmitCallArgs(FunctionCompiler& f, const Sig& sig, TlsUsage tls, CallCompileState* call)
+{
+    MOZ_ASSERT(NeedsTls(tls));
+
+    if (!f.startCall(call))
+        return false;
+
+    MDefinition* arg;
+    const ValTypeVector& argTypes = sig.args();
+    uint32_t numArgs = argTypes.length();
+    for (size_t i = 0; i < numArgs; ++i) {
+        ValType argType = argTypes[i];
+        if (!f.iter().readCallArg(argType, numArgs, i, &arg))
+            return false;
+        if (!f.passArg(arg, argType, call))
+            return false;
+    }
+
+    if (!f.iter().readCallArgsEnd(numArgs))
+        return false;
+
+    return f.finishCall(call, tls);
+}
+
+static bool
+EmitCall(FunctionCompiler& f)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    uint32_t funcIndex;
+    if (!f.iter().readCall(&funcIndex))
+        return false;
+
+    if (f.inDeadCode())
+        return true;
+
+    const Sig& sig = *f.mg().funcSigs[funcIndex];
+    bool import = f.mg().funcIsImport(funcIndex);
+
+    CallCompileState call(f, lineOrBytecode);
+    if (!EmitCallArgs(f, sig, import ? TlsUsage::CallerSaved : TlsUsage::Need, &call))
+        return false;
+
+    if (!f.iter().readCallReturn(sig.ret()))
+        return false;
+
+    MDefinition* def;
+    if (import) {
+        uint32_t globalDataOffset = f.mg().funcImportGlobalDataOffsets[funcIndex];
+        if (!f.callImport(globalDataOffset, call, sig.ret(), &def))
+            return false;
+    } else {
+        if (!f.callDirect(sig, funcIndex, call, &def))
+            return false;
+    }
+
+    if (IsVoid(sig.ret()))
+        return true;
+
+    f.iter().setResult(def);
+    return true;
+}
+
+static bool
+EmitCallIndirect(FunctionCompiler& f, bool oldStyle)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    uint32_t sigIndex;
+    MDefinition* callee;
+    if (oldStyle) {
+        if (!f.iter().readOldCallIndirect(&sigIndex))
+            return false;
+    } else {
+        if (!f.iter().readCallIndirect(&sigIndex, &callee))
+            return false;
+    }
+
+    if (f.inDeadCode())
+        return true;
+
+    const Sig& sig = f.mg().sigs[sigIndex];
+
+    TlsUsage tls = !f.mg().isAsmJS() && f.mg().tables[0].external
+                   ? TlsUsage::CallerSaved
+                   : TlsUsage::Need;
+
+    CallCompileState call(f, lineOrBytecode);
+    if (!EmitCallArgs(f, sig, tls, &call))
+        return false;
+
+    if (oldStyle) {
+        if (!f.iter().readOldCallIndirectCallee(&callee))
+            return false;
+    }
+
+    if (!f.iter().readCallReturn(sig.ret()))
+        return false;
+
+    MDefinition* def;
+    if (!f.callIndirect(sigIndex, callee, call, &def))
+        return false;
+
+    if (IsVoid(sig.ret()))
+        return true;
+
+    f.iter().setResult(def);
+    return true;
+}
+
+static bool
+EmitGetLocal(FunctionCompiler& f)
+{
+    uint32_t id;
+    if (!f.iter().readGetLocal(f.locals(), &id))
+        return false;
+
+    f.iter().setResult(f.getLocalDef(id));
+    return true;
+}
+
+static bool
+EmitSetLocal(FunctionCompiler& f)
+{
+    uint32_t id;
+    MDefinition* value;
+    if (!f.iter().readSetLocal(f.locals(), &id, &value))
+        return false;
+
+    f.assign(id, value);
+    return true;
+}
+
+static bool
+EmitTeeLocal(FunctionCompiler& f)
+{
+    uint32_t id;
+    MDefinition* value;
+    if (!f.iter().readTeeLocal(f.locals(), &id, &value))
+        return false;
+
+    f.assign(id, value);
+    return true;
+}
+
+static bool
+EmitGetGlobal(FunctionCompiler& f)
+{
+    uint32_t id;
+    if (!f.iter().readGetGlobal(f.mg().globals, &id))
+        return false;
+
+    const GlobalDesc& global = f.mg().globals[id];
+    if (!global.isConstant()) {
+        f.iter().setResult(f.loadGlobalVar(global.offset(), !global.isMutable(),
+                                           ToMIRType(global.type())));
+        return true;
+    }
+
+    Val value = global.constantValue();
+    MIRType mirType = ToMIRType(value.type());
+
+    MDefinition* result;
+    switch (value.type()) {
+      case ValType::I32:
+        result = f.constant(Int32Value(value.i32()), mirType);
+        break;
+      case ValType::I64:
+        result = f.constant(int64_t(value.i64()));
+        break;
+      case ValType::F32:
+        result = f.constant(value.f32());
+        break;
+      case ValType::F64:
+        result = f.constant(value.f64());
+        break;
+      case ValType::I8x16:
+        result = f.constant(SimdConstant::CreateX16(value.i8x16()), mirType);
+        break;
+      case ValType::I16x8:
+        result = f.constant(SimdConstant::CreateX8(value.i16x8()), mirType);
+        break;
+      case ValType::I32x4:
+        result = f.constant(SimdConstant::CreateX4(value.i32x4()), mirType);
+        break;
+      case ValType::F32x4:
+        result = f.constant(SimdConstant::CreateX4(value.f32x4()), mirType);
+        break;
+      default:
+        MOZ_CRASH("unexpected type in EmitGetGlobal");
+    }
+
+    f.iter().setResult(result);
+    return true;
+}
+
+static bool
+EmitSetGlobal(FunctionCompiler& f)
+{
+    uint32_t id;
+    MDefinition* value;
+    if (!f.iter().readSetGlobal(f.mg().globals, &id, &value))
+        return false;
+
+    const GlobalDesc& global = f.mg().globals[id];
+    MOZ_ASSERT(global.isMutable());
+
+    f.storeGlobalVar(global.offset(), value);
+    return true;
+}
+
+static bool
+EmitTeeGlobal(FunctionCompiler& f)
+{
+    uint32_t id;
+    MDefinition* value;
+    if (!f.iter().readTeeGlobal(f.mg().globals, &id, &value))
+        return false;
+
+    const GlobalDesc& global = f.mg().globals[id];
+    MOZ_ASSERT(global.isMutable());
+
+    f.storeGlobalVar(global.offset(), value);
+    return true;
+}
+
+template <typename MIRClass>
+static bool
+EmitUnary(FunctionCompiler& f, ValType operandType)
+{
+    MDefinition* input;
+    if (!f.iter().readUnary(operandType, &input))
+        return false;
+
+    f.iter().setResult(f.unary<MIRClass>(input));
+    return true;
+}
+
+template <typename MIRClass>
+static bool
+EmitConversion(FunctionCompiler& f, ValType operandType, ValType resultType)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(operandType, resultType, &input))
+        return false;
+
+    f.iter().setResult(f.unary<MIRClass>(input));
+    return true;
+}
+
+template <typename MIRClass>
+static bool
+EmitUnaryWithType(FunctionCompiler& f, ValType operandType, MIRType mirType)
+{
+    MDefinition* input;
+    if (!f.iter().readUnary(operandType, &input))
+        return false;
+
+    f.iter().setResult(f.unary<MIRClass>(input, mirType));
+    return true;
+}
+
+template <typename MIRClass>
+static bool
+EmitConversionWithType(FunctionCompiler& f,
+                       ValType operandType, ValType resultType, MIRType mirType)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(operandType, resultType, &input))
+        return false;
+
+    f.iter().setResult(f.unary<MIRClass>(input, mirType));
+    return true;
+}
+
+static bool
+EmitTruncate(FunctionCompiler& f, ValType operandType, ValType resultType,
+             bool isUnsigned)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(operandType, resultType, &input))
+        return false;
+
+    if (resultType == ValType::I32) {
+        if (f.mg().isAsmJS())
+            f.iter().setResult(f.unary<MTruncateToInt32>(input));
+        else
+            f.iter().setResult(f.truncate<MWasmTruncateToInt32>(input, isUnsigned));
+    } else {
+        MOZ_ASSERT(resultType == ValType::I64);
+        MOZ_ASSERT(!f.mg().isAsmJS());
+        f.iter().setResult(f.truncate<MWasmTruncateToInt64>(input, isUnsigned));
+    }
+    return true;
+}
+
+static bool
+EmitExtendI32(FunctionCompiler& f, bool isUnsigned)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(ValType::I32, ValType::I64, &input))
+        return false;
+
+    f.iter().setResult(f.extendI32(input, isUnsigned));
+    return true;
+}
+
+static bool
+EmitConvertI64ToFloatingPoint(FunctionCompiler& f,
+                              ValType resultType, MIRType mirType, bool isUnsigned)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(ValType::I64, resultType, &input))
+        return false;
+
+    f.iter().setResult(f.convertI64ToFloatingPoint(input, mirType, isUnsigned));
+    return true;
+}
+
+static bool
+EmitReinterpret(FunctionCompiler& f, ValType resultType, ValType operandType, MIRType mirType)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(operandType, resultType, &input))
+        return false;
+
+    f.iter().setResult(f.unary<MWasmReinterpret>(input, mirType));
+    return true;
+}
+
+static bool
+EmitAdd(FunctionCompiler& f, ValType type, MIRType mirType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(type, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binary<MAdd>(lhs, rhs, mirType));
+    return true;
+}
+
+static bool
+EmitSub(FunctionCompiler& f, ValType type, MIRType mirType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(type, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.sub(lhs, rhs, mirType));
+    return true;
+}
+
+static bool
+EmitRotate(FunctionCompiler& f, ValType type, bool isLeftRotation)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(type, &lhs, &rhs))
+        return false;
+
+    MDefinition* result = f.rotate(lhs, rhs, ToMIRType(type), isLeftRotation);
+    f.iter().setResult(result);
+    return true;
+}
+
+static bool
+EmitBitNot(FunctionCompiler& f, ValType operandType)
+{
+    MDefinition* input;
+    if (!f.iter().readUnary(operandType, &input))
+        return false;
+
+    f.iter().setResult(f.bitnot(input));
+    return true;
+}
+
+template <typename MIRClass>
+static bool
+EmitBitwise(FunctionCompiler& f, ValType operandType, MIRType mirType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binary<MIRClass>(lhs, rhs, mirType));
+    return true;
+}
+
+static bool
+EmitMul(FunctionCompiler& f, ValType operandType, MIRType mirType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.mul(lhs, rhs, mirType,
+                       mirType == MIRType::Int32 ? MMul::Integer : MMul::Normal));
+    return true;
+}
+
+static bool
+EmitDiv(FunctionCompiler& f, ValType operandType, MIRType mirType, bool isUnsigned)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.div(lhs, rhs, mirType, isUnsigned));
+    return true;
+}
+
+static bool
+EmitRem(FunctionCompiler& f, ValType operandType, MIRType mirType, bool isUnsigned)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.mod(lhs, rhs, mirType, isUnsigned));
+    return true;
+}
+
+static bool
+EmitMinMax(FunctionCompiler& f, ValType operandType, MIRType mirType, bool isMax)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.minMax(lhs, rhs, mirType, isMax));
+    return true;
+}
+
+static bool
+EmitCopySign(FunctionCompiler& f, ValType operandType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binary<MCopySign>(lhs, rhs, ToMIRType(operandType)));
+    return true;
+}
+
+static bool
+EmitComparison(FunctionCompiler& f,
+               ValType operandType, JSOp compareOp, MCompare::CompareType compareType)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readComparison(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.compare(lhs, rhs, compareOp, compareType));
+    return true;
+}
+
+static bool
+EmitSelect(FunctionCompiler& f)
+{
+    ValType type;
+    MDefinition* trueValue;
+    MDefinition* falseValue;
+    MDefinition* condition;
+    if (!f.iter().readSelect(&type, &trueValue, &falseValue, &condition))
+        return false;
+
+    f.iter().setResult(f.select(trueValue, falseValue, condition));
+    return true;
+}
+
+static bool
+EmitLoad(FunctionCompiler& f, ValType type, Scalar::Type viewType)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    if (!f.iter().readLoad(type, Scalar::byteSize(viewType), &addr))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, f.trapIfNotAsmJS());
+    f.iter().setResult(f.load(addr.base, access, type));
+    return true;
+}
+
+static bool
+EmitStore(FunctionCompiler& f, ValType resultType, Scalar::Type viewType)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    MDefinition* value;
+    if (!f.iter().readStore(resultType, Scalar::byteSize(viewType), &addr, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, f.trapIfNotAsmJS());
+
+    f.store(addr.base, access, value);
+    return true;
+}
+
+static bool
+EmitTeeStore(FunctionCompiler& f, ValType resultType, Scalar::Type viewType)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    MDefinition* value;
+    if (!f.iter().readTeeStore(resultType, Scalar::byteSize(viewType), &addr, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, f.trapIfNotAsmJS());
+
+    f.store(addr.base, access, value);
+    return true;
+}
+
+static bool
+EmitTeeStoreWithCoercion(FunctionCompiler& f, ValType resultType, Scalar::Type viewType)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    MDefinition* value;
+    if (!f.iter().readTeeStore(resultType, Scalar::byteSize(viewType), &addr, &value))
+        return false;
+
+    if (resultType == ValType::F32 && viewType == Scalar::Float64)
+        value = f.unary<MToDouble>(value);
+    else if (resultType == ValType::F64 && viewType == Scalar::Float32)
+        value = f.unary<MToFloat32>(value);
+    else
+        MOZ_CRASH("unexpected coerced store");
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, f.trapIfNotAsmJS());
+
+    f.store(addr.base, access, value);
+    return true;
+}
+
+static bool
+EmitUnaryMathBuiltinCall(FunctionCompiler& f, SymbolicAddress callee, ValType operandType)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    CallCompileState call(f, lineOrBytecode);
+    if (!f.startCall(&call))
+        return false;
+
+    MDefinition* input;
+    if (!f.iter().readUnary(operandType, &input))
+        return false;
+
+    if (!f.passArg(input, operandType, &call))
+        return false;
+
+    if (!f.finishCall(&call, TlsUsage::Unused))
+        return false;
+
+    MDefinition* def;
+    if (!f.builtinCall(callee, call, operandType, &def))
+        return false;
+
+    f.iter().setResult(def);
+    return true;
+}
+
+static bool
+EmitBinaryMathBuiltinCall(FunctionCompiler& f, SymbolicAddress callee, ValType operandType)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    CallCompileState call(f, lineOrBytecode);
+    if (!f.startCall(&call))
+        return false;
+
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(operandType, &lhs, &rhs))
+        return false;
+
+    if (!f.passArg(lhs, operandType, &call))
+        return false;
+
+    if (!f.passArg(rhs, operandType, &call))
+        return false;
+
+    if (!f.finishCall(&call, TlsUsage::Unused))
+        return false;
+
+    MDefinition* def;
+    if (!f.builtinCall(callee, call, operandType, &def))
+        return false;
+
+    f.iter().setResult(def);
+    return true;
+}
+
+static bool
+EmitAtomicsLoad(FunctionCompiler& f)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    Scalar::Type viewType;
+    if (!f.iter().readAtomicLoad(&addr, &viewType))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()), 0,
+                            MembarBeforeLoad, MembarAfterLoad);
+
+    f.iter().setResult(f.load(addr.base, access, ValType::I32));
+    return true;
+}
+
+static bool
+EmitAtomicsStore(FunctionCompiler& f)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    Scalar::Type viewType;
+    MDefinition* value;
+    if (!f.iter().readAtomicStore(&addr, &viewType, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()), 0,
+                            MembarBeforeStore, MembarAfterStore);
+
+    f.store(addr.base, access, value);
+    f.iter().setResult(value);
+    return true;
+}
+
+static bool
+EmitAtomicsBinOp(FunctionCompiler& f)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    Scalar::Type viewType;
+    jit::AtomicOp op;
+    MDefinition* value;
+    if (!f.iter().readAtomicBinOp(&addr, &viewType, &op, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()));
+
+    f.iter().setResult(f.atomicBinopHeap(op, addr.base, access, value));
+    return true;
+}
+
+static bool
+EmitAtomicsCompareExchange(FunctionCompiler& f)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    Scalar::Type viewType;
+    MDefinition* oldValue;
+    MDefinition* newValue;
+    if (!f.iter().readAtomicCompareExchange(&addr, &viewType, &oldValue, &newValue))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()));
+
+    f.iter().setResult(f.atomicCompareExchangeHeap(addr.base, access, oldValue, newValue));
+    return true;
+}
+
+static bool
+EmitAtomicsExchange(FunctionCompiler& f)
+{
+    LinearMemoryAddress<MDefinition*> addr;
+    Scalar::Type viewType;
+    MDefinition* value;
+    if (!f.iter().readAtomicExchange(&addr, &viewType, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()));
+
+    f.iter().setResult(f.atomicExchangeHeap(addr.base, access, value));
+    return true;
+}
+
+static bool
+EmitSimdUnary(FunctionCompiler& f, ValType type, SimdOperation simdOp)
+{
+    MSimdUnaryArith::Operation op;
+    switch (simdOp) {
+      case SimdOperation::Fn_abs:
+        op = MSimdUnaryArith::abs;
+        break;
+      case SimdOperation::Fn_neg:
+        op = MSimdUnaryArith::neg;
+        break;
+      case SimdOperation::Fn_not:
+        op = MSimdUnaryArith::not_;
+        break;
+      case SimdOperation::Fn_sqrt:
+        op = MSimdUnaryArith::sqrt;
+        break;
+      case SimdOperation::Fn_reciprocalApproximation:
+        op = MSimdUnaryArith::reciprocalApproximation;
+        break;
+      case SimdOperation::Fn_reciprocalSqrtApproximation:
+        op = MSimdUnaryArith::reciprocalSqrtApproximation;
+        break;
+      default:
+        MOZ_CRASH("not a simd unary arithmetic operation");
+    }
+
+    MDefinition* input;
+    if (!f.iter().readUnary(type, &input))
+        return false;
+
+    f.iter().setResult(f.unarySimd(input, op, ToMIRType(type)));
+    return true;
+}
+
+template<class OpKind>
+inline bool
+EmitSimdBinary(FunctionCompiler& f, ValType type, OpKind op)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(type, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binarySimd(lhs, rhs, op, ToMIRType(type)));
+    return true;
+}
+
+static bool
+EmitSimdBinaryComp(FunctionCompiler& f, ValType operandType, MSimdBinaryComp::Operation op,
+                   SimdSign sign)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readSimdComparison(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binarySimdComp(lhs, rhs, op, sign));
+    return true;
+}
+
+static bool
+EmitSimdBinarySaturating(FunctionCompiler& f, ValType type, MSimdBinarySaturating::Operation op,
+                         SimdSign sign)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readBinary(type, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binarySimdSaturating(lhs, rhs, op, sign));
+    return true;
+}
+
+static bool
+EmitSimdShift(FunctionCompiler& f, ValType operandType, MSimdShift::Operation op)
+{
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readSimdShiftByScalar(operandType, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.binarySimdShift(lhs, rhs, op));
+    return true;
+}
+
+static ValType
+SimdToLaneType(ValType type)
+{
+    switch (type) {
+      case ValType::I8x16:
+      case ValType::I16x8:
+      case ValType::I32x4:  return ValType::I32;
+      case ValType::F32x4:  return ValType::F32;
+      case ValType::B8x16:
+      case ValType::B16x8:
+      case ValType::B32x4:  return ValType::I32; // Boolean lanes are Int32 in asm.
+      case ValType::I32:
+      case ValType::I64:
+      case ValType::F32:
+      case ValType::F64:
+        break;
+    }
+    MOZ_CRASH("bad simd type");
+}
+
+static bool
+EmitExtractLane(FunctionCompiler& f, ValType operandType, SimdSign sign)
+{
+    uint8_t lane;
+    MDefinition* vector;
+    if (!f.iter().readExtractLane(operandType, &lane, &vector))
+        return false;
+
+    f.iter().setResult(f.extractSimdElement(lane, vector,
+                                            ToMIRType(SimdToLaneType(operandType)), sign));
+    return true;
+}
+
+// Emit an I32 expression and then convert it to a boolean SIMD lane value, i.e. -1 or 0.
+static MDefinition*
+EmitSimdBooleanLaneExpr(FunctionCompiler& f, MDefinition* i32)
+{
+    // Compute !i32 - 1 to force the value range into {0, -1}.
+    MDefinition* noti32 = f.unary<MNot>(i32);
+    return f.binary<MSub>(noti32, f.constant(Int32Value(1), MIRType::Int32), MIRType::Int32);
+}
+
+static bool
+EmitSimdReplaceLane(FunctionCompiler& f, ValType simdType)
+{
+    if (IsSimdBoolType(simdType))
+        f.iter().setResult(EmitSimdBooleanLaneExpr(f, f.iter().getResult()));
+
+    uint8_t lane;
+    MDefinition* vector;
+    MDefinition* scalar;
+    if (!f.iter().readReplaceLane(simdType, &lane, &vector, &scalar))
+        return false;
+
+    f.iter().setResult(f.insertElementSimd(vector, scalar, lane, ToMIRType(simdType)));
+    return true;
+}
+
+inline bool
+EmitSimdBitcast(FunctionCompiler& f, ValType fromType, ValType toType)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(fromType, toType, &input))
+        return false;
+
+    f.iter().setResult(f.bitcastSimd(input, ToMIRType(fromType), ToMIRType(toType)));
+    return true;
+}
+
+inline bool
+EmitSimdConvert(FunctionCompiler& f, ValType fromType, ValType toType, SimdSign sign)
+{
+    MDefinition* input;
+    if (!f.iter().readConversion(fromType, toType, &input))
+        return false;
+
+    f.iter().setResult(f.convertSimd(input, ToMIRType(fromType), ToMIRType(toType), sign));
+    return true;
+}
+
+static bool
+EmitSimdSwizzle(FunctionCompiler& f, ValType simdType)
+{
+    uint8_t lanes[16];
+    MDefinition* vector;
+    if (!f.iter().readSwizzle(simdType, &lanes, &vector))
+        return false;
+
+    f.iter().setResult(f.swizzleSimd(vector, lanes, ToMIRType(simdType)));
+    return true;
+}
+
+static bool
+EmitSimdShuffle(FunctionCompiler& f, ValType simdType)
+{
+    uint8_t lanes[16];
+    MDefinition* lhs;
+    MDefinition* rhs;
+    if (!f.iter().readShuffle(simdType, &lanes, &lhs, &rhs))
+        return false;
+
+    f.iter().setResult(f.shuffleSimd(lhs, rhs, lanes, ToMIRType(simdType)));
+    return true;
+}
+
+static inline Scalar::Type
+SimdExprTypeToViewType(ValType type, unsigned* defaultNumElems)
+{
+    switch (type) {
+        case ValType::I8x16: *defaultNumElems = 16; return Scalar::Int8x16;
+        case ValType::I16x8: *defaultNumElems = 8; return Scalar::Int16x8;
+        case ValType::I32x4: *defaultNumElems = 4; return Scalar::Int32x4;
+        case ValType::F32x4: *defaultNumElems = 4; return Scalar::Float32x4;
+        default:              break;
+    }
+    MOZ_CRASH("type not handled in SimdExprTypeToViewType");
+}
+
+static bool
+EmitSimdLoad(FunctionCompiler& f, ValType resultType, unsigned numElems)
+{
+    unsigned defaultNumElems;
+    Scalar::Type viewType = SimdExprTypeToViewType(resultType, &defaultNumElems);
+
+    if (!numElems)
+        numElems = defaultNumElems;
+
+    LinearMemoryAddress<MDefinition*> addr;
+    if (!f.iter().readLoad(resultType, Scalar::byteSize(viewType), &addr))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()), numElems);
+
+    f.iter().setResult(f.load(addr.base, access, resultType));
+    return true;
+}
+
+static bool
+EmitSimdStore(FunctionCompiler& f, ValType resultType, unsigned numElems)
+{
+    unsigned defaultNumElems;
+    Scalar::Type viewType = SimdExprTypeToViewType(resultType, &defaultNumElems);
+
+    if (!numElems)
+        numElems = defaultNumElems;
+
+    LinearMemoryAddress<MDefinition*> addr;
+    MDefinition* value;
+    if (!f.iter().readTeeStore(resultType, Scalar::byteSize(viewType), &addr, &value))
+        return false;
+
+    MemoryAccessDesc access(viewType, addr.align, addr.offset, Some(f.trapOffset()), numElems);
+
+    f.store(addr.base, access, value);
+    return true;
+}
+
+static bool
+EmitSimdSelect(FunctionCompiler& f, ValType simdType)
+{
+    MDefinition* trueValue;
+    MDefinition* falseValue;
+    MDefinition* condition;
+    if (!f.iter().readSimdSelect(simdType, &trueValue, &falseValue, &condition))
+        return false;
+
+    f.iter().setResult(f.selectSimd(condition, trueValue, falseValue,
+                                    ToMIRType(simdType)));
+    return true;
+}
+
+static bool
+EmitSimdAllTrue(FunctionCompiler& f, ValType operandType)
+{
+    MDefinition* input;
+    if (!f.iter().readSimdBooleanReduction(operandType, &input))
+        return false;
+
+    f.iter().setResult(f.simdAllTrue(input));
+    return true;
+}
+
+static bool
+EmitSimdAnyTrue(FunctionCompiler& f, ValType operandType)
+{
+    MDefinition* input;
+    if (!f.iter().readSimdBooleanReduction(operandType, &input))
+        return false;
+
+    f.iter().setResult(f.simdAnyTrue(input));
+    return true;
+}
+
+static bool
+EmitSimdSplat(FunctionCompiler& f, ValType simdType)
+{
+    if (IsSimdBoolType(simdType))
+        f.iter().setResult(EmitSimdBooleanLaneExpr(f, f.iter().getResult()));
+
+    MDefinition* input;
+    if (!f.iter().readSplat(simdType, &input))
+        return false;
+
+    f.iter().setResult(f.splatSimd(input, ToMIRType(simdType)));
+    return true;
+}
+
+// Build a SIMD vector by inserting lanes one at a time into an initial constant.
+static bool
+EmitSimdChainedCtor(FunctionCompiler& f, ValType valType, MIRType type, const SimdConstant& init)
+{
+    const unsigned length = SimdTypeToLength(type);
+    MDefinition* val = f.constant(init, type);
+    for (unsigned i = 0; i < length; i++) {
+        MDefinition* scalar = 0;
+        if (!f.iter().readSimdCtorArg(ValType::I32, length, i, &scalar))
+            return false;
+        val = f.insertElementSimd(val, scalar, i, type);
+    }
+    if (!f.iter().readSimdCtorArgsEnd(length) || !f.iter().readSimdCtorReturn(valType))
+        return false;
+    f.iter().setResult(val);
+    return true;
+}
+
+// Build a boolean SIMD vector by inserting lanes one at a time into an initial constant.
+static bool
+EmitSimdBooleanChainedCtor(FunctionCompiler& f, ValType valType, MIRType type,
+                           const SimdConstant& init)
+{
+    const unsigned length = SimdTypeToLength(type);
+    MDefinition* val = f.constant(init, type);
+    for (unsigned i = 0; i < length; i++) {
+        MDefinition* scalar = 0;
+        if (!f.iter().readSimdCtorArg(ValType::I32, length, i, &scalar))
+            return false;
+        val = f.insertElementSimd(val, EmitSimdBooleanLaneExpr(f, scalar), i, type);
+    }
+    if (!f.iter().readSimdCtorArgsEnd(length) || !f.iter().readSimdCtorReturn(valType))
+        return false;
+    f.iter().setResult(val);
+    return true;
+}
+
+static bool
+EmitSimdCtor(FunctionCompiler& f, ValType type)
+{
+    if (!f.iter().readSimdCtor())
+        return false;
+
+    switch (type) {
+      case ValType::I8x16:
+        return EmitSimdChainedCtor(f, type, MIRType::Int8x16, SimdConstant::SplatX16(0));
+      case ValType::I16x8:
+        return EmitSimdChainedCtor(f, type, MIRType::Int16x8, SimdConstant::SplatX8(0));
+      case ValType::I32x4: {
+        MDefinition* args[4];
+        for (unsigned i = 0; i < 4; i++) {
+            if (!f.iter().readSimdCtorArg(ValType::I32, 4, i, &args[i]))
+                return false;
+        }
+        if (!f.iter().readSimdCtorArgsEnd(4) || !f.iter().readSimdCtorReturn(type))
+            return false;
+        f.iter().setResult(f.constructSimd<MSimdValueX4>(args[0], args[1], args[2], args[3],
+                                                         MIRType::Int32x4));
+        return true;
+      }
+      case ValType::F32x4: {
+        MDefinition* args[4];
+        for (unsigned i = 0; i < 4; i++) {
+            if (!f.iter().readSimdCtorArg(ValType::F32, 4, i, &args[i]))
+                return false;
+        }
+        if (!f.iter().readSimdCtorArgsEnd(4) || !f.iter().readSimdCtorReturn(type))
+            return false;
+        f.iter().setResult(f.constructSimd<MSimdValueX4>(args[0], args[1], args[2], args[3],
+                           MIRType::Float32x4));
+        return true;
+      }
+      case ValType::B8x16:
+        return EmitSimdBooleanChainedCtor(f, type, MIRType::Bool8x16, SimdConstant::SplatX16(0));
+      case ValType::B16x8:
+        return EmitSimdBooleanChainedCtor(f, type, MIRType::Bool16x8, SimdConstant::SplatX8(0));
+      case ValType::B32x4: {
+        MDefinition* args[4];
+        for (unsigned i = 0; i < 4; i++) {
+            MDefinition* i32;
+            if (!f.iter().readSimdCtorArg(ValType::I32, 4, i, &i32))
+                return false;
+            args[i] = EmitSimdBooleanLaneExpr(f, i32);
+        }
+        if (!f.iter().readSimdCtorArgsEnd(4) || !f.iter().readSimdCtorReturn(type))
+            return false;
+        f.iter().setResult(f.constructSimd<MSimdValueX4>(args[0], args[1], args[2], args[3],
+                           MIRType::Bool32x4));
+        return true;
+      }
+      case ValType::I32:
+      case ValType::I64:
+      case ValType::F32:
+      case ValType::F64:
+        break;
+    }
+    MOZ_CRASH("unexpected SIMD type");
+}
+
+static bool
+EmitSimdOp(FunctionCompiler& f, ValType type, SimdOperation op, SimdSign sign)
+{
+    switch (op) {
+      case SimdOperation::Constructor:
+        return EmitSimdCtor(f, type);
+      case SimdOperation::Fn_extractLane:
+        return EmitExtractLane(f, type, sign);
+      case SimdOperation::Fn_replaceLane:
+        return EmitSimdReplaceLane(f, type);
+      case SimdOperation::Fn_check:
+        MOZ_CRASH("only used in asm.js' type system");
+      case SimdOperation::Fn_splat:
+        return EmitSimdSplat(f, type);
+      case SimdOperation::Fn_select:
+        return EmitSimdSelect(f, type);
+      case SimdOperation::Fn_swizzle:
+        return EmitSimdSwizzle(f, type);
+      case SimdOperation::Fn_shuffle:
+        return EmitSimdShuffle(f, type);
+      case SimdOperation::Fn_load:
+        return EmitSimdLoad(f, type, 0);
+      case SimdOperation::Fn_load1:
+        return EmitSimdLoad(f, type, 1);
+      case SimdOperation::Fn_load2:
+        return EmitSimdLoad(f, type, 2);
+      case SimdOperation::Fn_store:
+        return EmitSimdStore(f, type, 0);
+      case SimdOperation::Fn_store1:
+        return EmitSimdStore(f, type, 1);
+      case SimdOperation::Fn_store2:
+        return EmitSimdStore(f, type, 2);
+      case SimdOperation::Fn_allTrue:
+        return EmitSimdAllTrue(f, type);
+      case SimdOperation::Fn_anyTrue:
+        return EmitSimdAnyTrue(f, type);
+      case SimdOperation::Fn_abs:
+      case SimdOperation::Fn_neg:
+      case SimdOperation::Fn_not:
+      case SimdOperation::Fn_sqrt:
+      case SimdOperation::Fn_reciprocalApproximation:
+      case SimdOperation::Fn_reciprocalSqrtApproximation:
+        return EmitSimdUnary(f, type, op);
+      case SimdOperation::Fn_shiftLeftByScalar:
+        return EmitSimdShift(f, type, MSimdShift::lsh);
+      case SimdOperation::Fn_shiftRightByScalar:
+        return EmitSimdShift(f, type, MSimdShift::rshForSign(sign));
+#define _CASE(OP) \
+      case SimdOperation::Fn_##OP: \
+        return EmitSimdBinaryComp(f, type, MSimdBinaryComp::OP, sign);
+        FOREACH_COMP_SIMD_OP(_CASE)
+#undef _CASE
+      case SimdOperation::Fn_and:
+        return EmitSimdBinary(f, type, MSimdBinaryBitwise::and_);
+      case SimdOperation::Fn_or:
+        return EmitSimdBinary(f, type, MSimdBinaryBitwise::or_);
+      case SimdOperation::Fn_xor:
+        return EmitSimdBinary(f, type, MSimdBinaryBitwise::xor_);
+#define _CASE(OP) \
+      case SimdOperation::Fn_##OP: \
+        return EmitSimdBinary(f, type, MSimdBinaryArith::Op_##OP);
+      FOREACH_NUMERIC_SIMD_BINOP(_CASE)
+      FOREACH_FLOAT_SIMD_BINOP(_CASE)
+#undef _CASE
+      case SimdOperation::Fn_addSaturate:
+        return EmitSimdBinarySaturating(f, type, MSimdBinarySaturating::add, sign);
+      case SimdOperation::Fn_subSaturate:
+        return EmitSimdBinarySaturating(f, type, MSimdBinarySaturating::sub, sign);
+      case SimdOperation::Fn_fromFloat32x4:
+        return EmitSimdConvert(f, ValType::F32x4, type, sign);
+      case SimdOperation::Fn_fromInt32x4:
+        return EmitSimdConvert(f, ValType::I32x4, type, SimdSign::Signed);
+      case SimdOperation::Fn_fromUint32x4:
+        return EmitSimdConvert(f, ValType::I32x4, type, SimdSign::Unsigned);
+      case SimdOperation::Fn_fromInt8x16Bits:
+      case SimdOperation::Fn_fromUint8x16Bits:
+        return EmitSimdBitcast(f, ValType::I8x16, type);
+      case SimdOperation::Fn_fromUint16x8Bits:
+      case SimdOperation::Fn_fromInt16x8Bits:
+        return EmitSimdBitcast(f, ValType::I16x8, type);
+      case SimdOperation::Fn_fromInt32x4Bits:
+      case SimdOperation::Fn_fromUint32x4Bits:
+        return EmitSimdBitcast(f, ValType::I32x4, type);
+      case SimdOperation::Fn_fromFloat32x4Bits:
+        return EmitSimdBitcast(f, ValType::F32x4, type);
+      case SimdOperation::Fn_load3:
+      case SimdOperation::Fn_store3:
+      case SimdOperation::Fn_fromFloat64x2Bits:
+        MOZ_CRASH("NYI");
+    }
+    MOZ_CRASH("unexpected opcode");
+}
+
+static bool
+EmitGrowMemory(FunctionCompiler& f)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    CallCompileState args(f, lineOrBytecode);
+    if (!f.startCall(&args))
+        return false;
+
+    if (!f.passInstance(&args))
+        return false;
+
+    MDefinition* delta;
+    if (!f.iter().readGrowMemory(&delta))
+        return false;
+
+    if (!f.passArg(delta, ValType::I32, &args))
+        return false;
+
+    // As a short-cut, pretend this is an inter-module call so that any pinned
+    // heap pointer will be reloaded after the call. This hack will go away once
+    // we can stop pinning registers.
+    f.finishCall(&args, TlsUsage::CallerSaved);
+
+    MDefinition* ret;
+    if (!f.builtinInstanceMethodCall(SymbolicAddress::GrowMemory, args, ValType::I32, &ret))
+        return false;
+
+    f.iter().setResult(ret);
+    return true;
+}
+
+static bool
+EmitCurrentMemory(FunctionCompiler& f)
+{
+    uint32_t lineOrBytecode = f.readCallSiteLineOrBytecode();
+
+    CallCompileState args(f, lineOrBytecode);
+
+    if (!f.iter().readCurrentMemory())
+        return false;
+
+    if (!f.startCall(&args))
+        return false;
+
+    if (!f.passInstance(&args))
+        return false;
+
+    f.finishCall(&args, TlsUsage::Need);
+
+    MDefinition* ret;
+    if (!f.builtinInstanceMethodCall(SymbolicAddress::CurrentMemory, args, ValType::I32, &ret))
+        return false;
+
+    f.iter().setResult(ret);
+    return true;
+}
+
+static bool
+EmitExpr(FunctionCompiler& f)
+{
+    if (!f.mirGen().ensureBallast())
+        return false;
+
+    uint16_t u16;
+    MOZ_ALWAYS_TRUE(f.iter().readOp(&u16));
+    Op op = Op(u16);
+
+    switch (op) {
+      // Control opcodes
+      case Op::Nop:
+        return f.iter().readNop();
+      case Op::Drop:
+        return f.iter().readDrop();
+      case Op::Block:
+        return EmitBlock(f);
+      case Op::Loop:
+        return EmitLoop(f);
+      case Op::If:
+        return EmitIf(f);
+      case Op::Else:
+        return EmitElse(f);
+      case Op::End:
+        return EmitEnd(f);
+      case Op::Br:
+        return EmitBr(f);
+      case Op::BrIf:
+        return EmitBrIf(f);
+      case Op::BrTable:
+        return EmitBrTable(f);
+      case Op::Return:
+        return EmitReturn(f);
+      case Op::Unreachable:
+        if (!f.iter().readUnreachable())
+            return false;
+        f.unreachableTrap();
+        return true;
+
+      // Calls
+      case Op::Call:
+        return EmitCall(f);
+      case Op::CallIndirect:
+        return EmitCallIndirect(f, /* oldStyle = */ false);
+      case Op::OldCallIndirect:
+        return EmitCallIndirect(f, /* oldStyle = */ true);
+
+      // Locals and globals
+      case Op::GetLocal:
+        return EmitGetLocal(f);
+      case Op::SetLocal:
+        return EmitSetLocal(f);
+      case Op::TeeLocal:
+        return EmitTeeLocal(f);
+      case Op::GetGlobal:
+        return EmitGetGlobal(f);
+      case Op::SetGlobal:
+        return EmitSetGlobal(f);
+      case Op::TeeGlobal:
+        return EmitTeeGlobal(f);
+
+      // Select
+      case Op::Select:
+        return EmitSelect(f);
+
+      // I32
+      case Op::I32Const: {
+        int32_t i32;
+        if (!f.iter().readI32Const(&i32))
+            return false;
+
+        f.iter().setResult(f.constant(Int32Value(i32), MIRType::Int32));
+        return true;
+      }
+      case Op::I32Add:
+        return EmitAdd(f, ValType::I32, MIRType::Int32);
+      case Op::I32Sub:
+        return EmitSub(f, ValType::I32, MIRType::Int32);
+      case Op::I32Mul:
+        return EmitMul(f, ValType::I32, MIRType::Int32);
+      case Op::I32DivS:
+      case Op::I32DivU:
+        return EmitDiv(f, ValType::I32, MIRType::Int32, op == Op::I32DivU);
+      case Op::I32RemS:
+      case Op::I32RemU:
+        return EmitRem(f, ValType::I32, MIRType::Int32, op == Op::I32RemU);
+      case Op::I32Min:
+      case Op::I32Max:
+        return EmitMinMax(f, ValType::I32, MIRType::Int32, op == Op::I32Max);
+      case Op::I32Eqz:
+        return EmitConversion<MNot>(f, ValType::I32, ValType::I32);
+      case Op::I32TruncSF32:
+      case Op::I32TruncUF32:
+        return EmitTruncate(f, ValType::F32, ValType::I32, op == Op::I32TruncUF32);
+      case Op::I32TruncSF64:
+      case Op::I32TruncUF64:
+        return EmitTruncate(f, ValType::F64, ValType::I32, op == Op::I32TruncUF64);
+      case Op::I32WrapI64:
+        return EmitConversion<MWrapInt64ToInt32>(f, ValType::I64, ValType::I32);
+      case Op::I32ReinterpretF32:
+        return EmitReinterpret(f, ValType::I32, ValType::F32, MIRType::Int32);
+      case Op::I32Clz:
+        return EmitUnaryWithType<MClz>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Ctz:
+        return EmitUnaryWithType<MCtz>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Popcnt:
+        return EmitUnaryWithType<MPopcnt>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Abs:
+        return EmitUnaryWithType<MAbs>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Neg:
+        return EmitUnaryWithType<MAsmJSNeg>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Or:
+        return EmitBitwise<MBitOr>(f, ValType::I32, MIRType::Int32);
+      case Op::I32And:
+        return EmitBitwise<MBitAnd>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Xor:
+        return EmitBitwise<MBitXor>(f, ValType::I32, MIRType::Int32);
+      case Op::I32Shl:
+        return EmitBitwise<MLsh>(f, ValType::I32, MIRType::Int32);
+      case Op::I32ShrS:
+        return EmitBitwise<MRsh>(f, ValType::I32, MIRType::Int32);
+      case Op::I32ShrU:
+        return EmitBitwise<MUrsh>(f, ValType::I32, MIRType::Int32);
+      case Op::I32BitNot:
+        return EmitBitNot(f, ValType::I32);
+      case Op::I32Load8S:
+        return EmitLoad(f, ValType::I32, Scalar::Int8);
+      case Op::I32Load8U:
+        return EmitLoad(f, ValType::I32, Scalar::Uint8);
+      case Op::I32Load16S:
+        return EmitLoad(f, ValType::I32, Scalar::Int16);
+      case Op::I32Load16U:
+        return EmitLoad(f, ValType::I32, Scalar::Uint16);
+      case Op::I32Load:
+        return EmitLoad(f, ValType::I32, Scalar::Int32);
+      case Op::I32Store8:
+        return EmitStore(f, ValType::I32, Scalar::Int8);
+      case Op::I32TeeStore8:
+        return EmitTeeStore(f, ValType::I32, Scalar::Int8);
+      case Op::I32Store16:
+        return EmitStore(f, ValType::I32, Scalar::Int16);
+      case Op::I32TeeStore16:
+        return EmitTeeStore(f, ValType::I32, Scalar::Int16);
+      case Op::I32Store:
+        return EmitStore(f, ValType::I32, Scalar::Int32);
+      case Op::I32TeeStore:
+        return EmitTeeStore(f, ValType::I32, Scalar::Int32);
+      case Op::I32Rotr:
+      case Op::I32Rotl:
+        return EmitRotate(f, ValType::I32, op == Op::I32Rotl);
+
+      // I64
+      case Op::I64Const: {
+        int64_t i64;
+        if (!f.iter().readI64Const(&i64))
+            return false;
+
+        f.iter().setResult(f.constant(i64));
+        return true;
+      }
+      case Op::I64Add:
+        return EmitAdd(f, ValType::I64, MIRType::Int64);
+      case Op::I64Sub:
+        return EmitSub(f, ValType::I64, MIRType::Int64);
+      case Op::I64Mul:
+        return EmitMul(f, ValType::I64, MIRType::Int64);
+      case Op::I64DivS:
+      case Op::I64DivU:
+        return EmitDiv(f, ValType::I64, MIRType::Int64, op == Op::I64DivU);
+      case Op::I64RemS:
+      case Op::I64RemU:
+        return EmitRem(f, ValType::I64, MIRType::Int64, op == Op::I64RemU);
+      case Op::I64TruncSF32:
+      case Op::I64TruncUF32:
+        return EmitTruncate(f, ValType::F32, ValType::I64, op == Op::I64TruncUF32);
+      case Op::I64TruncSF64:
+      case Op::I64TruncUF64:
+        return EmitTruncate(f, ValType::F64, ValType::I64, op == Op::I64TruncUF64);
+      case Op::I64ExtendSI32:
+      case Op::I64ExtendUI32:
+        return EmitExtendI32(f, op == Op::I64ExtendUI32);
+      case Op::I64ReinterpretF64:
+        return EmitReinterpret(f, ValType::I64, ValType::F64, MIRType::Int64);
+      case Op::I64Or:
+        return EmitBitwise<MBitOr>(f, ValType::I64, MIRType::Int64);
+      case Op::I64And:
+        return EmitBitwise<MBitAnd>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Xor:
+        return EmitBitwise<MBitXor>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Shl:
+        return EmitBitwise<MLsh>(f, ValType::I64, MIRType::Int64);
+      case Op::I64ShrS:
+        return EmitBitwise<MRsh>(f, ValType::I64, MIRType::Int64);
+      case Op::I64ShrU:
+        return EmitBitwise<MUrsh>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Rotr:
+      case Op::I64Rotl:
+        return EmitRotate(f, ValType::I64, op == Op::I64Rotl);
+      case Op::I64Eqz:
+        return EmitConversion<MNot>(f, ValType::I64, ValType::I32);
+      case Op::I64Clz:
+        return EmitUnaryWithType<MClz>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Ctz:
+        return EmitUnaryWithType<MCtz>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Popcnt:
+        return EmitUnaryWithType<MPopcnt>(f, ValType::I64, MIRType::Int64);
+      case Op::I64Load8S:
+        return EmitLoad(f, ValType::I64, Scalar::Int8);
+      case Op::I64Load8U:
+        return EmitLoad(f, ValType::I64, Scalar::Uint8);
+      case Op::I64Load16S:
+        return EmitLoad(f, ValType::I64, Scalar::Int16);
+      case Op::I64Load16U:
+        return EmitLoad(f, ValType::I64, Scalar::Uint16);
+      case Op::I64Load32S:
+        return EmitLoad(f, ValType::I64, Scalar::Int32);
+      case Op::I64Load32U:
+        return EmitLoad(f, ValType::I64, Scalar::Uint32);
+      case Op::I64Load:
+        return EmitLoad(f, ValType::I64, Scalar::Int64);
+      case Op::I64Store8:
+        return EmitStore(f, ValType::I64, Scalar::Int8);
+      case Op::I64TeeStore8:
+        return EmitTeeStore(f, ValType::I64, Scalar::Int8);
+      case Op::I64Store16:
+        return EmitStore(f, ValType::I64, Scalar::Int16);
+      case Op::I64TeeStore16:
+        return EmitTeeStore(f, ValType::I64, Scalar::Int16);
+      case Op::I64Store32:
+        return EmitStore(f, ValType::I64, Scalar::Int32);
+      case Op::I64TeeStore32:
+        return EmitTeeStore(f, ValType::I64, Scalar::Int32);
+      case Op::I64Store:
+        return EmitStore(f, ValType::I64, Scalar::Int64);
+      case Op::I64TeeStore:
+        return EmitTeeStore(f, ValType::I64, Scalar::Int64);
+
+      // F32
+      case Op::F32Const: {
+        RawF32 f32;
+        if (!f.iter().readF32Const(&f32))
+            return false;
+
+        f.iter().setResult(f.constant(f32));
+        return true;
+      }
+      case Op::F32Add:
+        return EmitAdd(f, ValType::F32, MIRType::Float32);
+      case Op::F32Sub:
+        return EmitSub(f, ValType::F32, MIRType::Float32);
+      case Op::F32Mul:
+        return EmitMul(f, ValType::F32, MIRType::Float32);
+      case Op::F32Div:
+        return EmitDiv(f, ValType::F32, MIRType::Float32, /* isUnsigned = */ false);
+      case Op::F32Min:
+      case Op::F32Max:
+        return EmitMinMax(f, ValType::F32, MIRType::Float32, op == Op::F32Max);
+      case Op::F32CopySign:
+        return EmitCopySign(f, ValType::F32);
+      case Op::F32Neg:
+        return EmitUnaryWithType<MAsmJSNeg>(f, ValType::F32, MIRType::Float32);
+      case Op::F32Abs:
+        return EmitUnaryWithType<MAbs>(f, ValType::F32, MIRType::Float32);
+      case Op::F32Sqrt:
+        return EmitUnaryWithType<MSqrt>(f, ValType::F32, MIRType::Float32);
+      case Op::F32Ceil:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::CeilF, ValType::F32);
+      case Op::F32Floor:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::FloorF, ValType::F32);
+      case Op::F32Trunc:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::TruncF, ValType::F32);
+      case Op::F32Nearest:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::NearbyIntF, ValType::F32);
+      case Op::F32DemoteF64:
+        return EmitConversion<MToFloat32>(f, ValType::F64, ValType::F32);
+      case Op::F32ConvertSI32:
+        return EmitConversion<MToFloat32>(f, ValType::I32, ValType::F32);
+      case Op::F32ConvertUI32:
+        return EmitConversion<MWasmUnsignedToFloat32>(f, ValType::I32, ValType::F32);
+      case Op::F32ConvertSI64:
+      case Op::F32ConvertUI64:
+        return EmitConvertI64ToFloatingPoint(f, ValType::F32, MIRType::Float32,
+                                             op == Op::F32ConvertUI64);
+      case Op::F32ReinterpretI32:
+        return EmitReinterpret(f, ValType::F32, ValType::I32, MIRType::Float32);
+
+      case Op::F32Load:
+        return EmitLoad(f, ValType::F32, Scalar::Float32);
+      case Op::F32Store:
+        return EmitStore(f, ValType::F32, Scalar::Float32);
+      case Op::F32TeeStore:
+        return EmitTeeStore(f, ValType::F32, Scalar::Float32);
+      case Op::F32TeeStoreF64:
+        return EmitTeeStoreWithCoercion(f, ValType::F32, Scalar::Float64);
+
+      // F64
+      case Op::F64Const: {
+        RawF64 f64;
+        if (!f.iter().readF64Const(&f64))
+            return false;
+
+        f.iter().setResult(f.constant(f64));
+        return true;
+      }
+      case Op::F64Add:
+        return EmitAdd(f, ValType::F64, MIRType::Double);
+      case Op::F64Sub:
+        return EmitSub(f, ValType::F64, MIRType::Double);
+      case Op::F64Mul:
+        return EmitMul(f, ValType::F64, MIRType::Double);
+      case Op::F64Div:
+        return EmitDiv(f, ValType::F64, MIRType::Double, /* isUnsigned = */ false);
+      case Op::F64Mod:
+        return EmitRem(f, ValType::F64, MIRType::Double, /* isUnsigned = */ false);
+      case Op::F64Min:
+      case Op::F64Max:
+        return EmitMinMax(f, ValType::F64, MIRType::Double, op == Op::F64Max);
+      case Op::F64CopySign:
+        return EmitCopySign(f, ValType::F64);
+      case Op::F64Neg:
+        return EmitUnaryWithType<MAsmJSNeg>(f, ValType::F64, MIRType::Double);
+      case Op::F64Abs:
+        return EmitUnaryWithType<MAbs>(f, ValType::F64, MIRType::Double);
+      case Op::F64Sqrt:
+        return EmitUnaryWithType<MSqrt>(f, ValType::F64, MIRType::Double);
+      case Op::F64Ceil:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::CeilD, ValType::F64);
+      case Op::F64Floor:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::FloorD, ValType::F64);
+      case Op::F64Trunc:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::TruncD, ValType::F64);
+      case Op::F64Nearest:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::NearbyIntD, ValType::F64);
+      case Op::F64Sin:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::SinD, ValType::F64);
+      case Op::F64Cos:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::CosD, ValType::F64);
+      case Op::F64Tan:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::TanD, ValType::F64);
+      case Op::F64Asin:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::ASinD, ValType::F64);
+      case Op::F64Acos:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::ACosD, ValType::F64);
+      case Op::F64Atan:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::ATanD, ValType::F64);
+      case Op::F64Exp:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::ExpD, ValType::F64);
+      case Op::F64Log:
+        return EmitUnaryMathBuiltinCall(f, SymbolicAddress::LogD, ValType::F64);
+      case Op::F64Pow:
+        return EmitBinaryMathBuiltinCall(f, SymbolicAddress::PowD, ValType::F64);
+      case Op::F64Atan2:
+        return EmitBinaryMathBuiltinCall(f, SymbolicAddress::ATan2D, ValType::F64);
+      case Op::F64PromoteF32:
+        return EmitConversion<MToDouble>(f, ValType::F32, ValType::F64);
+      case Op::F64ConvertSI32:
+        return EmitConversion<MToDouble>(f, ValType::I32, ValType::F64);
+      case Op::F64ConvertUI32:
+        return EmitConversion<MWasmUnsignedToDouble>(f, ValType::I32, ValType::F64);
+      case Op::F64ConvertSI64:
+      case Op::F64ConvertUI64:
+        return EmitConvertI64ToFloatingPoint(f, ValType::F64, MIRType::Double,
+                                             op == Op::F64ConvertUI64);
+      case Op::F64Load:
+        return EmitLoad(f, ValType::F64, Scalar::Float64);
+      case Op::F64Store:
+        return EmitStore(f, ValType::F64, Scalar::Float64);
+      case Op::F64TeeStore:
+        return EmitTeeStore(f, ValType::F64, Scalar::Float64);
+      case Op::F64TeeStoreF32:
+        return EmitTeeStoreWithCoercion(f, ValType::F64, Scalar::Float32);
+      case Op::F64ReinterpretI64:
+        return EmitReinterpret(f, ValType::F64, ValType::I64, MIRType::Double);
+
+      // Comparisons
+      case Op::I32Eq:
+        return EmitComparison(f, ValType::I32, JSOP_EQ, MCompare::Compare_Int32);
+      case Op::I32Ne:
+        return EmitComparison(f, ValType::I32, JSOP_NE, MCompare::Compare_Int32);
+      case Op::I32LtS:
+        return EmitComparison(f, ValType::I32, JSOP_LT, MCompare::Compare_Int32);
+      case Op::I32LeS:
+        return EmitComparison(f, ValType::I32, JSOP_LE, MCompare::Compare_Int32);
+      case Op::I32GtS:
+        return EmitComparison(f, ValType::I32, JSOP_GT, MCompare::Compare_Int32);
+      case Op::I32GeS:
+        return EmitComparison(f, ValType::I32, JSOP_GE, MCompare::Compare_Int32);
+      case Op::I32LtU:
+        return EmitComparison(f, ValType::I32, JSOP_LT, MCompare::Compare_UInt32);
+      case Op::I32LeU:
+        return EmitComparison(f, ValType::I32, JSOP_LE, MCompare::Compare_UInt32);
+      case Op::I32GtU:
+        return EmitComparison(f, ValType::I32, JSOP_GT, MCompare::Compare_UInt32);
+      case Op::I32GeU:
+        return EmitComparison(f, ValType::I32, JSOP_GE, MCompare::Compare_UInt32);
+      case Op::I64Eq:
+        return EmitComparison(f, ValType::I64, JSOP_EQ, MCompare::Compare_Int64);
+      case Op::I64Ne:
+        return EmitComparison(f, ValType::I64, JSOP_NE, MCompare::Compare_Int64);
+      case Op::I64LtS:
+        return EmitComparison(f, ValType::I64, JSOP_LT, MCompare::Compare_Int64);
+      case Op::I64LeS:
+        return EmitComparison(f, ValType::I64, JSOP_LE, MCompare::Compare_Int64);
+      case Op::I64GtS:
+        return EmitComparison(f, ValType::I64, JSOP_GT, MCompare::Compare_Int64);
+      case Op::I64GeS:
+        return EmitComparison(f, ValType::I64, JSOP_GE, MCompare::Compare_Int64);
+      case Op::I64LtU:
+        return EmitComparison(f, ValType::I64, JSOP_LT, MCompare::Compare_UInt64);
+      case Op::I64LeU:
+        return EmitComparison(f, ValType::I64, JSOP_LE, MCompare::Compare_UInt64);
+      case Op::I64GtU:
+        return EmitComparison(f, ValType::I64, JSOP_GT, MCompare::Compare_UInt64);
+      case Op::I64GeU:
+        return EmitComparison(f, ValType::I64, JSOP_GE, MCompare::Compare_UInt64);
+      case Op::F32Eq:
+        return EmitComparison(f, ValType::F32, JSOP_EQ, MCompare::Compare_Float32);
+      case Op::F32Ne:
+        return EmitComparison(f, ValType::F32, JSOP_NE, MCompare::Compare_Float32);
+      case Op::F32Lt:
+        return EmitComparison(f, ValType::F32, JSOP_LT, MCompare::Compare_Float32);
+      case Op::F32Le:
+        return EmitComparison(f, ValType::F32, JSOP_LE, MCompare::Compare_Float32);
+      case Op::F32Gt:
+        return EmitComparison(f, ValType::F32, JSOP_GT, MCompare::Compare_Float32);
+      case Op::F32Ge:
+        return EmitComparison(f, ValType::F32, JSOP_GE, MCompare::Compare_Float32);
+      case Op::F64Eq:
+        return EmitComparison(f, ValType::F64, JSOP_EQ, MCompare::Compare_Double);
+      case Op::F64Ne:
+        return EmitComparison(f, ValType::F64, JSOP_NE, MCompare::Compare_Double);
+      case Op::F64Lt:
+        return EmitComparison(f, ValType::F64, JSOP_LT, MCompare::Compare_Double);
+      case Op::F64Le:
+        return EmitComparison(f, ValType::F64, JSOP_LE, MCompare::Compare_Double);
+      case Op::F64Gt:
+        return EmitComparison(f, ValType::F64, JSOP_GT, MCompare::Compare_Double);
+      case Op::F64Ge:
+        return EmitComparison(f, ValType::F64, JSOP_GE, MCompare::Compare_Double);
+
+      // SIMD
+#define CASE(TYPE, OP, SIGN)                                                    \
+      case Op::TYPE##OP:                                                      \
+        return EmitSimdOp(f, ValType::TYPE, SimdOperation::Fn_##OP, SIGN);
+#define I8x16CASE(OP) CASE(I8x16, OP, SimdSign::Signed)
+#define I16x8CASE(OP) CASE(I16x8, OP, SimdSign::Signed)
+#define I32x4CASE(OP) CASE(I32x4, OP, SimdSign::Signed)
+#define F32x4CASE(OP) CASE(F32x4, OP, SimdSign::NotApplicable)
+#define B8x16CASE(OP) CASE(B8x16, OP, SimdSign::NotApplicable)
+#define B16x8CASE(OP) CASE(B16x8, OP, SimdSign::NotApplicable)
+#define B32x4CASE(OP) CASE(B32x4, OP, SimdSign::NotApplicable)
+#define ENUMERATE(TYPE, FORALL, DO)                                             \
+      case Op::TYPE##Constructor:                                             \
+        return EmitSimdOp(f, ValType::TYPE, SimdOperation::Constructor, SimdSign::NotApplicable); \
+      FORALL(DO)
+
+      ENUMERATE(I8x16, FORALL_INT8X16_ASMJS_OP, I8x16CASE)
+      ENUMERATE(I16x8, FORALL_INT16X8_ASMJS_OP, I16x8CASE)
+      ENUMERATE(I32x4, FORALL_INT32X4_ASMJS_OP, I32x4CASE)
+      ENUMERATE(F32x4, FORALL_FLOAT32X4_ASMJS_OP, F32x4CASE)
+      ENUMERATE(B8x16, FORALL_BOOL_SIMD_OP, B8x16CASE)
+      ENUMERATE(B16x8, FORALL_BOOL_SIMD_OP, B16x8CASE)
+      ENUMERATE(B32x4, FORALL_BOOL_SIMD_OP, B32x4CASE)
+
+#undef CASE
+#undef I8x16CASE
+#undef I16x8CASE
+#undef I32x4CASE
+#undef F32x4CASE
+#undef B8x16CASE
+#undef B16x8CASE
+#undef B32x4CASE
+#undef ENUMERATE
+
+      case Op::I8x16Const: {
+        I8x16 i8x16;
+        if (!f.iter().readI8x16Const(&i8x16))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX16(i8x16), MIRType::Int8x16));
+        return true;
+      }
+      case Op::I16x8Const: {
+        I16x8 i16x8;
+        if (!f.iter().readI16x8Const(&i16x8))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX8(i16x8), MIRType::Int16x8));
+        return true;
+      }
+      case Op::I32x4Const: {
+        I32x4 i32x4;
+        if (!f.iter().readI32x4Const(&i32x4))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX4(i32x4), MIRType::Int32x4));
+        return true;
+      }
+      case Op::F32x4Const: {
+        F32x4 f32x4;
+        if (!f.iter().readF32x4Const(&f32x4))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX4(f32x4), MIRType::Float32x4));
+        return true;
+      }
+      case Op::B8x16Const: {
+        I8x16 i8x16;
+        if (!f.iter().readB8x16Const(&i8x16))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX16(i8x16), MIRType::Bool8x16));
+        return true;
+      }
+      case Op::B16x8Const: {
+        I16x8 i16x8;
+        if (!f.iter().readB16x8Const(&i16x8))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX8(i16x8), MIRType::Bool16x8));
+        return true;
+      }
+      case Op::B32x4Const: {
+        I32x4 i32x4;
+        if (!f.iter().readB32x4Const(&i32x4))
+            return false;
+
+        f.iter().setResult(f.constant(SimdConstant::CreateX4(i32x4), MIRType::Bool32x4));
+        return true;
+      }
+
+      // SIMD unsigned integer operations.
+      case Op::I8x16addSaturateU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_addSaturate, SimdSign::Unsigned);
+      case Op::I8x16subSaturateU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_subSaturate, SimdSign::Unsigned);
+      case Op::I8x16shiftRightByScalarU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_shiftRightByScalar, SimdSign::Unsigned);
+      case Op::I8x16lessThanU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_lessThan, SimdSign::Unsigned);
+      case Op::I8x16lessThanOrEqualU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_lessThanOrEqual, SimdSign::Unsigned);
+      case Op::I8x16greaterThanU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_greaterThan, SimdSign::Unsigned);
+      case Op::I8x16greaterThanOrEqualU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_greaterThanOrEqual, SimdSign::Unsigned);
+      case Op::I8x16extractLaneU:
+        return EmitSimdOp(f, ValType::I8x16, SimdOperation::Fn_extractLane, SimdSign::Unsigned);
+
+      case Op::I16x8addSaturateU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_addSaturate, SimdSign::Unsigned);
+      case Op::I16x8subSaturateU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_subSaturate, SimdSign::Unsigned);
+      case Op::I16x8shiftRightByScalarU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_shiftRightByScalar, SimdSign::Unsigned);
+      case Op::I16x8lessThanU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_lessThan, SimdSign::Unsigned);
+      case Op::I16x8lessThanOrEqualU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_lessThanOrEqual, SimdSign::Unsigned);
+      case Op::I16x8greaterThanU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_greaterThan, SimdSign::Unsigned);
+      case Op::I16x8greaterThanOrEqualU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_greaterThanOrEqual, SimdSign::Unsigned);
+      case Op::I16x8extractLaneU:
+        return EmitSimdOp(f, ValType::I16x8, SimdOperation::Fn_extractLane, SimdSign::Unsigned);
+
+      case Op::I32x4shiftRightByScalarU:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_shiftRightByScalar, SimdSign::Unsigned);
+      case Op::I32x4lessThanU:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_lessThan, SimdSign::Unsigned);
+      case Op::I32x4lessThanOrEqualU:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_lessThanOrEqual, SimdSign::Unsigned);
+      case Op::I32x4greaterThanU:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_greaterThan, SimdSign::Unsigned);
+      case Op::I32x4greaterThanOrEqualU:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_greaterThanOrEqual, SimdSign::Unsigned);
+      case Op::I32x4fromFloat32x4U:
+        return EmitSimdOp(f, ValType::I32x4, SimdOperation::Fn_fromFloat32x4, SimdSign::Unsigned);
+
+      // Atomics
+      case Op::I32AtomicsLoad:
+        return EmitAtomicsLoad(f);
+      case Op::I32AtomicsStore:
+        return EmitAtomicsStore(f);
+      case Op::I32AtomicsBinOp:
+        return EmitAtomicsBinOp(f);
+      case Op::I32AtomicsCompareExchange:
+        return EmitAtomicsCompareExchange(f);
+      case Op::I32AtomicsExchange:
+        return EmitAtomicsExchange(f);
+      // Memory Operators
+      case Op::GrowMemory:
+        return EmitGrowMemory(f);
+      case Op::CurrentMemory:
+        return EmitCurrentMemory(f);
+      case Op::Limit:;
+    }
+
+    MOZ_CRASH("unexpected wasm opcode");
+}
+
+bool
+wasm::IonCompileFunction(IonCompileTask* task)
+{
+    MOZ_ASSERT(task->mode() == IonCompileTask::CompileMode::Ion);
+
+    const FuncBytes& func = task->func();
+    FuncCompileResults& results = task->results();
+
+    Decoder d(func.bytes());
+
+    // Build the local types vector.
+
+    ValTypeVector locals;
+    if (!locals.appendAll(func.sig().args()))
+        return false;
+    if (!DecodeLocalEntries(d, task->mg().kind, &locals))
+        return false;
+
+    // Set up for Ion compilation.
+
+    JitContext jitContext(&results.alloc());
+    const JitCompileOptions options;
+    MIRGraph graph(&results.alloc());
+    CompileInfo compileInfo(locals.length());
+    MIRGenerator mir(nullptr, options, &results.alloc(), &graph, &compileInfo,
+                     IonOptimizations.get(OptimizationLevel::Wasm));
+    mir.initMinWasmHeapLength(task->mg().minMemoryLength);
+
+    // Capture the prologue's trap site before decoding the function.
+
+    TrapOffset prologueTrapOffset;
+
+    // Build MIR graph
+    {
+        FunctionCompiler f(task->mg(), d, func, locals, mir, results);
+        if (!f.init())
+            return false;
+
+        prologueTrapOffset = f.iter().trapOffset();
+
+        if (!f.startBlock())
+            return false;
+
+        if (!f.iter().readFunctionStart(f.sig().ret()))
+            return false;
+
+        while (!f.done()) {
+            if (!EmitExpr(f))
+                return false;
+        }
+
+        if (f.inDeadCode() || IsVoid(f.sig().ret()))
+            f.returnVoid();
+        else
+            f.returnExpr(f.iter().getResult());
+
+        if (!f.iter().readFunctionEnd())
+            return false;
+
+        f.finish();
+    }
+
+    // Compile MIR graph
+    {
+        jit::SpewBeginFunction(&mir, nullptr);
+        jit::AutoSpewEndFunction spewEndFunction(&mir);
+
+        if (!OptimizeMIR(&mir))
+            return false;
+
+        LIRGraph* lir = GenerateLIR(&mir);
+        if (!lir)
+            return false;
+
+        SigIdDesc sigId = task->mg().funcSigs[func.index()]->id;
+
+        CodeGenerator codegen(&mir, lir, &results.masm());
+        if (!codegen.generateWasm(sigId, prologueTrapOffset, &results.offsets()))
+            return false;
+    }
+
+    return true;
+}
+
+bool
+wasm::CompileFunction(IonCompileTask* task)
+{
+    TraceLoggerThread* logger = TraceLoggerForCurrentThread();
+    AutoTraceLog logCompile(logger, TraceLogger_WasmCompilation);
+
+    switch (task->mode()) {
+      case wasm::IonCompileTask::CompileMode::Ion:
+        return wasm::IonCompileFunction(task);
+      case wasm::IonCompileTask::CompileMode::Baseline:
+        return wasm::BaselineCompileFunction(task);
+      case wasm::IonCompileTask::CompileMode::None:
+        break;
+    }
+
+    MOZ_CRASH("Uninitialized task");
+}