Add m-esr52 at 52.6.0

1 files changed, 1442 insertions, 0 deletions

diff --git a/js/src/jit/arm/Trampoline-arm.cpp b/js/src/jit/arm/Trampoline-arm.cpp
new file mode 100644
index 000000000..44144763c
--- /dev/null
+++ b/js/src/jit/arm/Trampoline-arm.cpp
@@ -0,0 +1,1442 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 4 -*-
+ * vim: set ts=8 sts=4 et sw=4 tw=99:
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+#include "jscompartment.h"
+
+#include "jit/arm/SharedICHelpers-arm.h"
+#include "jit/Bailouts.h"
+#include "jit/JitCompartment.h"
+#include "jit/JitFrames.h"
+#include "jit/JitSpewer.h"
+#include "jit/Linker.h"
+#ifdef JS_ION_PERF
+# include "jit/PerfSpewer.h"
+#endif
+#include "jit/VMFunctions.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+static const FloatRegisterSet NonVolatileFloatRegs =
+    FloatRegisterSet((1ULL << FloatRegisters::d8) |
+                     (1ULL << FloatRegisters::d9) |
+                     (1ULL << FloatRegisters::d10) |
+                     (1ULL << FloatRegisters::d11) |
+                     (1ULL << FloatRegisters::d12) |
+                     (1ULL << FloatRegisters::d13) |
+                     (1ULL << FloatRegisters::d14) |
+                     (1ULL << FloatRegisters::d15));
+
+static void
+GenerateReturn(MacroAssembler& masm, int returnCode, SPSProfiler* prof)
+{
+    // Restore non-volatile floating point registers.
+    masm.transferMultipleByRuns(NonVolatileFloatRegs, IsLoad, StackPointer, IA);
+
+    // Get rid of padding word.
+    masm.addPtr(Imm32(sizeof(void*)), sp);
+
+    // Set up return value
+    masm.ma_mov(Imm32(returnCode), r0);
+
+    // Pop and return
+    masm.startDataTransferM(IsLoad, sp, IA, WriteBack);
+    masm.transferReg(r4);
+    masm.transferReg(r5);
+    masm.transferReg(r6);
+    masm.transferReg(r7);
+    masm.transferReg(r8);
+    masm.transferReg(r9);
+    masm.transferReg(r10);
+    masm.transferReg(r11);
+    // r12 isn't saved, so it shouldn't be restored.
+    masm.transferReg(pc);
+    masm.finishDataTransfer();
+    masm.flushBuffer();
+}
+
+struct EnterJITStack
+{
+    double d8;
+    double d9;
+    double d10;
+    double d11;
+    double d12;
+    double d13;
+    double d14;
+    double d15;
+
+    // Padding.
+    void* padding;
+
+    // Non-volatile registers.
+    void* r4;
+    void* r5;
+    void* r6;
+    void* r7;
+    void* r8;
+    void* r9;
+    void* r10;
+    void* r11;
+    // The abi does not expect r12 (ip) to be preserved
+    void* lr;
+
+    // Arguments.
+    // code == r0
+    // argc == r1
+    // argv == r2
+    // frame == r3
+    CalleeToken token;
+    JSObject* scopeChain;
+    size_t numStackValues;
+    Value* vp;
+};
+
+/*
+ * This method generates a trampoline for a c++ function with the following
+ * signature:
+ *   void enter(void* code, int argc, Value* argv, InterpreterFrame* fp, CalleeToken
+ *              calleeToken, JSObject* scopeChain, Value* vp)
+ *   ...using standard EABI calling convention
+ */
+JitCode*
+JitRuntime::generateEnterJIT(JSContext* cx, EnterJitType type)
+{
+    const Address slot_token(sp, offsetof(EnterJITStack, token));
+    const Address slot_vp(sp, offsetof(EnterJITStack, vp));
+
+    MOZ_ASSERT(OsrFrameReg == r3);
+
+    MacroAssembler masm(cx);
+    Assembler* aasm = &masm;
+
+    // Save non-volatile registers. These must be saved by the trampoline,
+    // rather than the JIT'd code, because they are scanned by the conservative
+    // scanner.
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    masm.transferReg(r4); // [sp,0]
+    masm.transferReg(r5); // [sp,4]
+    masm.transferReg(r6); // [sp,8]
+    masm.transferReg(r7); // [sp,12]
+    masm.transferReg(r8); // [sp,16]
+    masm.transferReg(r9); // [sp,20]
+    masm.transferReg(r10); // [sp,24]
+    masm.transferReg(r11); // [sp,28]
+    // The abi does not expect r12 (ip) to be preserved
+    masm.transferReg(lr);  // [sp,32]
+    // The 5th argument is located at [sp, 36]
+    masm.finishDataTransfer();
+
+    // Add padding word.
+    masm.subPtr(Imm32(sizeof(void*)), sp);
+
+    // Push the float registers.
+    masm.transferMultipleByRuns(NonVolatileFloatRegs, IsStore, sp, DB);
+
+    // Save stack pointer into r8
+    masm.movePtr(sp, r8);
+
+    // Load calleeToken into r9.
+    masm.loadPtr(slot_token, r9);
+
+    // Save stack pointer.
+    if (type == EnterJitBaseline)
+        masm.movePtr(sp, r11);
+
+    // Load the number of actual arguments into r10.
+    masm.loadPtr(slot_vp, r10);
+    masm.unboxInt32(Address(r10, 0), r10);
+
+    {
+        Label noNewTarget;
+        masm.branchTest32(Assembler::Zero, r9, Imm32(CalleeToken_FunctionConstructing),
+                          &noNewTarget);
+
+        masm.add32(Imm32(1), r1);
+
+        masm.bind(&noNewTarget);
+    }
+
+    // Guarantee stack alignment of Jit frames.
+    //
+    // This code moves the stack pointer to the location where it should be when
+    // we enter the Jit frame.  It moves the stack pointer such that we have
+    // enough space reserved for pushing the arguments, and the JitFrameLayout.
+    // The stack pointer is also aligned on the alignment expected by the Jit
+    // frames.
+    //
+    // At the end the register r4, is a pointer to the stack where the first
+    // argument is expected by the Jit frame.
+    //
+    aasm->as_sub(r4, sp, O2RegImmShift(r1, LSL, 3));    // r4 = sp - argc*8
+    aasm->as_bic(r4, r4, Imm8(JitStackAlignment - 1));
+    // r4 is now the aligned on the bottom of the list of arguments.
+    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
+      "No need to consider the JitFrameLayout for aligning the stack");
+    // sp' = ~(JitStackAlignment - 1) & (sp - argc * sizeof(Value)) - sizeof(JitFrameLayout)
+    aasm->as_sub(sp, r4, Imm8(sizeof(JitFrameLayout)));
+
+    // Get a copy of the number of args to use as a decrement counter, also set
+    // the zero condition code.
+    aasm->as_mov(r5, O2Reg(r1), SetCC);
+
+    // Loop over arguments, copying them from an unknown buffer onto the Ion
+    // stack so they can be accessed from JIT'ed code.
+    {
+        Label header, footer;
+        // If there aren't any arguments, don't do anything.
+        aasm->as_b(&footer, Assembler::Zero);
+        // Get the top of the loop.
+        masm.bind(&header);
+        aasm->as_sub(r5, r5, Imm8(1), SetCC);
+        // We could be more awesome, and unroll this, using a loadm
+        // (particularly since the offset is effectively 0) but that seems more
+        // error prone, and complex.
+        // BIG FAT WARNING: this loads both r6 and r7.
+        aasm->as_extdtr(IsLoad,  64, true, PostIndex, r6, EDtrAddr(r2, EDtrOffImm(8)));
+        aasm->as_extdtr(IsStore, 64, true, PostIndex, r6, EDtrAddr(r4, EDtrOffImm(8)));
+        aasm->as_b(&header, Assembler::NonZero);
+        masm.bind(&footer);
+    }
+
+    masm.ma_sub(r8, sp, r8);
+    masm.makeFrameDescriptor(r8, JitFrame_Entry, JitFrameLayout::Size());
+
+    masm.startDataTransferM(IsStore, sp, IB, NoWriteBack);
+                           // [sp]    = return address (written later)
+    masm.transferReg(r8);  // [sp',4] = descriptor, argc*8+20
+    masm.transferReg(r9);  // [sp',8]  = callee token
+    masm.transferReg(r10); // [sp',12]  = actual arguments
+    masm.finishDataTransfer();
+
+    Label returnLabel;
+    if (type == EnterJitBaseline) {
+        // Handle OSR.
+        AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+        regs.take(JSReturnOperand);
+        regs.takeUnchecked(OsrFrameReg);
+        regs.take(r11);
+        regs.take(ReturnReg);
+
+        const Address slot_numStackValues(r11, offsetof(EnterJITStack, numStackValues));
+
+        Label notOsr;
+        masm.branchTestPtr(Assembler::Zero, OsrFrameReg, OsrFrameReg, &notOsr);
+
+        Register scratch = regs.takeAny();
+
+        Register numStackValues = regs.takeAny();
+        masm.load32(slot_numStackValues, numStackValues);
+
+        // Write return address. On ARM, CodeLabel is only used for tableswitch,
+        // so we can't use it here to get the return address. Instead, we use pc
+        // + a fixed offset to a jump to returnLabel. The pc register holds pc +
+        // 8, so we add the size of 2 instructions to skip the instructions
+        // emitted by storePtr and jump(&skipJump).
+        {
+            AutoForbidPools afp(&masm, 5);
+            Label skipJump;
+            masm.mov(pc, scratch);
+            masm.addPtr(Imm32(2 * sizeof(uint32_t)), scratch);
+            masm.storePtr(scratch, Address(sp, 0));
+            masm.jump(&skipJump);
+            masm.jump(&returnLabel);
+            masm.bind(&skipJump);
+        }
+
+        // Push previous frame pointer.
+        masm.push(r11);
+
+        // Reserve frame.
+        Register framePtr = r11;
+        masm.subPtr(Imm32(BaselineFrame::Size()), sp);
+        masm.mov(sp, framePtr);
+
+#ifdef XP_WIN
+        // Can't push large frames blindly on windows. Touch frame memory
+        // incrementally.
+        masm.ma_lsl(Imm32(3), numStackValues, scratch);
+        masm.subPtr(scratch, framePtr);
+        {
+            masm.ma_sub(sp, Imm32(WINDOWS_BIG_FRAME_TOUCH_INCREMENT), scratch);
+
+            Label touchFrameLoop;
+            Label touchFrameLoopEnd;
+            masm.bind(&touchFrameLoop);
+            masm.branchPtr(Assembler::Below, scratch, framePtr, &touchFrameLoopEnd);
+            masm.store32(Imm32(0), Address(scratch, 0));
+            masm.subPtr(Imm32(WINDOWS_BIG_FRAME_TOUCH_INCREMENT), scratch);
+            masm.jump(&touchFrameLoop);
+            masm.bind(&touchFrameLoopEnd);
+        }
+        masm.mov(sp, framePtr);
+#endif
+
+        // Reserve space for locals and stack values.
+        masm.ma_lsl(Imm32(3), numStackValues, scratch);
+        masm.ma_sub(sp, scratch, sp);
+
+        // Enter exit frame.
+        masm.addPtr(Imm32(BaselineFrame::Size() + BaselineFrame::FramePointerOffset), scratch);
+        masm.makeFrameDescriptor(scratch, JitFrame_BaselineJS, ExitFrameLayout::Size());
+        masm.push(scratch);
+        masm.push(Imm32(0)); // Fake return address.
+        // No GC things to mark on the stack, push a bare token.
+        masm.enterFakeExitFrame(ExitFrameLayoutBareToken);
+
+        masm.push(framePtr); // BaselineFrame
+        masm.push(r0); // jitcode
+
+        masm.setupUnalignedABICall(scratch);
+        masm.passABIArg(r11); // BaselineFrame
+        masm.passABIArg(OsrFrameReg); // InterpreterFrame
+        masm.passABIArg(numStackValues);
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, jit::InitBaselineFrameForOsr));
+
+        Register jitcode = regs.takeAny();
+        masm.pop(jitcode);
+        masm.pop(framePtr);
+
+        MOZ_ASSERT(jitcode != ReturnReg);
+
+        Label error;
+        masm.addPtr(Imm32(ExitFrameLayout::SizeWithFooter()), sp);
+        masm.addPtr(Imm32(BaselineFrame::Size()), framePtr);
+        masm.branchIfFalseBool(ReturnReg, &error);
+
+        // If OSR-ing, then emit instrumentation for setting lastProfilerFrame
+        // if profiler instrumentation is enabled.
+        {
+            Label skipProfilingInstrumentation;
+            Register realFramePtr = numStackValues;
+            AbsoluteAddress addressOfEnabled(cx->runtime()->spsProfiler.addressOfEnabled());
+            masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0),
+                          &skipProfilingInstrumentation);
+            masm.as_add(realFramePtr, framePtr, Imm8(sizeof(void*)));
+            masm.profilerEnterFrame(realFramePtr, scratch);
+            masm.bind(&skipProfilingInstrumentation);
+        }
+
+        masm.jump(jitcode);
+
+        // OOM: Load error value, discard return address and previous frame
+        // pointer and return.
+        masm.bind(&error);
+        masm.mov(framePtr, sp);
+        masm.addPtr(Imm32(2 * sizeof(uintptr_t)), sp);
+        masm.moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
+        masm.jump(&returnLabel);
+
+        masm.bind(&notOsr);
+        // Load the scope chain in R1.
+        MOZ_ASSERT(R1.scratchReg() != r0);
+        masm.loadPtr(Address(r11, offsetof(EnterJITStack, scopeChain)), R1.scratchReg());
+    }
+
+    // The Data transfer is pushing 4 words, which already account for the
+    // return address space of the Jit frame.  We have to undo what the data
+    // transfer did before making the call.
+    masm.addPtr(Imm32(sizeof(uintptr_t)), sp);
+
+    // The callee will push the return address on the stack, thus we check that
+    // the stack would be aligned once the call is complete.
+    masm.assertStackAlignment(JitStackAlignment, sizeof(uintptr_t));
+
+    // Call the function.
+    masm.callJitNoProfiler(r0);
+
+    if (type == EnterJitBaseline) {
+        // Baseline OSR will return here.
+        masm.bind(&returnLabel);
+    }
+
+    // The top of the stack now points to the address of the field following the
+    // return address because the return address is popped for the return, so we
+    // need to remove the size of the return address field.
+    aasm->as_sub(sp, sp, Imm8(4));
+
+    // Load off of the stack the size of our local stack.
+    masm.loadPtr(Address(sp, JitFrameLayout::offsetOfDescriptor()), r5);
+    aasm->as_add(sp, sp, lsr(r5, FRAMESIZE_SHIFT));
+
+    // Store the returned value into the slot_vp
+    masm.loadPtr(slot_vp, r5);
+    masm.storeValue(JSReturnOperand, Address(r5, 0));
+
+    // :TODO: Optimize storeValue with:
+    // We're using a load-double here. In order for that to work, the data needs
+    // to be stored in two consecutive registers, make sure this is the case
+    //   MOZ_ASSERT(JSReturnReg_Type.code() == JSReturnReg_Data.code()+1);
+    //   aasm->as_extdtr(IsStore, 64, true, Offset,
+    //                   JSReturnReg_Data, EDtrAddr(r5, EDtrOffImm(0)));
+
+    // Restore non-volatile registers and return.
+    GenerateReturn(masm, true, &cx->runtime()->spsProfiler);
+
+    Linker linker(masm);
+    AutoFlushICache afc("EnterJIT");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "EnterJIT");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateInvalidator(JSContext* cx)
+{
+    // See large comment in x86's JitRuntime::generateInvalidator.
+    MacroAssembler masm(cx);
+    // At this point, one of two things has happened:
+    // 1) Execution has just returned from C code, which left the stack aligned
+    // 2) Execution has just returned from Ion code, which left the stack unaligned.
+    // The old return address should not matter, but we still want the stack to
+    // be aligned, and there is no good reason to automatically align it with a
+    // call to setupUnalignedABICall.
+    masm.as_bic(sp, sp, Imm8(7));
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // We don't have to push everything, but this is likely easier.
+    // Setting regs_.
+    for (uint32_t i = 0; i < Registers::Total; i++)
+        masm.transferReg(Register::FromCode(i));
+    masm.finishDataTransfer();
+
+    // Since our datastructures for stack inspection are compile-time fixed,
+    // if there are only 16 double registers, then we need to reserve
+    // space on the stack for the missing 16.
+    if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
+        ScratchRegisterScope scratch(masm);
+        int missingRegs = FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
+        masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
+    }
+
+    masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
+    for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++)
+        masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
+    masm.finishFloatTransfer();
+
+    masm.ma_mov(sp, r0);
+    const int sizeOfRetval = sizeof(size_t)*2;
+    masm.reserveStack(sizeOfRetval);
+    masm.mov(sp, r1);
+    const int sizeOfBailoutInfo = sizeof(void*)*2;
+    masm.reserveStack(sizeOfBailoutInfo);
+    masm.mov(sp, r2);
+    masm.setupAlignedABICall();
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+    masm.passABIArg(r2);
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, InvalidationBailout));
+
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(0)), r2);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_ldr(Address(sp, sizeOfBailoutInfo), r1, scratch);
+    }
+    // Remove the return address, the IonScript, the register state
+    // (InvaliationBailoutStack) and the space that was allocated for the return
+    // value.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(sizeof(InvalidationBailoutStack) + sizeOfRetval + sizeOfBailoutInfo), sp, scratch);
+    }
+    // Remove the space that this frame was using before the bailout (computed
+    // by InvalidationBailout)
+    masm.ma_add(sp, r1, sp);
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.branch(bailoutTail);
+
+    Linker linker(masm);
+    AutoFlushICache afc("Invalidator");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+    JitSpew(JitSpew_IonInvalidate, "   invalidation thunk created at %p", (void*) code->raw());
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "Invalidator");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateArgumentsRectifier(JSContext* cx, void** returnAddrOut)
+{
+    MacroAssembler masm(cx);
+    masm.pushReturnAddress();
+
+    // ArgumentsRectifierReg contains the |nargs| pushed onto the current frame.
+    // Including |this|, there are (|nargs| + 1) arguments to copy.
+    MOZ_ASSERT(ArgumentsRectifierReg == r8);
+
+    // Copy number of actual arguments into r0.
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(RectifierFrameLayout::offsetOfNumActualArgs())), r0);
+
+    // Load the number of |undefined|s to push into r6.
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(RectifierFrameLayout::offsetOfCalleeToken())), r1);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_and(Imm32(CalleeTokenMask), r1, r6, scratch);
+    }
+    masm.ma_ldrh(EDtrAddr(r6, EDtrOffImm(JSFunction::offsetOfNargs())), r6);
+
+    masm.ma_sub(r6, r8, r2);
+
+    // Get the topmost argument.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_alu(sp, lsl(r8, 3), r3, OpAdd); // r3 <- r3 + nargs * 8
+        masm.ma_add(r3, Imm32(sizeof(RectifierFrameLayout)), r3, scratch);
+    }
+
+    {
+        Label notConstructing;
+
+        masm.branchTest32(Assembler::Zero, r1, Imm32(CalleeToken_FunctionConstructing),
+                          &notConstructing);
+
+        // Add sizeof(Value) to overcome |this|
+        masm.as_extdtr(IsLoad, 64, true, Offset, r4, EDtrAddr(r3, EDtrOffImm(8)));
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+
+        // Include the newly pushed newTarget value in the frame size
+        // calculated below.
+        masm.add32(Imm32(1), r6);
+
+        masm.bind(&notConstructing);
+    }
+
+    // Push undefined.
+    masm.moveValue(UndefinedValue(), r5, r4);
+    {
+        Label undefLoopTop;
+        masm.bind(&undefLoopTop);
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+        masm.as_sub(r2, r2, Imm8(1), SetCC);
+
+        masm.ma_b(&undefLoopTop, Assembler::NonZero);
+    }
+
+    // Push arguments, |nargs| + 1 times (to include |this|).
+    {
+        Label copyLoopTop;
+        masm.bind(&copyLoopTop);
+        masm.as_extdtr(IsLoad, 64, true, PostIndex, r4, EDtrAddr(r3, EDtrOffImm(-8)));
+        masm.as_extdtr(IsStore, 64, true, PreIndex, r4, EDtrAddr(sp, EDtrOffImm(-8)));
+
+        masm.as_sub(r8, r8, Imm8(1), SetCC);
+        masm.ma_b(&copyLoopTop, Assembler::NotSigned);
+    }
+
+    // translate the framesize from values into bytes
+    masm.as_add(r6, r6, Imm8(1));
+    masm.ma_lsl(Imm32(3), r6, r6);
+
+    // Construct sizeDescriptor.
+    masm.makeFrameDescriptor(r6, JitFrame_Rectifier, JitFrameLayout::Size());
+
+    // Construct JitFrameLayout.
+    masm.ma_push(r0); // actual arguments.
+    masm.ma_push(r1); // callee token
+    masm.ma_push(r6); // frame descriptor.
+
+    // Call the target function.
+    // Note that this code assumes the function is JITted.
+    masm.andPtr(Imm32(CalleeTokenMask), r1);
+    masm.ma_ldr(DTRAddr(r1, DtrOffImm(JSFunction::offsetOfNativeOrScript())), r3);
+    masm.loadBaselineOrIonRaw(r3, r3, nullptr);
+    uint32_t returnOffset = masm.callJitNoProfiler(r3);
+
+    // arg1
+    //  ...
+    // argN
+    // num actual args
+    // callee token
+    // sizeDescriptor     <- sp now
+    // return address
+
+    // Remove the rectifier frame.
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_dtr(IsLoad, sp, Imm32(12), r4, scratch, PostIndex);
+    }
+
+    // arg1
+    //  ...
+    // argN               <- sp now; r4 <- frame descriptor
+    // num actual args
+    // callee token
+    // sizeDescriptor
+    // return address
+
+    // Discard pushed arguments.
+    masm.ma_alu(sp, lsr(r4, FRAMESIZE_SHIFT), sp, OpAdd);
+
+    masm.ret();
+    Linker linker(masm);
+    AutoFlushICache afc("ArgumentsRectifier");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+    if (returnAddrOut)
+        *returnAddrOut = (void*) (code->raw() + returnOffset);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ArgumentsRectifier");
+#endif
+
+    return code;
+}
+
+static void
+PushBailoutFrame(MacroAssembler& masm, uint32_t frameClass, Register spArg)
+{
+    // the stack should look like:
+    // [IonFrame]
+    // bailoutFrame.registersnapshot
+    // bailoutFrame.fpsnapshot
+    // bailoutFrame.snapshotOffset
+    // bailoutFrame.frameSize
+
+    // STEP 1a: Save our register sets to the stack so Bailout() can read
+    // everything.
+    // sp % 8 == 0
+
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // We don't have to push everything, but this is likely easier.
+    // Setting regs_.
+    for (uint32_t i = 0; i < Registers::Total; i++)
+        masm.transferReg(Register::FromCode(i));
+    masm.finishDataTransfer();
+
+    ScratchRegisterScope scratch(masm);
+
+    // Since our datastructures for stack inspection are compile-time fixed,
+    // if there are only 16 double registers, then we need to reserve
+    // space on the stack for the missing 16.
+    if (FloatRegisters::ActualTotalPhys() != FloatRegisters::TotalPhys) {
+        int missingRegs = FloatRegisters::TotalPhys - FloatRegisters::ActualTotalPhys();
+        masm.ma_sub(Imm32(missingRegs * sizeof(double)), sp, scratch);
+    }
+    masm.startFloatTransferM(IsStore, sp, DB, WriteBack);
+    for (uint32_t i = 0; i < FloatRegisters::ActualTotalPhys(); i++)
+        masm.transferFloatReg(FloatRegister(i, FloatRegister::Double));
+    masm.finishFloatTransfer();
+
+    // STEP 1b: Push both the "return address" of the function call (the address
+    //          of the instruction after the call that we used to get here) as
+    //          well as the callee token onto the stack. The return address is
+    //          currently in r14. We will proceed by loading the callee token
+    //          into a sacrificial register <= r14, then pushing both onto the
+    //          stack.
+
+    // Now place the frameClass onto the stack, via a register.
+    masm.ma_mov(Imm32(frameClass), r4);
+    // And onto the stack. Since the stack is full, we need to put this one past
+    // the end of the current stack. Sadly, the ABI says that we need to always
+    // point to the lowest place that has been written. The OS is free to do
+    // whatever it wants below sp.
+    masm.startDataTransferM(IsStore, sp, DB, WriteBack);
+    // Set frameClassId_.
+    masm.transferReg(r4);
+    // Set tableOffset_; higher registers are stored at higher locations on the
+    // stack.
+    masm.transferReg(lr);
+    masm.finishDataTransfer();
+
+    masm.ma_mov(sp, spArg);
+}
+
+static void
+GenerateBailoutThunk(JSContext* cx, MacroAssembler& masm, uint32_t frameClass)
+{
+    PushBailoutFrame(masm, frameClass, r0);
+
+    // SP % 8 == 4
+    // STEP 1c: Call the bailout function, giving a pointer to the
+    //          structure we just blitted onto the stack.
+    const int sizeOfBailoutInfo = sizeof(void*)*2;
+    masm.reserveStack(sizeOfBailoutInfo);
+    masm.mov(sp, r1);
+    masm.setupAlignedABICall();
+
+    // Decrement sp by another 4, so we keep alignment. Not Anymore! Pushing
+    // both the snapshotoffset as well as the: masm.as_sub(sp, sp, Imm8(4));
+
+    // Set the old (4-byte aligned) value of the sp as the first argument.
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+
+    // Sp % 8 == 0
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, Bailout));
+    masm.ma_ldr(DTRAddr(sp, DtrOffImm(0)), r2);
+    {
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(sizeOfBailoutInfo), sp, scratch);
+    }
+
+    // Common size of a bailout frame.
+    uint32_t bailoutFrameSize = 0
+        + sizeof(void*) // frameClass
+        + sizeof(RegisterDump);
+
+    if (frameClass == NO_FRAME_SIZE_CLASS_ID) {
+        // Make sure the bailout frame size fits into the offset for a load.
+        masm.as_dtr(IsLoad, 32, Offset,
+                    r4, DTRAddr(sp, DtrOffImm(4)));
+        // Used to be: offsetof(BailoutStack, frameSize_)
+        // This structure is no longer available to us :(
+        // We add 12 to the bailoutFrameSize because:
+        // sizeof(uint32_t) for the tableOffset that was pushed onto the stack
+        // sizeof(uintptr_t) for the snapshotOffset;
+        // alignment to round the uintptr_t up to a multiple of 8 bytes.
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(bailoutFrameSize+12), sp, scratch);
+        masm.as_add(sp, sp, O2Reg(r4));
+    } else {
+        ScratchRegisterScope scratch(masm);
+        uint32_t frameSize = FrameSizeClass::FromClass(frameClass).frameSize();
+        masm.ma_add(Imm32(// The frame that was added when we entered the most
+                          // recent function.
+                          frameSize
+                          // The size of the "return address" that was dumped on
+                          // the stack.
+                          + sizeof(void*)
+                          // Everything else that was pushed on the stack.
+                          + bailoutFrameSize)
+                    , sp, scratch);
+    }
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r2.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.branch(bailoutTail);
+}
+
+JitCode*
+JitRuntime::generateBailoutTable(JSContext* cx, uint32_t frameClass)
+{
+    MacroAssembler masm(cx);
+
+    {
+        // Emit the table without any pools being inserted.
+        Label bailout;
+        AutoForbidPools afp(&masm, BAILOUT_TABLE_SIZE);
+        for (size_t i = 0; i < BAILOUT_TABLE_SIZE; i++)
+            masm.ma_bl(&bailout);
+        masm.bind(&bailout);
+    }
+
+    GenerateBailoutThunk(cx, masm, frameClass);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutTable");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutTable");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateBailoutHandler(JSContext* cx)
+{
+    MacroAssembler masm(cx);
+    GenerateBailoutThunk(cx, masm, NO_FRAME_SIZE_CLASS_ID);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutHandler");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutHandler");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateVMWrapper(JSContext* cx, const VMFunction& f)
+{
+    MOZ_ASSERT(functionWrappers_);
+    MOZ_ASSERT(functionWrappers_->initialized());
+    VMWrapperMap::AddPtr p = functionWrappers_->lookupForAdd(&f);
+    if (p)
+        return p->value();
+
+    // Generate a separated code for the wrapper.
+    MacroAssembler masm(cx);
+    AllocatableGeneralRegisterSet regs(Register::Codes::WrapperMask);
+
+    // Wrapper register set is a superset of Volatile register set.
+    JS_STATIC_ASSERT((Register::Codes::VolatileMask & ~Register::Codes::WrapperMask) == 0);
+
+    // The context is the first argument; r0 is the first argument register.
+    Register cxreg = r0;
+    regs.take(cxreg);
+
+    // Stack is:
+    //    ... frame ...
+    //  +8  [args] + argPadding
+    //  +0  ExitFrame
+    //
+    // We're aligned to an exit frame, so link it up.
+    // If it isn't a tail call, then the return address needs to be saved
+    if (f.expectTailCall == NonTailCall)
+        masm.pushReturnAddress();
+
+    masm.enterExitFrame(&f);
+    masm.loadJSContext(cxreg);
+
+    // Save the base of the argument set stored on the stack.
+    Register argsBase = InvalidReg;
+    if (f.explicitArgs) {
+        argsBase = r5;
+        regs.take(argsBase);
+        ScratchRegisterScope scratch(masm);
+        masm.ma_add(sp, Imm32(ExitFrameLayout::SizeWithFooter()), argsBase, scratch);
+    }
+
+    // Reserve space for the outparameter.
+    Register outReg = InvalidReg;
+    switch (f.outParam) {
+      case Type_Value:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(Value));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Handle:
+        outReg = r4;
+        regs.take(outReg);
+        masm.PushEmptyRooted(f.outParamRootType);
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Int32:
+      case Type_Pointer:
+      case Type_Bool:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(int32_t));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      case Type_Double:
+        outReg = r4;
+        regs.take(outReg);
+        masm.reserveStack(sizeof(double));
+        masm.ma_mov(sp, outReg);
+        break;
+
+      default:
+        MOZ_ASSERT(f.outParam == Type_Void);
+        break;
+    }
+
+    if (!generateTLEnterVM(cx, masm, f))
+        return nullptr;
+
+    masm.setupUnalignedABICall(regs.getAny());
+    masm.passABIArg(cxreg);
+
+    size_t argDisp = 0;
+
+    // Copy any arguments.
+    for (uint32_t explicitArg = 0; explicitArg < f.explicitArgs; explicitArg++) {
+        MoveOperand from;
+        switch (f.argProperties(explicitArg)) {
+          case VMFunction::WordByValue:
+            masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::DoubleByValue:
+            // Values should be passed by reference, not by value, so we assert
+            // that the argument is a double-precision float.
+            MOZ_ASSERT(f.argPassedInFloatReg(explicitArg));
+            masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::DOUBLE);
+            argDisp += sizeof(double);
+            break;
+          case VMFunction::WordByRef:
+            masm.passABIArg(MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS), MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::DoubleByRef:
+            masm.passABIArg(MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS), MoveOp::GENERAL);
+            argDisp += 2 * sizeof(void*);
+            break;
+        }
+    }
+
+    // Copy the implicit outparam, if any.
+    if (outReg != InvalidReg)
+        masm.passABIArg(outReg);
+
+    masm.callWithABI(f.wrapped);
+
+    if (!generateTLExitVM(cx, masm, f))
+        return nullptr;
+
+    // Test for failure.
+    switch (f.failType()) {
+      case Type_Object:
+        masm.branchTestPtr(Assembler::Zero, r0, r0, masm.failureLabel());
+        break;
+      case Type_Bool:
+        masm.branchIfFalseBool(r0, masm.failureLabel());
+        break;
+      default:
+        MOZ_CRASH("unknown failure kind");
+    }
+
+    // Load the outparam and free any allocated stack.
+    switch (f.outParam) {
+      case Type_Handle:
+        masm.popRooted(f.outParamRootType, ReturnReg, JSReturnOperand);
+        break;
+
+      case Type_Value:
+        masm.loadValue(Address(sp, 0), JSReturnOperand);
+        masm.freeStack(sizeof(Value));
+        break;
+
+      case Type_Int32:
+      case Type_Pointer:
+        masm.load32(Address(sp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Bool:
+        masm.load8ZeroExtend(Address(sp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Double:
+        if (cx->runtime()->jitSupportsFloatingPoint)
+            masm.loadDouble(Address(sp, 0), ReturnDoubleReg);
+        else
+            masm.assumeUnreachable("Unable to load into float reg, with no FP support.");
+        masm.freeStack(sizeof(double));
+        break;
+
+      default:
+        MOZ_ASSERT(f.outParam == Type_Void);
+        break;
+    }
+    masm.leaveExitFrame();
+    masm.retn(Imm32(sizeof(ExitFrameLayout) +
+                    f.explicitStackSlots() * sizeof(void*) +
+                    f.extraValuesToPop * sizeof(Value)));
+
+    Linker linker(masm);
+    AutoFlushICache afc("VMWrapper");
+    JitCode* wrapper = linker.newCode<NoGC>(cx, OTHER_CODE);
+    if (!wrapper)
+        return nullptr;
+
+    // linker.newCode may trigger a GC and sweep functionWrappers_ so we have to
+    // use relookupOrAdd instead of add.
+    if (!functionWrappers_->relookupOrAdd(p, &f, wrapper))
+        return nullptr;
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(wrapper, "VMWrapper");
+#endif
+
+    return wrapper;
+}
+
+JitCode*
+JitRuntime::generatePreBarrier(JSContext* cx, MIRType type)
+{
+    MacroAssembler masm(cx);
+
+    LiveRegisterSet save;
+    if (cx->runtime()->jitSupportsFloatingPoint) {
+        save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                                 FloatRegisterSet(FloatRegisters::VolatileDoubleMask));
+    } else {
+        save.set() = RegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                                 FloatRegisterSet());
+    }
+    save.add(lr);
+    masm.PushRegsInMask(save);
+
+    MOZ_ASSERT(PreBarrierReg == r1);
+    masm.movePtr(ImmPtr(cx->runtime()), r0);
+
+    masm.setupUnalignedABICall(r2);
+    masm.passABIArg(r0);
+    masm.passABIArg(r1);
+    masm.callWithABI(IonMarkFunction(type));
+    save.take(AnyRegister(lr));
+    save.add(pc);
+    masm.PopRegsInMask(save);
+
+    Linker linker(masm);
+    AutoFlushICache afc("PreBarrier");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "PreBarrier");
+#endif
+
+    return code;
+}
+
+typedef bool (*HandleDebugTrapFn)(JSContext*, BaselineFrame*, uint8_t*, bool*);
+static const VMFunction HandleDebugTrapInfo =
+    FunctionInfo<HandleDebugTrapFn>(HandleDebugTrap, "HandleDebugTrap");
+
+JitCode*
+JitRuntime::generateDebugTrapHandler(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    Register scratch1 = r0;
+    Register scratch2 = r1;
+
+    // Load BaselineFrame pointer in scratch1.
+    masm.mov(r11, scratch1);
+    masm.subPtr(Imm32(BaselineFrame::Size()), scratch1);
+
+    // Enter a stub frame and call the HandleDebugTrap VM function. Ensure the
+    // stub frame has a nullptr ICStub pointer, since this pointer is marked
+    // during GC.
+    masm.movePtr(ImmPtr(nullptr), ICStubReg);
+    EmitBaselineEnterStubFrame(masm, scratch2);
+
+    JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
+    if (!code)
+        return nullptr;
+
+    masm.push(lr);
+    masm.push(scratch1);
+    EmitBaselineCallVM(code, masm);
+
+    EmitBaselineLeaveStubFrame(masm);
+
+    // If the stub returns |true|, we have to perform a forced return (return
+    // from the JS frame). If the stub returns |false|, just return from the
+    // trap stub so that execution continues at the current pc.
+    Label forcedReturn;
+    masm.branchTest32(Assembler::NonZero, ReturnReg, ReturnReg, &forcedReturn);
+    masm.mov(lr, pc);
+
+    masm.bind(&forcedReturn);
+    masm.loadValue(Address(r11, BaselineFrame::reverseOffsetOfReturnValue()),
+                   JSReturnOperand);
+    masm.mov(r11, sp);
+    masm.pop(r11);
+
+    // Before returning, if profiling is turned on, make sure that lastProfilingFrame
+    // is set to the correct caller frame.
+    {
+        Label skipProfilingInstrumentation;
+        AbsoluteAddress addressOfEnabled(cx->runtime()->spsProfiler.addressOfEnabled());
+        masm.branch32(Assembler::Equal, addressOfEnabled, Imm32(0), &skipProfilingInstrumentation);
+        masm.profilerExitFrame();
+        masm.bind(&skipProfilingInstrumentation);
+    }
+
+    masm.ret();
+
+    Linker linker(masm);
+    AutoFlushICache afc("DebugTrapHandler");
+    JitCode* codeDbg = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(codeDbg, "DebugTrapHandler");
+#endif
+
+    return codeDbg;
+}
+
+JitCode*
+JitRuntime::generateExceptionTailStub(JSContext* cx, void* handler)
+{
+    MacroAssembler masm;
+
+    masm.handleFailureWithHandlerTail(handler);
+
+    Linker linker(masm);
+    AutoFlushICache afc("ExceptionTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ExceptionTailStub");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateBailoutTailStub(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    masm.generateBailoutTail(r1, r2);
+
+    Linker linker(masm);
+    AutoFlushICache afc("BailoutTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "BailoutTailStub");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateProfilerExitFrameTailStub(JSContext* cx)
+{
+    MacroAssembler masm;
+
+    Register scratch1 = r5;
+    Register scratch2 = r6;
+    Register scratch3 = r7;
+    Register scratch4 = r8;
+
+    //
+    // The code generated below expects that the current stack pointer points
+    // to an Ion or Baseline frame, at the state it would be immediately
+    // before a ret().  Thus, after this stub's business is done, it executes
+    // a ret() and returns directly to the caller script, on behalf of the
+    // callee script that jumped to this code.
+    //
+    // Thus the expected stack is:
+    //
+    //                                   StackPointer ----+
+    //                                                    v
+    // ..., ActualArgc, CalleeToken, Descriptor, ReturnAddr
+    // MEM-HI                                       MEM-LOW
+    //
+    //
+    // The generated jitcode is responsible for overwriting the
+    // jitActivation->lastProfilingFrame field with a pointer to the previous
+    // Ion or Baseline jit-frame that was pushed before this one. It is also
+    // responsible for overwriting jitActivation->lastProfilingCallSite with
+    // the return address into that frame.  The frame could either be an
+    // immediate "caller" frame, or it could be a frame in a previous
+    // JitActivation (if the current frame was entered from C++, and the C++
+    // was entered by some caller jit-frame further down the stack).
+    //
+    // So this jitcode is responsible for "walking up" the jit stack, finding
+    // the previous Ion or Baseline JS frame, and storing its address and the
+    // return address into the appropriate fields on the current jitActivation.
+    //
+    // There are a fixed number of different path types that can lead to the
+    // current frame, which is either a baseline or ion frame:
+    //
+    // <Baseline-Or-Ion>
+    // ^
+    // |
+    // ^--- Ion
+    // |
+    // ^--- Baseline Stub <---- Baseline
+    // |
+    // ^--- Argument Rectifier
+    // |    ^
+    // |    |
+    // |    ^--- Ion
+    // |    |
+    // |    ^--- Baseline Stub <---- Baseline
+    // |
+    // ^--- Entry Frame (From C++)
+    //
+    Register actReg = scratch4;
+    AbsoluteAddress activationAddr(GetJitContext()->runtime->addressOfProfilingActivation());
+    masm.loadPtr(activationAddr, actReg);
+
+    Address lastProfilingFrame(actReg, JitActivation::offsetOfLastProfilingFrame());
+    Address lastProfilingCallSite(actReg, JitActivation::offsetOfLastProfilingCallSite());
+
+#ifdef DEBUG
+    // Ensure that frame we are exiting is current lastProfilingFrame
+    {
+        masm.loadPtr(lastProfilingFrame, scratch1);
+        Label checkOk;
+        masm.branchPtr(Assembler::Equal, scratch1, ImmWord(0), &checkOk);
+        masm.branchPtr(Assembler::Equal, StackPointer, scratch1, &checkOk);
+        masm.assumeUnreachable(
+            "Mismatch between stored lastProfilingFrame and current stack pointer.");
+        masm.bind(&checkOk);
+    }
+#endif
+
+    // Load the frame descriptor into |scratch1|, figure out what to do depending on its type.
+    masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfDescriptor()), scratch1);
+
+    // Going into the conditionals, we will have:
+    //      FrameDescriptor.size in scratch1
+    //      FrameDescriptor.type in scratch2
+    {
+        ScratchRegisterScope asmScratch(masm);
+        masm.ma_and(Imm32((1 << FRAMETYPE_BITS) - 1), scratch1, scratch2, asmScratch);
+    }
+    masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch1);
+
+    // Handling of each case is dependent on FrameDescriptor.type
+    Label handle_IonJS;
+    Label handle_BaselineStub;
+    Label handle_Rectifier;
+    Label handle_IonAccessorIC;
+    Label handle_Entry;
+    Label end;
+
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_IonJS), &handle_IonJS);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_BaselineJS), &handle_IonJS);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_BaselineStub), &handle_BaselineStub);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_Rectifier), &handle_Rectifier);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_IonAccessorIC), &handle_IonAccessorIC);
+    masm.branch32(Assembler::Equal, scratch2, Imm32(JitFrame_Entry), &handle_Entry);
+
+    masm.assumeUnreachable("Invalid caller frame type when exiting from Ion frame.");
+
+    //
+    // JitFrame_IonJS
+    //
+    // Stack layout:
+    //                  ...
+    //                  Ion-Descriptor
+    //     Prev-FP ---> Ion-ReturnAddr
+    //                  ... previous frame data ... |- Descriptor.Size
+    //                  ... arguments ...           |
+    //                  ActualArgc          |
+    //                  CalleeToken         |- JitFrameLayout::Size()
+    //                  Descriptor          |
+    //        FP -----> ReturnAddr          |
+    //
+    masm.bind(&handle_IonJS);
+    {
+        // |scratch1| contains Descriptor.size
+
+        // returning directly to an IonJS frame.  Store return addr to frame
+        // in lastProfilingCallSite.
+        masm.loadPtr(Address(StackPointer, JitFrameLayout::offsetOfReturnAddress()), scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        // Store return frame in lastProfilingFrame.
+        // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.as_add(scratch2, scratch2, Imm8(JitFrameLayout::Size()));
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+    //
+    // JitFrame_BaselineStub
+    //
+    // Look past the stub and store the frame pointer to
+    // the baselineJS frame prior to it.
+    //
+    // Stack layout:
+    //              ...
+    //              BL-Descriptor
+    // Prev-FP ---> BL-ReturnAddr
+    //      +-----> BL-PrevFramePointer
+    //      |       ... BL-FrameData ...
+    //      |       BLStub-Descriptor
+    //      |       BLStub-ReturnAddr
+    //      |       BLStub-StubPointer          |
+    //      +------ BLStub-SavedFramePointer    |- Descriptor.Size
+    //              ... arguments ...           |
+    //              ActualArgc          |
+    //              CalleeToken         |- JitFrameLayout::Size()
+    //              Descriptor          |
+    //    FP -----> ReturnAddr          |
+    //
+    // We take advantage of the fact that the stub frame saves the frame
+    // pointer pointing to the baseline frame, so a bunch of calculation can
+    // be avoided.
+    //
+    masm.bind(&handle_BaselineStub);
+    {
+        masm.ma_add(StackPointer, scratch1, scratch3);
+        Address stubFrameReturnAddr(scratch3,
+                                    JitFrameLayout::Size() +
+                                    BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        Address stubFrameSavedFramePtr(scratch3,
+                                       JitFrameLayout::Size() - (2 * sizeof(void*)));
+        masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+        masm.addPtr(Imm32(sizeof(void*)), scratch2); // Skip past BL-PrevFramePtr
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+
+    //
+    // JitFrame_Rectifier
+    //
+    // The rectifier frame can be preceded by either an IonJS or a
+    // BaselineStub frame.
+    //
+    // Stack layout if caller of rectifier was Ion:
+    //
+    //              Ion-Descriptor
+    //              Ion-ReturnAddr
+    //              ... ion frame data ... |- Rect-Descriptor.Size
+    //              < COMMON LAYOUT >
+    //
+    // Stack layout if caller of rectifier was Baseline:
+    //
+    //              BL-Descriptor
+    // Prev-FP ---> BL-ReturnAddr
+    //      +-----> BL-SavedFramePointer
+    //      |       ... baseline frame data ...
+    //      |       BLStub-Descriptor
+    //      |       BLStub-ReturnAddr
+    //      |       BLStub-StubPointer          |
+    //      +------ BLStub-SavedFramePointer    |- Rect-Descriptor.Size
+    //              ... args to rectifier ...   |
+    //              < COMMON LAYOUT >
+    //
+    // Common stack layout:
+    //
+    //              ActualArgc          |
+    //              CalleeToken         |- IonRectitiferFrameLayout::Size()
+    //              Rect-Descriptor     |
+    //              Rect-ReturnAddr     |
+    //              ... rectifier data & args ... |- Descriptor.Size
+    //              ActualArgc      |
+    //              CalleeToken     |- JitFrameLayout::Size()
+    //              Descriptor      |
+    //    FP -----> ReturnAddr      |
+    //
+    masm.bind(&handle_Rectifier);
+    {
+        // scratch2 := StackPointer + Descriptor.size*1 + JitFrameLayout::Size();
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.add32(Imm32(JitFrameLayout::Size()), scratch2);
+        masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfDescriptor()), scratch3);
+        masm.ma_lsr(Imm32(FRAMESIZE_SHIFT), scratch3, scratch1);
+        masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch3);
+
+        // Now |scratch1| contains Rect-Descriptor.Size
+        // and |scratch2| points to Rectifier frame
+        // and |scratch3| contains Rect-Descriptor.Type
+
+        // Check for either Ion or BaselineStub frame.
+        Label handle_Rectifier_BaselineStub;
+        masm.branch32(Assembler::NotEqual, scratch3, Imm32(JitFrame_IonJS),
+                      &handle_Rectifier_BaselineStub);
+
+        // Handle Rectifier <- IonJS
+        // scratch3 := RectFrame[ReturnAddr]
+        masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfReturnAddress()), scratch3);
+        masm.storePtr(scratch3, lastProfilingCallSite);
+
+        // scratch3 := RectFrame + Rect-Descriptor.Size + RectifierFrameLayout::Size()
+        masm.ma_add(scratch2, scratch1, scratch3);
+        masm.add32(Imm32(RectifierFrameLayout::Size()), scratch3);
+        masm.storePtr(scratch3, lastProfilingFrame);
+        masm.ret();
+
+        // Handle Rectifier <- BaselineStub <- BaselineJS
+        masm.bind(&handle_Rectifier_BaselineStub);
+#ifdef DEBUG
+        {
+            Label checkOk;
+            masm.branch32(Assembler::Equal, scratch3, Imm32(JitFrame_BaselineStub), &checkOk);
+            masm.assumeUnreachable("Unrecognized frame preceding baselineStub.");
+            masm.bind(&checkOk);
+        }
+#endif
+        masm.ma_add(scratch2, scratch1, scratch3);
+        Address stubFrameReturnAddr(scratch3, RectifierFrameLayout::Size() +
+                                              BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        Address stubFrameSavedFramePtr(scratch3,
+                                       RectifierFrameLayout::Size() - (2 * sizeof(void*)));
+        masm.loadPtr(stubFrameSavedFramePtr, scratch2);
+        masm.addPtr(Imm32(sizeof(void*)), scratch2);
+        masm.storePtr(scratch2, lastProfilingFrame);
+        masm.ret();
+    }
+
+    // JitFrame_IonAccessorIC
+    //
+    // The caller is always an IonJS frame.
+    //
+    //              Ion-Descriptor
+    //              Ion-ReturnAddr
+    //              ... ion frame data ... |- AccFrame-Descriptor.Size
+    //              StubCode             |
+    //              AccFrame-Descriptor  |- IonAccessorICFrameLayout::Size()
+    //              AccFrame-ReturnAddr  |
+    //              ... accessor frame data & args ... |- Descriptor.Size
+    //              ActualArgc      |
+    //              CalleeToken     |- JitFrameLayout::Size()
+    //              Descriptor      |
+    //    FP -----> ReturnAddr      |
+    masm.bind(&handle_IonAccessorIC);
+    {
+        // scratch2 := StackPointer + Descriptor.size + JitFrameLayout::Size()
+        masm.ma_add(StackPointer, scratch1, scratch2);
+        masm.addPtr(Imm32(JitFrameLayout::Size()), scratch2);
+
+        // scratch3 := AccFrame-Descriptor.Size
+        masm.loadPtr(Address(scratch2, IonAccessorICFrameLayout::offsetOfDescriptor()), scratch3);
+#ifdef DEBUG
+        // Assert previous frame is an IonJS frame.
+        masm.movePtr(scratch3, scratch1);
+        masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch1);
+        {
+            Label checkOk;
+            masm.branch32(Assembler::Equal, scratch1, Imm32(JitFrame_IonJS), &checkOk);
+            masm.assumeUnreachable("IonAccessorIC frame must be preceded by IonJS frame");
+            masm.bind(&checkOk);
+        }
+#endif
+        masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch3);
+
+        // lastProfilingCallSite := AccFrame-ReturnAddr
+        masm.loadPtr(Address(scratch2, IonAccessorICFrameLayout::offsetOfReturnAddress()), scratch1);
+        masm.storePtr(scratch1, lastProfilingCallSite);
+
+        // lastProfilingFrame := AccessorFrame + AccFrame-Descriptor.Size +
+        //                       IonAccessorICFrameLayout::Size()
+        masm.ma_add(scratch2, scratch3, scratch1);
+        masm.addPtr(Imm32(IonAccessorICFrameLayout::Size()), scratch1);
+        masm.storePtr(scratch1, lastProfilingFrame);
+        masm.ret();
+    }
+
+    //
+    // JitFrame_Entry
+    //
+    // If at an entry frame, store null into both fields.
+    //
+    masm.bind(&handle_Entry);
+    {
+        masm.movePtr(ImmPtr(nullptr), scratch1);
+        masm.storePtr(scratch1, lastProfilingCallSite);
+        masm.storePtr(scratch1, lastProfilingFrame);
+        masm.ret();
+    }
+
+    Linker linker(masm);
+    AutoFlushICache afc("ProfilerExitFrameTailStub");
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ProfilerExitFrameStub");
+#endif
+
+    return code;
+}