Add m-esr52 at 52.6.0

1 files changed, 1303 insertions, 0 deletions

diff --git a/js/src/jit/x64/Trampoline-x64.cpp b/js/src/jit/x64/Trampoline-x64.cpp
new file mode 100644
index 000000000..aebacdd1c
--- /dev/null
+++ b/js/src/jit/x64/Trampoline-x64.cpp
@@ -0,0 +1,1303 @@
+/* -*- 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 "jit/Bailouts.h"
+#include "jit/JitCompartment.h"
+#include "jit/JitFrames.h"
+#include "jit/Linker.h"
+#ifdef JS_ION_PERF
+# include "jit/PerfSpewer.h"
+#endif
+#include "jit/VMFunctions.h"
+#include "jit/x64/SharedICHelpers-x64.h"
+
+#include "jit/MacroAssembler-inl.h"
+
+using namespace js;
+using namespace js::jit;
+
+using mozilla::IsPowerOfTwo;
+
+// All registers to save and restore. This includes the stack pointer, since we
+// use the ability to reference register values on the stack by index.
+static const LiveRegisterSet AllRegs =
+    LiveRegisterSet(GeneralRegisterSet(Registers::AllMask),
+                         FloatRegisterSet(FloatRegisters::AllMask));
+
+// Generates a trampoline for calling Jit compiled code from a C++ function.
+// The trampoline use the EnterJitCode signature, with the standard x64 fastcall
+// calling convention.
+JitCode*
+JitRuntime::generateEnterJIT(JSContext* cx, EnterJitType type)
+{
+    MacroAssembler masm(cx);
+    masm.assertStackAlignment(ABIStackAlignment, -int32_t(sizeof(uintptr_t)) /* return address */);
+
+    const Register reg_code  = IntArgReg0;
+    const Register reg_argc  = IntArgReg1;
+    const Register reg_argv  = IntArgReg2;
+    MOZ_ASSERT(OsrFrameReg == IntArgReg3);
+
+#if defined(_WIN64)
+    const Address token  = Address(rbp, 16 + ShadowStackSpace);
+    const Operand scopeChain = Operand(rbp, 24 + ShadowStackSpace);
+    const Operand numStackValuesAddr = Operand(rbp, 32 + ShadowStackSpace);
+    const Operand result = Operand(rbp, 40 + ShadowStackSpace);
+#else
+    const Register token = IntArgReg4;
+    const Register scopeChain = IntArgReg5;
+    const Operand numStackValuesAddr = Operand(rbp, 16 + ShadowStackSpace);
+    const Operand result = Operand(rbp, 24 + ShadowStackSpace);
+#endif
+
+    // Save old stack frame pointer, set new stack frame pointer.
+    masm.push(rbp);
+    masm.mov(rsp, rbp);
+
+    // Save non-volatile registers. These must be saved by the trampoline, rather
+    // than by the JIT'd code, because they are scanned by the conservative scanner.
+    masm.push(rbx);
+    masm.push(r12);
+    masm.push(r13);
+    masm.push(r14);
+    masm.push(r15);
+#if defined(_WIN64)
+    masm.push(rdi);
+    masm.push(rsi);
+
+    // 16-byte aligment for vmovdqa
+    masm.subq(Imm32(16 * 10 + 8), rsp);
+
+    masm.vmovdqa(xmm6, Operand(rsp, 16 * 0));
+    masm.vmovdqa(xmm7, Operand(rsp, 16 * 1));
+    masm.vmovdqa(xmm8, Operand(rsp, 16 * 2));
+    masm.vmovdqa(xmm9, Operand(rsp, 16 * 3));
+    masm.vmovdqa(xmm10, Operand(rsp, 16 * 4));
+    masm.vmovdqa(xmm11, Operand(rsp, 16 * 5));
+    masm.vmovdqa(xmm12, Operand(rsp, 16 * 6));
+    masm.vmovdqa(xmm13, Operand(rsp, 16 * 7));
+    masm.vmovdqa(xmm14, Operand(rsp, 16 * 8));
+    masm.vmovdqa(xmm15, Operand(rsp, 16 * 9));
+#endif
+
+    // Save arguments passed in registers needed after function call.
+    masm.push(result);
+
+    // Remember stack depth without padding and arguments.
+    masm.mov(rsp, r14);
+
+    // Remember number of bytes occupied by argument vector
+    masm.mov(reg_argc, r13);
+
+    // if we are constructing, that also needs to include newTarget
+    {
+        Label noNewTarget;
+        masm.branchTest32(Assembler::Zero, token, Imm32(CalleeToken_FunctionConstructing),
+                          &noNewTarget);
+
+        masm.addq(Imm32(1), r13);
+
+        masm.bind(&noNewTarget);
+    }
+
+    masm.shll(Imm32(3), r13);   // r13 = argc * sizeof(Value)
+    static_assert(sizeof(Value) == 1 << 3, "Constant is baked in assembly code");
+
+    // Guarantee stack alignment of Jit frames.
+    //
+    // This code compensates for the offset created by the copy of the vector of
+    // arguments, such that the jit frame will be aligned once the return
+    // address is pushed on the stack.
+    //
+    // In the computation of the offset, we omit the size of the JitFrameLayout
+    // which is pushed on the stack, as the JitFrameLayout size is a multiple of
+    // the JitStackAlignment.
+    masm.mov(rsp, r12);
+    masm.subq(r13, r12);
+    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
+      "No need to consider the JitFrameLayout for aligning the stack");
+    masm.andl(Imm32(JitStackAlignment - 1), r12);
+    masm.subq(r12, rsp);
+
+    /***************************************************************
+    Loop over argv vector, push arguments onto stack in reverse order
+    ***************************************************************/
+
+    // r13 still stores the number of bytes in the argument vector.
+    masm.addq(reg_argv, r13); // r13 points above last argument or newTarget
+
+    // while r13 > rdx, push arguments.
+    {
+        Label header, footer;
+        masm.bind(&header);
+
+        masm.cmpPtr(r13, reg_argv);
+        masm.j(AssemblerX86Shared::BelowOrEqual, &footer);
+
+        masm.subq(Imm32(8), r13);
+        masm.push(Operand(r13, 0));
+        masm.jmp(&header);
+
+        masm.bind(&footer);
+    }
+
+    // Push the number of actual arguments.  |result| is used to store the
+    // actual number of arguments without adding an extra argument to the enter
+    // JIT.
+    masm.movq(result, reg_argc);
+    masm.unboxInt32(Operand(reg_argc, 0), reg_argc);
+    masm.push(reg_argc);
+
+    // Push the callee token.
+    masm.push(token);
+
+    /*****************************************************************
+    Push the number of bytes we've pushed so far on the stack and call
+    *****************************************************************/
+    masm.subq(rsp, r14);
+
+    // Create a frame descriptor.
+    masm.makeFrameDescriptor(r14, JitFrame_Entry, JitFrameLayout::Size());
+    masm.push(r14);
+
+    CodeLabel returnLabel;
+    CodeLabel oomReturnLabel;
+    if (type == EnterJitBaseline) {
+        // Handle OSR.
+        AllocatableGeneralRegisterSet regs(GeneralRegisterSet::All());
+        regs.takeUnchecked(OsrFrameReg);
+        regs.take(rbp);
+        regs.take(reg_code);
+
+        // Ensure that |scratch| does not end up being JSReturnOperand.
+        // Do takeUnchecked because on Win64/x64, reg_code (IntArgReg0) and JSReturnOperand are
+        // the same (rcx).  See bug 849398.
+        regs.takeUnchecked(JSReturnOperand);
+        Register scratch = regs.takeAny();
+
+        Label notOsr;
+        masm.branchTestPtr(Assembler::Zero, OsrFrameReg, OsrFrameReg, &notOsr);
+
+        Register numStackValues = regs.takeAny();
+        masm.movq(numStackValuesAddr, numStackValues);
+
+        // Push return address
+        masm.mov(returnLabel.patchAt(), scratch);
+        masm.push(scratch);
+
+        // Push previous frame pointer.
+        masm.push(rbp);
+
+        // Reserve frame.
+        Register framePtr = rbp;
+        masm.subPtr(Imm32(BaselineFrame::Size()), rsp);
+        masm.mov(rsp, framePtr);
+
+#ifdef XP_WIN
+        // Can't push large frames blindly on windows.  Touch frame memory incrementally.
+        masm.mov(numStackValues, scratch);
+        masm.lshiftPtr(Imm32(3), scratch);
+        masm.subPtr(scratch, framePtr);
+        {
+            masm.movePtr(rsp, scratch);
+            masm.subPtr(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(rsp, framePtr);
+#endif
+
+        // Reserve space for locals and stack values.
+        Register valuesSize = regs.takeAny();
+        masm.mov(numStackValues, valuesSize);
+        masm.shll(Imm32(3), valuesSize);
+        masm.subPtr(valuesSize, rsp);
+
+        // Enter exit frame.
+        masm.addPtr(Imm32(BaselineFrame::Size() + BaselineFrame::FramePointerOffset), valuesSize);
+        masm.makeFrameDescriptor(valuesSize, JitFrame_BaselineJS, ExitFrameLayout::Size());
+        masm.push(valuesSize);
+        masm.push(Imm32(0)); // Fake return address.
+        // No GC things to mark, push a bare token.
+        masm.enterFakeExitFrame(ExitFrameLayoutBareToken);
+
+        regs.add(valuesSize);
+
+        masm.push(framePtr);
+        masm.push(reg_code);
+
+        masm.setupUnalignedABICall(scratch);
+        masm.passABIArg(framePtr); // BaselineFrame
+        masm.passABIArg(OsrFrameReg); // InterpreterFrame
+        masm.passABIArg(numStackValues);
+        masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, jit::InitBaselineFrameForOsr));
+
+        masm.pop(reg_code);
+        masm.pop(framePtr);
+
+        MOZ_ASSERT(reg_code != ReturnReg);
+
+        Label error;
+        masm.addPtr(Imm32(ExitFrameLayout::SizeWithFooter()), rsp);
+        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.lea(Operand(framePtr, sizeof(void*)), realFramePtr);
+            masm.profilerEnterFrame(realFramePtr, scratch);
+            masm.bind(&skipProfilingInstrumentation);
+        }
+
+        masm.jump(reg_code);
+
+        // OOM: load error value, discard return address and previous frame
+        // pointer and return.
+        masm.bind(&error);
+        masm.mov(framePtr, rsp);
+        masm.addPtr(Imm32(2 * sizeof(uintptr_t)), rsp);
+        masm.moveValue(MagicValue(JS_ION_ERROR), JSReturnOperand);
+        masm.mov(oomReturnLabel.patchAt(), scratch);
+        masm.jump(scratch);
+
+        masm.bind(&notOsr);
+        masm.movq(scopeChain, R1.scratchReg());
+    }
+
+    // The call 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 function.
+    masm.callJitNoProfiler(reg_code);
+
+    if (type == EnterJitBaseline) {
+        // Baseline OSR will return here.
+        masm.use(returnLabel.target());
+        masm.addCodeLabel(returnLabel);
+        masm.use(oomReturnLabel.target());
+        masm.addCodeLabel(oomReturnLabel);
+    }
+
+    // Pop arguments and padding from stack.
+    masm.pop(r14);              // Pop and decode descriptor.
+    masm.shrq(Imm32(FRAMESIZE_SHIFT), r14);
+    masm.addq(r14, rsp);        // Remove arguments.
+
+    /*****************************************************************
+    Place return value where it belongs, pop all saved registers
+    *****************************************************************/
+    masm.pop(r12); // vp
+    masm.storeValue(JSReturnOperand, Operand(r12, 0));
+
+    // Restore non-volatile registers.
+#if defined(_WIN64)
+    masm.vmovdqa(Operand(rsp, 16 * 0), xmm6);
+    masm.vmovdqa(Operand(rsp, 16 * 1), xmm7);
+    masm.vmovdqa(Operand(rsp, 16 * 2), xmm8);
+    masm.vmovdqa(Operand(rsp, 16 * 3), xmm9);
+    masm.vmovdqa(Operand(rsp, 16 * 4), xmm10);
+    masm.vmovdqa(Operand(rsp, 16 * 5), xmm11);
+    masm.vmovdqa(Operand(rsp, 16 * 6), xmm12);
+    masm.vmovdqa(Operand(rsp, 16 * 7), xmm13);
+    masm.vmovdqa(Operand(rsp, 16 * 8), xmm14);
+    masm.vmovdqa(Operand(rsp, 16 * 9), xmm15);
+
+    masm.addq(Imm32(16 * 10 + 8), rsp);
+
+    masm.pop(rsi);
+    masm.pop(rdi);
+#endif
+    masm.pop(r15);
+    masm.pop(r14);
+    masm.pop(r13);
+    masm.pop(r12);
+    masm.pop(rbx);
+
+    // Restore frame pointer and return.
+    masm.pop(rbp);
+    masm.ret();
+
+    Linker linker(masm);
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "EnterJIT");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateInvalidator(JSContext* cx)
+{
+    AutoJitContextAlloc ajca(cx);
+    MacroAssembler masm(cx);
+
+    // See explanatory comment in x86's JitRuntime::generateInvalidator.
+
+    masm.addq(Imm32(sizeof(uintptr_t)), rsp);
+
+    // Push registers such that we can access them from [base + code].
+    masm.PushRegsInMask(AllRegs);
+
+    masm.movq(rsp, rax); // Argument to jit::InvalidationBailout.
+
+    // Make space for InvalidationBailout's frameSize outparam.
+    masm.reserveStack(sizeof(size_t));
+    masm.movq(rsp, rbx);
+
+    // Make space for InvalidationBailout's bailoutInfo outparam.
+    masm.reserveStack(sizeof(void*));
+    masm.movq(rsp, r9);
+
+    masm.setupUnalignedABICall(rdx);
+    masm.passABIArg(rax);
+    masm.passABIArg(rbx);
+    masm.passABIArg(r9);
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, InvalidationBailout));
+
+    masm.pop(r9); // Get the bailoutInfo outparam.
+    masm.pop(rbx); // Get the frameSize outparam.
+
+    // Pop the machine state and the dead frame.
+    masm.lea(Operand(rsp, rbx, TimesOne, sizeof(InvalidationBailoutStack)), rsp);
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r9.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.jmp(bailoutTail);
+
+    Linker linker(masm);
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "Invalidator");
+#endif
+
+    return code;
+}
+
+JitCode*
+JitRuntime::generateArgumentsRectifier(JSContext* cx, void** returnAddrOut)
+{
+    // Do not erase the frame pointer in this function.
+
+    MacroAssembler masm(cx);
+    // Caller:
+    // [arg2] [arg1] [this] [[argc] [callee] [descr] [raddr]] <- rsp
+    // '--- #r8 ---'
+
+    // ArgumentsRectifierReg contains the |nargs| pushed onto the current frame.
+    // Including |this|, there are (|nargs| + 1) arguments to copy.
+    MOZ_ASSERT(ArgumentsRectifierReg == r8);
+
+    // Add |this|, in the counter of known arguments.
+    masm.addl(Imm32(1), r8);
+
+    // Load |nformals| into %rcx.
+    masm.loadPtr(Address(rsp, RectifierFrameLayout::offsetOfCalleeToken()), rax);
+    masm.mov(rax, rcx);
+    masm.andq(Imm32(uint32_t(CalleeTokenMask)), rcx);
+    masm.movzwl(Operand(rcx, JSFunction::offsetOfNargs()), rcx);
+
+    // Stash another copy in r11, since we are going to do destructive operations
+    // on rcx
+    masm.mov(rcx, r11);
+
+    static_assert(CalleeToken_FunctionConstructing == 1,
+      "Ensure that we can use the constructing bit to count the value");
+    masm.mov(rax, rdx);
+    masm.andq(Imm32(uint32_t(CalleeToken_FunctionConstructing)), rdx);
+
+    // Including |this|, and |new.target|, there are (|nformals| + 1 + isConstructing)
+    // arguments to push to the stack.  Then we push a JitFrameLayout.  We
+    // compute the padding expressed in the number of extra |undefined| values
+    // to push on the stack.
+    static_assert(sizeof(JitFrameLayout) % JitStackAlignment == 0,
+      "No need to consider the JitFrameLayout for aligning the stack");
+    static_assert(JitStackAlignment % sizeof(Value) == 0,
+      "Ensure that we can pad the stack by pushing extra UndefinedValue");
+    static_assert(IsPowerOfTwo(JitStackValueAlignment),
+                  "must have power of two for masm.andl to do its job");
+
+    masm.addl(Imm32(JitStackValueAlignment - 1 /* for padding */ + 1 /* for |this| */), rcx);
+    masm.addl(rdx, rcx);
+    masm.andl(Imm32(~(JitStackValueAlignment - 1)), rcx);
+
+    // Load the number of |undefined|s to push into %rcx.
+    masm.subq(r8, rcx);
+
+    // Caller:
+    // [arg2] [arg1] [this] [[argc] [callee] [descr] [raddr]] <- rsp <- r9
+    // '------ #r8 -------'
+    //
+    // Rectifier frame:
+    // [undef] [undef] [undef] [arg2] [arg1] [this] [[argc] [callee] [descr] [raddr]]
+    // '------- #rcx --------' '------ #r8 -------'
+
+    // Copy the number of actual arguments
+    masm.loadPtr(Address(rsp, RectifierFrameLayout::offsetOfNumActualArgs()), rdx);
+
+    masm.moveValue(UndefinedValue(), r10);
+
+    masm.movq(rsp, r9); // Save %rsp.
+
+    // Push undefined. (including the padding)
+    {
+        Label undefLoopTop;
+        masm.bind(&undefLoopTop);
+
+        masm.push(r10);
+        masm.subl(Imm32(1), rcx);
+        masm.j(Assembler::NonZero, &undefLoopTop);
+    }
+
+    // Get the topmost argument.
+    static_assert(sizeof(Value) == 8, "TimesEight is used to skip arguments");
+
+    // | - sizeof(Value)| is used to put rcx such that we can read the last
+    // argument, and not the value which is after.
+    BaseIndex b = BaseIndex(r9, r8, TimesEight, sizeof(RectifierFrameLayout) - sizeof(Value));
+    masm.lea(Operand(b), rcx);
+
+    // Copy & Push arguments, |nargs| + 1 times (to include |this|).
+    {
+        Label copyLoopTop;
+
+        masm.bind(&copyLoopTop);
+        masm.push(Operand(rcx, 0x0));
+        masm.subq(Imm32(sizeof(Value)), rcx);
+        masm.subl(Imm32(1), r8);
+        masm.j(Assembler::NonZero, &copyLoopTop);
+    }
+
+    // if constructing, copy newTarget
+    {
+        Label notConstructing;
+
+        masm.branchTest32(Assembler::Zero, rax, Imm32(CalleeToken_FunctionConstructing),
+                          &notConstructing);
+
+        // thisFrame[numFormals] = prevFrame[argc]
+        ValueOperand newTarget(r10);
+
+        // +1 for |this|. We want vp[argc], so don't subtract 1
+        BaseIndex newTargetSrc(r9, rdx, TimesEight, sizeof(RectifierFrameLayout) + sizeof(Value));
+        masm.loadValue(newTargetSrc, newTarget);
+
+        // Again, 1 for |this|
+        BaseIndex newTargetDest(rsp, r11, TimesEight, sizeof(Value));
+        masm.storeValue(newTarget, newTargetDest);
+
+        masm.bind(&notConstructing);
+    }
+
+
+    // Caller:
+    // [arg2] [arg1] [this] [[argc] [callee] [descr] [raddr]] <- r9
+    //
+    //
+    // Rectifier frame:
+    // [undef] [undef] [undef] [arg2] [arg1] [this] <- rsp [[argc] [callee] [descr] [raddr]]
+    //
+
+    // Construct descriptor.
+    masm.subq(rsp, r9);
+    masm.makeFrameDescriptor(r9, JitFrame_Rectifier, JitFrameLayout::Size());
+
+    // Construct JitFrameLayout.
+    masm.push(rdx); // numActualArgs
+    masm.push(rax); // callee token
+    masm.push(r9); // descriptor
+
+    // Call the target function.
+    // Note that this code assumes the function is JITted.
+    masm.andq(Imm32(uint32_t(CalleeTokenMask)), rax);
+    masm.loadPtr(Address(rax, JSFunction::offsetOfNativeOrScript()), rax);
+    masm.loadBaselineOrIonRaw(rax, rax, nullptr);
+    uint32_t returnOffset = masm.callJitNoProfiler(rax);
+
+    // Remove the rectifier frame.
+    masm.pop(r9);             // r9 <- descriptor with FrameType.
+    masm.shrq(Imm32(FRAMESIZE_SHIFT), r9);
+    masm.pop(r11);            // Discard calleeToken.
+    masm.pop(r11);            // Discard numActualArgs.
+    masm.addq(r9, rsp);       // Discard pushed arguments.
+
+    masm.ret();
+
+    Linker linker(masm);
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ArgumentsRectifier");
+#endif
+
+    if (returnAddrOut)
+        *returnAddrOut = (void*)(code->raw() + returnOffset);
+    return code;
+}
+
+static void
+PushBailoutFrame(MacroAssembler& masm, Register spArg)
+{
+    // Push registers such that we can access them from [base + code].
+    if (JitSupportsSimd()) {
+        masm.PushRegsInMask(AllRegs);
+    } else {
+        // When SIMD isn't supported, PushRegsInMask reduces the set of float
+        // registers to be double-sized, while the RegisterDump expects each of
+        // the float registers to have the maximal possible size
+        // (Simd128DataSize). To work around this, we just spill the double
+        // registers by hand here, using the register dump offset directly.
+        for (GeneralRegisterBackwardIterator iter(AllRegs.gprs()); iter.more(); ++iter)
+            masm.Push(*iter);
+
+        masm.reserveStack(sizeof(RegisterDump::FPUArray));
+        for (FloatRegisterBackwardIterator iter(AllRegs.fpus()); iter.more(); ++iter) {
+            FloatRegister reg = *iter;
+            Address spillAddress(StackPointer, reg.getRegisterDumpOffsetInBytes());
+            masm.storeDouble(reg, spillAddress);
+        }
+    }
+
+    // Get the stack pointer into a register, pre-alignment.
+    masm.movq(rsp, spArg);
+}
+
+static void
+GenerateBailoutThunk(JSContext* cx, MacroAssembler& masm, uint32_t frameClass)
+{
+    PushBailoutFrame(masm, r8);
+
+    // Make space for Bailout's bailoutInfo outparam.
+    masm.reserveStack(sizeof(void*));
+    masm.movq(rsp, r9);
+
+    // Call the bailout function.
+    masm.setupUnalignedABICall(rax);
+    masm.passABIArg(r8);
+    masm.passABIArg(r9);
+    masm.callWithABI(JS_FUNC_TO_DATA_PTR(void*, Bailout));
+
+    masm.pop(r9); // Get the bailoutInfo outparam.
+
+    // Stack is:
+    //     [frame]
+    //     snapshotOffset
+    //     frameSize
+    //     [bailoutFrame]
+    //
+    // Remove both the bailout frame and the topmost Ion frame's stack.
+    static const uint32_t BailoutDataSize = sizeof(RegisterDump);
+    masm.addq(Imm32(BailoutDataSize), rsp);
+    masm.pop(rcx);
+    masm.lea(Operand(rsp, rcx, TimesOne, sizeof(void*)), rsp);
+
+    // Jump to shared bailout tail. The BailoutInfo pointer has to be in r9.
+    JitCode* bailoutTail = cx->runtime()->jitRuntime()->getBailoutTail();
+    masm.jmp(bailoutTail);
+}
+
+JitCode*
+JitRuntime::generateBailoutTable(JSContext* cx, uint32_t frameClass)
+{
+    MOZ_CRASH("x64 does not use bailout tables");
+}
+
+JitCode*
+JitRuntime::generateBailoutHandler(JSContext* cx)
+{
+    MacroAssembler masm;
+    GenerateBailoutThunk(cx, masm, NO_FRAME_SIZE_CLASS_ID);
+
+    Linker linker(masm);
+    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;
+
+    // Avoid conflicts with argument registers while discarding the result after
+    // the function call.
+    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.
+    Register cxreg = IntArgReg0;
+    regs.take(cxreg);
+
+    // Stack is:
+    //    ... frame ...
+    //  +12 [args]
+    //  +8  descriptor
+    //  +0  returnAddress
+    //
+    // We're aligned to an exit frame, so link it up.
+    masm.enterExitFrame(&f);
+    masm.loadJSContext(cxreg);
+
+    // Save the current stack pointer as the base for copying arguments.
+    Register argsBase = InvalidReg;
+    if (f.explicitArgs) {
+        argsBase = r10;
+        regs.take(argsBase);
+        masm.lea(Operand(rsp, ExitFrameLayout::SizeWithFooter()), argsBase);
+    }
+
+    // Reserve space for the outparameter.
+    Register outReg = InvalidReg;
+    switch (f.outParam) {
+      case Type_Value:
+        outReg = regs.takeAny();
+        masm.reserveStack(sizeof(Value));
+        masm.movq(esp, outReg);
+        break;
+
+      case Type_Handle:
+        outReg = regs.takeAny();
+        masm.PushEmptyRooted(f.outParamRootType);
+        masm.movq(esp, outReg);
+        break;
+
+      case Type_Int32:
+      case Type_Bool:
+        outReg = regs.takeAny();
+        masm.reserveStack(sizeof(int32_t));
+        masm.movq(esp, outReg);
+        break;
+
+      case Type_Double:
+        outReg = regs.takeAny();
+        masm.reserveStack(sizeof(double));
+        masm.movq(esp, outReg);
+        break;
+
+      case Type_Pointer:
+        outReg = regs.takeAny();
+        masm.reserveStack(sizeof(uintptr_t));
+        masm.movq(esp, 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 arguments.
+    for (uint32_t explicitArg = 0; explicitArg < f.explicitArgs; explicitArg++) {
+        MoveOperand from;
+        switch (f.argProperties(explicitArg)) {
+          case VMFunction::WordByValue:
+            if (f.argPassedInFloatReg(explicitArg))
+                masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::DOUBLE);
+            else
+                masm.passABIArg(MoveOperand(argsBase, argDisp), MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::WordByRef:
+            masm.passABIArg(MoveOperand(argsBase, argDisp, MoveOperand::EFFECTIVE_ADDRESS),
+                            MoveOp::GENERAL);
+            argDisp += sizeof(void*);
+            break;
+          case VMFunction::DoubleByValue:
+          case VMFunction::DoubleByRef:
+            MOZ_CRASH("NYI: x64 callVM should not be used with 128bits values.");
+        }
+    }
+
+    // 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, rax, rax, masm.failureLabel());
+        break;
+      case Type_Bool:
+        masm.testb(rax, rax);
+        masm.j(Assembler::Zero, 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(esp, 0), JSReturnOperand);
+        masm.freeStack(sizeof(Value));
+        break;
+
+      case Type_Int32:
+        masm.load32(Address(esp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Bool:
+        masm.load8ZeroExtend(Address(esp, 0), ReturnReg);
+        masm.freeStack(sizeof(int32_t));
+        break;
+
+      case Type_Double:
+        MOZ_ASSERT(cx->runtime()->jitSupportsFloatingPoint);
+        masm.loadDouble(Address(esp, 0), ReturnDoubleReg);
+        masm.freeStack(sizeof(double));
+        break;
+
+      case Type_Pointer:
+        masm.loadPtr(Address(esp, 0), ReturnReg);
+        masm.freeStack(sizeof(uintptr_t));
+        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);
+    JitCode* wrapper = linker.newCode<NoGC>(cx, OTHER_CODE);
+    if (!wrapper)
+        return nullptr;
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(wrapper, "VMWrapper");
+#endif
+
+    // 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;
+
+    return wrapper;
+}
+
+JitCode*
+JitRuntime::generatePreBarrier(JSContext* cx, MIRType type)
+{
+    MacroAssembler masm;
+
+    LiveRegisterSet regs =
+        LiveRegisterSet(GeneralRegisterSet(Registers::VolatileMask),
+                             FloatRegisterSet(FloatRegisters::VolatileMask));
+    masm.PushRegsInMask(regs);
+
+    MOZ_ASSERT(PreBarrierReg == rdx);
+    masm.mov(ImmPtr(cx->runtime()), rcx);
+
+    masm.setupUnalignedABICall(rax);
+    masm.passABIArg(rcx);
+    masm.passABIArg(rdx);
+    masm.callWithABI(IonMarkFunction(type));
+
+    masm.PopRegsInMask(regs);
+    masm.ret();
+
+    Linker linker(masm);
+    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;
+#ifndef JS_USE_LINK_REGISTER
+    // The first value contains the return addres,
+    // which we pull into ICTailCallReg for tail calls.
+    masm.setFramePushed(sizeof(intptr_t));
+#endif
+
+    Register scratch1 = rax;
+    Register scratch2 = rcx;
+    Register scratch3 = rdx;
+
+    // Load the return address in scratch1.
+    masm.loadPtr(Address(rsp, 0), scratch1);
+
+    // Load BaselineFrame pointer in scratch2.
+    masm.mov(rbp, scratch2);
+    masm.subPtr(Imm32(BaselineFrame::Size()), scratch2);
+
+    // 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, scratch3);
+
+    JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
+    if (!code)
+        return nullptr;
+
+    masm.push(scratch1);
+    masm.push(scratch2);
+    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.ret();
+
+    masm.bind(&forcedReturn);
+    masm.loadValue(Address(ebp, BaselineFrame::reverseOffsetOfReturnValue()),
+                   JSReturnOperand);
+    masm.mov(rbp, rsp);
+    masm.pop(rbp);
+
+    // 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);
+    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);
+    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(rdx, r9);
+
+    Linker linker(masm);
+    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 = r8;
+    Register scratch2 = r9;
+    Register scratch3 = r10;
+    Register scratch4 = r11;
+
+    //
+    // 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
+    masm.movePtr(scratch1, scratch2);
+    masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch1);
+    masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch2);
+
+    // 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);
+    {
+        // 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.lea(Operand(StackPointer, scratch1, TimesOne, JitFrameLayout::Size()), scratch2);
+        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);
+    {
+        BaseIndex stubFrameReturnAddr(StackPointer, scratch1, TimesOne,
+                                      JitFrameLayout::Size() +
+                                      BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch2);
+        masm.storePtr(scratch2, lastProfilingCallSite);
+
+        BaseIndex stubFrameSavedFramePtr(StackPointer, scratch1, TimesOne,
+                                         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 + JitFrameLayout::Size()
+        masm.lea(Operand(StackPointer, scratch1, TimesOne, JitFrameLayout::Size()), scratch2);
+        masm.loadPtr(Address(scratch2, RectifierFrameLayout::offsetOfDescriptor()), scratch3);
+        masm.movePtr(scratch3, scratch1);
+        masm.and32(Imm32((1 << FRAMETYPE_BITS) - 1), scratch3);
+        masm.rshiftPtr(Imm32(FRAMESIZE_SHIFT), scratch1);
+
+        // 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.lea(Operand(scratch2, scratch1, TimesOne, 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
+        BaseIndex stubFrameReturnAddr(scratch2, scratch1, TimesOne,
+                                         RectifierFrameLayout::Size() +
+                                         BaselineStubFrameLayout::offsetOfReturnAddress());
+        masm.loadPtr(stubFrameReturnAddr, scratch3);
+        masm.storePtr(scratch3, lastProfilingCallSite);
+
+        BaseIndex stubFrameSavedFramePtr(scratch2, scratch1, TimesOne,
+                                         RectifierFrameLayout::Size() - (2 * sizeof(void*)));
+        masm.loadPtr(stubFrameSavedFramePtr, scratch3);
+        masm.addPtr(Imm32(sizeof(void*)), scratch3);
+        masm.storePtr(scratch3, 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.lea(Operand(StackPointer, scratch1, TimesOne, 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.lea(Operand(scratch2, scratch3, TimesOne, 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);
+    JitCode* code = linker.newCode<NoGC>(cx, OTHER_CODE);
+
+#ifdef JS_ION_PERF
+    writePerfSpewerJitCodeProfile(code, "ProfilerExitFrameStub");
+#endif
+
+    return code;
+}