diff --git a/js/src/jit/BaselineIC.cpp b/js/src/jit/BaselineIC.cpp
index ae9ad0652d65..3b5ef9751d59 100644
--- a/js/src/jit/BaselineIC.cpp
+++ b/js/src/jit/BaselineIC.cpp
@@ -3293,7 +3293,7 @@ ICGetElemNativeCompiler<T>::emitCallScripted(MacroAssembler& masm, Register objR
     // Push argc, callee, and descriptor.
     {
         Register callScratch = regs.takeAny();
-        EmitCreateStubFrameDescriptor(masm, callScratch);
+        EmitBaselineCreateStubFrameDescriptor(masm, callScratch);
         masm.Push(Imm32(0));  // ActualArgc is 0
         masm.Push(callee);
         masm.Push(callScratch);
@@ -7215,7 +7215,7 @@ ICGetProp_CallScripted::Compiler::generateStubCode(MacroAssembler& masm)
     // Note that we use Push, not push, so that callJit will align the stack
     // properly on ARM.
     masm.Push(R0);
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
     masm.Push(Imm32(0));  // ActualArgc is 0
     masm.Push(callee);
     masm.Push(scratch);
@@ -8747,7 +8747,7 @@ ICSetProp_CallScripted::Compiler::generateStubCode(MacroAssembler& masm)
     // Stack: [ ..., R0, R1, ..STUBFRAME-HEADER.., padding? ]
     masm.PushValue(Address(BaselineFrameReg, STUB_FRAME_SIZE));
     masm.Push(R0);
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
     masm.Push(Imm32(1));  // ActualArgc is 1
     masm.Push(callee);
     masm.Push(scratch);
@@ -10171,7 +10171,7 @@ ICCallScriptedCompiler::generateStubCode(MacroAssembler& masm)
     masm.popValue(val);
     callee = masm.extractObject(val, ExtractTemp0);
 
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
 
     // Note that we use Push, not push, so that callJit will align the stack
     // properly on ARM.
@@ -10474,7 +10474,7 @@ ICCall_Native::Compiler::generateStubCode(MacroAssembler& masm)
     masm.push(argcReg);
 
     Register scratch = regs.takeAny();
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
     masm.push(scratch);
     masm.push(ICTailCallReg);
     masm.enterFakeExitFrame(NativeExitFrameLayout::Token());
@@ -10572,7 +10572,7 @@ ICCall_ClassHook::Compiler::generateStubCode(MacroAssembler& masm)
     // Construct a native exit frame.
     masm.push(argcReg);
 
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
     masm.push(scratch);
     masm.push(ICTailCallReg);
     masm.enterFakeExitFrame(NativeExitFrameLayout::Token());
@@ -10659,7 +10659,7 @@ ICCall_ScriptedApplyArray::Compiler::generateStubCode(MacroAssembler& masm)
     // All pushes after this use Push instead of push to make sure ARM can align
     // stack properly for call.
     Register scratch = regs.takeAny();
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
 
     // Reload argc from length of array.
     masm.extractObject(arrayVal, argcReg);
@@ -10760,7 +10760,7 @@ ICCall_ScriptedApplyArguments::Compiler::generateStubCode(MacroAssembler& masm)
     // All pushes after this use Push instead of push to make sure ARM can align
     // stack properly for call.
     Register scratch = regs.takeAny();
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
 
     masm.loadPtr(Address(BaselineFrameReg, 0), argcReg);
     masm.loadPtr(Address(argcReg, BaselineFrame::offsetOfNumActualArgs()), argcReg);
@@ -10893,7 +10893,7 @@ ICCall_ScriptedFunCall::Compiler::generateStubCode(MacroAssembler& masm)
     callee = masm.extractObject(val, ExtractTemp0);
 
     Register scratch = regs.takeAny();
-    EmitCreateStubFrameDescriptor(masm, scratch);
+    EmitBaselineCreateStubFrameDescriptor(masm, scratch);
 
     // Note that we use Push, not push, so that callJit will align the stack
     // properly on ARM.
diff --git a/js/src/jit/SharedIC.cpp b/js/src/jit/SharedIC.cpp
index 5539e92f3269..a3f3a85ec1a3 100644
--- a/js/src/jit/SharedIC.cpp
+++ b/js/src/jit/SharedIC.cpp
@@ -746,7 +746,12 @@ ICStubCompiler::tailCallVM(const VMFunction& fun, MacroAssembler& masm)
 
     MOZ_ASSERT(fun.expectTailCall == TailCall);
     uint32_t argSize = fun.explicitStackSlots() * sizeof(void*);
-    EmitTailCallVM(code, masm, argSize);
+    if (engine_ == Engine::Baseline) {
+        EmitBaselineTailCallVM(code, masm, argSize);
+    } else {
+        uint32_t stackSize = argSize + fun.extraValuesToPop * sizeof(Value);
+        EmitIonTailCallVM(code, masm, stackSize);
+    }
     return true;
 }
 
@@ -760,7 +765,10 @@ ICStubCompiler::callVM(const VMFunction& fun, MacroAssembler& masm)
         return false;
 
     MOZ_ASSERT(fun.expectTailCall == NonTailCall);
-    EmitCallVM(code, masm);
+    if (engine_ == Engine::Baseline)
+        EmitBaselineCallVM(code, masm);
+    else
+        EmitIonCallVM(code, fun.explicitStackSlots(), masm);
     return true;
 }
 
@@ -778,7 +786,10 @@ ICStubCompiler::callTypeUpdateIC(MacroAssembler& masm, uint32_t objectOffset)
 void
 ICStubCompiler::enterStubFrame(MacroAssembler& masm, Register scratch)
 {
-    EmitEnterStubFrame(masm, scratch);
+    if (engine_ == Engine::Baseline)
+        EmitBaselineEnterStubFrame(masm, scratch);
+    else
+        EmitIonEnterStubFrame(masm, scratch);
 
     MOZ_ASSERT(!inStubFrame_);
     inStubFrame_ = true;
@@ -793,12 +804,21 @@ ICStubCompiler::leaveStubFrame(MacroAssembler& masm, bool calledIntoIon)
 {
     MOZ_ASSERT(entersStubFrame_ && inStubFrame_);
     inStubFrame_ = false;
-    EmitLeaveStubFrame(masm, calledIntoIon);
+
+    if (engine_ == Engine::Baseline)
+        EmitBaselineLeaveStubFrame(masm, calledIntoIon);
+    else
+        EmitIonLeaveStubFrame(masm);
 }
 
 void
 ICStubCompiler::pushFramePtr(MacroAssembler& masm, Register scratch)
 {
+    if (engine_ == Engine::IonMonkey) {
+        masm.push(Imm32(0));
+        return;
+    }
+
     if (inStubFrame_) {
         masm.loadPtr(Address(BaselineFrameReg, 0), scratch);
         masm.pushBaselineFramePtr(scratch, scratch);
diff --git a/js/src/jit/arm/SharedICHelpers-arm.h b/js/src/jit/arm/SharedICHelpers-arm.h
index 9f1419a01054..8e9a9cda842a 100644
--- a/js/src/jit/arm/SharedICHelpers-arm.h
+++ b/js/src/jit/arm/SharedICHelpers-arm.h
@@ -79,7 +79,7 @@ EmitChangeICReturnAddress(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
+EmitBaselineTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 {
     // We assume during this that R0 and R1 have been pushed, and that R2 is
     // unused.
@@ -106,7 +106,13 @@ EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 }
 
 inline void
-EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
+EmitIonTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t stackSize)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 {
     // Compute stub frame size. We have to add two pointers: the stub reg and
     // previous frame pointer pushed by EmitEnterStubFrame.
@@ -118,19 +124,25 @@ EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitCallVM(JitCode* target, MacroAssembler& masm)
+EmitBaselineCallVM(JitCode* target, MacroAssembler& masm)
 {
-    EmitCreateStubFrameDescriptor(masm, r0);
+    EmitBaselineCreateStubFrameDescriptor(masm, r0);
     masm.push(r0);
     masm.call(target);
 }
 
+inline void
+EmitIonCallVM(JitCode* target, size_t stackSlots, MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 // Size of vales pushed by EmitEnterStubFrame.
 static const uint32_t STUB_FRAME_SIZE = 4 * sizeof(void*);
 static const uint32_t STUB_FRAME_SAVED_STUB_OFFSET = sizeof(void*);
 
 inline void
-EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
+EmitBaselineEnterStubFrame(MacroAssembler& masm, Register scratch)
 {
     MOZ_ASSERT(scratch != ICTailCallReg);
 
@@ -159,7 +171,13 @@ EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
 }
 
 inline void
-EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
+EmitIonEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
 {
     // Ion frames do not save and restore the frame pointer. If we called into
     // Ion, we have to restore the stack pointer from the frame descriptor. If
@@ -183,6 +201,12 @@ EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
     masm.pop(ScratchRegister);
 }
 
+inline void
+EmitIonLeaveStubFrame(MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 inline void
 EmitStowICValues(MacroAssembler& masm, int values)
 {
@@ -262,7 +286,7 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.j(Assembler::Equal, &success);
 
     // If the IC failed, then call the update fallback function.
-    EmitEnterStubFrame(masm, R1.scratchReg());
+    EmitBaselineEnterStubFrame(masm, R1.scratchReg());
 
     masm.loadValue(Address(BaselineStackReg, STUB_FRAME_SIZE + objectOffset), R1);
 
@@ -274,8 +298,8 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.loadPtr(Address(BaselineFrameReg, 0), R0.scratchReg());
     masm.pushBaselineFramePtr(R0.scratchReg(), R0.scratchReg());
 
-    EmitCallVM(code, masm);
-    EmitLeaveStubFrame(masm);
+    EmitBaselineCallVM(code, masm);
+    EmitBaselineLeaveStubFrame(masm);
 
     // Success at end.
     masm.bind(&success);
diff --git a/js/src/jit/arm/Trampoline-arm.cpp b/js/src/jit/arm/Trampoline-arm.cpp
index 9baeb12259b4..7eca4cdaee5e 100644
--- a/js/src/jit/arm/Trampoline-arm.cpp
+++ b/js/src/jit/arm/Trampoline-arm.cpp
@@ -980,7 +980,7 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
     // stub frame has a nullptr ICStub pointer, since this pointer is marked
     // during GC.
     masm.movePtr(ImmPtr(nullptr), ICStubReg);
-    EmitEnterStubFrame(masm, scratch2);
+    EmitBaselineEnterStubFrame(masm, scratch2);
 
     JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
     if (!code)
@@ -988,9 +988,9 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
 
     masm.push(lr);
     masm.push(scratch1);
-    EmitCallVM(code, masm);
+    EmitBaselineCallVM(code, masm);
 
-    EmitLeaveStubFrame(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
diff --git a/js/src/jit/mips32/SharedICHelpers-mips32.h b/js/src/jit/mips32/SharedICHelpers-mips32.h
index e0269ad7e3d6..68a398a67911 100644
--- a/js/src/jit/mips32/SharedICHelpers-mips32.h
+++ b/js/src/jit/mips32/SharedICHelpers-mips32.h
@@ -78,7 +78,7 @@ EmitChangeICReturnAddress(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
+EmitBaselineTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 {
     // We assume during this that R0 and R1 have been pushed, and that R2 is
     // unused.
@@ -107,7 +107,13 @@ EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 }
 
 inline void
-EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
+EmitIonTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t stackSize)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 {
     // Compute stub frame size. We have to add two pointers: the stub reg and
     // previous frame pointer pushed by EmitEnterStubFrame.
@@ -119,13 +125,19 @@ EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitCallVM(JitCode* target, MacroAssembler& masm)
+EmitBaselineCallVM(JitCode* target, MacroAssembler& masm)
 {
-    EmitCreateStubFrameDescriptor(masm, t6);
+    EmitBaselineCreateStubFrameDescriptor(masm, t6);
     masm.push(t6);
     masm.call(target);
 }
 
+inline void
+EmitIonCallVM(JitCode* target, size_t stackSlots, MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 struct BaselineStubFrame {
     uintptr_t savedFrame;
     uintptr_t savedStub;
@@ -137,7 +149,7 @@ static const uint32_t STUB_FRAME_SIZE = sizeof(BaselineStubFrame);
 static const uint32_t STUB_FRAME_SAVED_STUB_OFFSET = offsetof(BaselineStubFrame, savedStub);
 
 inline void
-EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
+mitBaselineEnterStubFrame(MacroAssembler& masm, Register scratch)
 {
     MOZ_ASSERT(scratch != ICTailCallReg);
 
@@ -170,7 +182,13 @@ EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
 }
 
 inline void
-EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
+EmitIonEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
 {
     // Ion frames do not save and restore the frame pointer. If we called
     // into Ion, we have to restore the stack pointer from the frame descriptor.
@@ -198,6 +216,12 @@ EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
     masm.addPtr(Imm32(STUB_FRAME_SIZE), StackPointer);
 }
 
+inline void
+EmitIonLeaveStubFrame(MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 inline void
 EmitStowICValues(MacroAssembler& masm, int values)
 {
@@ -274,7 +298,7 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.ma_b(R1.scratchReg(), Imm32(1), &success, Assembler::Equal, ShortJump);
 
     // If the IC failed, then call the update fallback function.
-    EmitEnterStubFrame(masm, R1.scratchReg());
+    EmitBaselineEnterStubFrame(masm, R1.scratchReg());
 
     masm.loadValue(Address(BaselineStackReg, STUB_FRAME_SIZE + objectOffset), R1);
 
@@ -286,8 +310,8 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.loadPtr(Address(BaselineFrameReg, 0), R0.scratchReg());
     masm.pushBaselineFramePtr(R0.scratchReg(), R0.scratchReg());
 
-    EmitCallVM(code, masm);
-    EmitLeaveStubFrame(masm);
+    EmitBaselineCallVM(code, masm);
+    EmitBaselineLeaveStubFrame(masm);
 
     // Success at end.
     masm.bind(&success);
diff --git a/js/src/jit/mips32/Trampoline-mips32.cpp b/js/src/jit/mips32/Trampoline-mips32.cpp
index e899a2b3babf..d57865c0a08d 100644
--- a/js/src/jit/mips32/Trampoline-mips32.cpp
+++ b/js/src/jit/mips32/Trampoline-mips32.cpp
@@ -948,7 +948,7 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
     // the stub frame has a nullptr ICStub pointer, since this pointer is
     // marked during GC.
     masm.movePtr(ImmPtr(nullptr), ICStubReg);
-    EmitEnterStubFrame(masm, scratch2);
+    EmitBaselineEnterStubFrame(masm, scratch2);
 
     JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
     if (!code)
@@ -958,9 +958,9 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
     masm.storePtr(ra, Address(StackPointer, sizeof(uintptr_t)));
     masm.storePtr(scratch1, Address(StackPointer, 0));
 
-    EmitCallVM(code, masm);
+    EmitBaselineCallVM(code, masm);
 
-    EmitLeaveStubFrame(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
diff --git a/js/src/jit/none/SharedICHelpers-none.h b/js/src/jit/none/SharedICHelpers-none.h
index a35d6e0196bd..1cb33aaad097 100644
--- a/js/src/jit/none/SharedICHelpers-none.h
+++ b/js/src/jit/none/SharedICHelpers-none.h
@@ -20,11 +20,15 @@ inline void EmitCallIC(CodeOffsetLabel*, MacroAssembler&) { MOZ_CRASH(); }
 inline void EmitEnterTypeMonitorIC(MacroAssembler&, size_t v = 0) { MOZ_CRASH(); }
 inline void EmitReturnFromIC(MacroAssembler&) { MOZ_CRASH(); }
 inline void EmitChangeICReturnAddress(MacroAssembler&, Register) { MOZ_CRASH(); }
-inline void EmitTailCallVM(JitCode*, MacroAssembler&, uint32_t) { MOZ_CRASH(); }
-inline void EmitCreateStubFrameDescriptor(MacroAssembler&, Register) { MOZ_CRASH(); }
-inline void EmitCallVM(JitCode*, MacroAssembler&) { MOZ_CRASH(); }
-inline void EmitEnterStubFrame(MacroAssembler&, Register) { MOZ_CRASH(); }
-inline void EmitLeaveStubFrame(MacroAssembler&, bool v = false) { MOZ_CRASH(); }
+inline void EmitBaselineTailCallVM(JitCode*, MacroAssembler&, uint32_t) { MOZ_CRASH(); }
+inline void EmitIonTailCallVM(JitCode*, MacroAssembler&, uint32_t) { MOZ_CRASH(); }
+inline void EmitBaselineCreateStubFrameDescriptor(MacroAssembler&, Register) { MOZ_CRASH(); }
+inline void EmitBaselineCallVM(JitCode*, MacroAssembler&) { MOZ_CRASH(); }
+inline void EmitIonCallVM(JitCode*, size_t, MacroAssembler&) { MOZ_CRASH(); }
+inline void EmitBaselineEnterStubFrame(MacroAssembler&, Register) { MOZ_CRASH(); }
+inline void EmitIonEnterStubFrame(MacroAssembler&, Register) { MOZ_CRASH(); }
+inline void EmitBaselineLeaveStubFrame(MacroAssembler&, bool v = false) { MOZ_CRASH(); }
+inline void EmitIonLeaveStubFrame(MacroAssembler&) { MOZ_CRASH(); }
 inline void EmitStowICValues(MacroAssembler&, int) { MOZ_CRASH(); }
 inline void EmitUnstowICValues(MacroAssembler&, int, bool v = false) { MOZ_CRASH(); }
 inline void EmitCallTypeUpdateIC(MacroAssembler&, JitCode*, uint32_t) { MOZ_CRASH(); }
diff --git a/js/src/jit/x64/SharedICHelpers-x64.h b/js/src/jit/x64/SharedICHelpers-x64.h
index f00d2569914d..11203017cb8c 100644
--- a/js/src/jit/x64/SharedICHelpers-x64.h
+++ b/js/src/jit/x64/SharedICHelpers-x64.h
@@ -70,7 +70,7 @@ EmitChangeICReturnAddress(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
+EmitBaselineTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 {
     // We an assume during this that R0 and R1 have been pushed.
     masm.movq(BaselineFrameReg, ScratchReg);
@@ -90,7 +90,13 @@ EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 }
 
 inline void
-EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
+EmitIonTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t stackSize)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 {
     // Compute stub frame size. We have to add two pointers: the stub reg and previous
     // frame pointer pushed by EmitEnterStubFrame.
@@ -102,19 +108,25 @@ EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitCallVM(JitCode* target, MacroAssembler& masm)
+EmitBaselineCallVM(JitCode* target, MacroAssembler& masm)
 {
-    EmitCreateStubFrameDescriptor(masm, ScratchReg);
+    EmitBaselineCreateStubFrameDescriptor(masm, ScratchReg);
     masm.push(ScratchReg);
     masm.call(target);
 }
 
+inline void
+EmitIonCallVM(JitCode* target, size_t stackSlots, MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 // Size of vales pushed by EmitEnterStubFrame.
 static const uint32_t STUB_FRAME_SIZE = 4 * sizeof(void*);
 static const uint32_t STUB_FRAME_SAVED_STUB_OFFSET = sizeof(void*);
 
 inline void
-EmitEnterStubFrame(MacroAssembler& masm, Register)
+EmitBaselineEnterStubFrame(MacroAssembler& masm, Register)
 {
     EmitRestoreTailCallReg(masm);
 
@@ -140,7 +152,13 @@ EmitEnterStubFrame(MacroAssembler& masm, Register)
 }
 
 inline void
-EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
+EmitIonEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
 {
     // Ion frames do not save and restore the frame pointer. If we called
     // into Ion, we have to restore the stack pointer from the frame descriptor.
@@ -165,6 +183,12 @@ EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
     masm.storePtr(ICTailCallReg, Address(BaselineStackReg, 0));
 }
 
+inline void
+EmitIonLeaveStubFrame(MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 inline void
 EmitStowICValues(MacroAssembler& masm, int values)
 {
@@ -242,7 +266,7 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.j(Assembler::Equal, &success);
 
     // If the IC failed, then call the update fallback function.
-    EmitEnterStubFrame(masm, R1.scratchReg());
+    EmitBaselineEnterStubFrame(masm, R1.scratchReg());
 
     masm.loadValue(Address(BaselineStackReg, STUB_FRAME_SIZE + objectOffset), R1);
 
@@ -254,8 +278,8 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.loadPtr(Address(BaselineFrameReg, 0), R0.scratchReg());
     masm.pushBaselineFramePtr(R0.scratchReg(), R0.scratchReg());
 
-    EmitCallVM(code, masm);
-    EmitLeaveStubFrame(masm);
+    EmitBaselineCallVM(code, masm);
+    EmitBaselineLeaveStubFrame(masm);
 
     // Success at end.
     masm.bind(&success);
diff --git a/js/src/jit/x64/Trampoline-x64.cpp b/js/src/jit/x64/Trampoline-x64.cpp
index 48afad42d99d..9a7893045016 100644
--- a/js/src/jit/x64/Trampoline-x64.cpp
+++ b/js/src/jit/x64/Trampoline-x64.cpp
@@ -872,7 +872,7 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
     // the stub frame has a nullptr ICStub pointer, since this pointer is marked
     // during GC.
     masm.movePtr(ImmPtr(nullptr), ICStubReg);
-    EmitEnterStubFrame(masm, scratch3);
+    EmitBaselineEnterStubFrame(masm, scratch3);
 
     JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
     if (!code)
@@ -880,9 +880,9 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
 
     masm.push(scratch1);
     masm.push(scratch2);
-    EmitCallVM(code, masm);
+    EmitBaselineCallVM(code, masm);
 
-    EmitLeaveStubFrame(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
diff --git a/js/src/jit/x86/SharedICHelpers-x86.h b/js/src/jit/x86/SharedICHelpers-x86.h
index d8d6135e92a8..1be795ad493b 100644
--- a/js/src/jit/x86/SharedICHelpers-x86.h
+++ b/js/src/jit/x86/SharedICHelpers-x86.h
@@ -71,7 +71,7 @@ EmitChangeICReturnAddress(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
+EmitBaselineTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 {
     // We assume during this that R0 and R1 have been pushed.
 
@@ -93,7 +93,13 @@ EmitTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t argSize)
 }
 
 inline void
-EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
+EmitIonTailCallVM(JitCode* target, MacroAssembler& masm, uint32_t stackSize)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 {
     // Compute stub frame size. We have to add two pointers: the stub reg and previous
     // frame pointer pushed by EmitEnterStubFrame.
@@ -105,19 +111,25 @@ EmitCreateStubFrameDescriptor(MacroAssembler& masm, Register reg)
 }
 
 inline void
-EmitCallVM(JitCode* target, MacroAssembler& masm)
+EmitBaselineCallVM(JitCode* target, MacroAssembler& masm)
 {
-    EmitCreateStubFrameDescriptor(masm, eax);
+    EmitBaselineCreateStubFrameDescriptor(masm, eax);
     masm.push(eax);
     masm.call(target);
 }
 
+inline void
+EmitIonCallVM(JitCode* target, size_t stackSlots, MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 // Size of vales pushed by EmitEnterStubFrame.
 static const uint32_t STUB_FRAME_SIZE = 4 * sizeof(void*);
 static const uint32_t STUB_FRAME_SAVED_STUB_OFFSET = sizeof(void*);
 
 inline void
-EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
+EmitBaselineEnterStubFrame(MacroAssembler& masm, Register scratch)
 {
     MOZ_ASSERT(scratch != ICTailCallReg);
 
@@ -145,7 +157,13 @@ EmitEnterStubFrame(MacroAssembler& masm, Register scratch)
 }
 
 inline void
-EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
+EmitIonEnterStubFrame(MacroAssembler& masm, Register scratch)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
+inline void
+EmitBaselineLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
 {
     // Ion frames do not save and restore the frame pointer. If we called
     // into Ion, we have to restore the stack pointer from the frame descriptor.
@@ -171,6 +189,12 @@ EmitLeaveStubFrame(MacroAssembler& masm, bool calledIntoIon = false)
     masm.storePtr(ICTailCallReg, Address(BaselineStackReg, 0));
 }
 
+inline void
+EmitIonLeaveStubFrame(MacroAssembler& masm)
+{
+    MOZ_CRASH("Not implemented yet.");
+}
+
 inline void
 EmitStowICValues(MacroAssembler& masm, int values)
 {
@@ -248,7 +272,7 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.j(Assembler::Equal, &success);
 
     // If the IC failed, then call the update fallback function.
-    EmitEnterStubFrame(masm, R1.scratchReg());
+    EmitBaselineEnterStubFrame(masm, R1.scratchReg());
 
     masm.loadValue(Address(BaselineStackReg, STUB_FRAME_SIZE + objectOffset), R1);
 
@@ -260,8 +284,8 @@ EmitCallTypeUpdateIC(MacroAssembler& masm, JitCode* code, uint32_t objectOffset)
     masm.loadPtr(Address(BaselineFrameReg, 0), R0.scratchReg());
     masm.pushBaselineFramePtr(R0.scratchReg(), R0.scratchReg());
 
-    EmitCallVM(code, masm);
-    EmitLeaveStubFrame(masm);
+    EmitBaselineCallVM(code, masm);
+    EmitBaselineLeaveStubFrame(masm);
 
     // Success at end.
     masm.bind(&success);
diff --git a/js/src/jit/x86/Trampoline-x86.cpp b/js/src/jit/x86/Trampoline-x86.cpp
index 7194759ef59a..f5f87edd10c8 100644
--- a/js/src/jit/x86/Trampoline-x86.cpp
+++ b/js/src/jit/x86/Trampoline-x86.cpp
@@ -900,7 +900,7 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
     // the stub frame has a nullptr ICStub pointer, since this pointer is
     // marked during GC.
     masm.movePtr(ImmPtr(nullptr), ICStubReg);
-    EmitEnterStubFrame(masm, scratch3);
+    EmitBaselineEnterStubFrame(masm, scratch3);
 
     JitCode* code = cx->runtime()->jitRuntime()->getVMWrapper(HandleDebugTrapInfo);
     if (!code)
@@ -908,9 +908,9 @@ JitRuntime::generateDebugTrapHandler(JSContext* cx)
 
     masm.push(scratch1);
     masm.push(scratch2);
-    EmitCallVM(code, masm);
+    EmitBaselineCallVM(code, masm);
 
-    EmitLeaveStubFrame(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