X87: Now that vector ics are established for load, keyed load and call ics, let's...

port 323ced9e272e234d19db13d407b5bb9da266681d (r28422).

original commit message:

BUG=

Review URL: https://codereview.chromium.org/1142713007

Cr-Commit-Position: refs/heads/master@{#28467}

diff --git a/src/ic/x87/handler-compiler-x87.cc b/src/ic/x87/handler-compiler-x87.cc
index e9c8e4f..32ca191 100644 (file)
--- a/src/ic/x87/handler-compiler-x87.cc
+++ b/src/ic/x87/handler-compiler-x87.cc
@@ -130,10 +130,9 @@ void NamedLoadHandlerCompiler::GenerateDirectLoadGlobalFunctionPrototype(
 void NamedLoadHandlerCompiler::GenerateLoadFunctionPrototype(
     MacroAssembler* masm, Register receiver, Register scratch1,
     Register scratch2, Label* miss_label) {
-  DCHECK(!FLAG_vector_ics);
-  __ TryGetFunctionPrototype(receiver, scratch1, scratch2, miss_label);
-  __ mov(eax, scratch1);
-  __ ret(0);
+  // TODO(mvstanton): This isn't used on ia32. Move all the other
+  // platform implementations into a code stub so this method can be removed.
+  UNREACHABLE();
 }
 
 

diff --git a/src/ic/x87/ic-x87.cc b/src/ic/x87/ic-x87.cc
index 92005bd..13173fc 100644 (file)
--- a/src/ic/x87/ic-x87.cc
+++ b/src/ic/x87/ic-x87.cc
@@ -399,26 +399,21 @@ void KeyedLoadIC::GenerateMegamorphic(MacroAssembler* masm) {
          Immediate(isolate->factory()->hash_table_map()));
   __ j(equal, &probe_dictionary);
 
-  if (FLAG_vector_ics) {
-    // When vector ics are in use, the handlers in the stub cache expect a
-    // vector and slot. Since we won't change the IC from any downstream
-    // misses, a dummy vector can be used.
-    Handle<TypeFeedbackVector> dummy_vector = Handle<TypeFeedbackVector>::cast(
-        isolate->factory()->keyed_load_dummy_vector());
-    int slot = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
-    __ push(Immediate(Smi::FromInt(slot)));
-    __ push(Immediate(dummy_vector));
-  }
+  // The handlers in the stub cache expect a vector and slot. Since we won't
+  // change the IC from any downstream misses, a dummy vector can be used.
+  Handle<TypeFeedbackVector> dummy_vector = Handle<TypeFeedbackVector>::cast(
+      isolate->factory()->keyed_load_dummy_vector());
+  int slot = dummy_vector->GetIndex(FeedbackVectorICSlot(0));
+  __ push(Immediate(Smi::FromInt(slot)));
+  __ push(Immediate(dummy_vector));
 
   Code::Flags flags = Code::RemoveTypeAndHolderFromFlags(
       Code::ComputeHandlerFlags(Code::LOAD_IC));
   masm->isolate()->stub_cache()->GenerateProbe(masm, Code::KEYED_LOAD_IC, flags,
                                                false, receiver, key, ebx, edi);
 
-  if (FLAG_vector_ics) {
-    __ pop(VectorLoadICDescriptor::VectorRegister());
-    __ pop(VectorLoadICDescriptor::SlotRegister());
-  }
+  __ pop(VectorLoadICDescriptor::VectorRegister());
+  __ pop(VectorLoadICDescriptor::SlotRegister());
 
   // Cache miss.
   GenerateMiss(masm);
@@ -733,26 +728,18 @@ void LoadIC::GenerateNormal(MacroAssembler* masm) {
 static void LoadIC_PushArgs(MacroAssembler* masm) {
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register name = LoadDescriptor::NameRegister();
-  if (FLAG_vector_ics) {
-    Register slot = VectorLoadICDescriptor::SlotRegister();
-    Register vector = VectorLoadICDescriptor::VectorRegister();
-    DCHECK(!edi.is(receiver) && !edi.is(name) && !edi.is(slot) &&
-           !edi.is(vector));
-
-    __ pop(edi);
-    __ push(receiver);
-    __ push(name);
-    __ push(slot);
-    __ push(vector);
-    __ push(edi);
-  } else {
-    DCHECK(!ebx.is(receiver) && !ebx.is(name));
-
-    __ pop(ebx);
-    __ push(receiver);
-    __ push(name);
-    __ push(ebx);
-  }
+
+  Register slot = VectorLoadICDescriptor::SlotRegister();
+  Register vector = VectorLoadICDescriptor::VectorRegister();
+  DCHECK(!edi.is(receiver) && !edi.is(name) && !edi.is(slot) &&
+         !edi.is(vector));
+
+  __ pop(edi);
+  __ push(receiver);
+  __ push(name);
+  __ push(slot);
+  __ push(vector);
+  __ push(edi);
 }
 
 
@@ -764,7 +751,7 @@ void LoadIC::GenerateMiss(MacroAssembler* masm) {
   // Perform tail call to the entry.
   ExternalReference ref =
       ExternalReference(IC_Utility(kLoadIC_Miss), masm->isolate());
-  int arg_count = FLAG_vector_ics ? 4 : 2;
+  int arg_count = 4;
   __ TailCallExternalReference(ref, arg_count, 1);
 }
 
@@ -794,7 +781,7 @@ void KeyedLoadIC::GenerateMiss(MacroAssembler* masm) {
   // Perform tail call to the entry.
   ExternalReference ref =
       ExternalReference(IC_Utility(kKeyedLoadIC_Miss), masm->isolate());
-  int arg_count = FLAG_vector_ics ? 4 : 2;
+  int arg_count = 4;
   __ TailCallExternalReference(ref, arg_count, 1);
 }
 

diff --git a/src/x87/code-stubs-x87.cc b/src/x87/code-stubs-x87.cc
index 971dd4a..b12c651 100644 (file)
--- a/src/x87/code-stubs-x87.cc
+++ b/src/x87/code-stubs-x87.cc
@@ -333,20 +333,15 @@ void MathPowStub::Generate(MacroAssembler* masm) {
 void FunctionPrototypeStub::Generate(MacroAssembler* masm) {
   Label miss;
   Register receiver = LoadDescriptor::ReceiverRegister();
+  // With careful management, we won't have to save slot and vector on
+  // the stack. Simply handle the possibly missing case first.
+  // TODO(mvstanton): this code can be more efficient.
+  __ cmp(FieldOperand(receiver, JSFunction::kPrototypeOrInitialMapOffset),
+         Immediate(isolate()->factory()->the_hole_value()));
+  __ j(equal, &miss);
+  __ TryGetFunctionPrototype(receiver, eax, ebx, &miss);
+  __ ret(0);
 
-  if (FLAG_vector_ics) {
-    // With careful management, we won't have to save slot and vector on
-    // the stack. Simply handle the possibly missing case first.
-    // TODO(mvstanton): this code can be more efficient.
-    __ cmp(FieldOperand(receiver, JSFunction::kPrototypeOrInitialMapOffset),
-           Immediate(isolate()->factory()->the_hole_value()));
-    __ j(equal, &miss);
-    __ TryGetFunctionPrototype(receiver, eax, ebx, &miss);
-    __ ret(0);
-  } else {
-    NamedLoadHandlerCompiler::GenerateLoadFunctionPrototype(masm, receiver, eax,
-                                                            ebx, &miss);
-  }
   __ bind(&miss);
   PropertyAccessCompiler::TailCallBuiltin(
       masm, PropertyAccessCompiler::MissBuiltin(Code::LOAD_IC));
@@ -393,9 +388,8 @@ void LoadIndexedStringStub::Generate(MacroAssembler* masm) {
   DCHECK(!scratch.is(receiver) && !scratch.is(index));
   Register result = eax;
   DCHECK(!result.is(scratch));
-  DCHECK(!FLAG_vector_ics ||
-         (!scratch.is(VectorLoadICDescriptor::VectorRegister()) &&
-          result.is(VectorLoadICDescriptor::SlotRegister())));
+  DCHECK(!scratch.is(VectorLoadICDescriptor::VectorRegister()) &&
+         result.is(VectorLoadICDescriptor::SlotRegister()));
 
   // StringCharAtGenerator doesn't use the result register until it's passed
   // the different miss possibilities. If it did, we would have a conflict
@@ -2664,7 +2658,7 @@ void StringCharCodeAtGenerator::GenerateSlow(
               index_not_number_,
               DONT_DO_SMI_CHECK);
   call_helper.BeforeCall(masm);
-  if (FLAG_vector_ics && embed_mode == PART_OF_IC_HANDLER) {
+  if (embed_mode == PART_OF_IC_HANDLER) {
     __ push(VectorLoadICDescriptor::VectorRegister());
     __ push(VectorLoadICDescriptor::SlotRegister());
   }
@@ -2683,7 +2677,7 @@ void StringCharCodeAtGenerator::GenerateSlow(
     __ mov(index_, eax);
   }
   __ pop(object_);
-  if (FLAG_vector_ics && embed_mode == PART_OF_IC_HANDLER) {
+  if (embed_mode == PART_OF_IC_HANDLER) {
     __ pop(VectorLoadICDescriptor::SlotRegister());
     __ pop(VectorLoadICDescriptor::VectorRegister());
   }

diff --git a/src/x87/debug-x87.cc b/src/x87/debug-x87.cc
index 0bbee14..02902ee 100644 (file)
--- a/src/x87/debug-x87.cc
+++ b/src/x87/debug-x87.cc
@@ -182,10 +182,8 @@ void DebugCodegen::GenerateLoadICDebugBreak(MacroAssembler* masm) {
   // Register state for IC load call (from ic-x87.cc).
   Register receiver = LoadDescriptor::ReceiverRegister();
   Register name = LoadDescriptor::NameRegister();
-  RegList regs = receiver.bit() | name.bit();
-  if (FLAG_vector_ics) {
-    regs |= VectorLoadICTrampolineDescriptor::SlotRegister().bit();
-  }
+  RegList regs = receiver.bit() | name.bit() |
+                 VectorLoadICTrampolineDescriptor::SlotRegister().bit();
   Generate_DebugBreakCallHelper(masm, regs, 0, false);
 }
 

diff --git a/src/x87/full-codegen-x87.cc b/src/x87/full-codegen-x87.cc
index 5c51fe3..703ec75 100644 (file)
--- a/src/x87/full-codegen-x87.cc
+++ b/src/x87/full-codegen-x87.cc
@@ -1252,13 +1252,9 @@ void FullCodeGenerator::EmitLoadHomeObject(SuperReference* expr) {
   Handle<Symbol> home_object_symbol(isolate()->heap()->home_object_symbol());
   __ mov(LoadDescriptor::NameRegister(), home_object_symbol);
 
-  if (FLAG_vector_ics) {
-    __ mov(VectorLoadICDescriptor::SlotRegister(),
-           Immediate(SmiFromSlot(expr->HomeObjectFeedbackSlot())));
-    CallLoadIC(NOT_CONTEXTUAL);
-  } else {
-    CallLoadIC(NOT_CONTEXTUAL, expr->HomeObjectFeedbackId());
-  }
+  __ mov(VectorLoadICDescriptor::SlotRegister(),
+         Immediate(SmiFromSlot(expr->HomeObjectFeedbackSlot())));
+  CallLoadIC(NOT_CONTEXTUAL);
 
   __ cmp(eax, isolate()->factory()->undefined_value());
   Label done;
@@ -1333,10 +1329,8 @@ void FullCodeGenerator::EmitLoadGlobalCheckExtensions(VariableProxy* proxy,
   // load IC call.
   __ mov(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
   __ mov(LoadDescriptor::NameRegister(), proxy->var()->name());
-  if (FLAG_vector_ics) {
-    __ mov(VectorLoadICDescriptor::SlotRegister(),
-           Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
-  }
+  __ mov(VectorLoadICDescriptor::SlotRegister(),
+         Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
 
   ContextualMode mode = (typeof_state == INSIDE_TYPEOF)
       ? NOT_CONTEXTUAL
@@ -1421,10 +1415,8 @@ void FullCodeGenerator::EmitVariableLoad(VariableProxy* proxy) {
       Comment cmnt(masm_, "[ Global variable");
       __ mov(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
       __ mov(LoadDescriptor::NameRegister(), var->name());
-      if (FLAG_vector_ics) {
-        __ mov(VectorLoadICDescriptor::SlotRegister(),
-               Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
-      }
+      __ mov(VectorLoadICDescriptor::SlotRegister(),
+             Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
       CallGlobalLoadIC(var->name());
       context()->Plug(eax);
       break;
@@ -2116,10 +2108,8 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
       // result = receiver[f](arg);
       __ bind(&l_call);
       __ mov(load_receiver, Operand(esp, kPointerSize));
-      if (FLAG_vector_ics) {
-        __ mov(VectorLoadICDescriptor::SlotRegister(),
-               Immediate(SmiFromSlot(expr->KeyedLoadFeedbackSlot())));
-      }
+      __ mov(VectorLoadICDescriptor::SlotRegister(),
+             Immediate(SmiFromSlot(expr->KeyedLoadFeedbackSlot())));
       Handle<Code> ic = CodeFactory::KeyedLoadIC(isolate()).code();
       CallIC(ic, TypeFeedbackId::None());
       __ mov(edi, eax);
@@ -2136,10 +2126,8 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
       __ Move(load_receiver, eax);                       // result
       __ mov(load_name,
              isolate()->factory()->done_string());       // "done"
-      if (FLAG_vector_ics) {
-        __ mov(VectorLoadICDescriptor::SlotRegister(),
-               Immediate(SmiFromSlot(expr->DoneFeedbackSlot())));
-      }
+      __ mov(VectorLoadICDescriptor::SlotRegister(),
+             Immediate(SmiFromSlot(expr->DoneFeedbackSlot())));
       CallLoadIC(NOT_CONTEXTUAL);                        // result.done in eax
       Handle<Code> bool_ic = ToBooleanStub::GetUninitialized(isolate());
       CallIC(bool_ic);
@@ -2150,10 +2138,8 @@ void FullCodeGenerator::VisitYield(Yield* expr) {
       __ pop(load_receiver);                              // result
       __ mov(load_name,
              isolate()->factory()->value_string());       // "value"
-      if (FLAG_vector_ics) {
-        __ mov(VectorLoadICDescriptor::SlotRegister(),
-               Immediate(SmiFromSlot(expr->ValueFeedbackSlot())));
-      }
+      __ mov(VectorLoadICDescriptor::SlotRegister(),
+             Immediate(SmiFromSlot(expr->ValueFeedbackSlot())));
       CallLoadIC(NOT_CONTEXTUAL);                         // result.value in eax
       context()->DropAndPlug(2, eax);                     // drop iter and g
       break;
@@ -2291,13 +2277,9 @@ void FullCodeGenerator::EmitNamedPropertyLoad(Property* prop) {
   DCHECK(!prop->IsSuperAccess());
 
   __ mov(LoadDescriptor::NameRegister(), Immediate(key->value()));
-  if (FLAG_vector_ics) {
-    __ mov(VectorLoadICDescriptor::SlotRegister(),
-           Immediate(SmiFromSlot(prop->PropertyFeedbackSlot())));
-    CallLoadIC(NOT_CONTEXTUAL);
-  } else {
-    CallLoadIC(NOT_CONTEXTUAL, prop->PropertyFeedbackId());
-  }
+  __ mov(VectorLoadICDescriptor::SlotRegister(),
+         Immediate(SmiFromSlot(prop->PropertyFeedbackSlot())));
+  CallLoadIC(NOT_CONTEXTUAL);
 }
 
 
@@ -2316,13 +2298,9 @@ void FullCodeGenerator::EmitNamedSuperPropertyLoad(Property* prop) {
 void FullCodeGenerator::EmitKeyedPropertyLoad(Property* prop) {
   SetSourcePosition(prop->position());
   Handle<Code> ic = CodeFactory::KeyedLoadIC(isolate()).code();
-  if (FLAG_vector_ics) {
-    __ mov(VectorLoadICDescriptor::SlotRegister(),
-           Immediate(SmiFromSlot(prop->PropertyFeedbackSlot())));
-    CallIC(ic);
-  } else {
-    CallIC(ic, prop->PropertyFeedbackId());
-  }
+  __ mov(VectorLoadICDescriptor::SlotRegister(),
+         Immediate(SmiFromSlot(prop->PropertyFeedbackSlot())));
+  CallIC(ic);
 }
 
 
@@ -4543,13 +4521,9 @@ void FullCodeGenerator::EmitLoadJSRuntimeFunction(CallRuntime* expr) {
   // Load the function from the receiver.
   __ mov(LoadDescriptor::ReceiverRegister(), Operand(esp, 0));
   __ mov(LoadDescriptor::NameRegister(), Immediate(expr->name()));
-  if (FLAG_vector_ics) {
-    __ mov(VectorLoadICDescriptor::SlotRegister(),
-           Immediate(SmiFromSlot(expr->CallRuntimeFeedbackSlot())));
-    CallLoadIC(NOT_CONTEXTUAL);
-  } else {
-    CallLoadIC(NOT_CONTEXTUAL, expr->CallRuntimeFeedbackId());
-  }
+  __ mov(VectorLoadICDescriptor::SlotRegister(),
+         Immediate(SmiFromSlot(expr->CallRuntimeFeedbackSlot())));
+  CallLoadIC(NOT_CONTEXTUAL);
 }
 
 
@@ -4988,10 +4962,8 @@ void FullCodeGenerator::VisitForTypeofValue(Expression* expr) {
     Comment cmnt(masm_, "[ Global variable");
     __ mov(LoadDescriptor::ReceiverRegister(), GlobalObjectOperand());
     __ mov(LoadDescriptor::NameRegister(), Immediate(proxy->name()));
-    if (FLAG_vector_ics) {
-      __ mov(VectorLoadICDescriptor::SlotRegister(),
-             Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
-    }
+    __ mov(VectorLoadICDescriptor::SlotRegister(),
+           Immediate(SmiFromSlot(proxy->VariableFeedbackSlot())));
     // Use a regular load, not a contextual load, to avoid a reference
     // error.
     CallLoadIC(NOT_CONTEXTUAL);

diff --git a/src/x87/lithium-codegen-x87.cc b/src/x87/lithium-codegen-x87.cc
index cee37cf..ca42917 100644 (file)
--- a/src/x87/lithium-codegen-x87.cc
+++ b/src/x87/lithium-codegen-x87.cc
@@ -3144,7 +3144,6 @@ void LCodeGen::DoReturn(LReturn* instr) {
 
 template <class T>
 void LCodeGen::EmitVectorLoadICRegisters(T* instr) {
-  DCHECK(FLAG_vector_ics);
   Register vector_register = ToRegister(instr->temp_vector());
   Register slot_register = VectorLoadICDescriptor::SlotRegister();
   DCHECK(vector_register.is(VectorLoadICDescriptor::VectorRegister()));
@@ -3167,9 +3166,7 @@ void LCodeGen::DoLoadGlobalGeneric(LLoadGlobalGeneric* instr) {
   DCHECK(ToRegister(instr->result()).is(eax));
 
   __ mov(LoadDescriptor::NameRegister(), instr->name());
-  if (FLAG_vector_ics) {
-    EmitVectorLoadICRegisters<LLoadGlobalGeneric>(instr);
-  }
+  EmitVectorLoadICRegisters<LLoadGlobalGeneric>(instr);
   ContextualMode mode = instr->for_typeof() ? NOT_CONTEXTUAL : CONTEXTUAL;
   Handle<Code> ic = CodeFactory::LoadICInOptimizedCode(isolate(), mode,
                                                        PREMONOMORPHIC).code();
@@ -3280,9 +3277,7 @@ void LCodeGen::DoLoadNamedGeneric(LLoadNamedGeneric* instr) {
   DCHECK(ToRegister(instr->result()).is(eax));
 
   __ mov(LoadDescriptor::NameRegister(), instr->name());
-  if (FLAG_vector_ics) {
-    EmitVectorLoadICRegisters<LLoadNamedGeneric>(instr);
-  }
+  EmitVectorLoadICRegisters<LLoadNamedGeneric>(instr);
   Handle<Code> ic = CodeFactory::LoadICInOptimizedCode(
                         isolate(), NOT_CONTEXTUAL,
                         instr->hydrogen()->initialization_state()).code();
@@ -3751,27 +3746,6 @@ void LCodeGen::CallKnownFunction(Handle<JSFunction> function,
 }
 
 
-void LCodeGen::DoTailCallThroughMegamorphicCache(
-    LTailCallThroughMegamorphicCache* instr) {
-  Register receiver = ToRegister(instr->receiver());
-  Register name = ToRegister(instr->name());
-  DCHECK(receiver.is(LoadDescriptor::ReceiverRegister()));
-  DCHECK(name.is(LoadDescriptor::NameRegister()));
-  Register scratch = ebx;
-  Register extra = edi;
-  DCHECK(!scratch.is(receiver) && !scratch.is(name));
-  DCHECK(!extra.is(receiver) && !extra.is(name));
-
-  // The probe will tail call to a handler if found.
-  // If --vector-ics is on, then it knows to pop the two args first.
-  isolate()->stub_cache()->GenerateProbe(masm(), Code::LOAD_IC,
-                                         instr->hydrogen()->flags(), false,
-                                         receiver, name, scratch, extra);
-
-  LoadIC::GenerateMiss(masm());
-}
-
-
 void LCodeGen::DoCallWithDescriptor(LCallWithDescriptor* instr) {
   DCHECK(ToRegister(instr->result()).is(eax));
 

diff --git a/src/x87/lithium-x87.cc b/src/x87/lithium-x87.cc
index 82d746f..233d12c 100644 (file)
--- a/src/x87/lithium-x87.cc
+++ b/src/x87/lithium-x87.cc
@@ -1164,20 +1164,6 @@ LInstruction* LChunkBuilder::DoCallWithDescriptor(
 }
 
 
-LInstruction* LChunkBuilder::DoTailCallThroughMegamorphicCache(
-    HTailCallThroughMegamorphicCache* instr) {
-  LOperand* context = UseFixed(instr->context(), esi);
-  LOperand* receiver_register =
-      UseFixed(instr->receiver(), LoadDescriptor::ReceiverRegister());
-  LOperand* name_register =
-      UseFixed(instr->name(), LoadDescriptor::NameRegister());
-
-  // Not marked as call. It can't deoptimize, and it never returns.
-  return new (zone()) LTailCallThroughMegamorphicCache(
-      context, receiver_register, name_register);
-}
-
-
 LInstruction* LChunkBuilder::DoInvokeFunction(HInvokeFunction* instr) {
   LOperand* context = UseFixed(instr->context(), esi);
   LOperand* function = UseFixed(instr->function(), edi);

diff --git a/src/x87/lithium-x87.h b/src/x87/lithium-x87.h
index e1b5c48..cc4620d 100644 (file)
--- a/src/x87/lithium-x87.h
+++ b/src/x87/lithium-x87.h
@@ -156,7 +156,6 @@ class LCodeGen;
   V(StringCompareAndBranch)                  \
   V(SubI)                                    \
   V(TaggedToI)                               \
-  V(TailCallThroughMegamorphicCache)         \
   V(ThisFunction)                            \
   V(ToFastProperties)                        \
   V(TransitionElementsKind)                  \
@@ -486,26 +485,6 @@ class LCallStub final : public LTemplateInstruction<1, 1, 0> {
 };
 
 
-class LTailCallThroughMegamorphicCache final
-    : public LTemplateInstruction<0, 3, 0> {
- public:
-  LTailCallThroughMegamorphicCache(LOperand* context, LOperand* receiver,
-                                   LOperand* name) {
-    inputs_[0] = context;
-    inputs_[1] = receiver;
-    inputs_[2] = name;
-  }
-
-  LOperand* context() { return inputs_[0]; }
-  LOperand* receiver() { return inputs_[1]; }
-  LOperand* name() { return inputs_[2]; }
-
-  DECLARE_CONCRETE_INSTRUCTION(TailCallThroughMegamorphicCache,
-                               "tail-call-through-megamorphic-cache")
-  DECLARE_HYDROGEN_ACCESSOR(TailCallThroughMegamorphicCache)
-};
-
-
 class LUnknownOSRValue final : public LTemplateInstruction<1, 0, 0> {
  public:
   bool HasInterestingComment(LCodeGen* gen) const override { return false; }