[builtins] Tweak optimized check in InterpreterEntryTrampoline

Reorders the Smi check and the empty OptimizationMarker check as the
latter implies the first and means there is now just a single comparison
on the fast path.

Bug: v8:9771
Change-Id: Ibba1f322944b17186842983e227684b301ed5f31
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/1833683
Commit-Queue: Dan Elphick <delphick@chromium.org>
Reviewed-by: Ross McIlroy <rmcilroy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#64110}

src/builtins/arm/builtins-arm.cc

@@ -1049,9 +1049,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   __ cmp(r4, Operand(FEEDBACK_VECTOR_TYPE));
   __ b(ne, &push_stack_frame);
 
-  Label has_optimization_marker;
-  Label maybe_has_optimized_code;
-
   Register optimized_code_entry = r4;
 
   // Read off the optimized code slot in the feedback vector.
@@ -1059,14 +1056,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
          FieldMemOperand(feedback_vector,
                          FeedbackVector::kOptimizedCodeWeakOrSmiOffset));
 
-  // If not a Smi, then it must be a weak reference to the optimized code.
-  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
-
-  // Check if there is an optimization marker, if so carry onto the the
-  // MaybeOptimizeCode path.
+  // Check if the optimized code slot is not empty.
+  Label optimized_code_slot_not_empty;
   __ cmp(optimized_code_entry,
          Operand(Smi::FromEnum(OptimizationMarker::kNone)));
-  __ b(ne, &has_optimization_marker);
+  __ b(ne, &optimized_code_slot_not_empty);
 
   Label not_optimized;
   __ bind(&not_optimized);
@@ -1179,7 +1173,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   LeaveInterpreterFrame(masm, r2);
   __ Jump(lr);
 
-  __ bind(&has_optimization_marker);
+  __ bind(&optimized_code_slot_not_empty);
+  Label maybe_has_optimized_code;
+  // Check if optimized code marker is actually a weak reference to the
+  // optimized code.
+  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
   MaybeOptimizeCode(masm, feedback_vector, optimized_code_entry);
   // Fall through if there's no runnable optimized code.
   __ jmp(&not_optimized);

src/builtins/arm64/builtins-arm64.cc

@@ -1179,9 +1179,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   __ Cmp(x7, FEEDBACK_VECTOR_TYPE);
   __ B(ne, &push_stack_frame);
 
-  Label has_optimization_marker;
-  Label maybe_has_optimized_code;
-
   // Read off the optimized code slot in the feedback vector, and if there
   // is optimized code or an optimization marker, call that instead.
   Register optimized_code_entry = x7;
@@ -1190,14 +1187,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
       FieldMemOperand(feedback_vector,
                       FeedbackVector::kOptimizedCodeWeakOrSmiOffset));
 
-  // If not a Smi, then it must be a weak reference to the optimized code.
-  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
-
-  // Check if there is an optimization marker and if so carry onto the the
-  // MaybeOptimizeCode path.
+  // Check if the optimized code slot is not empty.
+  Label optimized_code_slot_not_empty;
   __ CompareTaggedAndBranch(optimized_code_entry,
                             Operand(Smi::FromEnum(OptimizationMarker::kNone)),
-                            ne, &has_optimization_marker);
+                            ne, &optimized_code_slot_not_empty);
 
   Label not_optimized;
   __ bind(&not_optimized);
@@ -1318,7 +1312,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   LeaveInterpreterFrame(masm, x2);
   __ Ret();
 
-  __ bind(&has_optimization_marker);
+  __ bind(&optimized_code_slot_not_empty);
+  Label maybe_has_optimized_code;
+  // Check if optimized code marker is actually a weak reference to the
+  // optimized code as opposed to an optimization marker.
+  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
   MaybeOptimizeCode(masm, feedback_vector, optimized_code_entry);
   // Fall through if there's no runnable optimized code.
   __ jmp(&not_optimized);

src/builtins/ia32/builtins-ia32.cc

@@ -954,9 +954,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   __ CmpInstanceType(eax, FEEDBACK_VECTOR_TYPE);
   __ j(not_equal, &push_stack_frame);
 
-  Label has_optimization_marker;
-  Label maybe_has_optimized_code;
-
   // Read off the optimized code slot in the feedback vector.
   // Load the optimized code from the feedback vector and re-use the register.
   Register optimized_code_entry = ecx;
@@ -964,14 +961,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
          FieldOperand(feedback_vector,
                       FeedbackVector::kOptimizedCodeWeakOrSmiOffset));
 
-  // If not a Smi, then it must be a weak reference to the optimized code.
-  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
-
-  // Check if there is an optimization marker and if so carry onto the the
-  // MaybeOptimizeCode path.
+  // Check if the optimized code slot is not empty.
+  Label optimized_code_slot_not_empty;
   __ cmp(optimized_code_entry,
          Immediate(Smi::FromEnum(OptimizationMarker::kNone)));
-  __ j(not_equal, &has_optimization_marker);
+  __ j(not_equal, &optimized_code_slot_not_empty);
 
   Label not_optimized;
   __ bind(&not_optimized);
@@ -1107,7 +1101,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   LeaveInterpreterFrame(masm, edx, ecx);
   __ ret(0);
 
-  __ bind(&has_optimization_marker);
+  __ bind(&optimized_code_slot_not_empty);
+  Label maybe_has_optimized_code;
+  // Check if optimized code marker is actually a weak reference to the
+  // optimized code as opposed to an optimization marker.
+  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
   MaybeOptimizeCode(masm, optimized_code_entry);
   // Fall through if there's no runnable optimized code.
   __ jmp(&not_optimized);

src/builtins/x64/builtins-x64.cc

@@ -1069,8 +1069,6 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   __ CmpInstanceType(rcx, FEEDBACK_VECTOR_TYPE);
   __ j(not_equal, &push_stack_frame);
 
-  Label has_optimization_marker;
-  Label maybe_has_optimized_code;
   // Read off the optimized code slot in the feedback vector, and if there
   // is optimized code or an optimization marker, call that instead.
 
@@ -1083,13 +1081,10 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
                    FeedbackVector::kOptimizedCodeWeakOrSmiOffset),
       decompr_scratch);
 
-  // If not a Smi, then it must be a weak reference to the optimized code.
-  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
-
-  // Check if there is an optimization marker and if so carry onto the the
-  // MaybeOptimizeCode path.
-  __ SmiCompare(optimized_code_entry, Smi::FromEnum(OptimizationMarker::kNone));
-  __ j(not_equal, &has_optimization_marker);
+  // Check if the optimized code slot is not empty.
+  Label optimized_code_slot_not_empty;
+  __ Cmp(optimized_code_entry, Smi::FromEnum(OptimizationMarker::kNone));
+  __ j(not_equal, &optimized_code_slot_not_empty);
 
   Label not_optimized;
   __ bind(&not_optimized);
@@ -1210,7 +1205,11 @@ void Builtins::Generate_InterpreterEntryTrampoline(MacroAssembler* masm) {
   GenerateTailCallToReturnedCode(masm, Runtime::kCompileLazy);
   __ int3();  // Should not return.
 
-  __ bind(&has_optimization_marker);
+  __ bind(&optimized_code_slot_not_empty);
+  Label maybe_has_optimized_code;
+  // Check if optimized code marker is actually a weak reference to the
+  // optimized code as opposed to an optimization marker.
+  __ JumpIfNotSmi(optimized_code_entry, &maybe_has_optimized_code);
   MaybeOptimizeCode(masm, feedback_vector, optimized_code_entry);
   // Fall through if there's no runnable optimized code.
   __ jmp(&not_optimized);