[strong] Implement strong mode semantics for the count operation.

src/arm64/full-codegen-arm64.cc

 // Copyright 2013 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #if V8_TARGET_ARCH_ARM64
 
 #include "src/code-factory.h"
 #include "src/code-stubs.h"
@@ skipping 4690 matching lines @@
       }
     }
 
     __ Adds(x0, x0, Smi::FromInt(count_value));
     __ B(vc, &done);
     // Call stub. Undo operation first.
     __ Sub(x0, x0, Smi::FromInt(count_value));
     __ B(&stub_call);
     __ Bind(&slow);
   }
-  ToNumberStub convert_stub(isolate());
-  __ CallStub(&convert_stub);
-  PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  if (!is_strong(language_mode())) {
+    ToNumberStub convert_stub(isolate());
+    __ CallStub(&convert_stub);
+    PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  }
 
   // Save result for postfix expressions.
   if (expr->is_postfix()) {
     if (!context()->IsEffect()) {
       // Save the result on the stack. If we have a named or keyed property
       // we store the result under the receiver that is currently on top
       // of the stack.
       switch (assign_type) {
         case VARIABLE:
           __ Push(x0);
@@ skipping 24 matching lines @@
   {
     Assembler::BlockPoolsScope scope(masm_);
     Handle<Code> code =
         CodeFactory::BinaryOpIC(isolate(), Token::ADD,
                                 strength(language_mode())).code();
     CallIC(code, expr->CountBinOpFeedbackId());
     patch_site.EmitPatchInfo();
   }
   __ Bind(&done);
 
+  if (is_strong(language_mode())) {
+    PrepareForBailoutForId(expr->ToNumberId(), TOS_REG);
+  }
   // Store the value returned in x0.
   switch (assign_type) {
     case VARIABLE:
       if (expr->is_postfix()) {
         { EffectContext context(this);
           EmitVariableAssignment(expr->expression()->AsVariableProxy()->var(),
                                  Token::ASSIGN, expr->CountSlot());
           PrepareForBailoutForId(expr->AssignmentId(), TOS_REG);
           context.Plug(x0);
         }
@@ skipping 829 matching lines @@
   }
 
   return INTERRUPT;
 }
 
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_TARGET_ARCH_ARM64