Only to the relevant checks in LoadFunctionPrototype

src/x64/macro-assembler-x64.cc

Index: src/x64/macro-assembler-x64.cc
diff --git a/src/x64/macro-assembler-x64.cc b/src/x64/macro-assembler-x64.cc
index a5e2972620ad4f147bcc6c80e53b98f748f9c2dc..079f9b057113ad9b08b7b43f9164cc78584c88f3 100644
--- a/src/x64/macro-assembler-x64.cc
+++ b/src/x64/macro-assembler-x64.cc
@@ -3745,15 +3745,16 @@ void MacroAssembler::TryGetFunctionPrototype(Register function,
                                              Register result,
                                              Label* miss,
                                              bool miss_on_bound_function) {
-  // Check that the receiver isn't a smi.
-  testl(function, Immediate(kSmiTagMask));
-  j(zero, miss);
+  Label non_instance;
+  if (miss_on_bound_function) {
+    // Check that the receiver isn't a smi.
+    testl(function, Immediate(kSmiTagMask));
+    j(zero, miss);
 
-  // Check that the function really is a function.
-  CmpObjectType(function, JS_FUNCTION_TYPE, result);
-  j(not_equal, miss);
+    // Check that the function really is a function.
+    CmpObjectType(function, JS_FUNCTION_TYPE, result);
+    j(not_equal, miss);
 
-  if (miss_on_bound_function) {
     movp(kScratchRegister,
          FieldOperand(function, JSFunction::kSharedFunctionInfoOffset));
     // It's not smi-tagged (stored in the top half of a smi-tagged 8-byte
@@ -3762,13 +3763,12 @@ void MacroAssembler::TryGetFunctionPrototype(Register function,
         SharedFunctionInfo::kCompilerHintsOffset,
         SharedFunctionInfo::kBoundFunction);
     j(not_zero, miss);
-  }
 
-  // Make sure that the function has an instance prototype.
-  Label non_instance;
-  testb(FieldOperand(result, Map::kBitFieldOffset),
-        Immediate(1 << Map::kHasNonInstancePrototype));
-  j(not_zero, &non_instance, Label::kNear);
+    // Make sure that the function has an instance prototype.
+    testb(FieldOperand(result, Map::kBitFieldOffset),
+          Immediate(1 << Map::kHasNonInstancePrototype));
+    j(not_zero, &non_instance, Label::kNear);
+  }
 
   // Get the prototype or initial map from the function.
   movp(result,
@@ -3787,12 +3787,15 @@ void MacroAssembler::TryGetFunctionPrototype(Register function,
 
   // Get the prototype from the initial map.
   movp(result, FieldOperand(result, Map::kPrototypeOffset));
-  jmp(&done, Label::kNear);
 
-  // Non-instance prototype: Fetch prototype from constructor field
-  // in initial map.
-  bind(&non_instance);
-  movp(result, FieldOperand(result, Map::kConstructorOffset));
+  if (miss_on_bound_function) {
+    jmp(&done, Label::kNear);
+
+    // Non-instance prototype: Fetch prototype from constructor field
+    // in initial map.
+    bind(&non_instance);
+    movp(result, FieldOperand(result, Map::kConstructorOffset));
+  }
 
   // All done.
   bind(&done);