[strong] Function arity check should be based on required parameters

src/x64/builtins-x64.cc

 // Copyright 2012 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_X64
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 1626 matching lines @@
     __ subp(rax, Immediate(kPointerSize));
     __ cmpp(r8, rbx);
     __ j(less, &copy);
     __ jmp(&invoke);
   }
 
   {  // Too few parameters: Actual < expected.
     __ bind(&too_few);
 
     // If the function is strong we need to throw an error.
-    Label weak_function;
+    Label no_strong_error;
     __ movp(kScratchRegister,
             FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
     __ testb(FieldOperand(kScratchRegister,
                           SharedFunctionInfo::kStrongModeByteOffset),
              Immediate(1 << SharedFunctionInfo::kStrongModeBitWithinByte));
-    __ j(equal, &weak_function, Label::kNear);
+    __ j(equal, &no_strong_error, Label::kNear);
+
+    // What we really care about is the required number of arguments.
+
+    if (kPointerSize == kInt32Size) {
+      __ movp(
+          kScratchRegister,
+          FieldOperand(kScratchRegister, SharedFunctionInfo::kLengthOffset));
+      __ SmiToInteger32(kScratchRegister, kScratchRegister);
+    } else {
+      // See comment near kLengthOffset in src/objects.h
+      __ movsxlq(
+          kScratchRegister,
+          FieldOperand(kScratchRegister, SharedFunctionInfo::kLengthOffset));
+      __ shrq(kScratchRegister, Immediate(1));
+    }
+
+    __ cmpp(rax, kScratchRegister);
+    __ j(greater_equal, &no_strong_error, Label::kNear);
 
     {
       FrameScope frame(masm, StackFrame::MANUAL);
       EnterArgumentsAdaptorFrame(masm);
       __ CallRuntime(Runtime::kThrowStrongModeTooFewArguments, 0);
     }
 
-    __ bind(&weak_function);
+    __ bind(&no_strong_error);
     EnterArgumentsAdaptorFrame(masm);
 
     // Copy receiver and all actual arguments.
     const int offset = StandardFrameConstants::kCallerSPOffset;
     __ leap(rdi, Operand(rbp, rax, times_pointer_size, offset));
     __ Set(r8, -1);  // account for receiver
 
     Label copy;
     __ bind(&copy);
     __ incp(r8);
@@ skipping 93 matching lines @@
   __ bind(&ok);
   __ ret(0);
 }
 
 
 #undef __
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64