X87: [strong] Function arity check should be based on required parameters

src/x87/builtins-x87.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_X87
 
 #include "src/code-factory.h"
 #include "src/codegen.h"
@@ skipping 1561 matching lines @@
     __ sub(eax, Immediate(kPointerSize));
     __ cmp(edi, ebx);
     __ 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;
     __ mov(ecx, FieldOperand(edi, JSFunction::kSharedFunctionInfoOffset));
     __ test_b(FieldOperand(ecx, SharedFunctionInfo::kStrongModeByteOffset),
               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.
+    __ mov(ecx, FieldOperand(ecx, SharedFunctionInfo::kLengthOffset));
+    __ SmiUntag(ecx);
+    __ cmp(eax, ecx);
+    __ 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;
     __ lea(edi, Operand(ebp, eax, times_4, offset));
     // ebx = expected - actual.
     __ sub(ebx, eax);
     // eax = -actual - 1
     __ neg(eax);
     __ sub(eax, Immediate(1));
@@ skipping 97 matching lines @@
 
   __ bind(&ok);
   __ ret(0);
 }
 
 #undef __
 }
 }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X87