Fix stack corruption when calling non-function.

src/x64/builtins-x64.cc

Index: src/x64/builtins-x64.cc
diff --git a/src/x64/builtins-x64.cc b/src/x64/builtins-x64.cc
index 8482023f361c1effe6e0211cdff1bf8be051b592..de30646d92c2967ecb0bdb58e637f2997fb22e0d 100644
--- a/src/x64/builtins-x64.cc
+++ b/src/x64/builtins-x64.cc
@@ -185,14 +185,14 @@ void Builtins::Generate_ArgumentsAdaptorTrampoline(MacroAssembler* masm) {
 
 void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
   // Stack Layout:
-  // rsp: return address
-  //  +1: Argument n
-  //  +2: Argument n-1
+  // rsp[0]:   Return address
+  // rsp[1]:   Argument n
+  // rsp[2]:   Argument n-1
   //  ...
-  //  +n: Argument 1 = receiver
-  //  +n+1: Argument 0 = function to call
+  // rsp[n]:   Argument 1
+  // rsp[n+1]: Receiver (function to call)
   //
-  // rax contains the number of arguments, n, not counting the function.
+  // rax contains the number of arguments, n, not counting the receiver.
   //
   // 1. Make sure we have at least one argument.
   { Label done;
@@ -205,31 +205,26 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
     __ bind(&done);
   }
 
-  // 2. Get the function to call from the stack.
-  { Label done, non_function, function;
+  // 2. Get the function to call (passed as receiver) from the stack, check
+  //    if it is a function.
+  Label non_function;
+  { Label function;
     // The function to call is at position n+1 on the stack.
-    __ movq(rdi, Operand(rsp, rax, times_pointer_size, +1 * kPointerSize));
+    __ movq(rdi, Operand(rsp, rax, times_pointer_size, 1 * kPointerSize));
     __ JumpIfSmi(rdi, &non_function);
     __ CmpObjectType(rdi, JS_FUNCTION_TYPE, rcx);
-    __ j(equal, &function);
-
-    // Non-function called: Clear the function to force exception.
-    __ bind(&non_function);
-    __ xor_(rdi, rdi);
-    __ jmp(&done);
-
-    // Function called: Change context eagerly to get the right global object.
+    __ j(not_equal, &non_function);
     __ bind(&function);
-    __ movq(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
-
-    __ bind(&done);
   }
 
-  // 3. Make sure first argument is an object; convert if necessary.
-  { Label call_to_object, use_global_receiver, patch_receiver, done;
-    __ movq(rbx, Operand(rsp, rax, times_pointer_size, 0));
+  // 3a. Patch the first argument if necessary when calling a function.
+  Label shift_arguments;
+  { Label convert_to_object, use_global_receiver, patch_receiver;
+    // Change context eagerly in case we need the global receiver.
+    __ movq(rsi, FieldOperand(rdi, JSFunction::kContextOffset));
 
-    __ JumpIfSmi(rbx, &call_to_object);
+    __ movq(rbx, Operand(rsp, rax, times_pointer_size, 0));
+    __ JumpIfSmi(rbx, &convert_to_object);
 
     __ CompareRoot(rbx, Heap::kNullValueRootIndex);
     __ j(equal, &use_global_receiver);
@@ -237,31 +232,28 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
     __ j(equal, &use_global_receiver);
 
     __ CmpObjectType(rbx, FIRST_JS_OBJECT_TYPE, rcx);
-    __ j(below, &call_to_object);
+    __ j(below, &convert_to_object);
     __ CmpInstanceType(rcx, LAST_JS_OBJECT_TYPE);
-    __ j(below_equal, &done);
-
-    __ bind(&call_to_object);
-    __ EnterInternalFrame();  // preserves rax, rbx, rdi
+    __ j(below_equal, &shift_arguments);
 
-    // Store the arguments count on the stack (smi tagged).
+    __ bind(&convert_to_object);
+    __ EnterInternalFrame();  // In order to preserve argument count.
     __ Integer32ToSmi(rax, rax);
     __ push(rax);
 
-    __ push(rdi);  // save edi across the call
     __ push(rbx);
     __ InvokeBuiltin(Builtins::TO_OBJECT, CALL_FUNCTION);
     __ movq(rbx, rax);
-    __ pop(rdi);  // restore edi after the call
 
-    // Get the arguments count and untag it.
     __ pop(rax);
     __ SmiToInteger32(rax, rax);
-
     __ LeaveInternalFrame();
+    // Restore the function to rdi.
+    __ movq(rdi, Operand(rsp, rax, times_pointer_size, 1 * kPointerSize));
     __ jmp(&patch_receiver);
 
-    // Use the global receiver object from the called function as the receiver.
+    // Use the global receiver object from the called function as the
+    // receiver.
     __ bind(&use_global_receiver);
     const int kGlobalIndex =
         Context::kHeaderSize + Context::GLOBAL_INDEX * kPointerSize;
@@ -273,41 +265,47 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
     __ bind(&patch_receiver);
     __ movq(Operand(rsp, rax, times_pointer_size, 0), rbx);
 
-    __ bind(&done);
+    __ jmp(&shift_arguments);
   }
 
-  // 4. Check that the function really is a function.
-  { Label real_function;
-    __ testq(rdi, rdi);
-    __ j(not_zero, &real_function);
-    __ xor_(rbx, rbx);
-    // CALL_NON_FUNCTION will expect to find the non-function callee on the
-    // expression stack of the caller.  Transfer it from receiver to the
-    // caller's expression stack (and make the first argument the receiver
-    // for CALL_NON_FUNCTION) by decrementing the argument count.
-    __ decq(rax);
-    __ GetBuiltinEntry(rdx, Builtins::CALL_NON_FUNCTION);
-    __ Jump(Handle<Code>(builtin(ArgumentsAdaptorTrampoline)),
-            RelocInfo::CODE_TARGET);
 
-    __ bind(&real_function);
-  }
+  // 3b. Patch the first argument when calling a non-function.  The
+  //     CALL_NON_FUNCTION builtin expects the non-function callee as
+  //     receiver, so overwrite the first argument which will ultimately
+  //     become the receiver.
+  __ bind(&non_function);
+  __ movq(Operand(rsp, rax, times_pointer_size, 0), rdi);
+  __ xor_(rdi, rdi);
 
-  // 5. Shift arguments and return address one slot down on the stack
-  //    (overwriting the receiver).
+  // 4. Shift arguments and return address one slot down on the stack
+  //    (overwriting the original receiver).  Adjust argument count to make
+  //    the original first argument the new receiver.
+  __ bind(&shift_arguments);
   { Label loop;
     __ movq(rcx, rax);
     __ bind(&loop);
     __ movq(rbx, Operand(rsp, rcx, times_pointer_size, 0));
     __ movq(Operand(rsp, rcx, times_pointer_size, 1 * kPointerSize), rbx);
     __ decq(rcx);
-    __ j(not_sign, &loop);
+    __ j(not_sign, &loop);  // While non-negative (to copy return address).
     __ pop(rbx);  // Discard copy of return address.
     __ decq(rax);  // One fewer argument (first argument is new receiver).
   }
 
-  // 6. Get the code to call from the function and check that the number of
-  // expected arguments matches what we're providing.
+  // 5a. Call non-function via tail call to CALL_NON_FUNCTION builtin.
+  { Label function;
+    __ testq(rdi, rdi);
+    __ j(not_zero, &function);
+    __ xor_(rbx, rbx);
+    __ GetBuiltinEntry(rdx, Builtins::CALL_NON_FUNCTION);
+    __ Jump(Handle<Code>(builtin(ArgumentsAdaptorTrampoline)),
+            RelocInfo::CODE_TARGET);
+    __ bind(&function);
+  }
+
+  // 5b. Get the code to call from the function and check that the number of
+  //     expected arguments matches what we're providing.  If so, jump
+  //     (tail-call) to the code in register edx without checking arguments.
   __ movq(rdx, FieldOperand(rdi, JSFunction::kSharedFunctionInfoOffset));
   __ movsxlq(rbx,
          FieldOperand(rdx, SharedFunctionInfo::kFormalParameterCountOffset));
@@ -318,7 +316,6 @@ void Builtins::Generate_FunctionCall(MacroAssembler* masm) {
        Handle<Code>(builtin(ArgumentsAdaptorTrampoline)),
        RelocInfo::CODE_TARGET);
 
-  // 7. Jump (tail-call) to the code in register edx without checking arguments.
   ParameterCount expected(0);
   __ InvokeCode(rdx, expected, expected, JUMP_FUNCTION);
 }
@@ -905,7 +902,11 @@ void Builtins::Generate_JSConstructCall(MacroAssembler* masm) {
   // edi: called object
   // eax: number of arguments
   __ bind(&non_function_call);
-  // Set expected number of arguments to zero (not changing eax).
+  // CALL_NON_FUNCTION expects the non-function constructor as receiver
+  // (instead of the original receiver from the call site).  The receiver is
+  // stack element argc+1.
+  __ movq(Operand(rsp, rax, times_pointer_size, kPointerSize), rdi);
+  // Set expected number of arguments to zero (not changing rax).
   __ movq(rbx, Immediate(0));
   __ GetBuiltinEntry(rdx, Builtins::CALL_NON_FUNCTION_AS_CONSTRUCTOR);
   __ Jump(Handle<Code>(builtin(ArgumentsAdaptorTrampoline)),