X64: Fix issue 678. Bug in some Win64 C calls from generated code.

src/x64/macro-assembler-x64.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
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 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
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@@ skipping 2623 matching lines @@
       movq(dst, FieldOperand(dst, JSFunction::kContextOffset));
     }
     // The context may be an intermediate context, not a function context.
     movq(dst, Operand(dst, Context::SlotOffset(Context::FCONTEXT_INDEX)));
   } else {  // context is the current function context.
     // The context may be an intermediate context, not a function context.
     movq(dst, Operand(rsi, Context::SlotOffset(Context::FCONTEXT_INDEX)));
   }
 }
 
+
 int MacroAssembler::ArgumentStackSlotsForCFunctionCall(int num_arguments) {
   // On Windows stack slots are reserved by the caller for all arguments
-  // including the ones passed in registers. On Linux 6 arguments are passed in
-  // registers and the caller does not reserve stack slots for them.
+  // including the ones passed in registers, and space is alwaysallocated for

[Rico, 2010/05/28 08:20:02]

always->allocated -> always allocated

+  // the four register arguments even if the function takes fewer than four
+  // arguments.
+  // On Linux the first six arguments are passed in registers and the caller
+  // does not reserve stack slots for them.
   ASSERT(num_arguments >= 0);
 #ifdef _WIN64
-  static const int kArgumentsWithoutStackSlot = 0;
+  static const int kMinimumStackSlots = 4;
+  if (num_arguments < kMinimumStackSlots) return kMinimumStackSlots;
+  return num_arguments;
 #else
-  static const int kArgumentsWithoutStackSlot = 6;
+  static const int kRegisterPassedArguments = 6;
+  if (num_arguments < kRegisterPassedArguments) return 0;
+  return num_arguments - kRegisterPassedArguments;
 #endif
-  return num_arguments > kArgumentsWithoutStackSlot ?
-      num_arguments - kArgumentsWithoutStackSlot : 0;
 }
 
+
 void MacroAssembler::PrepareCallCFunction(int num_arguments) {
   int frame_alignment = OS::ActivationFrameAlignment();
   ASSERT(frame_alignment != 0);
   ASSERT(num_arguments >= 0);
   // Make stack end at alignment and allocate space for arguments and old rsp.
   movq(kScratchRegister, rsp);
   ASSERT(IsPowerOf2(frame_alignment));
   int argument_slots_on_stack =
       ArgumentStackSlotsForCFunctionCall(num_arguments);
   subq(rsp, Immediate((argument_slots_on_stack + 1) * kPointerSize));
@@ skipping 38 matching lines @@
   CPU::FlushICache(address_, size_);
 
   // Check that the code was patched as expected.
   ASSERT(masm_.pc_ == address_ + size_);
   ASSERT(masm_.reloc_info_writer.pos() == address_ + size_ + Assembler::kGap);
 }
 
 } }  // namespace v8::internal
 
 #endif  // V8_TARGET_ARCH_X64