Add stack alignment check to ia32 and x64

src/x64/codegen-x64.cc

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 8231 matching lines @@
   // rsp: stack pointer  (restored after C call).
   // r14: number of arguments including receiver (C callee-saved).
   // r15: pointer to the first argument (C callee-saved).
   //      This pointer is reused in LeaveExitFrame(), so it is stored in a
   //      callee-saved register.
 
   // Simple results returned in rax (both AMD64 and Win64 calling conventions).
   // Complex results must be written to address passed as first argument.
   // AMD64 calling convention: a struct of two pointers in rax+rdx
 
+  // Check stack alignment.
+  if (FLAG_debug_code) {
+    __ CheckStackAlignment();
+  }
+
   if (do_gc) {
-    // Pass failure code returned from last attempt as first argument to GC.
+    // Pass failure code returned from last attempt as first argument to
+    // PerformGC. No need to use PrepareCallCFunction/CallCFunction here as the
+    // stack is known to be aligned. This function takes one argument which is
+    // passed in register.
 #ifdef _WIN64
     __ movq(rcx, rax);
 #else  // ! defined(_WIN64)
     __ movq(rdi, rax);
 #endif
     __ movq(kScratchRegister,
             FUNCTION_ADDR(Runtime::PerformGC),
             RelocInfo::RUNTIME_ENTRY);
     __ call(kScratchRegister);
   }
@@ skipping 2165 matching lines @@
   // Call the function from C++.
   return FUNCTION_CAST<ModuloFunction>(buffer);
 }
 
 #endif
 
 
 #undef __
 
 } }  // namespace v8::internal