8250269: Replace ATTRIBUTE_ALIGNED with alignas

Reviewed-by: rkennke, kbarrett

src/hotspot/share/utilities/globalDefinitions.hpp

@@ -50,7 +50,7 @@ class oopDesc;
 #endif
 
 #ifndef ATTRIBUTE_ALIGNED
-#define ATTRIBUTE_ALIGNED(x)
+#define ATTRIBUTE_ALIGNED(x) alignas(x)
 #endif
 
 #ifndef ATTRIBUTE_FLATTEN

src/hotspot/share/utilities/globalDefinitions_gcc.hpp

@@ -141,7 +141,7 @@ inline int g_isfinite(jdouble f)                 { return isfinite(f); }
 // temporarily disabled.
 #define offset_of(klass,field)                          \
 ([]() {                                                 \
-  char space[sizeof (klass)] ATTRIBUTE_ALIGNED(16);     \
+  alignas(16) char space[sizeof (klass)];               \
   klass* dummyObj = (klass*)space;                      \
   char* c = (char*)(void*)&dummyObj->field;             \
   return (size_t)(c - space);                           \
@@ -160,8 +160,4 @@ inline int g_isfinite(jdouble f)                 { return isfinite(f); }
 #define ALWAYSINLINE inline __attribute__ ((always_inline))
 #define ATTRIBUTE_FLATTEN __attribute__ ((flatten))
 
-// Alignment
-//
-#define ATTRIBUTE_ALIGNED(x) __attribute__((aligned(x)))
-
 #endif // SHARE_UTILITIES_GLOBALDEFINITIONS_GCC_HPP

src/hotspot/share/utilities/globalDefinitions_visCPP.hpp

@@ -115,9 +115,6 @@ inline int g_isfinite(jdouble f)                 { return _finite(f); }
 #define NOINLINE     __declspec(noinline)
 #define ALWAYSINLINE __forceinline
 
-// Alignment
-#define ATTRIBUTE_ALIGNED(x) __declspec(align(x))
-
 #ifdef _M_ARM64
 #define USE_VECTORED_EXCEPTION_HANDLING
 #endif