added alignment test

and fix an incorrect alignment check in cwksp which was failing on m68k

lib/common/mem.h

@@ -80,6 +80,26 @@ extern "C" {
 #endif
 
 
+/*-**************************************************************
+*  Alignment check
+*****************************************************************/
+
+/* C11 support */
+#if defined(__STDC_VERSION__) && (__STDC_VERSION__ >= 201112L)
+
+#include <stdalign.h>
+# define MEM_ALIGN_COND(T) alignof(T)
+
+#elif defined(__GNUC__) || defined(_MSC_VER)
+
+# define MEM_ALIGN_COND(T) __alignof(T)
+
+#else
+
+# define MEM_ALIGN_COND(T) 1  /* most likely incorrect, just to pass tests */
+
+#endif
+
 /*-**************************************************************
 *  Memory I/O API
 *****************************************************************/

lib/compress/zstd_cwksp.h

@@ -422,8 +422,8 @@ MEM_STATIC void* ZSTD_cwksp_reserve_object(ZSTD_cwksp* ws, size_t bytes) {
     DEBUGLOG(5,
         "cwksp: reserving %p object %zd bytes (rounded to %zd), %zd bytes remaining",
         alloc, bytes, roundedBytes, ZSTD_cwksp_available_space(ws) - roundedBytes);
-    assert(((size_t)alloc & (sizeof(void*)-1)) == 0);
+    assert((size_t)alloc % MEM_ALIGN_COND(void*) == 0);
-    assert((bytes & (sizeof(void*)-1)) == 0);
+    assert(bytes % MEM_ALIGN_COND(void*) == 0);
     ZSTD_cwksp_assert_internal_consistency(ws);
     /* we must be in the first phase, no advance is possible */
     if (ws->phase != ZSTD_cwksp_alloc_objects || end > ws->workspaceEnd) {