Index: compile.c
===================================================================
--- compile.c	(revision 48106)
+++ compile.c	(working copy)
@@ -583,6 +583,29 @@
 /* definition of data structure for compiler */
 /*********************************************/
 
+/* check if word-aligned memory access is needed */
+#if defined(__sparc) /* sparc 32-bit and 64-bit (sparc v9) */
+  #define STRICT_ADDRESS_ALIGNMENT
+#endif
+
+#ifdef STRICT_ADDRESS_ALIGNMENT
+/* 
+ * On sparc V8 (32-bit), because sizeof(long long) > sizeof(VALUE) and
+ * sizeof(double) > sizeof(VALUE), a struct that may contain long long or
+ * double is aligned to sizeof(double) or sizeof(long long), respectively.
+ */
+  #if defined(HAVE_TRUE_LONG_LONG) && SIZEOF_LONG_LONG > SIZEOF_VALUE && \
+      SIZEOF_LONG_LONG >= SIZEOF_DOUBLE
+    #define ALIGN_SIZE SIZEOF_LONG_LONG
+  #elif SIZEOF_DOUBLE > SIZEOF_VALUE
+    #define ALIGN_SIZE SIZEOF_DOUBLE
+  #else
+    #define ALIGN_SIZE SIZEOF_VALUE
+  #endif
+  /* ALIGN_SIZE must be 2 ** N. */
+  #define ALIGN_SIZE_MASK ((size_t)((ALIGN_SIZE) - 1))
+#endif /* STRICT_ADDRESS_ALIGNMENT */
+
 static void *
 compile_data_alloc(rb_iseq_t *iseq, size_t size)
 {
@@ -590,9 +613,33 @@
     struct iseq_compile_data_storage *storage =
 	iseq->compile_data->storage_current;
 
-    if (storage->pos + size > storage->size) {
+#ifdef STRICT_ADDRESS_ALIGNMENT
+    size_t padding = 0;
+    size_t mis;
+#else
+    const size_t padding = 0; /* to be optimized by compiler */
+#endif
+
+#ifdef STRICT_ADDRESS_ALIGNMENT
+    mis = (size_t)storage->pos & ALIGN_SIZE_MASK;
+    if (mis > 0) {
+        padding = ALIGN_SIZE - mis;
+/* Optimize when a VALUE is requested on 32-bit sparc or equivalents. */
+#if ALIGN_SIZE > SIZEOF_VALUE
+        if (padding == sizeof(VALUE)) {
+            padding = 0;
+        }
+#endif
+    }
+#endif /* STRICT_ADDRESS_ALIGNMENT */
+
+    if (storage->pos + padding + size > storage->size) {
 	unsigned long alloc_size = storage->size * 2;
 
+#ifdef STRICT_ADDRESS_ALIGNMENT
+        padding = 0; /* assumes that start address is always aligned. */
+#endif
+
       retry:
 	if (alloc_size < size) {
 	    alloc_size *= 2;
@@ -608,6 +655,9 @@
 	storage->buff = (char *)(&storage->buff + 1);
     }
 
+#ifdef STRICT_ADDRESS_ALIGNMENT
+    storage->pos += padding;
+#endif
     ptr = (void *)&storage->buff[storage->pos];
     storage->pos += size;
     return ptr;