rb_execution_context_t: pack bits, 256 -> 252 bytes (on 32-bit)

Maybe execution contexts will become more common.

git-svn-id: svn+ssh://ci.ruby-lang.org/ruby/trunk@65183 b2dd03c8-39d4-4d8f-98ff-823fe69b080e

eval_error.c

@@ -268,7 +268,7 @@ VALUE rb_get_message(VALUE exc);
 void
 rb_ec_error_print(rb_execution_context_t * volatile ec, volatile VALUE errinfo)
 {
-    volatile int raised_flag = ec->raised_flag;
+    volatile uint8_t raised_flag = ec->raised_flag;
     volatile VALUE errat = Qundef;
     volatile VALUE emesg = Qundef;
 

vm_core.h

@@ -845,8 +845,12 @@ typedef struct rb_execution_context_struct {
     VALUE errinfo;
     VALUE passed_block_handler; /* for rb_iterate */
     const rb_callable_method_entry_t *passed_bmethod_me; /* for bmethod */
-    int raised_flag;
-    enum method_missing_reason method_missing_reason;
+
+    uint8_t raised_flag; /* only 3 bits needed */
+
+    /* n.b. only 7 bits needed, really: */
+    BITFIELD(enum method_missing_reason, method_missing_reason, 8);
+
     VALUE private_const_reference;
 
     /* for GC */