Tweak the bit-field definitions introduced since r813 to address Bug #20877.

rw_lock_t: Do not make writer_is_wait_ex a bit-field.  There are no fields
yet that could be fused to the same machine word, but we play it safe,
because the field writer_is_wait_ex may be modified by several threads
simultaneously.  Such fields should always be allocated an own machine
word.

dict_table_t: Change the type of all bit-fields to "unsigned".  Make
"space" a bit-field of 32 bits.  Move name_hash and id_hash after all
bit-fields, so that the bit-fields can be allocated together.  Do not
make autoinc_inited a bit-field, as we cannot allocate any field
from the same machine word.

dict_build_table_def_step(): Pass a local variable to
fil_create_new_single_table_tablespace() and initialize table->space
from it after the call, now that table->space is a bit-field.

dict/dict0crea.c

@@ -240,7 +240,7 @@ dict_build_table_def_step(
 		- page 3 will contain the root of the clustered index of the
 		table we create here. */
 
-		table->space = 0;	/* reset to zero for the call below */
+		ulint	space = 0;	/* reset to zero for the call below */
 
 		if (table->dir_path_of_temp_table) {
 			/* We place tables created with CREATE TEMPORARY
@@ -253,9 +253,11 @@ dict_build_table_def_step(
 			is_path = FALSE;
 		}
 
-		error = fil_create_new_single_table_tablespace
-			(&table->space, path_or_name, is_path,
-			 FIL_IBD_FILE_INITIAL_SIZE);
+		error = fil_create_new_single_table_tablespace(
+			&space, path_or_name, is_path,
+			FIL_IBD_FILE_INITIAL_SIZE);
+		table->space = space;
+
 		if (error != DB_SUCCESS) {
 
 			return(error);

include/dict0mem.h

@@ -262,23 +262,27 @@ struct dict_table_struct{
 				innodb_file_per_table is defined in my.cnf;
 				in Unix this is usually /tmp/..., in Windows
 				\temp\... */
-	ulint		space;	/* space where the clustered index of the
+	unsigned	space:32;
+				/* space where the clustered index of the
 				table is placed */
-	ibool		ibd_file_missing:1;/* TRUE if this is in a single-table
+	unsigned	ibd_file_missing:1;
+				/* TRUE if this is in a single-table
 				tablespace and the .ibd file is missing; then
 				we must return in ha_innodb.cc an error if the
 				user tries to query such an orphaned table */
-	ibool		tablespace_discarded:1;/* this flag is set TRUE when the
-				user calls DISCARD TABLESPACE on this table,
-				and reset to FALSE in IMPORT TABLESPACE */
-	ibool		cached:1;/* TRUE if the table object has been added
+	unsigned	tablespace_discarded:1;
+				/* this flag is set TRUE when the user
+				calls DISCARD TABLESPACE on this
+				table, and reset to FALSE in IMPORT
+				TABLESPACE */
+	unsigned	cached:1;/* TRUE if the table object has been added
 				to the dictionary cache */
-	ulint		flags:8;/* DICT_TF_COMPACT, ... */
-	hash_node_t	name_hash; /* hash chain node */
-	hash_node_t	id_hash; /* hash chain node */
+	unsigned	flags:8;/* DICT_TF_COMPACT, ... */
 	ulint		n_def:10;/* number of columns defined so far */
 	ulint		n_cols:10;/* number of columns */
 	dict_col_t*	cols;	/* array of column descriptions */
+	hash_node_t	name_hash; /* hash chain node */
+	hash_node_t	id_hash; /* hash chain node */
 	UT_LIST_BASE_NODE_T(dict_index_t)
 			indexes; /* list of indexes of the table */
 	UT_LIST_BASE_NODE_T(dict_foreign_t)
@@ -362,7 +366,7 @@ struct dict_table_struct{
 	mutex_t		autoinc_mutex;
 				/* mutex protecting the autoincrement
 				counter */
-	ibool		autoinc_inited:1;
+	ibool		autoinc_inited;
 				/* TRUE if the autoinc counter has been
 				inited; MySQL gets the init value by executing
 				SELECT MAX(auto inc column) */

include/sync0rw.h

@@ -438,7 +438,7 @@ struct rw_lock_struct {
 	const char*	cfile_name;/* File name where lock created */
 	const char*	last_s_file_name;/* File name where last s-locked */
 	const char*	last_x_file_name;/* File name where last x-locked */
-	unsigned	writer_is_wait_ex:1;
+	ibool		writer_is_wait_ex;
 				/* This is TRUE if the writer field is
 				RW_LOCK_WAIT_EX; this field is located far
 				from the memory update hotspot fields which