compiler: add a sizeof_field() macro

Determining the size of a field is useful when you don't have a struct
variable handy.  Open-coding this is ugly.

This patch adds the sizeof_field() macro, which is similar to
typeof_field().  Existing instances are updated to use the macro.

Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>
Reviewed-by: John Snow <jsnow@redhat.com>
Message-id: 20180614164431.29305-1-stefanha@redhat.com
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 10 insertions, 10 deletions

diff --git a/target/s390x/arch_dump.c b/target/s390x/arch_dump.c
index 6f61ff95af..c9ef0a6e60 100644
--- a/target/s390x/arch_dump.c
+++ b/target/s390x/arch_dump.c
@@ -184,20 +184,20 @@ typedef struct NoteFuncDescStruct {
 } NoteFuncDesc;
 
 static const NoteFuncDesc note_core[] = {
-    {sizeof(((Note *)0)->contents.prstatus), s390x_write_elf64_prstatus},
-    {sizeof(((Note *)0)->contents.fpregset), s390x_write_elf64_fpregset},
+    {sizeof_field(Note, contents.prstatus), s390x_write_elf64_prstatus},
+    {sizeof_field(Note, contents.fpregset), s390x_write_elf64_fpregset},
     { 0, NULL}
 };
 
 static const NoteFuncDesc note_linux[] = {
-    {sizeof(((Note *)0)->contents.prefix),   s390x_write_elf64_prefix},
-    {sizeof(((Note *)0)->contents.ctrs),     s390x_write_elf64_ctrs},
-    {sizeof(((Note *)0)->contents.timer),    s390x_write_elf64_timer},
-    {sizeof(((Note *)0)->contents.todcmp),   s390x_write_elf64_todcmp},
-    {sizeof(((Note *)0)->contents.todpreg),  s390x_write_elf64_todpreg},
-    {sizeof(((Note *)0)->contents.vregslo),  s390x_write_elf64_vregslo},
-    {sizeof(((Note *)0)->contents.vregshi),  s390x_write_elf64_vregshi},
-    {sizeof(((Note *)0)->contents.gscb),     s390x_write_elf64_gscb},
+    {sizeof_field(Note, contents.prefix),   s390x_write_elf64_prefix},
+    {sizeof_field(Note, contents.ctrs),     s390x_write_elf64_ctrs},
+    {sizeof_field(Note, contents.timer),    s390x_write_elf64_timer},
+    {sizeof_field(Note, contents.todcmp),   s390x_write_elf64_todcmp},
+    {sizeof_field(Note, contents.todpreg),  s390x_write_elf64_todpreg},
+    {sizeof_field(Note, contents.vregslo),  s390x_write_elf64_vregslo},
+    {sizeof_field(Note, contents.vregshi),  s390x_write_elf64_vregshi},
+    {sizeof_field(Note, contents.gscb),     s390x_write_elf64_gscb},
     { 0, NULL}
 };