pahole: Add --inner_anon option
Allow making the inner struct/enum/union anonymous. This permits using
the header to inspect pointer values using -E, without having to care
about avoiding duplicate type definitions such as:
struct foo { ... };
struct bar {
struct foo {
....
} a;
};
With --inner_anon, the conflict between the two definitions of struct
foo is gone:
struct foo { ... };
struct bar {
struct {
....
} a;
};
Committer testing:
$ cat inner_anon.c
struct foo {
int a;
char b;
};
struct bar {
struct foo c;
int d;
} bla;
$ gcc -g -c inner_anon.c -o inner_anon.o
No expansion:
$ pahole inner_anon.o
struct foo {
int a; /* 0 4 */
char b; /* 4 1 */
/* size: 8, cachelines: 1, members: 2 */
/* padding: 3 */
/* last cacheline: 8 bytes */
};
struct bar {
struct foo c; /* 0 8 */
/* XXX last struct has 3 bytes of padding */
int d; /* 8 4 */
/* size: 12, cachelines: 1, members: 2 */
/* paddings: 1, sum paddings: 3 */
/* last cacheline: 12 bytes */
};
Expanding types:
$ pahole -E inner_anon.o
struct foo {
int a; /* 0 4 */
char b; /* 4 1 */
/* size: 8, cachelines: 1, members: 2 */
/* padding: 3 */
/* last cacheline: 8 bytes */
};
struct bar {
struct foo {
int a; /* 0 4 */
char b; /* 4 1 */
}c; /* 0 8 */
/* XXX last struct has 3 bytes of padding */
int d; /* 8 4 */
/* size: 12, cachelines: 1, members: 2 */
/* paddings: 1, sum paddings: 3 */
/* last cacheline: 12 bytes */
};
Anonymising the inner struct:
$ pahole -E --inner_anon inner_anon.o
struct foo {
int a; /* 0 4 */
char b; /* 4 1 */
/* size: 8, cachelines: 1, members: 2 */
/* padding: 3 */
/* last cacheline: 8 bytes */
};
struct bar {
struct /* foo */ {
int a; /* 0 4 */
char b; /* 4 1 */
}c; /* 0 8 */
/* XXX last struct has 3 bytes of padding */
int d; /* 8 4 */
/* size: 12, cachelines: 1, members: 2 */
/* paddings: 1, sum paddings: 3 */
/* last cacheline: 12 bytes */
};
Signed-off-by: Douglas Raillard <douglas.raillard@arm.com>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
[ Added man page entry for --inner_anon, refreshed the patch to cope with the btf_tag series ]
Link: https://lore.kernel.org/all/20211019100724.325570-3-douglas.raillard@arm.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
2 files changed
