diff options
| author | Sam James <sam@gentoo.org> | 2024-03-13 23:34:55 +0000 |
|---|---|---|
| committer | Guillem Jover <guillem@hadrons.org> | 2024-03-14 09:33:34 +0100 |
| commit | b62f36f3055262faf28e4ff12dd7ed03c44e09d8 (patch) | |
| tree | 8707b5123e78589920ab80ae59dbaad1dd460005 | |
| parent | 2a3d521318533bb1d0535b989be578b4f5c5ff1a (diff) | |
test: nlist: make resilient against -Wl,--gc-sections
With linker sections GC enabled, we get a test failure in `nlist.c`:
```
nlist: nlist.c:72: main: Assertion `rc == 0' failed.
```
This turns out to be because several sections used by the test can be discarded:
```
ld: removing unused section '.text.func_pub' in file 'nlist.o'
ld: removing unused section '.bss.data_pub_uninit' in file 'nlist.o'
ld: removing unused section '.data.data_pub_init' in file 'nlist.o'
```
Reproduced with `CFLAGS="-Og -fdata-sections -ffunction-sections"` and
`LDFLAGS="-Wl,-O1 -Wl,--as-needed -Wl,--gc-sections -Wl,-z,start-stop-gc"`.
Additionally, `LDFLAGS="... -Wl,--print-gc-sections"` can help with diagnosing
which sections get removed.
We already mark these symbols as `used`, but we need `retain` [0] for them
to survive linker GC too.
[0] https://releases.llvm.org/18.1.0/tools/lld/docs/ELF/start-stop-gc.html#annotate-c-identifier-name-sections
Closes: !29
Signed-off-by: Sam James <sam@gentoo.org>
Signed-off-by: Guillem Jover <guillem@hadrons.org>
| -rw-r--r-- | test/nlist.c | 18 |
1 files changed, 15 insertions, 3 deletions
diff --git a/test/nlist.c b/test/nlist.c index 558524f..0031a4d 100644 --- a/test/nlist.c +++ b/test/nlist.c @@ -33,17 +33,29 @@ #include <fcntl.h> #include <nlist.h> +#if defined(__has_attribute) +#if __has_attribute(__retain__) +#define ATTRIBUTE_RETAIN __attribute__((__retain__)) +#else +#define ATTRIBUTE_RETAIN +#endif +#endif + static int data_prv_init = 50; extern int data_pub_init; extern int data_pub_uninit[2048]; extern int *data_pub_ptr; +/* GCC's __has_attribute has odd behavior for retain: https://gcc.gnu.org/PR99587 */ +#pragma GCC diagnostic push +#pragma GCC diagnostic ignored "-Wattributes" int *data_pub_ptr = &data_prv_init; -int data_pub_init __attribute__((__used__)) = 10; -int data_pub_uninit[2048] __attribute__((__used__)); +int data_pub_init ATTRIBUTE_RETAIN __attribute__((__used__)) = 10; +int data_pub_uninit[2048] ATTRIBUTE_RETAIN __attribute__((__used__)); extern int -func_pub(void) __attribute__((__used__)) ; +func_pub(void) ATTRIBUTE_RETAIN __attribute__((__used__)); +#pragma GCC diagnostic pop int func_pub(void) |