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remove unnecessary and problematic _Noreturn from crt/ldso startup

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after commit a48ccc159a removed the use
of _Noreturn on the stage3_func type (which only worked due to it
being defined to the "GNU C" attribute in C99 mode), GCC could no
longer assume that the ends of __dls2 and __dls2b are unreachable, and
produced a warning that a function marked _Noreturn returns.

also, since commit 4390383b32, the
_Noreturn declaration for __libc_start_main in crt1/rcrt1 has been not
only inconsistent with the definition, but wrong. formally,
__libc_start_main does return, via a (hopefully) tail call to a helper
function after the barrier. incorrect usage of _Noreturn in the
declaration was probably formal UB.

the _Noreturn specifiers were not useful in any of these places, so
remove them all. now, the only remaining usage of _Noreturn is in
public interfaces where _Noreturn is part of their contract.
This commit is contained in:
Rich Felker 2019-06-25 18:50:05 -04:00
parent 95dfa3dd12
commit 54b7564b72
3 changed files with 5 additions and 5 deletions
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2
crt/crt1.c
View File

@ -8,7 +8,7 @@
int main();
weak void _init();
weak void _fini();
_Noreturn int __libc_start_main(int (*)(), int, char **,
int __libc_start_main(int (*)(), int, char **,
void (*)(), void(*)(), void(*)());
void _start_c(long *p)

4
crt/rcrt1.c
View File

@ -5,10 +5,10 @@
int main();
weak void _init();
weak void _fini();
_Noreturn int __libc_start_main(int (*)(), int, char **,
int __libc_start_main(int (*)(), int, char **,
void (*)(), void(*)(), void(*)());
hidden _Noreturn void __dls2(unsigned char *base, size_t *sp)
hidden void __dls2(unsigned char *base, size_t *sp)
{
__libc_start_main(main, *sp, (void *)(sp+1), _init, _fini, 0);
}

4
ldso/dynlink.c
View File

@ -1644,7 +1644,7 @@ hidden void __dls2(unsigned char *base, size_t *sp)
* so that loads of the thread pointer and &errno can be pure/const and
* thereby hoistable. */
_Noreturn void __dls2b(size_t *sp)
void __dls2b(size_t *sp)
{
/* Setup early thread pointer in builtin_tls for ldso/libc itself to
* use during dynamic linking. If possible it will also serve as the
@ -1665,7 +1665,7 @@ _Noreturn void __dls2b(size_t *sp)
* process dependencies and relocations for the main application and
* transfer control to its entry point. */
_Noreturn void __dls3(size_t *sp)
void __dls3(size_t *sp)
{
static struct dso app, vdso;
size_t aux[AUX_CNT], *auxv;