From 54b7564b72c1edcc79fca083047521fb56eaea00 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Tue, 25 Jun 2019 18:50:05 -0400 Subject: [PATCH] remove unnecessary and problematic _Noreturn from crt/ldso startup after commit a48ccc159a5fa061a18419296100ee48a1cd6cc9 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 4390383b32250a941ec616e8bff6f568a801b1c0, 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. --- crt/crt1.c | 2 +- crt/rcrt1.c | 4 ++-- ldso/dynlink.c | 4 ++-- 3 files changed, 5 insertions(+), 5 deletions(-) diff --git a/crt/crt1.c b/crt/crt1.c index 7b12665f..8fe8ab5d 100644 --- a/crt/crt1.c +++ b/crt/crt1.c @@ -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) diff --git a/crt/rcrt1.c b/crt/rcrt1.c index 7bb3322f..901dff68 100644 --- a/crt/rcrt1.c +++ b/crt/rcrt1.c @@ -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); } diff --git a/ldso/dynlink.c b/ldso/dynlink.c index 1398ff45..db543c19 100644 --- a/ldso/dynlink.c +++ b/ldso/dynlink.c @@ -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; -- 2.25.1