https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71104
--- Comment #17 from rguenther at suse dot de <rguenther at suse dot de> --- On Thu, 14 Jul 2016, bernd.edlinger at hotmail dot de wrote: > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71104 > > --- Comment #16 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- > (In reply to rguent...@suse.de from comment #15) > > On Thu, 14 Jul 2016, bernd.edlinger at hotmail dot de wrote: > > > > > https://gcc.gnu.org/bugzilla/show_bug.cgi?id=71104 > > > > > > --- Comment #14 from Bernd Edlinger <bernd.edlinger at hotmail dot de> --- > > > One question though... > > > > > > This depends on a special knowledge about "vfork", > > > but it seems that gcc does not honor -ffreestanding > > > correctly in this case, because: > > > > > > gcc -ffreestanding pr71104-1.c > > > > > > should not have crashed (before your patch, but it did). > > > > Even with -ffreestanding we handle some functions conservatively. > > See special_function_p. > > Oh, I see. > Handling vfork that may be conservative, but longjmp is not conservative. Yeah, returning ECF_NORETURN isn't conservative. OTOH this code only looking at the name of the function rather than using the corresponding builtin pre-dates my GCC involvement. Can you open a separate bug please? > > test.c: > > void foo(void); > int longjmp(void); > int *p; > > void bar(void) > { > foo(); > *p = longjmp(); > } > > gcc -Wall -S -O3 -ffreestanding test.c > gives zero warning, and invalid code: > > bar: > .LFB0: > .cfi_startproc > subq $8, %rsp > .cfi_def_cfa_offset 16 > call foo > call longjmp > .cfi_endproc > >
