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. 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
