https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114116
--- Comment #9 from Lukas Grätz <lukas.gra...@tu-darmstadt.de> --- (In reply to H.J. Lu from comment #8) > (In reply to Lukas Grätz from comment #7) > > (In reply to H.J. Lu from comment #6) > > > (In reply to Jakub Jelinek from comment #5) > > > > Yeah. Not to mention, one can call backtrace even if -g0; you just > > > > don't > > > > get nice names for the addresses. Without the patch you get crashes in > > > > the > > > > unwinder when doing backtrace. > > > > > > Should we generate REG_CFA_UNDEFINED for unsaved callee-saved registers to > > > help unwinder: > > > > > > https://patchwork.sourceware.org/project/gcc/list/?series=30327 > > > > Yes. Also for gdb this is needed. > > > > Perhaps I did something wrong. On my computer, I could get the first patch > > working to save rbp, I also applied the patch which should omit the > > .cfi_undefined. But somehow, I still not get .cfi_undefined for any of the > > examples. > > > > > > $ ./gcc/host-x86_64-pc-linux-gnu/gcc/cc1 -O3 > > gcc/gcc/testsuite/gcc.target/i386/pr38534-7.c -o pr38534-7.S > > > > $ cat pr38534-7.S > > [...] > > no_return_to_caller: > > .LFB0: > > .cfi_startproc > > pushq %rbp > > .cfi_def_cfa_offset 16 > > .cfi_offset 6, -16 > > movl $array+67108860, %eax > > xorl %r13d, %r13d > > [...] > > > > > > The ".cfi_undefined 13" is still missing... > > It is generated only when -g is used. Not on my computer. When I used -g I got: no_return_to_caller: .LFB0: .loc 1 16 1 view -0 .cfi_startproc .loc 1 17 3 view .LVU1 .loc 1 18 3 view .LVU2 .LVL0: .loc 1 18 26 discriminator 1 view .LVU3 .loc 1 16 1 is_stmt 0 view .LVU4 pushq %rbp .cfi_def_cfa_offset 16 .cfi_offset 6, -16 movl $array+67108860, %eax .loc 1 21 31 view .LVU5 xorl %r13d, %r13d .loc 1 16 1 view .LVU6 Still no .cfi_undefined 13. In principle, it should also be generated without -g, as the rest of .cfi_offset and friends.
