[Bug target/114116] [14 Regression] Broken backtraces in bootstrapped x86_64 gcc

[lukas.graetz@tu-darmstadt.de]

https://gcc.gnu.org/bugzilla/show_bug.cgi?id=114116

Lukas Grätz <lukas.graetz@tu-darmstadt.de> changed:

           What    |Removed                     |Added
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                 CC|                            |lukas.graetz@tu-darmstadt.d
                   |                            |e

--- Comment #7 from Lukas Grätz <lukas.graetz@tu-darmstadt.de> ---
(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...