Re: [PATCH] [gdb/testsuite] Add gdb.base/unwind-on-each-insn-{amd64, i386}.exp

[Tom de Vries <tdevries@suse.de>]

On 1/25/23 21:09, Tom de Vries via Gdb-patches wrote:
> The gcc 4.4.x (and earlier) compilers had the problem that the unwind info in
> the epilogue was inaccurate.
> 
> In order to work around this in gdb, epilogue unwinders were added with a
> higher priority than the dwarf unwinders in the amd64 and i386 targets:
> - amd64_epilogue_frame_unwind, and
> - i386_epilogue_frame_unwind.
> 
> Subsequently, the epilogue unwind info problem got fixed in gcc 4.5.0.
> 
> However, the epilogue unwinders prevented gdb from taking advantage of the
> fixed epilogue unwind info, so the scope of the epilogue unwinders was
> limited, bailing out for gcc >= 4.5.0.
> 
> There was no regression test added for this preference scheme, so if we now
> declare epilogue unwind info from all gcc versions as trusted, no test will
> start failing.
> 
> Fix this by adding an amd64 and i386 regression test for this.
> 
> I have no gcc 4.4.x lying around, so I fabricated the assembly files by:
> - commenting out some .cfi directives to break the epilogue unwind info, and
> - hand-editing the producer info to 4.4.7 to activate the fix.
> 
> Tested on x86_64-linux, target boards unix/{-m64,-m32}.
> ---
>   .../gdb.base/unwind-on-each-insn-amd64.exp    |  42 +++
>   .../gdb.base/unwind-on-each-insn-amd64.s      | 263 ++++++++++++++++++
>   .../gdb.base/unwind-on-each-insn-i386.exp     |  39 +++
>   .../gdb.base/unwind-on-each-insn-i386.s       | 262 +++++++++++++++++
>   .../gdb.base/unwind-on-each-insn.exp          | 160 +----------
>   .../gdb.base/unwind-on-each-insn.exp.tcl      | 180 ++++++++++++
>   6 files changed, 792 insertions(+), 154 deletions(-)
>   create mode 100644 gdb/testsuite/gdb.base/unwind-on-each-insn-amd64.exp
>   create mode 100644 gdb/testsuite/gdb.base/unwind-on-each-insn-amd64.s
>   create mode 100644 gdb/testsuite/gdb.base/unwind-on-each-insn-i386.exp
>   create mode 100644 gdb/testsuite/gdb.base/unwind-on-each-insn-i386.s
>   create mode 100644 gdb/testsuite/gdb.base/unwind-on-each-insn.exp.tcl

I've fixed some nits and pushed this.

I did wonder about eliminating commonality between 
unwind-on-each-insn-i386.exp and unwind-on-each-insn-amd64.exp, but 
decided it was not worth the trouble.

Thanks,
- Tom