Re: [PATCH] perf annotate: fix parsing aarch64 branch instructions after objdump update

From: Thomas-Mich Richter
Date: Fri Aug 24 2018 - 03:59:36 EST

On 08/24/2018 02:10 AM, Kim Phillips wrote:
> Starting with binutils 2.28, aarch64 objdump adds comments to the
> disassembly output to show the alternative names of a condition code [1].
> It is assumed that commas in objdump comments could occur in other arches
> now or in the future, so this fix is arch-independent.
> The fix could have been done with arm64 specific jump__parse and
> jump__scnprintf functions, but the jump__scnprintf instruction would
> have to have its comment character be a literal, since the scnprintf
> functions cannot receive a struct arch easily.
> This inconvenience also applies to the generic jump__scnprintf, which
> is why we add a raw_comment pointer to struct ins_operands, so the
> __parse function assigns it to be re-used by its corresponding __scnprintf
> function.
> Example differences in 'perf annotate --stdio2' output on an
> aarch64 file:
> BEFORE: â b.cs ffff200008133d1c <unwind_frame+0x18c> // b.hs, dffff7ecc47b
> AFTER : â b.cs 18c
> BEFORE: â ffff200008d8d9cc <get_alloc_profile+0x31c> // b.lo, b.ul, dffff727295b
> AFTER : â 31c
> The branch target labels 18c and 31c also now appear in the output:
> BEFORE: add x26, x29, #0x80
> AFTER : 18c: add x26, x29, #0x80
> BEFORE: add x21, x21, #0x8
> AFTER : 31c: add x21, x21, #0x8
> The Fixes: tag below is added so stable branches will get the update; it
> doesn't necessarily mean that commit was broken at the time, rather it
> didn't withstand the aarch64 objdump update.
> Tested no difference in output for sample x86_64, power arch files.

Tested, no difference in output on s390. Just to let you know.
Thomas Richter, Dept 3303, IBM s390 Linux Development, Boeblingen, Germany
Vorsitzende des Aufsichtsrats: Martina Koederitz
GeschÃftsfÃhrung: Dirk Wittkopp
Sitz der Gesellschaft: BÃblingen / Registergericht: Amtsgericht Stuttgart, HRB 243294