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Re: [PATCH 2/3] record-btrace, disas: omit pc prefix
On Mon, 25 Feb 2013 17:15:16 +0100, markus.t.metzger@intel.com wrote:
> From: Markus Metzger <markus.t.metzger@intel.com>
>
> Add a disassembly flag to omit the pc prefix and use it in the "record
> instruction-history" command of record-btrace.
>
> The pc prefix would appear multiple times in the branch trace disassembly,
> which is more confusing than helpful.
I do not see it, moreover I find the output better without this patch:
with the patch:
(gdb) record instruction-history
warning: Recorded trace may be corrupted.
warning: Recorded trace may be corrupted.
warning: Recorded trace may be corrupted.
0x00007ffff62fe56a <_int_malloc+298>: add $0xa8,%rsp
0x00007ffff62fe571 <_int_malloc+305>: mov %r12,%rax
0x00007ffff62fe574 <_int_malloc+308>: pop %rbx
0x00007ffff62fe575 <_int_malloc+309>: pop %rbp
0x00007ffff62fe576 <_int_malloc+310>: pop %r12
0x00007ffff62fe578 <_int_malloc+312>: pop %r13
0x00007ffff62fe57a <_int_malloc+314>: pop %r14
0x00007ffff62fe57c <_int_malloc+316>: pop %r15
0x00007ffff62fe57e <_int_malloc+318>: retq
0x00007ffff6300ecc <__GI___libc_malloc+92>: test %rax,%rax
(gdb) p/x $pc
$1 = 0x7ffff6300ecc
without the patch:
(gdb) record instruction-history
0x00007ffff6303f51 <freehook+209>: mov %rax,0x0(%rbp)
0x00007ffff6303f55 <freehook+213>: pop %rbx
0x00007ffff6303f56 <freehook+214>: pop %rbp
0x00007ffff6303f57 <freehook+215>: pop %r12
0x00007ffff6303f59 <freehook+217>: pop %r13
0x00007ffff6303f5b <freehook+219>: pop %r14
0x00007ffff6303f5d <freehook+221>: retq
0x00007ffff62c8921 <_IO_vfprintf_internal+257>: mov %r12,%rdi
0x00007ffff62c8924 <_IO_vfprintf_internal+260>: callq 0x7ffff62a03d0 <free@plt+64>
=> 0x00007ffff62a03d0 <free@plt+64>: jmpq *0x399c9a(%rip) # 0x7ffff663a070
(gdb) p/x $pc
$1 = 0x7ffff62a03d0
It seems to me like the preference of "=> " or not "=> " is not related to
"record instruction-history".
If you do like disassemblies more without "=> " it can be made some new global
option unrelated to "record".
> 2013-02-25 Markus Metzger <markus.t.metzger@intel.com>
>
> * record-btrace.c (btrace_insn_history): Omit the pc prefix in
> the instruction history disassembly.
> * disasm.c (dump_insns): Omit the pc prefix, if requested.
> * disasm.h (DISASSEMBLY_OMIT_PC): New.
Thanks,
Jan